Growth responses of Castanopsis hystrix and Pinus massoniana plantations to throughfall reduction in subtropical China.

Abstract

To better predict and evaluate responses of tree growth and forest productivity to the changes of precipitation pattern and seasonal drought under global climate change scenarios, throughfall reduction experiments including 50% of throughfall and natural rainfall (control) treatments were conducted in Castanopsis hystrix and Pinus massoniana plantations of warm subtropical region over a three-year period (2015-2017). Diameter at breast height (DBH), litterfall production and leaf area index of both plantations were investigated, respectively. The results showed that throughfall reduction resulted in a 31.8% decrease of annual increment of DBH of C. hystrix in 2017 and had no significant impact on that of P. massoniana. Leaf area index under throughfall reduction decreased by 8.8% in C. hystrix plantation and decreased by 7.2% or remained unchanged in P. massoniana plantation. Branch litterfall in 2015 and total litterfall in 2017 of C. hystrix increased by 29.6% and 35.8% by throughfall reduction, but leaf litterfall of other tree species (except for P. massoniana) in P. massoniana plantation declined by 50.7% in 2015, with no significant difference for other litterfall components. In conclusion, throughfall reduction had consequences of drought stress in both C. hystrix and P. massoniana plantations, with inter-annual variation and inter-specific differences.