Savannas are a crucial terrestrial biome. They are typically more sensitive to changes in precipitation than other biomes; therefore, declines in precipitation are expected to impact their carbon sequestration ability. However, no studies have assessed the effects of declines in precipitation on the productivity of savannas in China. Therefore, quantifying the variation in productivity under declines in precipitation in savannas is critical.
Researchers from Xishuangbanna Tropical Botanical Garden (XTBG) performed a field precipitation manipulation experiment in Yuanjiang savanna ecosystem, Yunnan. They aimed to disentangle the effects of declines in precipitation on the productivity of savanna ecosystems.
The researchers used a 4-year dataset to explore the response of net primary productivity to precipitation exclusion (PE) across different plant functional types.
Their results showed that precipitation exclusion significantly reduced the total net primary productivity (NPP) and NPP of trees, shrubs and litterfall in the savanna ecosystem, indicating that declines in precipitation can affect the productivity of savannas.
They observed contrasting NPP responses to declines in precipitation between the perennials and the annuals, with a decrease in the NPP of the perennials and an increase in that of the annuals.
In their 4-year study, declines in precipitation affected plant growth and caused shifts in community dynamics, both of which are involved in the variation of ecosystem productivity under declines in precipitation.
“Our findings have a crucial implication that ongoing climate change and especially declines in precipitation will accelerate the loss of production, drive changes in carbon accumulation, and substantially alter ecosystem functions and services in savannas worldwide”, said Prof. ZHANG Yiping, principal investigator of the study.