峰丛洼地不同林龄核桃生物量与土壤养分的关系

文章以喀斯特峰丛洼地的核桃（Juglans regia）人工林为研究对象，采用野外与室内相结合的方法，分析了不同林龄核桃生物量与土壤养分的变化规律，比较了土壤养分与环境因子（坡度、坡向、坡位和裸岩率）的相关性，探讨了土壤养分对生物量的影响作用。结果表明:(1) 核桃林生物量随林龄的增大而增大；不同林龄均以树干和根系比重为主，占整个生物量的60%以上；(2) 除速效钾外，土壤养分表现为盛产期(33年)>幼苗期(2年)>初果期(10年)，不同林龄之间的土壤养分差异显著；(3)相关分析表明，土壤养分与坡位、裸岩率无相关性，与坡度、植被覆盖率呈负相关；(4)主要影响核桃幼苗期生物量的是全磷，初果期的是速效磷，盛果期的是速效氮。因而土壤肥力状况是喀斯特地区核桃人工林培育需要考虑的重要因素之一。 

Relationships between biomass of the Juglans regia trees in different stand ages and soil nutrients in karst peak-cluster depression

The objective of this study is to explore the change process and the relationships between biomass and soil nutrients for different-aged Juglans regia plantation in karst peak-cluster depression in the northwest of Guangxi Province. Based on a combination of field investigation and laboratory analysis, this study analyzed the change in biomass and soil nutriens and the influence of soil nutrients on the biomass of the Juglans regia trees in different stand ages. It also discussed the biomass of the Juglans regia trees and associated soil nutrients; and established relationship between soil nutrients and environmental factors (e.g. slope aspect, gradient and position and bare rock rate). The biomass of the Juglans regia trees increases along with the stand age, of which the trunk and root accounted for more than 60% of the total biomass. Except for the available potassium, the soil nutrients have such a trend as rich fruiting period (33 years) > seedling stage (2 years) > early fruiting (10 years). The result of correlation analysis showed that there was no significant relationship between soil nutrient, slope position and bare rock rate. However, there was negatively significant correlation between soil nutrient, slope, and vegetation coverage. The biomass of the Juglans regia trees is a result of the combined influence of various factors and their growth at different stages is affected by different factors. For example, in seedling period the biomass of the Juglans regia trees is controlled by total phosphorus; but that is controlled by available phosphorus in early fruiting and by available nitrogen in rich fruiting. Based on these findings, soil nutrient should be considered as one of key factors in the Juglans regi plantation cultivation in karst regions.