Impacts of Agricultural Management Systems on Biodiversity and Ecosystem...

[Full title: Impacts of Agricultural Management Systems on Biodiversity and Ecosystem Services in Highly Simplified Dryland Landscapes]

sustainability Review Impacts of Agricultural Management Systems on Biodiversity and Ecosystem Services in Highly Simplified Dryland Landscapes Subodh Adhikari 1,2, * , Arjun Adhikari 3,4 , David K. Weaver 1 , Anton Bekkerman 5 and Fabian D. Menalled 1, * 1 Department of Land Resources and Environmental Sciences, Montana State University, P.O. Box 173120, Bozeman, MT 59717-3120, USA; weaver@montana.edu 2 Department of Entomology, Plant Pathology and Nematology; 875 Perimeter Drive MS 2329, Moscow, ID 83844-2329, USA 3 Department of Ecology, Montana State University, P.O. Box 173460, Bozeman, MT 59717-3460, USA; aadhikari@gmail.com 4 Natural Resource Ecology and Management, 008 C Agricultural Hall, Oklahoma State University, Stillwater, OK 74078, USA 5 Department of Agricultural Economics and Economics, P.O. Box 172920, Bozeman, MT 59717-3460, USA; anton.bekkerman@montana.edu * Correspondence: subodh.adhikari 1@gmail.com (S.A.); menalled@montana.edu (F.D.M.) Received: 2 May 2019; Accepted: 9 June 2019; Published: 11 June 2019 Abstract: Covering about 40% of Earth’s land surface and sustaining at least 38% of global population, drylands are key crop and animal production regions with high economic and social values. However, land use changes associated with industrialized agricultural managements are threatening the sustainability of these systems. While previous studies assessing the impacts of agricultural management systems on biodiversity and their services focused on more diversified mesic landscapes, there is a dearth of such research in highly simplified dryland agroecosystems. In this paper, we 1) summarize previous research on the effects of farm management systems and agricultural expansion on biodiversity and biodiversity-based ecosystem services, 2) present four case studies assessing the impacts of management systems on biodiversity and ecosystem services across highly simplified dryland landscapes of the Northern Great Plains (NGP), USA, 3) discuss approaches to sustain biodiversity-based ecosystem services in drylands, and 4) present a conceptual framework for enhancing agricultural sustainability in the drylands through research, policy, economic valuation, and adaptive management. An analysis of the land use changes due to agricultural expansion within the Golden Triangle, a representative agricultural area in the NGP, indicated that the proportion of land conversion to agriculture area was 84%, 8%, and 7% from grassland, riparian, and shrubland habitats, respectively. Our results showed this simplification was associated with a potential reduction of pollination services. Also, our economic analysis projected that if 30% parasitism could be achieved through better management systems, the estimated potential economic returns to pest regulation services through parasitoids in Montana, USA alone could reach about $11.23 million. Overall, while dryland agroecosystems showed a significant loss of native biodiversity and its services, greater pest incidence, and a decrease in plant pollinator networks, these trends were moderately reversed in organically managed farming systems. In conclusion, although land use changes due to agricultural expansion and industrialized farming threaten the sustainability of dryland agroecosystems, this impact can be partially offset by coupling ecologically-based farming practices with adaptive management strategies Keywords: agricultural expansion; biodiversity-based ecosystem services; farm management systems; Golden Triangle; Northern Great Plains Sustainability 2019 , 11 , 3223; doi:10.3390 / su 11113223 www.mdpi.com / journal / sustainability

Sustainability 2019 , 11 , 3223 2 of 16 1. Background Drylands are regions with an aridity index (ratio of precipitation to potential evapotranspiration) of 0.05 to 0.65 [ 1 ]. Covering about 40% of Earth’s land surface and sustaining approximately 38% of global population, drylands are key agricultural production regions [ 2 , 3 ]. Despite their ecological, economic, and societal importance, the sustainability of drylands is heavily limited by land use changes due to agricultural expansion, geographical constraints, elevated temperature, reduced moisture, variable rainfall, drought, wildfires, and environmental degradation [ 4 – 6 ]. Furthermore, the loss of species diversity due to land use changes and industrialized agriculture seriously threatens the sustainability of major ecosystem services provided by drylands, such as pollination and pest regulation [ 7 , 8 ]. Drylands have considerable agricultural and societal value, as crops of global importance including barley, cotton, olives, millet, sorghum, and wheat as well as domesticated animals including cow, camel, goat, horse, and sheep originated from these regions [ 9 ]. However, industrialized farming and climatic variability have resulted in serious ecological consequences including a reduction in biodiversity due to habitat loss, degradation of soil and water quality, changes in surface energy and water balances [ 10 ], as well as production losses in drylands [ 11 ]. However, drylands have received relatively little research attention [ 12 , 13 ], limiting the available information on the impact of land use intensification on biodiversity, ecosystem services, and sustainable management. For example, previous studies assessed the impacts of agricultural management systems on associated biodiversity including weeds, pollinators and their services, pollination networks, or pest regulation, but were conducted in more diversified and less arid systems in Europe [ 14 – 16 ], California [ 17 – 19 ], and the mid-western US [ 20 , 21 ]. Further, a recent global synthesis of 89 crop systems on the role of biodiversity and biodiversity-based ecosystem services to crop productions does not include the world’s agriculturally important dryland regions [ 22 ], such as the Northern Great Plains and the Pacific Northwest of North America [ 23 ]. Hence, there is a dearth of research into the impacts of agricultural expansion and management systems on biodiversity and ecosystem services in simplified dryland landscapes [ 24 – 26 ]. However, these systems are projected to expand to 48% of global land by 2025 due to the changing climate [ 27 ]. Understanding the impacts of farm management systems and land use changes on biodiversity and ecosystem services is thus essential to sustain dryland ecosystems in the face of global climate change, population growth, and increased food and fiber demands In this paper, we focus on the impact of agricultural management systems on biodiversity and ecosystem services in highly simplified dryland landscapes (i.e., the landscapes in semiarid regions, with an aridity index of 0.2-0.5 [ 23 , 28 ], that are heavily dominated with intensive non-irrigated agriculture), with an emphasis on the Northern Great Plains (NGP), one of the leading dryland agricultural regions in the world [ 29 – 33 ]. Specifically, we combine the results from previous research into pollinators and parasitoid responses to management systems with additional data on the extent of landscape conversion and the economic impact of ecosystem services to highlight potential avenues to enhancing agricultural sustainability in drylands. Because of the scarcity of information, we were precluded from conducting a formal systematic analysis of previous research on biodiversity and ecosystem services in highly simplified dryland agricultural landscapes, such as those in the Northern Great Plains. We hope this review will help future researchers fill the existing knowledge gaps 2. A Case Study of Land Use Changes due to Agricultural Expansion in the Drylands of the Northern Great Plains Once dominated by grassland, shrubland, and riparian habitats, the NGP dryland has experienced agricultural expansion after European settlement, heavily simplifying the landscape into annual cropping systems. We quantified the extent of such landscape simplification in the Golden Triangle region of Montana, a representative section of the NGP dryland, by assessing the biophysical setting (BpS) data at a spatial unit of ~ 1 km 2 from the LANDFIRE (a US government’s Landscape Fire and Resource Management Planning Tool) products [ 34 ] to represent major habitats: shrubland, grassland, conifer, riparian, hardwood, and sparse vegetation. The BpS layer was developed to represent

