台风对森林的影响

A review of the effect of typhoon on forests

台风通过树枝折断、吹落叶果、产生倒木和折干等许多途径影响林分结构和动态。森林受害程度随树种、林龄、森林类型、树高和地形而异。高密度的森林通常具有较差的根系和较大的树高/胸径比值,在台风袭击下,往往具有较高的受损和死亡的风险。台风疏开郁闭的林冠层,促进了先锋树种的大量增加、生长和成熟,形成的林隙也为个体更新提供了机会。强风造成了土壤基质的多样化,从而促进了实生苗和幼树的更新和生物多样性的增加。台风也通过改变粗木质残体,枯枝落叶层,地洞和土墩,以及繁殖可用性来影响生物多样性。台风产生的粗死木和枯枝落叶使森林的碳储量迅速归还土壤,并影响土壤的养分分布。台风减少了动物的食物供应和恶化栖息地的环境,减少鸟的数量,促进昆虫扩散。受害森林给害虫滋生提供了场所。今后的研究热点是受台风干扰森林的长期监测,不同森林土壤的有机碳贮藏,土壤和养分流失规律,台风和其他自然灾害的交叉影响,改进数学模型以准确预测台风损害。

Typhoons are one of the most important natural disturbances, which affect forest stand structures and dynamics in various ways such as by snapping branches, stripping leaves and fruits, uprooting trunks and breaking stem. Many factors, such as position in canopy, soil conditions, stage of growth, physiognomy, affect wind resistance of tree species. Moreover, there is a wind velocity beyond which all species are affected by the sheer magnitude of the wind＇s kinetic energy. Therefore, forest damage varies as a function of tree species, tree age, forest type, tree height and topographic location. High density forests often suffer great damage and mortality due to their relatively weak roots and a high ratio of tree height to diameter at breast height. In forest ecosystems, typhoon disturbance is one of the major agents generating a mosaic of heterogeneous habitat patches at various spatial scales. Canopy gaps caused by typhoon disturbance can occur in a variety of sizes, from single fallen trees to large-scale blowdowns, which is important factor affecting species composition and some critical ecosystem patterns and processes such as understory light environments, and nutrient cycling, and have major effects on patterns of forest regeneration through differential effects on tree species and impacts on resource availability. Light increases due to canopy gaps and soil nutrient availability in the understory also increases due to a decrease in uptake by disturbed canopy trees, which can promote the immigration of early successional species. Moreover, species richness is affected by coarse woody debris, litter layer, pits, and mounds, and the availability of propagules. Coarse woody debris and litterfall caused by typhoon promote return of forest carbon to soil, and affect distribution of soil nutrients. Typhoon disturbances can return large amounts of plant material into the forest floor. Litterfall, particularly green leaves resulting from the typhoons have higher nutrient concentrations than the normal litter for the nutrients that are translocated during senescence. This leads to an increase in nutrient availability and in soil after typhoons. The nutrient released from the rapid decomposition of fresh leaves might exceed the capacity of the vegetation, microorganisms, and the soil to retain the nutrients in the ecosystem, with nutrient transfer patterns of rapid loss for nutrients. Typhoon affects the animals by reducing food availability and deteriorating habitat, The passage of a typhoon can kill birds owing to exposure to wind and rain, particularly those vulnerable to wind and rain prior to the storm. Typhoon affects insect population numbers and causes local extinctions or dramatic outbreaks of populations through effects on either food sources and/or predators, it also damages forest place for pest propagation. Future research of typhoon effect on forests will focus on developing long-term monitoring of forests with typhoon interference, researching organic carbon storage of different forest soils, erosion patterns of soils and nutrients, intersection effect of typhoon and other natural disasters, improving mathematical models for forecasting typhoon damage.