木荷次生林林木更新与土壤特征的相关性

以湖南省青石冈林场木荷次生林为研究对象,在测定其土壤特征基础上,分析了林木天然更新指数和土壤理化性质的相关性。结果表明:1)8种林分更新状况有差异,更新状况由差到好的排序为:S-CP(0.46)S-DC(0.52)S-CD(0.64)S-CL(0.68)S-CM(0.69)S-CQ(0.69)S-PC(0.74)S-CP(0.88),其中与针叶树种混交的林分更新效果好。2)酸性环境更有利于林分的更新,且林地养分含量越高林分更新效果越好,有机碳、全N以及全P的含量高的林分更新指数明显大于其含量低的林分,土壤pH值、容重与更新指数变化规律相反,全K的含量与更新指数没有明显联系。3)林木更新指数与土壤容重呈显著性负相关关系(r=-0.86**),与土壤含水量(r=0.93**)、有机碳(r=0.90**)、全N(r=0.88**)、水解性氮(r=0.83*)和全P(r=0.78*)呈显著正相关关系,相关性依次减弱,且相关性在不同林分有一定差异,更新状况属于中等水平的林分相关性强,且15—45cm土层土壤理化性质与更新指数的相关性最强;经主成分分析发现,在众多影响林分天然更新的土壤特性当中,含水量、有机碳和全N决定该地区木荷次生林更新的关键因素。研究的结果为森林可持续利用以及木荷次生林的恢复和管理提供科学依据。

Changes in soil properties in regenerating Schima superba secondary forests

Soil physical and chemical properties may be altered in regenerating forests, which may affect site productivity and ecosystem services. In this study, soil physic-chemical characteristics were investigated in a series of regenerating Schima superba secondary forests in Qing Shigang Forest Farm, Hunan province. The correlations between the soil properties and the regeneration index were also examined in the studied sites. The result showed that the eight sampling stands were in different regenerating conditions with an order from poor to high condition as S-CP(0.46) < S-DC(0.52) < S-CD(0.64) < S-CL(0.68) < S-CM(0.69) < S-CQ(0.69) < S-PC(0.74) < S-CP(0.88). The best regenerating condition was found in the Schima superba and conifer mixed forests stands in the study area. Natural Schima superba regeneration was enhanced under acidic environments and in fertilized sites. The high regeneration indexes were found in those forest stands with high organic C, total N and total P contents in soils and low soil pH value and soil bulk density. No considerable relationship was found between the regeneration index and soil K content. The regeneration index was negatively related to soil bulk density (r=-0.86^{* *})and positively relative to soil water content (r=0.93^{* *}), soil organic carbon(r=0.90^{* *}), total nitrogen(r=0.88^{* *}), hydrolyzable nitrogen(r=0.83^*)and total phosphorus(r=0.78^*). The results obtained from the use of principal component analysis indicated that water content, organic carbon and total nitrogen in soils were critical factors in determining natural regeneration of Schima superba forests in the study region. Our results provide scientific basis and reference for restoration and sustainable management of Schima superba secondary forests.