Sustainability 2019 , 11 , 3223 3 of 16 vegetation patterns that may have been dominant prior to Euro-American settlement. This layer is based on present-day biophysical environments and the approximation of historical ranges of natural disturbance regimes. The current human land-use layers (developed area, roads, and agriculture) were overlaid on these modeled historical layers to estimate aerial extents of natural habitat loss within the Golden Triangle. The total change in area of each habitat was determined by dividing the di ff erence in area of selected classes between historical and present-day ecosystem area by total area of each ecosystem class Our study showed that the riparian habitat had the highest loss to land conversion ( − 76%), followed by grassland ( − 73%), shrubland ( − 62%), conifer ( − 17%), and sparse ( − 11%) habitats (Figure 1 ). The proportion of land converted into agricultural production has been estimated from grassland (84%), riparian (8%), and shrubland (7%) habitats (Figure 1 ). The agricultural expansion experienced in this area resulted in small remnant fragments of natural habitats within a matrix of monoculture crops, resulting in a highly simplified landscape where the remaining undisturbed natural habitats support a higher biodiversity compared to the intensified crop fields. For example, a 12-ha inventory of a remnant mixed-grass prairie conducted in 2009 near Havre (48.490 ◦ N, 109.802 ◦ W), Montana revealed a higher diversity of forbs, grass, and shrub species (Table 1 ) compared to previous studies conducted in croplands of this region [ 35 ]. This reduction in biodiversity, in turn, would constrain the ecosystem services they provide Sustainability 2019 , 11 , x FOR PEER REVIEW 3 of 18 annual cropping systems. We quantified the extent of such landscape simplification in the Golden Triangle region of Montana, a representative section of the NGP dryland, by assessing the biophysical setting (BpS) data at a spatial unit of ~ 1 km 2 from the LANDFIRE (a US government’s Landscape Fire and Resource Management Planning Tool) products [34] to represent major habitats: shrubland, grassland, conifer, riparian, hardwood, and sparse vegetation. The BpS layer was developed to represent vegetation patterns that may have been dominant prior to Euro-American settlement. This layer is based on present-day biophysical environments and the approximation of historical ranges of natural disturbance regimes. The current human land-use layers (developed area, roads, and agriculture) were overlaid on these modeled historical layers to estimate aerial extents of natural habitat loss within the Golden Triangle. The total change in area of each habitat was determined by dividing the difference in area of selected classes between historical and present-day ecosystem area by total area of each ecosystem class. Our study showed that the riparian habitat had the highest loss to land conversion ( − 76%), followed by grassland ( − 73%), shrubland ( − 62%), conifer ( − 17%), and sparse ( − 11%) habitats (Figure 1). The proportion of land converted into agricultural production has been estimated from grassland (84%), riparian (8%), and shrubland (7%) habitats (Figure 1). The agricultural expansion experienced in this area resulted in small remnant fragments of natural habitats within a matrix of monoculture crops, resulting in a highly simplified landscape where the remaining undisturbed natural habitats support a higher biodiversity compared to the intensified crop fields. For example, a 12-ha inventory of a remnant mixed-grass prairie conducted in 2009 near Havre (48.490°N, 109.802°W), Montana revealed a higher diversity of forbs, grass, and shrub species (Table 1) compared to previous studies conducted in croplands of this region [35]. This reduction in biodiversity, in turn, would constrain the ecosystem services they provide. Figure 1. Land use changes due to agricultural expansion in the Golden Triangle area of the Northern Great Plains: (a) pre-European settlements versus present-day ecosystem types, (b) proportion of ecosystem types prior to European settlements, (c) relative reduction in area due to the agricultural expansion of ecosystem types from pre-European settlements to the present-day, and (d) contribution of each pre-European settlement habitat type to agricultural land. Table 1. List of plant species identified in 2009 from a 12-ha mixed native prairie relict site near Havre, Montana (Welch, unpublished data). Figure 1. Land use changes due to agricultural expansion in the Golden Triangle area of the Northern Great Plains: ( A ) pre-European settlements versus present-day ecosystem types, ( B ) proportion of ecosystem types prior to European settlements, ( C ) relative reduction in area due to the agricultural expansion of ecosystem types from pre-European settlements to the present-day, and ( D ) contribution of each pre-European settlement habitat type to agricultural land.

Sustainability 2019 , 11 , 3223 4 of 16 Table 1. List of plant species identified in 2009 from a 12-ha mixed native prairie relict site near Havre, Montana (Welch, unpublished data) Plants Family Graminoids Koeleria macrantha (Ledeb.) J.A. Schultes Poaceae Hesperostipa comata (Trin. & Rupr.) Barkworth Poaceae Pascopyrum smithii (Rydb.) A. Love Poaceae Pseudoroegneria spicata (Pursh) A. Love Poaceae Muhlenbergia cuspidata (Torr. ex Hook.) Rydb Poaceae Calamovilfa longifolia (Hook.) Scribn Poaceae Poa sandbergii Vasey Poaceae Schizachyrium scoparium (Michx.) Nash Poaceae Bouteloua gracilis (Willd. ex Kunth.) Lag. ex Gri ffi ths Poaceae Nassella viridula (Trin.) Barkworth Poaceae Carex filifolia Nutt Cyperaceae * Bromus tectorum L Poaceae * Bromus japonicus Thunb Poaceae * Agropyron cristatum (L.) Gaertn Poaceae * Poa pratensis L Poaceae Forbs Pediomelum argophyllum (Pursh) J. Grimes Fabaceae Phlox hoodii Richardson Polemoniaceae Antennaria neglecta Greene Asteraceae Heterotheca villosa (Pursh) Shinners Asteraceae Cirsium undulatum (Nutt.) Spreng Asteraceae Penstemon grandiflorus Nutt Scrophulariaceae Plantago elongata Pursh Plantaginaceae Lygodesmia juncea (Pursh) D. Don ex Hook Asteraceae Comandra umbellata (L.) Nutt Santalaceae Thermopsis rhombifolia (Nutt. ex Pursh) Nutt. ex Richardson Fabaceae Gaillardia aristata Pursh Asteraceae Achillea millefolium L. var occidentalis DC Asteraceae Potentilla glandulosa Lindl Rosaceae Allium textile A. Nelson & J.F. Macbr Liliaceae Linum lewisii Pursh Linaceae Tetraneuris acaulis (Pursh) Greene Asteraceae Sphaeralcea coccinea (Nutt.) Rydb Malvaceae Vicia americana Muhl. ex Willd Fabaceae Liatris punctata Hook Asteraceae Nothocalais cuspidata (Pursh) Greene Asteraceae Symphyotrichum ericoides (L.) G.L. Nesom var pansum (S.F. Blake) G.L. Nesom Asteraceae Machaeranthera pinnatifida (Hook.) Shinners Asteraceae Ratibida columnifera (Nutt.) Wooton & Stand Asteraceae Opuntia polyacantha Haw Cactaceae Packera plattensis (Nutt.) W.A. Weber & Á . Löve Asteraceae Lycopodium L., spp Lycopodiaceae Bryopsida (Limpr.) Rothm., spp * Medicago sativa L Fabaceae * Melilotus o ffi cinalis (L.) Lam Fabaceae * Sinapis arvensis L. ssp arvensis Brassicaceae * Tragopogon pratensis L Asteraceae ** Taraxacum o ffi cinale F.H. Wigg Asteraceae ** Urtica dioica L Urticaceae

Sustainability 2019 , 11 , 3223 5 of 16 Table 1. Cont Plants Family Shrubs Symphoricarpos occidentalis Hook Caprifoliaceae Artemisia ludoviciana Nutt Asteraceae Artemisia dracunculus L Asteraceae Artemisia longifolia Nutt Asteraceae Artemisia frigida Willd Asteraceae Krascheninnikovia lanata (Pursh) A. Meeuse & Smi Chenopodiaceae Artemisia cana Pursh Asteraceae Rosa arkansana Porter Rosaceae Rosa acicularis Lindl Rosaceae Gutierrezia sarothrae (Pursh) Britton & Rusby Asteraceae * invasive, exotic; ** invasive, both native and exotic subspecies 3. Impacts of Agricultural Management Systems on Biodiversity and Ecosystem Services in Highly Simplified Drylands Flowering crops and weeds growing in arable lands may provide food resources to beneficial insects such as bees, parasitoids, and generalist predators for a limited amount of time. In the resource-depleted environments that dominate highly simplified agricultural landscapes, non-crop habitats are required to provide season-long nesting grounds, food resources, and refugia from disturbances [ 36 , 37 ]. However, with the degree of high landscape simplification observed in the NGP resulting from agricultural expansion, the ecosystem benefits provided by non-crop habitats could be either significantly reduced or absent. In this section, we summarize findings of our ongoing research aimed at evaluating the impacts of management systems on plant diversity and its importance on parasitoid abundance, pollination networks, and bee colony success in the simplified agricultural landscape that dominates the NGP. Our overall goal was to examine the consequences of management systems on biodiversity and ecosystem services in highly simplified dryland agricultural landscapes. This information will, in turn, allow us assess farm management strategies that can be helpful to sustain biodiversity in dryland agroecosystems. To our knowledge, these studies represent the first attempt to assess the impact of the associated floral biodiversity on pollinator communities and ecosystem services across the Northern Great Plains 3.1. Management Systems and Associated Plant Diversity Access to adequate food resources such as pollen and nectar as well as shelter from adverse conditions is essential for the survival and reproduction of beneficial insects such as predators, parasitoids, and pollinators [ 31 , 38 , 39 ]. In highly simplified and biodiversity-depleted agroecosystems, weedy forb species could represent a viable source of pollen and nectar. To evaluate the impacts of farm management systems on weed communities, between 2013 and 2015, we established 55 m transects within each of nine conventional and nine organic spring wheat fields located in the simplified agricultural landscape of Big Sandy, Montana, USA (see [ 24 – 26 ] for details) Compared to the remnant prairie (see Section 2 ; Table 1 ), we found a lower abundance and diversity of plants in the crop fields, regardless of farming system (Table 2 ). However, similar to Pollnac et al. [ 35 ], we observed increased weed species abundance and diversity in organic systems when compared to conventional ones. Even so, except for a single species ( Artemisia frigida Willd.) that was present in a low abundance in an organic field, none of the 10 species of perennial shrubs found in mixed grass prairie was observed in crop fields. Similarly, 27 native and 3 exotic forb species that were present in the remnant prairie were not observed in either conventional or organic crop fields Crops growing as volunteer weeds were the main contributors to forb diversity in the sampled organic crop fields. Overall, these results indicate that land use changes due to agricultural expansion and management systems adversely influence plant biodiversity; however, volunteer crop plants and other forbs contributed to the plant diversity observed during the growing season in organic crop fields.

