Climatic Influence on Asian Tropical Rain Forest Dynamics

在亚洲热带地区，厄尔尼诺事件会带来干旱，而拉尼娜则会导致潮湿的气候。本研究探讨两种截然不同的气候事件，厄尔尼诺和拉尼娜，对森林群落动态的热带雨林在东南亚地区。在马来西亚的一个低地热带雨林和泰国的一个低山区热带雨林进行了实地工作。在马来西亚的网站，所有的生活树木>1.0厘米胸径内52公顷的地块标记，映射，确定的物种，并在1992年测量的胸径。第二次统计在1997年进行。1999年，再次观察到枯死的树木。在一九九七年的359965棵活树中，有15798棵在两年后死亡，死亡率为每年0.022棵，较一九九二至一九九七年的每年0.013棵为高。死亡率的增加表明厄尔尼诺（1997/1998年）和拉尼娜（1998/1999年）对森林动态的影响。0.013/年的死亡率估计在1998年和1999年有9359棵死树， 关于我们 拉尼娜现象也不可能发生。因此，估计有6439棵树被厄尔尼诺和拉尼娜杀死。一九九九年，新山泥倾泻区面积为0.32公顷，区内的枯树数目为2235棵。因此，厄尔尼诺现象造成的树木死亡相当于4204棵。这些估计表明，厄尔尼诺造成的死亡率为0.012，拉尼娜造成的死亡率为0.0064。死亡率显然取决于地形，因为山脊的死亡率高于山谷。对沙捞越州的山核桃出口进行的多元回归分析显示，出口山核桃数量与吃水概率之间存在很强的相关性，吃水概率是由降雨量低于100毫米/月的气象站月数量与沙捞越州可用气象站月总数的比率定义的。在泰国的山地森林中，在15公顷的地块上监测壳斗科和樟科物种的种群动态。然而，没有观察到明确的共生关系，关于森林动态和厄尔尼诺/拉尼娜之间的关系。虽然在1999年12月25日观测到零下3.2摄氏度的异常低温，但在2000年春天没有开花，这表明另一种与马来西亚的龙脑香不同的开花触发因素。少

In the Asian tropics, an El Nino event brings a draught, while a La Nina induces wet climate. This study investigates the effect of two contrasting climatic events, El Nino and La Nina, on the forest community dynamics of tropical rain forest in Southeast Asia. Field work was conducted in a lowland tropical rain forest in Malaysia and a lower montane tropical rain forest in Thailand. In the Malaysian site, all the living trees>1.0 cm dbh within a 52-hecatre plot were labeled, mapped, identified to species, and measured by dbh in 1992. The second enumeration was conducted in 1997. The dead trees were observed again in 1999. Out of the 359965 living trees in 1997, 15798 trees died after two years, showing a mortality of 0.022/yr, which is greater than 0.013/yr observed in 1992-1997. The increase of mortality suggests the impact of El Nino(1997/1998)and La Nina(1998/1999)on forest dynamics. The mortality rate of 0.013/yr gives an estimate of 9359 dead trees in 1998 and 1999, when El Nino … More and La Nina could not hypothetically occurred. Therefore 6439 trees are estimated to be killed by El Nino and Lanina. The number of dead trees within the new landslide areas of 0.32 ha in 1999 is 2235. Hence the trees killed by El Nino are equivalent to 4204. These estimates suggest the mortality rate of 0.012 due to El Nino and that of 0.0064 due to La Nina. The dependency of mortality rates on topography is clear, since mortality rates are higher on ridges than in valleys. A multiple regression analysis on illipe nut exports from Sarawak showed a strong correlation between exported illipe nut quantities and draft probability, which is defined by the ratio of the monthly number of weather stations with rainfall less than 100 mm/month to the monthly total number of available weather stations in Sarawak. In the montane forest of Thailand, population dynamics of Fagaceae and Lauraceae speices were monitored in a 15 ha plot. However, no clear sympotoms were observed, concerning the relationships between forest dynamics and El Nino/La Nina. Although the unusual cold temperature of minus 3.2 C was observed on 25 December 1999, flowering did not occurred in the spring 2000, suggesting another flowering trigger different from dipterocarps in Malaysia. Less