摘要
以广东鹤山市退化丘陵荒坡地为材料 ,研究了这一特殊生态类型的土壤养分水平 ,土壤养分在剖面上的梯度和在坡面上的梯度特征 ,分析了养分间的相关性 ,应用聚类分析和主分量分析方法探讨了坡面上不同位置土壤的相似性。结果表明 ,表层土壤养分水平介于同地带森林土壤与极度退化土壤之间 ,有机质和全氮随深度增加而迅速下降 ,p H与全磷则成相反的趋势 ,而速效养分表现出双向梯度特征 ,即中间层次含量较低 ,表层与深层含量均较高。坡面上 ,有机质、全氮和速效磷随相对高度的增加而下降 ,p H在整个坡面上变化极小 ,全磷和 3个交换性阳离子则成双向梯度 ,即坡的中部含量较低 ,山顶与山脚含量较高。有机质与全氮间具有极高的相关性 ,p H与有机质含量在剖面样品上有较高的负相关 ,但在坡面样品上完全不相关 ,具有相似吸附特性的交换性钙镁间有极高的相关性 ,交换性钾亦与交换性钙镁有较好的相关性。聚类分析与排序分析结果显示 ,作为低丘陵荒坡地 ,坡面不同位置的土壤均较相似 ,但在一些位置出现养分含量上较独特的土壤 ,主要表现在一种或几种速效养分特别高 ,它们不规则地出现于一些集水区的山腰或山脚部位 ,但未出现于山顶部位 。
Discussed the nutrient properties in the soils of typical degraded hilly land in south China. Degraded hilly lands are caused by long-term intensive human disturbance. They are now partly cultivated mainly as fruit farms and partly abandoned with little disturbance as a result of economic development in rural areas. In this study, 6 small catchments, each approximately 5～8 hm2, were sampled. One or 2 soil profiles in each catchment were dug up to 1 m depth and soils were taken across the profiles. Each catchment was divided into upper, middle and foot parts. Each part was further sub-divided into left, middle and right positions. In each position, a mixed soil sample was taken consisting of 10 small soil cores, each with diameter of 3 cm and depth of 20 cm. Soil samples were analyzed for major nutrients such as organic matter (OM), total nitrogen, total phosphorus, available phosphorus, available potassium, C/N ratio, exchangeable calcium and exchangeable magnesium, including pH (water extract). Mean organic matter content of surface soil was determined to be 18.03 g/kg and total nitrogen 0.86 g/kg. Soil pH values ranged from 4.06 to 4.57 with mean of 4.25. Available nutrients were generally low, particularly for available phosphorus. Across the profile, both organic matter and total nitrogen decreased sharply with increasing depth, reflecting the features of grassy vegetation. Soil pH, as well as total phosphorus, increased with the increasing depth. The available nutrients exhibited a bi-directional gradient, that is, low in the middle layer and high in both surface layer and deep layer. On the hill slope, soil OM, total nitrogen and available phosphorus all decreased with altitude increasing. Total phosphorus and exchangeable potassium, calcium and magnesium were all bi-directional, that is, low in the middle position and high in both hill top and hill foot. OM and total nitrogen, both as bio-originated, were significantly correlated to each other. pH was negatively significantly correlated to OM in t
出处
《生态学报》
CAS
CSCD
北大核心
2003年第8期1648-1656,共9页
Acta Ecologica Sinica
基金
国家自然科学基金资助项目 ( 3 0 1 70 1 91
3 0 2 0 0 0 3 5 )
广东省自然科学基金资助项目 ( 2 0 0 0 0 976
0 0 3 0 3 1 )
中国 -澳大利亚合作资助项目 ( ACIAR Project FST97/77)
中国科学院华南植物研究所所长基金资助项目~~
关键词
退化丘陵荒坡地
土壤养分
小集水区
数量分析
degraded hilly land
soil nutrient content
small catchment
numerical analysis