Sustainability 2019 , 11 , 3223 6 of 16 Table 2. List of weed taxa with their relative abundance observed in organic and conventional wheat fields between 2013 and 2015. The table is adopted from Adhikari and Menalled [ 26 ]. Weed Taxa Percent Composition (Overall) Conventional Organic Amaranthus blitoides S. Watson < 0.01 < 0.01 Amaranthus retroflexus L < 0.01 0.47 Arabidopsis thaliana (L.) Heynh - < 0.01 Artemisia frigida Willd - < 0.01 Avena fatua L. * 4.71 4.70 Bassia scoparia (L.) A.J. Scott 0.07 0.14 Brassicaceae sp - 0.04 Bromus arvensis L. * 0.08 < 0.01 Bromus tectorum L. * 8.40 0.20 Buglossoides arvensis (L.) I.M. Johnst - < 0.01 Carthamus tinctorius L - 0.69 Chenopodium album L - 7.43 Chenopodium murale L - < 0.01 Cirsium arvense (L.) Scop 2.55 < 0.01 Descurainia pinnata (Walter) Britton < 0.01 0.03 Descurainia sophia (L.) Webb ex Prantl - 0.01 Fabaceae sp - < 0.01 Fagopyrum esculentum Moench - 0.03 Helianthus annuus L < 0.01 2.72 Hordeum jubatum L.* 5.03 0.04 Lactuca serriola L 0.12 0.43 Lens culinaris Medik - 0.15 Leptochloa fusca (L.) Kunth * < 0.01 - Medicago lupulina L - 0.01 Medicago sativa L 0.89 3.50 Melilotus o ffi cinalis (L.) Lam - 0.07 Monolepis nuttalliana (Schult.) Greene - < 0.01 Pisum sativum L - 1.08 Poa annua L.* < 0.01 - Polygonum aviculare L 0.01 0.14 Polygonum convolvulus L 0.13 6.70 Pseudoroegneria spicata (Pursh) * 0.81 - Salsola kali L 2.72 36.15 Salvia reflexa Hornem 0.10 0.01 Setaria viridis (L.) P. Beauv. * 0.13 0.05 Silene latifolia Poir - < 0.01 Sinapis arvensis L - 2.23 Sisymbrium altissimum L - 0.04 Solanum triflorum Nutt - < 0.01 Taraxacum o ffi cinale F.H. Wigg 0.34 0.04 Thlaspi arvense L - 1.31 Tragopogon dubius Scop < 0.01 - Trifolium sp - < 0.01 Triticum aestivum L. * - 3.50 Unknown (dicot) sp < 0.01 0.81 Unknown (grass) sp. * < 0.01 0.03 Vaccaria hispanica (Mill.) Rauschert - 0.63 Vicia americana Muhl. ex Willd < 0.01 0.43 * grasses.

Sustainability 2019 , 11 , 3223 7 of 16 3.2. Management Systems, Pest Infestation, Parasitoid Abundance, and Pest Regulation Services With an annual economic value in the United States of USD 4.5 billion [ 40 ], biological control-based pest regulation is an important ecosystem service for agriculture [ 41 – 43 ]. For example, the annual economic loss to wheat growers across NGP due to Cephus cinctus Norton (wheat stem sawfly), a native pest species [ 44 ], has been estimated at USD 350 million [ 45 ]. In this region, biological control of C. cinctus by two endemic specialist parasitoids, Bracon cephi (Gahan) and B. lissogaster Muesebeck, represents a pest regulation service to wheat growers [ 46 , 47 ] that can e ff ectively reduce yield losses by 19% when specific harvest outcomes are considered [ 48 ]. These parasitoids are highly specialized, and C. cinctus is their only known host [ 49 , 50 ]. Diversified cropping systems enhance C. cinctus parasitoid populations [ 25 , 51 , 52 ], ultimately helping to manage C. cinctus and thus reduce yield loss from infested fields. However, the conventionally-managed wheat–fallow rotations that dominate the dryland sections of the NGP can have negative impacts on parasitoid populations and effectiveness [ 48 , 53 ]. In a study assessing the effects of landscape composition and wheat cover on infestation by the native C. cinctus and parasitism by its endemic specialist parasitoids, Rand et al. [ 54 ] found the highest C. cinctus (wheat stem sawfly) infestation but lowest parasitism in conventionally grown wheat fields within Montana’s relatively dry Golden Triangle, a primary winter wheat production region when compared to other studied areas across North Dakota and South Dakota, USA. Surprisingly, they reported no correlation between increased natural grassland habitat and C. cinctus infestation or parasitism. The plausible explanations for this could be a) a lack of sufficient natural enemies to control pest population, b) insufficient natural habitat for supporting natural enemy populations needed for pest control, and / or c) an excessive reliance on farming practices that are unfavorable to the natural enemy communities (e.g., use of pesticides) [ 55 – 57 ] Agricultural management systems include not only determining which crops to grow and how to manage farms (e.g., conventionally or organically), but also when to plant a crop that could potentially have di ff erential e ff ects on pest infestation. To assess whether the timing of plantation a ff ects pest infestation, we compared the role of winter (i.e., fall-planted) and spring (i.e., spring-planted) wheat crops on the parasitism of C. cinctus using sample data collected from 1998–2011 in Montana wheat fields (n = 1945) across more intensively managed agricultural landscapes in the Golden Triangle (see Figure 1 ) and outside (n = 1895) (reported in [ 48 ]). Infestation in spring wheat fields outside the Golden Triangle was double that of spring wheat fields inside the region, while the opposite was true for winter wheat: the infestation was 20% lower outside the Golden Triangle (Table S 1). Interestingly, numbers of parasitoids were nearly half in spring wheat fields, and the surviving C. cinctus larval population was lower in the Golden Triangle than the outside region. For winter wheat, however, parasitism was nearly twice as high in the Golden Triangle as outside, but the percentage of stems with surviving C cinctus larvae was greater in the Golden Triangle. Overall, winter wheat inside the Golden Triangle was more exploited by C. cinctus and will benefit considerably from farming practices that favor increased parasitoid abundance and survivorship. With a total of 0.93 million hectares of land planted in winter wheat and 1.21 million hectares in spring wheat in 2016 in Montana only [ 58 ], the di ff erences in C cinctus populations associated with winter and spring wheat is a determining factor in parasitoid abundance [ 25 ]. Our result also indicates that outcomes related to ecosystem services provided by parasitoids that specialize on C. cinctus should be evaluated separately for each growing season (i.e., winter and spring), as suggested in Bekkerman and Weaver [ 48 ]. Further, to evaluate the impact of cropping systems on C. cinctus parasitism, we collected winter wheat samples between 2013 and 2015 from tilled organic and no-till conventional fields of a highly simplified landscape at Big Sandy, Montana, USA (see details in [ 25 ]). We then compared infestation by C. cinctus and subsequent parasitism across farming systems. Our results showed that, relative to conventionally-managed fields, organic management was associated with a 75% lower C. cinctus infestation and a quadrupling of parasitism by endemic braconids (Table 3 ). These results indicate that while simplified landscapes have relatively limited floral resources to parasitoids, by enhancing

