桂西南石漠化区不同微地形中茶条木种子和幼苗的数量特征

Quantitative Characteristics of the Seeds and Seedlings of Delavaya toxocarpa in Different Microtopography of Karst Rocky Desertification Area in Southwest Guangxi

关键词:  石漠化  微地形  茶条木  种子  幼苗  数量特征

Key words:  rocky desertification  microtopography  Delavaya toxocarpa  seed  seedling  quantitative characteristics

摘要:

为探讨微地形(Microtopography)对茶条木(Delavaya toxocarpa)种子和幼苗分布格局的影响，采用样方法对广西平果市龙何喀斯特生态重建示范区茶条木群落中不同微地形的茶条木种子密度、种子存活率、幼苗密度和幼苗年龄结构等进行研究。结果表明：茶条木群落中的微地形有石面、小平地、石沟、石窝和石缝等5种，各微地形的茶条木平均种子密度、平均种子存活率和平均幼苗密度分别为4.97-212.28粒/m²、35.7%-76.5%和0.09-44.85株/m²,石面的平均种子密度和平均幼苗密度显著小于其他4种微地形(P＜0.05)，平均种子存活率显著小于小平地、石沟和石窝；茶条木1年生、2年生和3年生以上的幼苗占比分别为84.44%-100.00%、0.00%-15.38%和0.00%-2.22%，3年生以上幼苗的总存活率不足1.0%。综上，在桂西南石漠化山区茶条木群落中，茶条木的种子密度、种子存活率和幼苗密度等受微地形的影响明显，多年生幼苗存活率低，林下更新能力差，其群落管理可采取冠层疏枝和林隙除杂等措施改善微环境，促进幼苗生长和种群更新。

Abstract:

In order to investigate the influence of microtopography on the distribution pattern of Delavaya toxocarpa seeds and seedlings,we applied plot method in Longhe Karst Ecological Reconstruction Demonstration Zone in Pingguo by determining the seed density,seed survival rate,seedling density and seedling age structure of D. toxocarpa. The results show that there were five types of microtopography in D.toxocarpa community,namely in term of stony surface,small flat,stony ditch,rocky nest and stony crevice.The average levels of seed density,seed survival rate and seedling density in each microtopography were 4.97-212.28 seedling·m^-2,35.7%-76.5% and 0.09-44.85 seedling·m^-2,respectively.While seed density and seedling density were significantly less in the stone surface than those in the other four microtopographies,and seed viability was significantly lower than in the small flat,stony ditch,and rocky nests.Proportion of 1-year-old,2-year-old,and over 3-year-old seedlings of D. toxocarpa was 84.44%-100.00%,0.00%-15.38% and 0.00%-2.22%,respectively,among which the overall survival rate of over 3-year-old seedlings was less than 1.0%.In conclusion,in the D. toxocarpa community in the rocky desertification mountainous area of southwestern Guangxi,the seed density,seed survival rate and seedling density are obviously affected by microtopography,with low survival rate of perennial seedlings and poor understory renewal ability,and its community management can take measures such as canopy thinning and forest gap removal to improve the microenvironment and promote seedling growth and population renewal.