Human footprint amplifies the response of photosynthetic activity to precipitation across a diverse range of tropical ecosystems

Photosynthesis constitutes the primary driver of the terrestrial biosphere, regulated by climatic factors and increasingly by human activities. Tropical ecosystems harbor the majority of global terrestrial biodiversity and play an essential role in climate regulation and biogeochemical cycling. However, the combined impact of climate and human activity on photosynthetic activity remain poorly understood across diverse tropical ecosystems. In Colombia an exceptional climatic diversity has given rise to more than 81 distinct terrestrial ecosystems that serve as a natural laboratory for studying how human activities modulate climate-photosynthesis relationships in the tropics. Using satellite-derived observations of Fraction of Absorbed Photosynthetically Active Radiation (FAPAR) from 1999–2019, we quantify spatiotemporal correlations between monthly precipitation, temperature, and FAPAR across a human footprint intensity gradient. Our analyses reveal a diversity of regional distinct responses: FAPAR correlates positively with both temperature and precipitation in Caribbean and Andean regions; positively with temperature but negatively with precipitation in the Amazon; and positively with precipitation but negatively with temperature in the Eastern Plains, where seasonal drought constrains photosynthetic activity. Across most ecosystems, precipitation emerges as the dominant climatic driver of FAPAR, with increasing human footprint consistently amplifying and accelerating ecosystem responses to rainfall. These findings reveal how climate and land-use change interact reshaping photosynthetic dynamics throughout tropical ecosystems. They underscore the urgent need to reconsider tropical land-use transformations and human-nature interactions to sustain ecosystem services and human well-being for future generations.