Creating territorialized sustainability indices to evaluate pollination

CONTEXT

Identifying sustainable practices and landscape features that enhance the abundance of organisms providing ecosystem services can be challenging due to a limited understanding of the link between these practices and ecosystem functioning. One approach to assessing system complexity is to incorporate reliable indices that are markers of an essential ecosystem regulation service such as insect pollination.

OBJECTIVE

Consolidate indicators of sustainable farming practices and landscape features into two indices that consider different spatial scales (regional and local) to categorize peri-urban farms within two gradients of territorialized environmental sustainability. These indices enable the assessment of agroecosystem sustainability for a particular ecosystem service (insect pollination), which is critical for many crops.

METHODS

The regional-scale index utilized four indicators of composition and configuration that reflected the landscape's heterogeneity and its influence on key resources and bee movement. For these features, we used three land classes: semi-natural, farm, and extensive crops within a 3000-m radius circle from the centre of the farm. The local-scale index included eight indicators relating to the sustainability of farming practices derived from semi-structured interviews with the farmers. Additionally, we included an indicator based on the extent of semi-natural areas within a 100-m radius circle.

RESULTS AND CONCLUSIONS

Both indices generated a synthesis to obtain two gradients (regional and local) of territorialized environmental sustainability for the farms. We validated these metrics through records of bee abundance on Cucurbita maxima flowers in each farm, as an indicator of the bee-pollination service. The variations of regional and local indices among and within the same farm (e.g., a high local-scale index and a low regional-scale index) emphasize the importance of considering both spatial contexts when evaluating ecosystem services. Both indices correlated with bee abundance, with the local-scale index exhibiting a positive stronger correlation than the regional (0.68 vs. 0.61 respectively). For farmers, making changes to farming practices at the local scale is more achievable than altering features at the regional scale, where government territorial planning and coordinated efforts among residents in the area are required. Consequently, enhancing a local-scale practice might be a more feasible way to increase farm sustainability.

SIGNIFICANCE

The indices will enable a more straightforward comparison of sustainability among farms or within the same farm over time than analyzing each socio-environmental metric separately. Following the methodology proposed here, other indices for other essential ecosystem services in agroecosystems could be developed.