水分条件变化对哀牢山亚热带常绿阔叶林林下幼苗死亡率的影响  

The influence of changes in water availability on seedling mortality of a subtropical evergreen broadleaf forest on Ailao Mountain

作　　者：杞金华[1,2] 章永江[1,3] 张一平[1,2] 刘玉洪[1,2] 鲁志云[1,2] 武传胜[1,2] 温韩东[1,2] 

机构地区：[1]中国科学院西双版纳热带植物园,勐仑666303 [2]中国科学院哀牢山亚热带森林生态系统研究站,景东676200 [3]哈佛大学有机和进化生物学系,美国剑桥02138

出　　处：《生态学报》2015年第8期2521-2528,共8页Acta Ecologica Sinica

基　　金：中国科学院哀牢山亚热带森林生态系统研究站研究基金

摘　　要：为探讨环境水分条件变化对亚热带森林林下乔木幼苗动态的影响,以及木材密度和幼苗在干旱中死亡率的关系,研究了哀牢山常绿阔叶林2005—2011年的总体和主要树种幼苗(黄心树、多果新木姜子、多花山矾、鸭公树和大花八角)的死亡率,并分析了幼苗死亡率和旱季幼苗根系所在土层土壤质量含水量、旱季降水量、旱季降水日数以及木材密度的关系。结果表明:1)幼苗死亡率与旱季降水日数、旱季浅层土壤平均质量含水量有显著的负相关关系,和旱季降水量无显著相关性;2)总幼苗及5种乔木幼苗的死亡率均在2010年(西南干旱)达到有观测以来最高,是2009年的2—10倍,其中多花山矾、黄心树幼苗的死亡率最高,大花八角幼苗的死亡率最低;3)在种间,幼苗2010年干旱中的死亡率和木材密度显著正相关,即木材密度较大的物种幼苗死亡率更高。研究表明林下幼苗由于根系较浅,对降雨变化较为敏感,因而受到了这次干旱的较大影响。由于木材密度较低的树种在干旱中有较低的死亡率,干旱频度和强度的增加可能使低木材密度幼苗的丰富度增加,森林的组成也将受到影响。In order to understand the influence of changes in water availability on the seedling dynamics of subtropical forests and the relationship between wood density and seedling mortality during a prolonged drought period, we studied seedling mortality patterns across all species and of 5 common tree species from an evergreen broadleaf forest on Ailao Mountain, southwest （SW） China from 2005 to 2011. The five tree species studied were Machilus bornbycina, Neolitsea polycarpa, Symplocos ramosissima, Neolitsea chuii, and IUicium macranthum. The relationships between seedling mortality and rainy days, rainfall, soil water mass content （0--20 era） during the dry season, and wood density were also analyzed. Our results showed that 1 ） Seedling mortality was negatively correlated with number of rainy days in the dry season and dry season soil water mass content, but not with total dry season rainfall; 2） The seedling mortalities of all species as a whole and of each of the 5 species studied reached a historical maximum in the 2010 SW China extreme drought, which were 2 to 10 times more intense than for 2009 （Machilus bombycina and Symplocos ramosissima had the highest seedling mortalities while Illicium macranthum had the lowest in 2010） ; 3 ） Across species, the seedling mortality in the 2010 drought was positively correlated with species-specific wood densities ; species with higher wood densities had higher seedling mortalities. Previous studies have shown that trees in this forest did not experience severe drought stress during the 2010 SW China drought. However, the present study suggests that the seedlings were severely influenced by the rainfall anomaly during the 2010 dry season, probably owing to their shallow rooting depths and consequently high sensitivities to changes in rainfall. Additionally, because of the lower seedling mortalities in lower wood density species, the potential increase in drought frequency and severity in the future may increase the relative abundance of low wood density spe

关 键 词：干旱 幼苗动态 土壤质量含水量 降水 木材密度 

分 类 号：S718.5[农业科学—林学]