Complex agricultural landscapes host more biodiversity than simple ones: A global meta-analysis

Abstract

Managing agricultural landscapes to support biodiversity conservation requires profound structural changes worldwide. Often, discussions are centered on management at the field level. However, a wide and growing body of evidence calls for zooming out and targeting agricultural policies, research, and interventions at the landscape level to halt and reverse the decline in biodiversity, increase biodiversity-mediated ecosystem services in agricultural landscapes, and improve the resilience and adaptability of these ecosystems. We conducted the most comprehensive assessment to date on landscape complexity effects on nondomesticated terrestrial biodiversity through a meta-analysis of 1,134 effect sizes from 157 peer-reviewed articles. Increasing landscape complexity through changes in composition, configuration, or heterogeneity significatively and positively affects biodiversity. More complex landscapes host more biodiversity (richness, abundance, and evenness) with potential benefits to sustainable agricultural production and conservation, and effects are likely underestimated. The few articles that assessed the combined contribution of linear (e.g., hedgerows) and areal (e.g., woodlots) elements resulted in a near-doubling of the effect sizes (i.e., biodiversity level) compared to the dominant number of studies measuring these elements separately. Similarly, positive effects on biodiversity are stronger in articles monitoring biodiversity for at least 2 y compared to the dominant 1-y monitoring efforts. Besides, positive and stronger effects exist when monitoring occurs in nonoverlapping landscapes, highlighting the need for long-term and robustly designed monitoring efforts. Living in harmony with nature will require shifting paradigms toward valuing and promoting multifunctional agriculture at the farm and landscape levels with a research agenda that untangles complex agricultural landscapes’ contributions to people and nature under current and future conditions.

Achieving a nature- and people-positive future

“…16,87 In addition to largely intact ecosystems, patches of (semi-) natu-ral habitats in converted lands, coasts, and cities help conserve species diversity 88 and provide access to nature's benefits to people. 44,87,89,90 Commensurate figures for freshwater and ocean systems are as yet less developed.…”

“…87 This helps to maintain the minimum level of ecosystem functional integrity that supports biodiversity, human well-being, and the provisioning of multiple benefits of nature simultaneously. 87,89,90 Ecological and planetary boundary approaches are founded on the notion of assuring that drivers stay a safe distance from critical boundary thresholds. 80 Actors must thus ''bend the curves'' of drivers of biodiversity decline for them to return/remain within their safe boundaries and to have any chance of bending the curve of biodiversity loss.…”

Landscape-scale forest cover drives the predictability of forest regeneration across the Neotropics

“…This does not imply that intermediately deforested and environmentally more complex landscapes have a lower conservation value. There is strong evidence worldwide that these are optimal landscape scenarios for biodiversity conservation and the delivery of goods and services to humans [35,73,74]. Our royalsocietypublishing.org/journal/rspb Proc.…”

Integrated modeling to achieve global goals: lessons from the Food, Agriculture, Biodiversity, Land-use, and Energy (FABLE) initiative

“…In all countries, there is a high uncertainty regarding feasible productivity increases, and the limits of feasibility are likely to shift under climate change. In addition, productivity increases need to be achieved using agroecological approaches to avoid the negative environmental consequences associated with intensification through synthetic pesticide use, excessive use of fertilizers, unsustainable irrigation, and simplification of farms and landscapes (Estrada-Carmona et al 2022;Sánchez et al 2022;Tscharntke et al 2021;Beckmann et al 2019;Liu et al 2017;Tuck et al 2014). Agroecological intensification may not be able to achieve the productivity increases that are possible with high chemical input use, although evidence shows that yield gaps created by removing chemical inputs are reduced and can be closed by increasing crop and non-crop diversity infield, e.g., with agroforestry, intercropping, cover crops, and use of flower strips (Beillouin et al 2021;Tamburini et al 2020;Ponisio et al 2015).…”