海南热带云雾林幼苗动态参数对磷添加的响应

Response of Seedling Dynamic Parameters to Phosphorus Addition in Hainan Tropical Cloud Forest

该研究以海南霸王岭热带云雾林幼苗群落为对象,结合原位磷添加实验和动态监测,设置对照组ck(0.0 gm^(-2)a^(-1))及5个不同水平的磷添加处理组,按磷添加浓度由低至高依次为p1(1.0gm^(-2)a^(-1))p2(2.0gm^(-2)a^(-1))、p3(4.0 gm^(-2)a^(-1))p4(8.0gm^(-2)a^(-1))p5(16.0gm^(-2)a^(-1))。从群落植物的生长、死亡与更新动态,探究热带云雾林幼苗对磷添加的生态响应。主要结果如下:基于幼苗动态监测数据的统计参数显示,在群落水平上,对照组与处理组之间、不同磷添加处理组之间的生长率、死亡率与增补率均无显著差异;种群水平上,处理组幼苗生长率(0.94±0.52)显著高于对照组(0.84±0.54),死亡率和增补率无显著差异。随磷添加浓度升高,种群动态参数的频数分布格局发生了一定改变,种群死亡率和增补率均呈“倒J型”分布(即测度值为0的种群居多数)但程度分别有所降低与升高;生长率均近似正态分布但偏斜程度发生改变。此外,不同磷添加处理下幼苗种群的生长率与死亡率、死亡率与增补率之间的关联性均不显著;增补率与生长率之间均呈负关联(r=-0.356~-0.140),但随磷添加浓度升高由显著转变为不显著。上述发现有望为高海拔热带森林生态系统的管理和动态预测提供科学依据。

This study focused on the seedling community in a tropical cloud forest in the Bawangling area,Hainan Province.Based on in-situ phosphorus addition experiments and dynamic monitoring,this study aimed to examine and understand the ecological response of seedlings to phosphorus addition from the dynamics of growth,death,and regeneration.Specifically,we set up a control group(ck,0.0 gm^(-2)a^(-1))and five treatment groups with different phosphorus addition concentrations,ie.,1.0 gm^(-2)a^(-1)(p1),2.0gm^(-2)a^(-1)(p2),4.0 gm^(-2)a^(-1)(p3),8.0 gm^(-2)a^(-1)(p4),and 16.0gm^(-2)a^(-1)(p5).Based on the monitoring ofseedling dynamics,we did not find significant differences in growth rate,recruitment rate,and mortality between the six groups at the community scale.At the population scale,while there were no significant differences in recruitment rate and mortality,treatment groups showed significantly higher growth rates(0.94±0.52)than those of control groups(0.84±0.54).The frequency distributions of those population dynamic parameters remarkably changed across the experimental gradient of phosphorus addition.Specifically,frequency distributions of both recruitment rate and mortality exhibited an inverse J-shape pattern(i.e.,most populations had zero recruitment and mortality),but the degree of this pattern respectively decreased for mortality and increased for recruitment along the gradient.Though the distribution of growth rate generally resembled a normal bell-shaped curve,its skewness considerably differed among treatment groups.Besides,correlation analysis revealed that the relationships between growth and mortality rates were not significant nor between mortality and recruitment rates in each treatment group.The relationships between growth and recruitment rates were all negative across each treatment group(r=-0.356~-0.140),although the statistical significance of the correlations vanished away along the experimental gradient of phosphorus addition.These findings are expected to provide a scientific basis for the management and dynamic prediction of high-altitude tropical forest ecosystems.