广西杉木主产区连栽杉木林地土壤肥力综合评价

Assessment of soil fertility of continuous plantation of Cunninghamia lanceolata in main producing regions in Guangxi

利用空间换时间方法,选择p H值、有机质、全N含量等15个土壤理化性质指标作为评价指标,采用主成分分析方法综合评价广西主产区1、2代杉木幼林土壤肥力,旨在为广西连栽杉木人工林的可持续经营提供数据支持,为其它森林土壤肥力评价提供参考。结果表明:土壤大、中量元素含量是土壤肥力的决定性因素。广西杉木主产区不同代数的养分规律大致表现为:2代林0-20 cm>1代林0-20 cm>2代林20-40 cm>1代林20-40 cm。广西不同产区杉木林地土壤肥力规律:桂北>桂东>桂中,从各主产区看,F值为负值占总试验个数(12个)的41.66%。说明广西部分杉木林地土壤肥力较低,对于该部分的林地要重视科学合理施肥。广西连栽杉木土壤肥力综合评价指数F值在(-2.048)-2.676之间,2代杉木幼林的土壤肥力高于1代幼林,这可能是炼山和采伐剩余物归还于林等经营措施共同作用下的短期效应。可见采取有效的培肥沃土的森林经营措施,可一定程度上防止连栽林地土壤退化。

The space-for-time method was applied, soil pH value, organic matter and total nitrogen （ fifteen indexes） were chosen as evaluation indexes in principal component analysis in order to provide data supports for sustainable forest management of the continuous planting of Cunninghamia lanceolata （ Lamb. ） Hook. in Guangxi, so as to offer the references to the soil fertility quality assessment of forest ecosystems in other regions. Soil fertility quality between the first and second generations of the young C. lanceolata plantation was further assessed with principal component analysis. The results showed as follows. Soil macro-elements and microelements were key factors in determining soil fertility. Major nutrients in different generations of C. lanceolata plantation in Guangxi appeared to be in the following sequence, 0-20 cm layer of soil fertility in the second generation C. lanceolata plantation〉0-20 cm layer of soil fertility in the first generation C. lanceolata plantation 〉 20- 40 cm layer of soil fertility in the second generation C. lanceolata plantation〉20-40 cm layer of soil fertility in the first generation C. lanceolata plantation. The sequence of the soil fertility extent in the three major producing regions in Guangxi was ranked as north, south and central areas. In this experiment, 12 soil samples were set up, among those, the fischer ratio to a negative value constituted about 41.66 percent of the total samples, indicating fertility of the part of soil on C. lanceolata forest lands in Guangxi at a relatively low level. Therefore, the rational fertilization had to be advocated to ensure conservancy sustainable development of the field of successive planting C. lanceolata. Comprehensive scores from -2.048 to 2.676. The soil fertility quality of the second generations of the young C. lanceolata plantation was higher than the first one, it may he a temporary, synergism effect between buring and logging residue utilization in soil. Therefore, the soil fertility betterment measures can help to prevent soil degradation.