Data from: Grazing and climate interact to regulate greening trends in Mediterranean grasslands

A widespread increase in vegetation photosynthetic activity and biomass,
known as greening, has been detected since the 1980s. While global climate
change explains some of this trend, regional-level land-use management
also plays a significant role. In grasslands, the fine-scale movement of
livestock is a key driver of vegetation dynamics, likely affecting
greening. Here, we investigate how spatial changes in grazing pressure
interact with regional climate to determine long-term vegetation trends.
Our study focuses on a Mediterranean mountainous region in south-eastern
SpainF, with a long history of traditional grazing. We used GPS collar
data from 35 livestock herds to create a high-resolution map of herbivory
pressure. We then analysed vegetation dynamics from 1985 to 2024 using
NDVI time series and evaluated vegetation responses to climate and
herbivory with multivariate autoregressive models and logarithmic
regressions. Greening was the dominant trend occurring in 90 % of the
study area. However, increasing grazing pressure diminished this greening
tendency. We found a non-linear response: the greening trend reduced
sharply even under low levels of grazing and then stabilized at medium to
high intensities. Despite hotspots of grazing pressure, no significant
browning (vegetation decline) was detected. Vegetation became more
sensitive to climate under higher herbivory pressure. In heavily grazed
areas, vegetation greenness responded more strongly to increases in
precipitation and showed grater negative responses to rising temperatures.
This suggests that grazing regulates how grassland vegetation responds to
climatic shifts. Policy implications. Our results show that traditional
grazing systems can maintain grassland stability without causing
degradation, but they can also increase the ecosystem’s vulnerability to
climate change. We provide clear evidence that GPS-based livestock
monitoring is a powerful and scalable tool for sustainable rangeland
management. It provides land managers with fine-scale data on grazing
pressure, enabling them to identify areas at risk, enhance ecosystem
resilience to climate change, and support both conservation goals and
productive landscapes at local and regional scales.