缙云山常绿阔叶林凋落动态及组成

The Dynamics and Composition of Litter Fall of Evergreen Broad-leaved Forest on Mt. Jinyun

[目的]从组成群落的主要树种角度研究森林凋落物生产与物候的关系,分析群落尺度上的凋落物产量、组成、季节动态、分布及主要树种的叶凋落节律,探讨缙云山常绿阔叶林凋落物的基本特征和凋落高峰的形成原因,为其保护、恢复及管理经营提供科学参考,同时也为亚热带常绿阔叶林生态系统的物质循环和功能及维持生物多样性机制等研究提供基础资料。[方法]以研究地1 hm2常绿阔叶林群落固定监测样地为平台,通过均匀交叉布设173个凋落物收集器,每月对收集到的凋落物进行分类、鉴定、称量。[结果]表明:1)2013—2014年的年凋落量为5 310.52 kg·hm-2,其中叶凋落量(3 814.01 kg·hm-2)最多,占年总凋落量的71.82%(常绿树叶90.95%,落叶树叶9.05%),枝条占12.51%,花果等繁殖器官占8.74%,树皮碎屑占1.00%,杂物占6.04%。2)1 a内,凋落物收集器内共收集到36种树木的凋落叶,占样地内树种总数(43种)的83.72%。3)不同收集器之间凋落量存在较大差异,55个收集器中的凋落量在250 300 g,4个收集器的凋落量超过400 g;单个收集器全年最多可收集到24种树种的凋落叶,收到14种凋落叶种数的收集器最多(29个)。[结论]1)全年凋落量月动态呈明显双峰型,叶凋落量月动态与凋落总量变化相同。栲(Castanopsis fargesii Franch)、润楠(Machilus pingii(Oliv.)Hemsl)、薯豆(Elaeocarpus japonicus Sieb.et Zucc)三者落叶量之和为落叶总量的55.89%,是凋落叶的主要来源。2)主要树种均具有明显的叶凋落节律,根据其节律特点可分为2类:单峰型和双峰型。根据其出现时间可分为4类:在春末夏初和秋季均出现落叶高峰的常绿树;仅在春末夏初出现高峰的常绿树;仅在夏末秋初出现高峰的常绿树;以及在秋冬季出现高峰的落叶树。叶凋落高峰主要受物候的影响。

[Objective]Production of plant litter is one of the most important processes in terrestrial ecosystems.This process is essential to understand the biogeochemical cycling and productivity of ecosystems. Currently,researches on relationship between litter production and species composition at the community level are still inadequate,particularly for the evergreen broad-leaved forests. The aims of the present study are to explore the seasonal variation of leaf litter production of major tree species in an evergreen broad-leaved forest,and to provide basic knowledge for forest management and conservation. [Methods]The investigations of litter fall dynamics were conducted from October 2013 to September 2014 using litter fall traps. A total of 173 square traps were set in a 1 hm2 permanent plot located in an evergreen broad-leaved forest on Mt. Jinyun. Litter fall was collected monthly,and then identified,classified and weighed. [Results]The results showed that： 1） The annual litter production was 5 310. 52 kg·hm- 2between 2013 and 2014. Foliage accounted for 71. 82%（ evergreen foliage accounted for 90. 95% and deciduous foliage accounted for 9. 05%）,with tree bark and branches accounting for 12. 51%,reproductive organs accounting for 8. 74%,debris accounting for 6. 04% and broken barks accounting for 1. 00%. 2） Foliage litter was collected from 36 tree species（ 83. 72% of the total number of species）. 3） 250 300 g litter fall was collected from 55 traps,but from 4 traps,over 400 g was collected. Litter fall of a maximum of 24 species can be collected from one litter fall trap,and from most of the traps（ 29 traps）,litter fall of a maximum of 14 species can be collected.[Conclusions]1） Both monthly total litter fall and foliage litter fall showed double-peaked curves. 2） The main sources of foliage litter fall were Castanopsis fargesii Franch,Machilus pingii（ Oliv.） Hemsl and Elaeocarpus japonicus Sieb. et Zucc,accounting for 55. 89% of the total amount of collected litter. 3） The litter fall of main species had clear foliage litter dynamics,and the litter dynamics of main trees can be classified into two types（ i. e. singlepeaked and double-peaked） according to the dynamics,and classified into four types（ i. e. the evergreen trees with a peak in spring and autumn,the evergreen trees with a peak in spring,the evergreen trees with a peak in summer and the deciduous trees with a peak in autumn） according to the temporal pattern of peaks. Phenology had a great effect on the dynamics of the litter fall.