Sustainability 2019 , 11 , 3223 8 of 16 alternative sources of pollen and nectar via increased weed diversity [ 36 , 46 ], organic fields partially o ff set the negative e ff ects of landscape simplification on pest regulation in the drylands of the NGP Table 3. Number of stems infested with Cephus cinctus , C. cinctus infested stems with parasitoids, stems cut by C. cinctus , and total number of stems observed in tilled organic and no-till conventional winter wheat fields in Big Sandy, Montana between 2013 and 2015. The table is adopted from Adhikari et al. [ 25 ] Farming Systems Infested Stems Parasitoids Cut Stems Total Stems Observed Conventional 684 37 359 1835 Organic 195 54 48 969 To estimate the potential economic returns to pest regulation services (i.e., biodiversity-based ecosystem services) of C. cinctus parasitoids, we developed counterfactual analyses based on the model and data in Bekkerman and Weaver [ 48 ] to consider three parasitoid population scenarios: zero parasitoids (no parasitism), 2 x parasitoids (doubling the number of parasitoids present in original data), and parasitoids in 30% of all infested stems (which represents a reasonable population target, similar to observed populations reported above for organic fields [ 25 ]). Relative to a base-case scenario of sample means, each counterfactual analysis calculated the potential additional stem-level yield gains or losses from higher or lower parasitoid populations for winter and spring wheat, and then used ten-year average Montana production and price data to approximate state-level impacts. The results showed that because base-case parasitoid populations are relatively small, completely eliminating or doubling parasitoids had only modest state-level economic impacts. However, if parasitism reached a realistic optimum (i.e., 30%), estimated production losses were reduced significantly by 21%, representing an economic gain of USD 11.23 million (Table S 2). As our study shows, a target of 30% parasitism could be achieved through better management systems, such as transferring and incorporating the desirable features we observed in organic winter wheat systems into larger, more conventional farming practices 3.3. Management Systems and Bee Colony Success Bees (Hymenoptera: Apoidea, Apiformes) are key agents in pollinating about one-third of the leading global crop species [ 59 , 60 ]. However, a suite of anthropogenic stressors and perturbations including reduced regional floral resources, landscape simplification, habitat fragmentation, and exposure to pesticides, parasites and pathogens contribute to the declining bee biodiversity [ 61 – 63 ]. The NGP is a key agricultural region for cereal, forage, pulse, and oilseed production; however, the impact of available floral resources on bee colony success mediated by agricultural expansion and management systems is unknown By putting 60 mini-colonies of eastern bumble bee ( Bombus impatiens Cresson) at six conventional and six organic spring wheat fields over two growing seasons (2014–2015) across the abovementioned simplified agricultural landscape in Big Sandy, Montana, USA, we assessed the effects of farming systems on bee colonies’ relative growth rate, fecundity, worker lipid content and wing wear (see details in [ 24 ]). We found that colonies’ relative growth rate and fecundity were larger in weedier organic fields than in conventional fields and were positively associated with floral resources (see details in [ 24 ]). Similarly, workers from organic fields had lower wing wear and marginally greater body lipid content, indicating that foraging distances are smaller in organic than in conventional fields [ 24 ]. Overall, these results indicate that by increasing B. impatiens colony success and individual worker condition, the greater floral resources observed in organic systems can provide better biodiversity-based ecosystem services even in a highly simplified agricultural landscapes such as the ones that dominate the NGP 3.4. Management Systems and Bee–Flower Networks The decline in plant diversity due to conventional agricultural practices and landscape simplification observed across the NGP can ultimately impact the structure of pollinator communities and, in turn, plant–pollinator networks [ 61 , 64 ]. Despite the ecological and economic importance

Sustainability 2019 , 11 , 3223 9 of 16 of pollinators [ 59 , 65 ], there is limited information on their abundance and diversity in the dryland agroecosystems of the NGP. To assess the extent to which cropping systems impact plant–pollinator networks in dryland settings, we compared bee–flower interaction networks between conventional and organic fields in the simplified agricultural landscape at Big Sandy, MT during 2013–2015 [ 66 ]. By recording the identity and frequency of bee–flower interactions during 20 minutes of observations (51 hours in total) on each of nine conventional and nine organic fields between 2013–2015, we constructed bee–flower networks [ 66 , 67 ]. Our results indicated that bee–flower interactions were either absent or extremely simplified in conventionally managed fields. In contrast, because of the greater forb flower density and diversity observed in organic fields, bee–flower interactions were more common in these systems (Figure 2 ). However, the observed networks were far less connected when compared with those observed in more botanically diverse landscapes [ 68 – 70 ]. The study indicates that highly simplified agricultural landscapes in the NGP maintain relatively impoverished bee–flower interaction networks; however, by supporting more floral resources, diversified organic farming helps to increase plant–pollinator interactions Sustainability 2019 , 11 , x FOR PEER REVIEW 9 of 18 Figure 2. Bee–flower interaction networks from conventional and organic wheat fields in the Golden Triangle area, Montana, USA. The top yellow horizontal bars represent bee taxa and the bottom green horizontal bars represent forb species in the networks. The black lines connecting bee taxa and forb species represent interaction links (visits), and the thickness of these lines corresponds to the strength of the interactions between two species. Note: All observation data were pooled across months (June– August), fields (nine for each system), and years (2013–2015) to construct the networks in each system and show the general patterns of which bee and forb species were present in the landscape during our study. The figure is adopted from Adhikari [66]. 4. Discussion: Enhancing the Sustainability of Dryland Agroecosystems While a majority of previous studies assessing the impacts of land use changes due to farm management systems and agricultural expansion on plant diversity, pollinator communities and services, pollination networks, and pest regulation were conducted in diversified mesic systems [14,19,21,71], a limited amount of research has been conducted on highly simplified drylands. This review fills this gap by assessing biodiversity and biodiversity-based ecosystem services in the context of dryland agroecosystems. Our results underscore the importance of diversifying agroecosystems to enhance populations of beneficial insects including parasitoids and pollinators. Specifically, our results showed that most habitat types in the NGP have been converted into agricultural production after European settlement, significantly reducing non-crop habitats. While we observed a significant economic contribution of insect parasitoids on reducing crop production loss due to pests, effects of non-crop habitats alone in agricultural fields on biological pest regulation are not guaranteed, but instead depend on farming systems, landscape composition, local climatic factors, and their interactions [66,67,69]. Our studies indicated that, even in highly simplified dryland landscapes, the increased biodiversity observed in organic systems can help to enhance ecological networks and biodiversitybased ecosystem services [24–26,66]. These results are in line with others that have shown that greater plant diversity supported by more complex landscapes enhance natural enemy populations including parasitoids and predators of crop pests [42,72] and augment natural pest regulation [40], thereby reducing the heavy reliance on pesticide applications. For example, Rusch et al. [73] found that natural pest control in crop-dominated simplified landscapes was 46% lower than in more complex landscapes. Similarly, tachinid parasitoids [74] and predaceous syrphid fly larvae [75] in Figure 2. Bee–flower interaction networks from conventional and organic wheat fields in the Golden Triangle area, Montana, USA. The top yellow horizontal bars represent bee taxa and the bottom green horizontal bars represent forb species in the networks. The black lines connecting bee taxa and forb species represent interaction links (visits), and the thickness of these lines corresponds to the strength of the interactions between two species. Note: All observation data were pooled across months (June–August), fields (nine for each system), and years (2013–2015) to construct the networks in each system and show the general patterns of which bee and forb species were present in the landscape during our study. The figure is adopted from Adhikari [ 66 ]. 4. Discussion: Enhancing the Sustainability of Dryland Agroecosystems While a majority of previous studies assessing the impacts of land use changes due to farm management systems and agricultural expansion on plant diversity, pollinator communities and services, pollination networks, and pest regulation were conducted in diversified mesic systems [ 14 , 19 , 21 , 71 ], a limited amount of research has been conducted on highly simplified drylands This review fills this gap by assessing biodiversity and biodiversity-based ecosystem services in

