Biodiversity benefits pollination, pest control, and crop productivity but suffers from land-use intensification.

Significance: Decades of research have fostered the now-prevalent assumption that noncrop habitat facilitates better pest suppression by providing shelter and food resources to the predators and parasitoids of crop pests. Based on our analysis of the largest pest-control database of its kind, noncrop habitat surrounding farm fields does affect multiple dimensions of pest control, but the actual responses of pests and enemies are highly variable across geographies and cropping systems. Because noncrop habitat often does not enhance biological control, more information about local farming contexts is needed before habitat conservation can be recommended as a viable pest-suppression strategy. Consequently, when pest control does not benefit from noncrop vegetation, farms will need to be carefully comanaged for competing conservation and production objectives.

Summary: 1. The simplification of agricultural landscapes through the increase in cropped area has caused the loss of habitats for many species that fulfil important ecosystem services such as pest control and production. Evidence for detrimental effects on ecosystem services is scarce, particularly in tropical regions.2. We studied the effect of the percentage of cropped land in the landscape and altitude in tropical agro‐ecosystems in relation to crop pest regulation and yield. In the Colombian Andes, we established potato Solanum tuberosum plots along gradients of altitude and increasing proportion of cropped area to assess the effects on herbivores, their natural enemies, potato production and overall biodiversity.3. Increasing altitude and percentage cropped land reduced the richness and abundance of herbivores and their natural enemies, except for the specialist Guatemalan potato moth Tecia solanivora, which showed the opposite response.4. Potato yield was negatively affected by the presence of the Guatemalan potato moth, which increased in density as the percentage of cropped land and altitude increased. Other herbivores and natural enemies did not affect yield.5. Synthesis and applications. Tropical landscapes at lower altitude or with smaller areas of cropped land suffered less from the presence of the potato moth, which had a negative effect on yield. Our results suggest that conservation of natural habitats like the endangered Andean ecosystems would benefit farmers through ecosystem services such as reduced pest damage, higher yield and increased functional biodiversity.

The expansion of the agricultural frontier by the clearing of remnant forests has led to human-dominated landscape mosaics. Previous studies have evaluated the effect of these landscape mosaics on arthropod diversity at local spatial scales in temperate and tropical regions, but little is known about fragmentation effects in crop systems, such as the complex tropical traditional crop systems that maintain a high diversity of weeds and arthropods in low-Andean regions. To understand the factors that influence patterns of diversity in human-dominated landscapes, we investigate the effect of land use types on plant and arthropod diversity in traditionally managed cornfields, via surveys of plants and arthropods in twelve traditional cornfields in the Colombian Andes. We estimated alpha and beta diversity to analyze changes in diversity related to land uses within a radius of 100 m to 1 km around each cornfield. We observed that forests influenced alpha diversity of plants, but not of arthropods. Agricultural lands had a positive relationship with plants and herbivores, but a negative relationship with predators. Pastures positively influenced the diversity of plants and arthropods. In addition, forest cover seemed to influence changes in plant species composition and species turnover of herbivore communities among cornfields. The dominant plant species varied among fields, resulting in high differentiation of plant communities. Predator communities also exhibited high turnover among cornfields, but differences in composition arose mainly among rare species. The crop system evaluated in this study represents a widespread situation in the tropics, therefore, our results can be of broad significance. Our findings suggest that traditional agriculture may not homogenize biological communities, but instead could maintain the regional pool of species through high beta diversity.

Human land use threatens global biodiversity and compromises multiple ecosystem functions critical to food production. Whether crop yield-related ecosystem services can be maintained by few abundant species or rely on high richness remains unclear. Using a global database from 89 crop systems, we partition the relative importance of abundance and species richness for pollination, biological pest control and final yields in the context of on-going land-use change. Pollinator and enemy richness directly supported ecosystem services independent of abundance. Up to 50% of the negative effects of landscape simplification on ecosystem services was due to richness losses of service-providing organisms, with negative consequences for crop yields. Maintaining the biodiversity of ecosystem service providers is therefore vital to sustain the flow of key agroecosystem benefits to society.

Social-ecological resilience (SER), understood as the capacity to prevent, react to, and mitigate crises that affect social-ecological systems, provides an integrative framework to analyze agricultural challenges. Based on this approach, key points that affect the sustainability of productive landscapes are addressed and evaluated, providing a baseline from which to improve farming systems at different scales. Hence, the aim of this work is to assess SER in potato crops in the Nariño area in southwestern Colombia, a region where strategies to increase resilience must be implemented. Following the methodology proposed by the UNU-IAS (2014), potato producers’ thoughts and perceptions were evaluated by implementing eleven workshops in seven municipalities. Five main integrative factors (twenty indicators of resilience) were examined and scored during the assessment: (1) governance and social equity, (2) livelihood and well-being, (3) knowledge and innovation, (4) landscape diversity and ecosystem protection, and (5) agrobiodiversity and sustainable natural resource management. Participants evaluated each indicator from 1 to 5 (1 being low performance and 5 extremely good performance). The results were calculated and averaged. Prior to the assessment, participatory techniques to generate collective reflection on resilience and landscape management were performed. The results showed that farmers rated SER resilience from low to moderate (from 2.5 to 3.2), with “well-being” (2.5) and “knowledge and innovation” (2.7) being the worst-rated factors. The data evidence deficiencies in all the indicators examined. Issues that constrain SER are related to the lack of capacity to create bio-industries, small livelihood portfolios, pollution, loss of natural areas (which impacts biodiversity and ecosystem services), and the loss of ancestral knowledge. The producers requested, as short-term actions, increases in technical assistance (to promote innovation and business initiatives) and farm diversification programs (to take advantage of their native potatoes diversity). They also agreed on the need for associative figures to enhance capacity-building among producers. These findings confirm deficiencies that minimize the sustainability of this system. Actions that impact positively almost all indicators are required to improve not only productivity but also the population’s well-being.