气候变化领域集成服务门户

Drought and nitrogen deposition are predicted to increase with global change, but the interactive effects of the two factors on tree physiology are still poorly understood. We investigated the individual and interactive effects of drought and nitrogen addition on growth and leaf physiology of Pinus massoniana seedlings. Seedlings were grown in growth chambers with two soil water (i.e. well watered and drought stress) and two nitrogen conditions (i.e. 0 and 40 kg N hm(-2) a(-1)). Biomass accumulation and allocation, leaf relative water content (RWC), free leaf water content (FWC), leaf chlorophyll (Chl(a+b), Chl(a), Chl(b), Chl(a/b)), contents of carotenoid (Car), malondialdehyde (MDA) and proline (Pro), and superoxide dismutase (SOD) activity were examined throughout the entire experimental period. This study showed that the contents of MDA and Pro, SOD activity, root shoot ratio (R/S) and root mass ratio (RMR) were increased significantly in the drought treatment, while Chl(a+b), Chl(a), RWC and growth of seedlings were significantly decreased. In contrast, nitrogen addition had positive impacts on leaf chlorophyll content, leaf RWC and growth of seedlings. Leaf chlorophyll content had positive relationship with RWC irrespective of nitrogen supply, while MDA and Pro content had opposite trends. We also found that nitrogen addition could substantially ameliorate the negative impact of drought on P. massoniana, by increasing growth and limiting accumulation of MDA, Pro and SOD activity. This short term study suggests that current ambient nitrogen deposition in southern China may be helpful for establishment of P. massoniana seedlings in bare lands with limited water availability.