土壤增温调节中亚热带森林更新初期植物生物量分配格局

Effects of experimental soil warming on plant biomass allocation during the early stages of succession in a subtropical forest in China

全球变暖提高了温带森林生态系统植物的生产力,但对亚热带森林生产力的影响仍然不清楚。由于亚热带森林植物的碳储量巨大,因此了解全球变暖对亚热带森林植物生长的影响至关重要。采用加热电缆模拟土壤增温(+5℃),探讨中亚热带森林几种主要草本植物和木本植物的生长及其生物量分配格局对温度升高的响应。结果表明:增温显著增加五节芒(Miscanthus floridulus)、山油麻(Trema dielsiana)和东南野桐(Mallotus lianus)的高度,但黑莎草(Gahnia tristis)高度显著降低。增温显著增加木本植物的地上、地下和总生物量,而草本植物的地上、地下和总生物量均显著降低。增温对整个群落的地上和地下部分生物量分配模式无显著影响,但木本植物总生物量在各器官之间分配随温度发生改变,增温显著提高木本植物枝生物量比(BMR),降低干生物量比(SMR),而叶生物量比(LMR)和根生物量比(RMR)无显著影响,但显著降低了细根占总根系生物量比率。结果表明木本植物能够通过调节生物量分配模式应对未来全球气候变暖。

Climate warming is known to increase the plant productivity of temperate forest ecosystems, but it is unclear whether this occurs in subtropical forests. Improved understanding of plant growth in subtropical forests is important when studying climate warming because considerable amounts of carbon are sequestered by these ecosystems. In this study, a heat cable was used to assess the effects of warming （＋5℃） on the growth and biomass allocation of herbaceous and woody plants in a mid-subtropical forest. The results showed that warming increased the height of Miscanthus floridulus （herbaceous plant）,Trema dielsiana（woody plant） and Mallotus lianus （woody plant）, but deceased the height of Gahnia tristis （herbaceous plant）. Aboveground biomass, belowground biomass and total biomass of woody plants increased in response to warming but there was reduced the aboveground biomass, belowground biomass and total biomass of herbaceous. The branches mass ratio （BMR） for woody plants increased, but the stem mass ratio （SMR） decreased in response to warming. However, the leaf mass ratio （LMR） and the root mass ratio （RMR） showed no direct response to warming, while there was a significant reduction in the proportion of fine-root biomass to total root biomass. The community as a whole was resistant to short-term warming and showed no significant changes the patterns of biomass allocation. However, the woody plant biomass allocation patterns between organs did change with warming. This suggests that woody plants could adapt to climate warming in the future by adjusting their biomass allocation pattern.