China's national nature reserve network shows great imbalances in conserving the country's mega-diverse vegetation.

The National Nature Reserve (NNR) network forms a central element in China's governmental strategy to conserve the country's vast biodiversity and its varied ecosystems. Nonetheless, the effectiveness of the existing NNR network in protecting China's highly diverse habitats and the fauna and flora they contain has remained unclear. Here, we analyze how comprehensively the existing NNR network protects China's vegetation diversity, identifying potential gaps to inform future NNR designations. Covering ~15.7% of China's land area, the existing nature reserve network contains 18 main vegetation types and 26 sub-types. All main vegetation types are also contained in the National-level Nature Reserves (NNRs), but to highly differing degrees. NNRs cover ~24.0% of China's grasslands, but only ~3.3% of the country's monsoon forests. With regards to main vegetation regions, about 41.4% of the Qinghai-Xizang Plateau is covered by NNRs, in contrast to only ~4.6% of the region representing warm-temperate deciduous broad-leaved forests. In five main vegetation regions, NNRs cover <10% of the area and are scattered across a highly fragmented network, leading for example to China's highly biodiverse subtropical evergreen broad-leaved forests being conserved only in small, isolated NNRs. NNRs also greatly vary in the number of vegetation types they individually comprise, with only 64 NNRs (18.9%) individually containing >50% of the vegetation types in their respective region. Overall, NNR size increases and fragmentation decreases from China's south-east to its western provinces. The resulting, extremely uneven distribution of NNRs across China limits their effectiveness in protection the country's plant diversity treasure trove. The country's NNR network therefore needs significant adjustments to effectively conserve China's valuable natural resources for future generations.