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Abstract:
Although temporal heterogeneity is a well-accepted driver of
biodiversity, effects of interannual variation in land-use intensity
(LUI) have not been addressed yet. Additionally, responses to land
use can differ greatly among different organisms; therefore,
overall effects of land-use on total local biodiversity are hardly
known. To test for effects of LUI (quantified as the combined
intensity of fertilization, grazing, and mowing) and interannual
variation in LUI (SD in LUI across time), we introduce a unique
measure of whole-ecosystem biodiversity, multidiversity. This synthesizes
individual diversity measures across up to 49 taxonomic
groups of plants, animals, fungi, and bacteria from 150 grasslands.
Multidiversity declined with increasing LUI among grasslands, particularly
for rarer species and aboveground organisms, whereas
common species and belowground groups were less sensitive.
However, a high level of interannual variation in LUI increased
overall multidiversity at low LUI and was even more beneficial
for rarer species because it slowed the rate at which the multidiversity
of rare species declined with increasing LUI. In more intensively
managed grasslands, the diversity of rarer species was,
on average, 18% of the maximum diversity across all grasslands
when LUI was static over time but increased to 31% of the maximum
when LUI changed maximally over time. In addition to decreasing
overall LUI, we suggest varying LUI across years as a complementary strategy to promote biodiversity conservation.
