Differences in the ecological resilience of planted and natural Pinus massoniana and Cunninghamia lanceolata forests in response to drought in subtropical China

We sampled Pinus massoniana and Cunninghamia lanceolata in both plantation and natural forests in central and western Fujian Province, China. Using tree-ring width, tree-ring width index, and basal area increment, we reconstructed the annual growth of 109 conifer individuals from four sites for the 20-year period from 1993 to 2012. We then calculated resistance, recovery, and resilience indices of those trees in response to two consecutive extreme droughts (2003-2004 and 2011) and analyzed the differences in resistance and resilience between plantations and natural fore-sts. The results showed that there were temporal differences in moisture requirements between P. massoniana and C. lanceolata, which accounted for their inconsistent responses to drought in 2003-2004. For both species, drought induced a marked growth reduction, without any clear lag effect. The growth responses during and following the 2003-2004 drought were significantly stronger than that for the 2011 drought. Those results indicated that P. massoniana was more resilient to drought stress than C. lanceolata, and the natural forests were more sensitive than plantations, but with stronger capacity to recover. C. lanceolata plantations were more susceptible to frequent extreme drought events. To mitigate the vulnerability of plantation trees to more frequent droughts in the future, we suggested select trees from genetic provenances with strong drought resistance.