A land classification protocol for pollinator ecology research: An urbanization case study.

Abstract

Land‐use change is one of the most important drivers of widespread declines in pollinator populations. Comprehensive quantitative methods for land classification are critical to understanding these effects, but co‐option of existing human‐focussed land classifications is often inappropriate for pollinator research. Here, we present a flexible GIS‐based land classification protocol for pollinator research using a bottom‐up approach driven by reference to pollinator ecology, with urbanization as a case study. Our multistep method involves manually generating land cover maps at multiple biologically relevant radii surrounding study sites using GIS, with a focus on identifying land cover types that have a specific relevance to pollinators. This is followed by a three‐step refinement process using statistical tools: (i) definition of land‐use categories, (ii) principal components analysis on the categories, and (iii) cluster analysis to generate a categorical land‐use variable for use in subsequent analysis. Model selection is then used to determine the appropriate spatial scale for analysis. We demonstrate an application of our protocol using a case study of 38 sites across a gradient of urbanization in South‐East England. In our case study, the land classification generated a categorical land‐use variable at each of four radii based on the clustering of sites with different degrees of urbanization, open land, and flower‐rich habitat. Studies of land‐use effects on pollinators have historically employed a wide array of land classification techniques from descriptive and qualitative to complex and quantitative. We suggest that land‐use studies in pollinator ecology should broadly adopt GIS‐based multistep land classification techniques to enable robust analysis and aid comparative research. Our protocol offers a customizable approach that combines specific relevance to pollinator research with the potential for application to a wide range of ecological questions, including agroecological studies of pest control.