Landscape context affects patch habitat contributions to biodiversity in agroecosystems

Effective conservation schemes are needed to advance dual objectives of
biodiversity conservation and agronomic production in agricultural
landscapes. Understanding how plant and arthropod taxa respond to both
local habitat patch characteristics and landscape complexity is crucial
for planning effective agri-environment schemes. This study investigated
the relative effects of local (≤ 100 m from patch habitat center) and
landscape (≤ 5 km from patch habitat center) variables on diversity of
plants and arthropods within non-crop habitat patches (i) at different
spatial extents ranging from 0.1 km to 5 km, while (ii) quantifying
differential effects of local and landscape variables on unique components
of diversity (i.e. species richness and abundance), and accounting for
(iii) unique components of landscape extent (0.1, 0.5, 1, 2 and 5 km
radii) and complexity (i.e. landscape composition and configuration).
Landscape variables were significantly correlated with local plant and
arthropod species richness and abundance at all spatial extents.
Biodiversity responses to landscape variables were largely
scale-dependent, as pairwise comparisons were significantly different
between all spatial extents except between 1-km and 2-km extents, and
correlations were lowest at the 5-km extent. Partial R-squared values for
predicting local biodiversity were highest when both local and landscape
variables were included as predictors of species richness and abundance,
underscoring the importance of considering both local and landscape
effects on local diversity. Landscape configuration variables accounted
for more variation in plant and arthropod species richness than
composition variables. However, models performed best when composition and
configuration were considered together rather than alone, suggesting that
both components of landscape complexity should be considered for
identifying and managing conservation areas in crop fields. Conservation
schemes that incentivize farmers to create or conserve small patch habitat
within crop fields may be more effective when combined with
landscape-scale designs that enhance landscape complexity across the
Northern Great Plains. Local conservation efforts should be coordinated
with landscape-level efforts to ultimately enhance biodiversity and
desired ecosystem service outcomes across agricultural landscapes.