Sustainability 2019 , 11 , 3223 10 of 16 the context of dryland agroecosystems. Our results underscore the importance of diversifying agroecosystems to enhance populations of beneficial insects including parasitoids and pollinators. Specifically, our results showed that most habitat types in the NGP have been converted into agricultural production after European settlement, significantly reducing non-crop habitats. While we observed a significant economic contribution of insect parasitoids on reducing crop production loss due to pests, e ff ects of non-crop habitats alone in agricultural fields on biological pest regulation are not guaranteed, but instead depend on farming systems, landscape composition, local climatic factors, and their interactions [ 66 , 67 , 69 ]. Our studies indicated that, even in highly simplified dryland landscapes, the increased biodiversity observed in organic systems can help to enhance ecological networks and biodiversity-based ecosystem services [ 24 – 26 , 66 ]. These results are in line with others that have shown that greater plant diversity supported by more complex landscapes enhance natural enemy populations including parasitoids and predators of crop pests [ 42 , 72 ] and augment natural pest regulation [ 40 ], thereby reducing the heavy reliance on pesticide applications. For example, Rusch et al. [ 73 ] found that natural pest control in crop-dominated simplified landscapes was 46% lower than in more complex landscapes. Similarly, tachinid parasitoids [ 74 ] and predaceous syrphid fly larvae [ 75 ] in California’s agroecosystems were positively associated with semi-natural habitats surrounding farms and negatively associated with crop cover across the landscape. Additionally, landscape diversification in drylands may also increase the provision of other services such as water quality, soil fertility development, climate stability, greenhouse gas sequestration, and aesthetics [ 28 , 76 ]. Hence, practices that promote increased crop and weed diversity, such as the diversification of organic farming systems, support these parasitoids so that they can provide a significant economic contribution or ecosystem services by reducing crop production loss due to pests Conservation biological control (i.e., the maintenance of beneficial insects through habitat management in croplands) has received significant attention in the last two decades [ 41 , 72 ]. Relatively undisturbed and uncultivated lands within agricultural landscapes can provide refugia for natural enemies and generalist predators supporting pest management [ 41 , 72 ]. As this review shows, this concept can be used to conserve other beneficial insects such as pollinators. Floral resources present in crop fields may be abundant for a short period, making them usually insu ffi cient during the early and late seasons that are critical in bee life cycles for establishing colonies and producing o ff spring [ 77 , 78 ]. The increasing abundance and diversity of native plant communities and expanding natural habitats may enhance pollinator communities within agricultural landscapes which, in turn, could result in enhancing crop yields [ 21 , 79 ]. Conservation strategies for beneficial insects may include allocating 20–30% of agricultural landscape to uncultivated habitats, planting native flowers in hedgerows, and including forb crops in crop rotations [ 42 , 80 , 81 ]. Our results [ 24 – 26 , 66 ] indicate that combining these strategies with organic farming practices can help enhance beneficial insects’ nesting and foraging habitats, consequently bolstering their populations, and allowing growers to further reap the benefits of pest regulation and pollination The presented results and complementary studies [ 82 – 85 ] help produce a framework of adaptive management in drylands to enhance dryland agricultural resilience and sustainability. Our framework includes first identifying causes (e.g., agricultural expansion) and impacts (e.g., loss of biodiversity) of land use changes as the fundamental step (Figure 3 ). Second, assessing and evaluating biodiversity and its services and potential disservices would help identify and prioritize the proper farm management systems in the region. Third, identifying proper policies and extension programs based on monitoring and evaluation of ecosystem assessments could e ff ectively help redesign agricultural landscapes to help conserve natural habitats. Fourth, adaptive management strategies are key to continuously evaluating and adjusting new policies and approaches that are informed by research results and experiences [ 28 , 86 , 87 ].

Sustainability 2019 , 11 , 3223 11 of 16 Sustainability 2019 , 11 , x FOR PEER REVIEW 11 of 18 Figure 3. A conceptual framework for enhancing agricultural sustainability in the drylands through research, policy, economic valuation, and adaptive management 5. Conclusions While land use changes, overexploitation of resources, climatic variability, pollution, and species invasion have resulted in biodiversity loss and serious ecological consequences globally [88], dryland ecosystems and their associated human populations are more vulnerable than other ecosystems [28,89,90]. Due to their worldwide occurrence, drylands, despite several climatic and environmental constraints, provide significant ecological and socio-economic benefits to local, regional, and global populations [91–93]. However, if current farm management practices associated with modern agricultural intensifications are continued, they may further jeopardize drylands, and thus increase economic and ecological uncertainty for the growers [94]. Overall, the NGP region showed a significant expansion of agricultural lands after European settlement and illustrate consequent losses of biodiversity and associated impacts. Also, conventionally managed farming systems that rely on monoculture and off-farm synthetic inputs such as nitrogen fertilizers and herbicides contribute to the reduced biodiversity and hence biodiversity-based ecosystem services. Natural and human-induced processes coupled with socioeconomic factors are responsible for the habitat loss and biodiversity reduction observed in the dryland sections of the NGP [95,96]. To mitigate these losses, priority should be given to the adoption of more appropriate management practices such as diversified organic production that relies on crop rotation, multiple cropping, and avoidance of off-farm synthetic inputs. Figure 3. A conceptual framework for enhancing agricultural sustainability in the drylands through research, policy, economic valuation, and adaptive management 5. Conclusions While land use changes, overexploitation of resources, climatic variability, pollution, and species invasion have resulted in biodiversity loss and serious ecological consequences globally [ 88 ], dryland ecosystems and their associated human populations are more vulnerable than other ecosystems [ 28 , 89 , 90 ]. Due to their worldwide occurrence, drylands, despite several climatic and environmental constraints, provide significant ecological and socio-economic benefits to local, regional, and global populations [ 91 – 93 ]. However, if current farm management practices associated with modern agricultural intensifications are continued, they may further jeopardize drylands, and thus increase economic and ecological uncertainty for the growers [ 94 ]. Overall, the NGP region showed a significant expansion of agricultural lands after European settlement and illustrate consequent losses of biodiversity and associated impacts. Also, conventionally managed farming systems that rely on monoculture and o ff -farm synthetic inputs such as nitrogen fertilizers and herbicides contribute to the reduced biodiversity and hence biodiversity-based ecosystem services. Natural and human-induced processes coupled with socioeconomic factors are responsible for the habitat loss and biodiversity reduction observed in the dryland sections of the NGP [ 95 , 96 ]. To mitigate these losses, priority should be given to the adoption of more appropriate management practices such as diversified organic production that relies on crop rotation, multiple cropping, and avoidance of o ff -farm synthetic inputs Similarly, proactive farming practices in drylands should aim at increasing spatial and temporal habitat

