广西木论喀斯特森林土壤养分水平与植被及地形的关系

Relationship between Vegetation, Landform effects and Soil Nutrients in Karst Forest of Mulun, Guangxi, China

摘要:

研究了广西木论喀斯特森林原生植被和次生植被的土壤养分特征，测定了陡坡、缓坡、洼地3种主要地形内林地0~5 cm表层土壤中的有机质(SOM)、氮、磷、钾含量，以及它们在石土面、土面两类主要小生境间的差异。结果表明：林分成熟度高、优势种不明显的原生林积累了高水平的SOM，缓坡石土面最高, 达345 g kg-1，洼地的含量较低，但仍在80 g kg-1以上；土壤全氮(TN)、碱解氮(AN)含量也较高。以红背山麻杆(Alchornea trewioides)、广西野桐(Mallotus conspuyrcatus)、伞花木(Eurycorymbus cavaleriei)等为优势种的次生林，物种多样性较原生林低，SOM、TN、AN含量也低，缓坡石土面和土面小生境的SOM分别为110 g kg-1和77 g kg-1，是原生林的32%和35%，下降幅度最大，其次为陡坡，而洼地的差异不明显。全磷(TP)、有效磷(AP)、全钾(TK)、有效钾(AK)含量在两林型间差异无明显规律。原生林和次生林土壤养分含量(除TK外)以缓坡>陡坡>洼地；但次生林中三者间无显著差异。同类型样地内小生境土壤养分含量(除TK外)均为石土面含量高于土面。

Abstract:

The characteristics of soil nutrients in primary and secondary forests of Mulun Karst forest of Guangxi, China were studied, and the contents of SOM, N, P and K at 0~5 cm depth soil from the three main landforms, such as steep slope, gentle slope and depression, were detected, each including rock-soil (shallow and scattered soil) and soil surface microhabitat (relatively thick and continuous soil). The results showed that the contents of SOM, TN and AN were high in primary forest with high species diversity, with 345 g kg-1 of SOM in rock-soil surface microhabitat of gentle slope, while above 80 g kg-1 in soil surface microhabitat of depression. However, those decreased in secondary forest dominated by Alchornea trewioides, Mallotus conspuyrcatus, Eurycorymbus cavaleriei with lower species diversity. The SOM contents in rock-soil (110 g kg-1) and soil surface microhabitat (77 g kg-1) in gentle slope decreased significantly, which were only 32% and 35% of that in primary forest, respectively; but there were not significant differences in SOM, TN and AN contents in depression between the two vegetations. There were not obvious regularities in TP, AP, TK and AK contents between the two vegetations. The soil nutrient contents (except for TK) raged in order: gentle slope > steep slope > depression, but there were not significant differences among the three landforms in secondary forest. The soil nutrient contents (besides TK) in rock-soil surface microhabitat were higher than that in soil surface microhabitat.