CHARACTERISTICS OF LITTERFALL IN RELATION TO SOIL NUTRIENTS IN MATURE AND DEGRADED EVERGREEN BROAD-LEAVED FORESTS OF TIANTONG,EAST CHINA
CHARACTERISTICS OF LITTERFALL IN RELATION TO SOIL NUTRIENTS IN MATURE AND DEGRADED EVERGREEN BROAD-LEAVED FORESTS OF TIANTONG,EAST CHINA
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作者：
Y. En
凋落物在森林生态系统中起着连接地上和地下过程的重要作用。植物吸收的养分可以通过凋落物分解释放到土壤中并被植物再利用。尽管凋落物的组成和动态在过去的20年里得到了广泛的研究，但对凋落物、养分循环和植被类型之间的关系知之甚少。因此，方法在天童国家森林公园内对万年青阔叶林凋落物量进行研究（29° 52 'N，121° 39' E，200 m a.s.l），浙江，华东地区（木荷群落）、针叶万年青阔叶混交林（马尾松+木荷群落），针叶林（马尾松群落）和灌丛（石栎+木群落）代表不同退化阶段的森林和成熟的EBLF（栲树群落）代表参考顶极林。生产力，组成，2003年11月至2004年10月，每月测定凋落物养分含量和养分总量。结果表明：EBLF的降解显著降低了凋落物生产力，从成熟EBLF的13.03 Mg·hm-2降低到灌木林的6.38 Mg·hm-2，并显著降低了凋落物中的N浓度，而在成熟EBLF中，凋落物中的N浓度从13.03 Mg·hm-2降低到6.38 Mg·hm-2。土壤全N和全P通过凋落物归还的量随退化程度的增加而显著减少，土壤全N与凋落物年生产力呈显著正相关，但与凋落物N无显著相关性土壤全P与凋落物年生产力和凋落物P浓度均呈正相关，土壤无机N与凋落物年生产力和凋落物养分浓度均无相关性，土壤N硝化速率与凋落物年生产力和养分归还总量呈正相关，土壤氮素矿化与凋落物的任何性状均不相关，说明在EBLF的降解过程中，植物功能类型的转移和群落结构的简化使凋落物的质量和数量降低到较低的水平，从而减少了土壤养分库。
Aims Litterfall plays an important role in linking aboveground and belowground processes in forest ecosystems.Nutrients absorbed by plants can be released to the soil and re-utilized by plants via litter decomposition.Although litterfall composition and dynamics have been widely studied in the past two decades,the relationship among litterfall,nutrient cycling and vegetation types is poorly understood.Therefore,we studied litterfall in evergreen broad-leaved forests(EBLF) to enrich our knowledge of the relationship.Methods The research was conducted in Tiantong National Forest Park(29°52'N,121°39'E,200 m a.s.l),Zhejiang,East China.We chose secondary and young EBLF(Schima superba community),coniferous and evergreen broad-leaved mixed forest(Pinus massoniana+Schima superba community),coniferous forest(Pinus massoniana community) and shrubland(Lithocarpus glaber + Loropetalum chinense community) to represent forests at different degradation stages and mature EBLF(Castanopsis fargesii community) to represent reference climax forest.Productivity,composition,nutrient concentration and total nutrient amount of the litterfall were measured each month from November 2003 to October 2004.Litterfall traits were correlated with soil total N,total P,total inorganic N,N mineralization and nitrification rates.Important findings Degradation of EBLF significantly reduced litterfall productivity from 13.03 Mg·hm-2 in mature EBLF to 6.38 Mg·hm-2 in shrubland,and significantly reduced N concentration in litterfall.In contrast,P concentration showed no consistent pattern.Total N and total P amounts returned via litterfall decreased significantly with degradation.Soil total N was positively correlated with annual litterfall productivity but not litter N concentration.Soil total P was positively correlated with both annual litterfall productivity and litter P concentration.Soil inorganic N was not correlated with either productivity or litter nutrient concentration.Soil N nitrification rate was positively correlated with annual litterfall productivity and total amounts of nutrients returned,but was not correlated with litter N concentration.Soil N mineralization was not correlated with any litterfall traits.These results suggested that,during degradation of EBLF,shifting of plant functional types and simplifying of community structure reduced the quality and quantity of litterfall to a low level and consequently reduced soil nutrient pools.