Sustainability 2019 , 11 , 3223 12 of 16 heterogeneity [ 97 – 99 ]. Along with crop diversification across the landscape, the preservation and restoration of natural habitats is required to enhance pest regulation in the dryland agroecosystems [ 73 ]. Supplementary Materials: The following are available online at http: // www.mdpi.com / 2071-1050 / 11 / 11 / 3223 / s 1 , Table S 1: Cephus cinctus infestation and its parasitoid abundance in spring and winter wheat fields inside more intensively managed landscape of Golden Triangle, Montana, USA and outside. Table S 2: Estimated pest regulation service values by parasitoids of Cephus cinctus in Montana, USA. To estimate the values, a counterfactual analysis was done on C. cinctus infested spring and winter wheat stems and parasitoids presence on infested stems with four scenarios: base case, zero parasitoids, 2 x parasitoids, and parasitoids in 30% of infested stems Author Contributions: Each author contributed significantly to the manuscript. Conceptualization, S.A., A.A., & F.D.M.; Writing—original draft, S.A.; Data collection, analysis, and interpretation: S.A., A.A., D.K.W., A.B.; Resources, F.D.M.; Writing—review & editing, S.A., A.A., D.K.W., A.B., & F.D.M. All authors read and approved the final manuscript Funding: We would like to thank the United States Department of Agriculture, National Institute of Food and Agriculture (USDA NIFA) for its financial support to ORG grant 2015-51106-23970 Acknowledgments: The authors thank D. Boss, J. Broesder, J. Mangold, M. Manoukian, and especially T. Welch for providing the plant species records from their June 30, 2009 survey Conflicts of Interest: The authors declare no conflict of interest References 1 UNCCD United Nations Convention to Combat Desertification in Those Countries Experiencing Serious Drought and / or Desertification, Particularly in Africa ; United Nations Environment Programmes / Convention to Combat Desertification: Geneva, Switzerland, 1994 2 Feng, S.; Fu, Q. Expansion of global drylands under a warming climate Atmos. Chem. Phys 2013 , 13 , 10081–10094. [ CrossRef ] 3 Yirdaw, E.; Tigabu, M.; Monge, A. Rehabilitation of degraded dryland ecosystems—Review Silva Fenn 2017 , 51 . [ CrossRef ] 4 Puigdef á bregas, J. Ecological impacts of global change on drylands and their implications for desertification Land Degrad. Dev 1998 , 9 , 393–406. [ CrossRef ] 5 Cowie, A.L.; Penman, T.D.; Gorissen, L.; Winslow, M.D.; Lehmann, J.; Tyrrell, T.D.; Twomlow, S.; Wilkes, A.; Lal, R.; Jones, J.W.; et al. Towards sustainable land management in the drylands: Scientific connections in monitoring and assessing dryland degradation, climate change and biodiversity Land Degrad. Dev 2011 , 22 , 248–260. [ CrossRef ] 6 Sherwood, S.; Fu, Q. A Drier Future? Climate Change Science 2014 , 343 . [ CrossRef ] [ PubMed ] 7 Ste ff an-Dewenter, I.; Münzenberg, U.; Tscharntke, T. Pollination, seed set and seed predation on a landscape scale Proc. Biol. Sci 2001 , 268 , 1685–1690. [ CrossRef ] [ PubMed ] 8 Chaplin-Kramer, R.; O’Rourke, M.E.; Blitzer, E.J.; Kremen, C. A meta-analysis of crop pest and natural enemy response to landscape complexity Ecol. Lett 2011 , 14 , 922–932. [ CrossRef ] [ PubMed ] 9 Darkoh, M.B.K. Regional perspectives on agriculture and biodiversity in the drylands of Africa J. Arid Environ 2001 , 54 , 261–279. [ CrossRef ] 10 Hansen, A.J.; Rasker, R.; Maxwell, B.; Rotella, J.J.; Johnson, J.D.; Parmenter, A.W.; Langner, U.; Cohen, W.B.; Lawrence, R.L.; Kraska, M.P.V. Ecological Causes and Consequences of Demographic Change in the New WestAs natural amenities attract people and commerce to the rural west, the resulting land-use changes threaten biodiversity, even in protected areas, and challenge e ff orts to sustain local communities and ecosystems Bioscience 2002 , 52 , 151–162. [ CrossRef ] 11 Koohafkan, P.; Stewart, B.A Water and Cereals in Drylands . Available online: http: // www.fao.org / 3 / i 0372 e / i 0372 e.pdf (accessed on 1 June 2019) 12 Thomas, R.J.; Akhtar-Schuster, M.; Stringer, L.C.; Marques, M.J.; Escadafal, R.; Abraham, E.; Enne, G. Fertile ground? Options for a science-policy platform for land Environ. Sci. Policy 2012 , 16 , 122–135 [ CrossRef ] 13 Reynolds, J.F.; Mark, D.; Smith, S.; Lambin, E.F.; Ii, B.L.T.; Mortimore, M.; Batterbury, S.P.J.; Downing, T.E.; Dowlatabadi, H.; Fern á ndez, R.J.; et al. Global Desertification: Building a Science for Dryland Development Science 2007 , 316 , 847–851. [ CrossRef ] [ PubMed ]

Sustainability 2019 , 11 , 3223 13 of 16 14 Brittain, C.A.; Vighi, M.; Bommarco, R.; Settele, J.; Potts, S.G. Impacts of a pesticide on pollinator species richness at di ff erent spatial scales Basic Appl. Ecol 2010 , 11 , 106–115. [ CrossRef ] 15 Hole, D.G.; Perkins, A.J.; Wilson, J.D.; Alexander, I.H.; Grice, P.V.; Evans, A.D. Does organic farming benefit biodiversity? Biol. Conserv 2005 , 122 , 113–130. [ CrossRef ] 16 Tscharntke, T.; Klein, A.M.; Kruess, A.; Ste ff an-Dewenter, I.; Thies, C. Landscape perspectives on agricultural intensification and biodiversity—Ecosystem service management Ecol. Lett 2005 , 8 , 857–874. [ CrossRef ] 17 Kremen, C.; Williams, N.M.; Thorp, R.W. Crop pollination from native bees at risk from agricultural intensification Proc. Natl. Acad. Sci. USA 2002 , 99 , 16812–16816. [ CrossRef ] [ PubMed ] 18 Kremen, C.; Williams, N.M.; Bugg, R.L.; Fay, J.P.; Thorp, R.W. The area requirements of an ecosystem service: Crop pollination by native bee communities in California Ecol. Lett 2004 , 7 , 1109–1119. [ CrossRef ] 19 Williams, N.M.; Crone, E.E.; Roulston, T.H.; Minckley, R.L.; Packer, L.; Potts, S.G. Ecological and life-history traits predict bee species responses to environmental disturbances Biol. Conserv 2010 , 143 , 2280–2291 [ CrossRef ] 20 Isaacs, R.; Kirk, A.K. Pollination services provided to small and large highbush blueberry fields by wild and managed bees J. Appl. Ecol 2010 , 47 , 841–849. [ CrossRef ] 21 Isaacs, R.; Tuell, J.; Fiedler, A.; Gardiner, M.; Landis, D. Maximizing arthropod-mediated ecosystem services in agricultural landscapes: The role of native plants Front. Ecol. Environ 2009 , 7 , 196–203. [ CrossRef ] 22 Dainese, M.; Martin, E.A.; Aizen, M.; Albrecht, M.; Bartomeus, I.; Bommarco, R.; Carvalheiro, L.G.; Chaplin-Kramer, R.; Gagic, V.; Garibaldi, L.A.; et al. A global synthesis reveals biodiversity-mediated benefits for crop production bioRxiv 2019 , 554170. [ CrossRef ] 23 Hansen, N.C.; Allen, B.L.; Anapalli, S.; Blackshaw, R.E.; Lyon, D.J.; Machado, S. Dryland Agriculture in North America. In Innovations in Dryland Agriculture ; Springer International Publishing: Cham, Switzerland, 2016; pp. 415–441 24 Adhikari, S.; Burkle, L.A.; O’Neill, K.M.; Weaver, D.K.; Menalled, F.D. Dryland organic farming increases floral resources and bee colony success in highly simplified agricultural landscapes Agric. Ecosyst. Environ 2019 , 270–271 , 9–18. [ CrossRef ] 25 Adhikari, S.; Seipel, T.; Menalled, F.D.; Weaver, D.K. Farming system and wheat cultivar a ff ect infestation of, and parasitism on, Cephus cinctus in the Northern Great Plains Pest Manag. Sci 2018 , 74 , 2480–2487 [ CrossRef ] [ PubMed ] 26 Adhikari, S.; Menalled, F. Impacts of Dryland Farm Management Systems on Weeds and Ground Beetles (Carabidae) in the Northern Great Plains Sustainability 2018 , 10 , 2146. [ CrossRef ] 27 Huang, J.; Yu, H.; Guan, X.; Wang, G.; Guo, R. Accelerated dryland expansion under climate change Nat. Clim. Chang 2016 , 6 , 166–171. [ CrossRef ] 28 Millennium Ecosystem Assessment Ecosystems and Human Well-Being: Wetlands and Water ; World Resources Institute: Washington, DC, USA, 2005 29 Brester, G.W.; Grant, B.; Boland, M.A. Marketing Organic Pasta from Big Sandy to Rome: It’s a Long Kamut ® Rev. Agric. Econ 2009 , 31 , 359–369. [ CrossRef ] 30 Johnston, A.M.; Tanaka, D.L.; Miller, P.R.; Brandt, S.A.; Nielsen, D.C.; Lafond, G.P.; Riveland, N.R. Oilseed Crops for Semiarid Cropping Systems in the Northern Great Plains Agron. J 2002 , 94 , 231–240 [ CrossRef ] 31 North Dakota Wheat Commission. North Dakota Wheat Commission: Building Bigger Better Markets Available online: http: // www.ndwheat.com / default.asp (accessed on 29 October 2018) 32 Montana Agricultural Statistics USDA—National Agricultural Statistics Service and Montana Department of Agriculture ; Montana Agricultural Statistics, USDA: Washington, DC, USA, 2016 33 Lakkakula, P.; Olson, F.; Ripplinger, D Pea and Lentil Market Analysis ; North Dakota State University: Fargo, ND, USA, 2017 34 Barrett, S.; Havlina, D.; Jones, J.; Hann, W.; Frame, C.; Hamilton, D.; Schon, K.; Demeo, T.; Hutter, L.; Menakis, J. Interagency Fire Regime Condition Class Guidebook. Version 3.0. Available online: https: // www.landfire.gov / frcc / frcc_guidebooks.php (accessed on 29 October 2018) 35 Pollnac, F.W.; Rew, L.J.; Maxwell, B.D.; Menalled, F.D. Spatial patterns, species richness and cover in weed communities of organic and conventional no-tillage spring wheat systems Weed Res 2008 , 48 , 398–407 [ CrossRef ]

Sustainability 2019 , 11 , 3223 14 of 16 36 Danner, N.; Molitor, A.M.; Schiele, S.; Härtel, S.; Ste ff an-Dewenter, I. Season and landscape composition a ff ect pollen foraging distances and habitat use of honey bees Ecol. Appl 2016 . [ CrossRef ] 37 Landis, D.A.; Menalled, F.D.; Costamagna, A.C.; Wilkinson, T.K. Manipulating plant resources to enhance beneficial arthropods in agricultural landscapes Weed Sci 2005 , 53 , 902–908. [ CrossRef ] 38 Pywell, R.F.; Warman, E.A.; Carvell, C.; Sparks, T.H.; Dicks, L.V.; Bennett, D.; Wright, A.; Critchley, C.N.R.; Sherwood, A. Providing foraging resources for bumblebees in intensively farmed landscapes Biol. Conserv 2005 , 121 , 479–494. [ CrossRef ] 39 Nicholls, C.I.; Altieri, M.A. Plant biodiversity enhances bees and other insect pollinators in agroecosystems A review Agron. Sustain. Dev 2013 , 33 , 257–274. [ CrossRef ] 40 Losey, J.E.; Vaughn, M. The economic value of ecological services provided by insects Bioscience 2006 , 56 , 311–323. [ CrossRef ] 41 Barbosa, P. Agroecosystems and conservation biological control. In Conservation Biological Control ; Academic Press: San Diego, CA, USA, 1998; pp. 39–54 42 Landis, D.A. Designing agricultural landscapes for biodiversity-based ecosystem services Basic Appl. Ecol 2017 , 18 , 1–12. [ CrossRef ] 43 Power, A.G. Ecosystem services and agriculture: Tradeo ff s and synergies Philos. Trans. R. Soc. Lond B Biol. Sci 2010 , 365 , 2959–2971. [ CrossRef ] [ PubMed ] 44 Lesieur, V.; Martin, J.-F.; Weaver, D.K.; Hoelmer, K.A.; Smith, D.R.; Morrill, W.L.; Kadiri, N.; Peairs, F.B.; Cockrell, D.M.; Randolph, T.L.; et al. Phylogeography of the Wheat Stem Sawfly, Cephus cinctus Norton (Hymenoptera: Cephidae): Implications for Pest Management PLoS ONE 2016 , 11 , e 0168370. [ CrossRef ] [ PubMed ] 45 Beres, B.L.; Dosdall, L.M.; Weaver, D.K.; C á rcamo, H.A.; Spaner, D.M. Biology and integrated management of wheat stem sawfly and the need for continuing research Can. Entomol 2011 , 143 , 105–125. [ CrossRef ] 46 Weaver, D.K.; Nansen, C.; Runyon, J.B.; Sing, S.E.; Morrill, W.L. Spatial distributions of Cephus cinctus Norton (Hymenoptera: Cephidae) and its braconid parasitoids in Montana wheat fields Biol. Control 2005 , 34 , 1–11 [ CrossRef ] 47 Peterson, R.K.D.; Buteler, M.; Weaver, D.K.; Macedo, T.B.; Sun, Z.; Perez, O.G.; Pallipparambil, G.R. Parasitism and the demography of wheat stem sawfly larvae, Cephus cinctus Biol. Control 2011 , 56 , 831–839 [ CrossRef ] 48 Bekkerman, A.; Weaver, D.K. Modeling Joint Dependence of Managed Ecosystems Pests: The Case of the Wheat Stem Sawfly J. Agric. Resour. Econ 2018 , 43 , 172–194 49 Morrill, W.L.; Kushnak, G.D.; Gabor, J.W. Parasitism of the Wheat Stem Sawfly (Hymenoptera: Cephidae) in Montana Biol. Control 1998 , 12 , 159–163. [ CrossRef ] 50 Runyon, J.B.; Hurley, R.L.; Morrill, W.L.; Weaver, D.K. Distinguishing adults of Bracon cephi and Bracon lissogaster (Hymenoptera: Braconidae), parasitoids of the wheat stem sawfly (Hymenoptera: Cephidae) Can. Entomol 2001 , 133 , 215–217. [ CrossRef ] 51 Runyon, J.B.; Morrill, W.L.; Weaver, D.K.; Miller, P.R. Parasitism of the Wheat Stem Sawfly (Hymenoptera: Cephidae) by Bracon cephi and B. lissogaster (Hymenoptera: Braconidae) in Wheat Fields Bordering Tilled and Untilled Fallow in Montana J. Econ. Entomol 2002 , 95 , 1130–1134. [ CrossRef ] [ PubMed ] 52 Weaver, D.K.; Sing, S.E.; Runyon, J.B.; Morrill, W.L.; Weaver, D. Potential Impact of Cultural Practices on Wheat Stem Sawfly (Hymenoptera: Cephidae) and Associated Parasitoids J. Agric. Urban Entomol 2004 , 21 , 271–287 53 Buteler, M.; Weaver, D.K.; Miller, P.R. Wheat stem sawfly-infested plants benefit from parasitism of the herbivorous larvae Agric. For. Entomol 2008 , 10 , 347–354. [ CrossRef ] 54 Rand, T.A.; Waters, D.K.; Blodgett, S.L.; Knodel, J.J.; Harris, M.O. Increased area of a highly suitable host crop increases herbivore pressure in intensified agricultural landscapes Agric. Ecosyst. Environ 2014 , 186 , 135–143. [ CrossRef ] 55 Tscharntke, T.; Karp, D.S.; Chaplin-Kramer, R.; Bat á ry, P.; DeClerck, F.; Gratton, C.; Hunt, L.; Ives, A.; Jonsson, M.; Larsen, A.; et al. When natural habitat fails to enhance biological pest control—Five hypotheses Biol. Conserv 2016 , 204 , 449–458. [ CrossRef ]

Sustainability 2019 , 11 , 3223 15 of 16 56 Karp, D.S.; Chaplin-Kramer, R.; Meehan, T.D.; Martin, E.A.; DeClerck, F.; Grab, H.; Gratton, C.; Hunt, L.; Larsen, A.E.; Mart í nez-Salinas, A.; et al. Crop pests and predators exhibit inconsistent responses to surrounding landscape composition Proc. Natl. Acad. Sci. USA 2018 , 115 , E 7863–E 7870. [ CrossRef ] [ PubMed ] 57 Settele, J.; Settle, W.H. Conservation biological control: Improving the science base Proc. Natl. Acad. Sci. USA 2018 , 115 , 8241–8243. [ CrossRef ] 58 NASS 2016 Wheat Varieties Grown in Montana ; NASS: Washington, DC, USA, 2016 59 Kevan, P.G. Pollinators as bioindicators of the state of the environment: Species, activity and diversity Agric Ecosyst. Environ 1999 , 74 , 373–393. [ CrossRef ] 60 Moisset, B.B.; Buchmann, S Bee Basics: An Introduction to Our Native Bees ; Lulu.com: Morrisville, NC, USA, 2011 61 Goulson, D.; Nicholls, E.; Botias, C.; Rotheray, E.L. Bee declines driven by combined stress from parasites, pesticides, and lack of flowers Science 2015 , 347 , 1255957. [ CrossRef ] 62 Goulson, D.; Lye, G.C.; Darvill, B. Decline and Conservation of Bumble Bees Annu. Rev. Entomol 2008 , 53 , 191–208. [ CrossRef ] [ PubMed ] 63 Potts, S.G.; Biesmeijer, J.C.; Kremen, C.; Neumann, P.; Schweiger, O.; Kunin, W.E. Global pollinator declines: Trends, impacts and drivers Trends Ecol. Evol 2010 , 25 , 345–353. [ CrossRef ] [ PubMed ] 64 Kremen, C.; Miles, A. Ecosystem Services in Biologically Diversified versus Conventional Farming Systems: Benefits, Externalitites, and Trade-O ff s Ecol. Soc 2012 , 17 , 1–23. [ CrossRef ] 65 Gallai, N.; Salles, J.M.; Settele, J.; Vaissi è re, B.E. Economic valuation of the vulnerability of world agriculture confronted with pollinator decline Ecol. Econ 2009 , 68 , 810–821. [ CrossRef ] 66 Adhikari, S Impacts of Dryland Farming Systems on Biodiversity, Plant-Insect Interactions, and Ecosystem Services ; Montana State University: Bozeman, MT, USA, 2018 67 Adhikari, S.; Burkle, L.A.; O’Neill, K.M.; Weaver, D.K.; Delphia, C.M.; Menalled, F.D. Dryland Organic Farming Partially O ff sets Negative E ff ects of Highly Simplified Agricultural Landscapes on Forbs, Bees, and Bee–Flower Networks Environ. Entomol 2019 . [ CrossRef ] [ PubMed ] 68 Kehinde, T.; Samways, M.J. Insect-flower interactions: Network structure in organic versus conventional vineyards Anim. Conserv 2014 , 17 , 401–409. [ CrossRef ] 69 Power, E.F.; Stout, J.C. Organic dairy farming: Impacts on insect-flower interaction networks and pollination J. Appl. Ecol 2011 , 48 , 561–569. [ CrossRef ] 70 Tucker, E.M.; Rehan, S.M. Wild Bee Community Assemblages Across Agricultural Landscapes J. Agric Urban Entomol 2017 , 33 , 77–104. [ CrossRef ] 71 Spiesman, B.J.; Bennett, A.; Isaacs, R.; Gratton, C. Bumble bee colony growth and reproduction depend on local flower dominance and natural habitat area in the surrounding landscape Biol. Conserv 2017 , 206 , 217–223. [ CrossRef ] 72 Landis, D.A.; Wratten, S.D.; Gurr, G.M. Habitat Management to Conserve Natural Enemies of Arthropod Pests in Agriculture Annu. Rev. Entomol 2000 , 45 , 175–201. [ CrossRef ] 73 Rusch, A.; Chaplin-Kramer, R.; Gardiner, M.M.; Hawro, V.; Holland, J.; Landis, D.; Thies, C.; Tscharntke, T.; Weisser, W.W.; Winqvist, C.; et al. Agricultural landscape simplification reduces natural pest control: A quantitative synthesis Agric. Ecosyst. Environ 2016 , 221 , 198–204. [ CrossRef ] 74 Letourneau, D.K.; Bothwell Allen, S.G.; Stireman, J.O. Perennial habitat fragments, parasitoid diversity and parasitism in ephemeral crops J. Appl. Ecol 2012 , 49 , 1405–1416. [ CrossRef ] 75 Chaplin-Kramer, R.; de Valpine, P.; Mills, N.J.; Kremen, C. Detecting pest control services across spatial and temporal scales Agric. Ecosyst. Environ 2013 , 181 , 206–212. [ CrossRef ] 76 Philip Robertson, G.; Gross, K.L.; Hamilton, S.K.; Landis, D.A.; Schmidt, T.M.; Snapp, S.S.; Swinton, S.M. Farming for Ecosystem Services: An Ecological Approach to Production Agriculture Bioscience 2014 , 64 , 404–415. [ CrossRef ] [ PubMed ] 77 Mallinger, R.E.; Gibbs, J.; Gratton, C. Diverse landscapes have a higher abundance and species richness of spring wild bees by providing complementary floral resources over bees’ foraging periods Landsc. Ecol 2016 , 31 , 1523–1535. [ CrossRef ] 78 Walther-Hellwig, K.; Frankl, R. Foraging habitats and foraging distances of bumblebees, Bombus spp. (Hym., Apidae), in an agricultural landscape J. Appl. Entomol 2000 , 124 , 299–306. [ CrossRef ] 79 Morandin, L.A.; Winston, M.L.; Abbott, V.A.; Franklin, M.T. Can pastureland increase wild bee abundance in agriculturally intense areas? Basic Appl. Ecol 2007 , 8 , 117–124. [ CrossRef ]

Sustainability 2019 , 11 , 3223 16 of 16 80 Morandin, L.A.; Kremen, C. Hedgerow restoration promotes pollinator populations and exports native bees to adjacent fields Ecol. Appl 2013 , 23 , 829–839. [ CrossRef ] [ PubMed ] 81 Morandin, L.A.; Winston, M.L. Pollinators provide economic incentive to preserve natural land in agroecosystems Agric. Ecosyst. Environ 2006 , 116 , 289–292. [ CrossRef ] 82 Peterson, C.A.; Eviner, V.T.; Gaudin, A.C.M. Ways forward for resilience research in agroecosystems Agric. Syst 2018 , 162 , 19–27. [ CrossRef ] 83 Zhang, W.; Ricketts, T.H.; Kremen, C.; Carney, K. Ecosystem services and dis-services to agriculture Ecol. Econ 2007 , 64 , 253–260. [ CrossRef ] 84 Duru, M.; Therond, O.; Martin, G.; Martin-Clouaire, R.; Magne, M.-A.; Justes, E.; Journet, E.-P.; Aubertot, J.-N.; Savary, S.; Bergez, J.-E.; et al. How to implement biodiversity-based agriculture to enhance ecosystem services: A review Agron. Sustain. Dev 2015 , 35 , 1259–1281. [ CrossRef ] 85 Sandifer, P.A.; Sutton-Grier, A.E.; Ward, B.P. Exploring connections among nature, biodiversity, ecosystem services, and human health and well-being: Opportunities to enhance health and biodiversity conservation Ecosyst. Serv 2015 , 12 , 1–15. [ CrossRef ] 86 Birg é , H.E.; Allen, C.R.; Garmestani, A.S.; Pope, K.L. Adaptive management for ecosystem services J. Environ. Manag 2016 , 183 , 343–352. [ CrossRef ] [ PubMed ] 87 Lin, B.B. Resilience in Agriculture through Crop Diversification: Adaptive Management for Environmental Change Bioscience 2011 , 61 , 183–193. [ CrossRef ] 88 Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES); IPBES Secretariat, U.C.G. IPBES Global Assessment Report. Available online: https: // www.ipbes.net / news / ipbes-globalassessment-preview (accessed on 2 June 2019) 89 Global Drylands: A UN System-Wide Response ; United Nations Environment Management Groups: Geneva, Switzerland, 2011 90 Farooq, M.; Siddique, K.H.M. Innovations in Dryland Agriculture. In Innovations in Dryland Agriculture ; Springer International Publishing: Cham, Switzerland, 2016; pp. 215–236 91 Lu, N.; Wang, M.; Ning, B.; Yu, D. Research advances in ecosystem services in drylands under global environmental changes Curr. Opin. Environ. Sustain 2018 , 33 , 92–98. [ CrossRef ] 92 Schild, J.E.M.; Vermaat, J.E.; de Groot, R.S.; Quatrini, S.; van Bodegom, P.M. A global meta-analysis on the monetary valuation of dryland ecosystem services: The role of socio-economic, environmental and methodological indicators Ecosyst. Serv 2018 , 32 , 78–89. [ CrossRef ] 93 Schild, J.E.M.; Vermaat, J.E.; van Bodegom, P.M. Di ff erential e ff ects of valuation method and ecosystem type on the monetary valuation of dryland ecosystem services: A quantitative analysis J. Arid Environ 2018 , 159 , 11–21. [ CrossRef ] 94 Lawrence, P.G.; Maxwell, B.D.; Rew, L.J.; Ellis, C.; Bekkerman, A. Vulnerability of dryland agricultural regimes to economic and climatic change Ecol. Soc 2018 , 23 , art 34. [ CrossRef ] 95 Adhikari, A.; Hansen, A.J. Land use change and habitat fragmentation of wildland ecosystems of the North Central United States Landsc. Urban Plan 2018 , 177 , 196–216. [ CrossRef ] 96 DeFries, R.S.; Foley, J.A.; Asner, G.P. Land-use choices: Balancing human needs and ecosystem function Front. Ecol. Environ 2004 , 2 , 249–257. [ CrossRef ] 97 Altieri, M.A. The ecological role of biodiversity in agroecosystems Agric. Ecosyst. Environ 1999 , 74 , 19–31 [ CrossRef ] 98 Benton, T.G.; Vickery, J.A.; Wilson, J.D. Farmland biodiversity: Is habitat heterogeneity the key? Trends Ecol. Evol 2003 , 18 , 182–188. [ CrossRef ] 99 Gaba, S.; Lescourret, F.; Boudsocq, S.; Enjalbert, J.; Hinsinger, P.; Journet, E.-P.; Navas, M.-L.; Wery, J.; Louarn, G.; Mal é zieux, E.; et al. Multiple cropping systems as drivers for providing multiple ecosystem services: From concepts to design Agron. Sustain. Dev 2015 , 35 , 607–623. [ CrossRef ] © 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http: // creativecommons.org / licenses / by / 4.0 / ).