浙江省临安市山核桃产区林地土壤有机碳分布特征

Distribution characteristics of soil organic carbon in Carya cathayensis producing regions of Lin'an City,Zhejiang Province

为阐明我国特色干果山核桃(Carya cathayensis)林地土壤有机碳的分布特征,于2008年7—8月采用1km×1km网格在浙江省临安市域内设置山核桃林样地306个,采集0～30cm土壤样品,分析其有机碳和其他养分含量及其空间分布特征.结果表明,不同区域山核桃林地表层土壤有机碳质量分数、碳密度存在较大的差异,平均值分别为18.87g/kg和60.92t/hm2,明显低于相同区域的常绿次生阔叶林.多元协方差分析表明,海拔、乡镇和母岩类型等3因素是影响临安市山核桃林地土壤有机碳含量的主要因素.大峡谷镇山核桃林地土壤有机碳平均含量最高,显著高于河桥、马啸、湍口、清凉峰等乡镇;随着海拔高度的升高,山核桃林地土壤有机碳含量增加,海拔在800m以上的山核桃林地土壤有机碳含量显著高于600m以下的山核桃林地土壤;花岗岩发育的山核桃林地土壤有机碳含量显著高于砂页岩发育的土壤.临安市山核桃林主要分布在西部山区,面积29 047.1hm2,0～30cm土壤有机碳总贮量为1 828.92×103t.土壤有机碳含量与pH、容重呈极显著负相关(R2=0.187 1～0.207 6,n=306,P<0.01),而与碱解氮、有效磷、速效钾和有效硫含量呈极显著正相关(R2=0.193 1～0.708 7,n=306,P<0.01).

Hickory（Carya cathayensis）is a plant famous for production of edible nuts and oil in southeast China,which is mainly distributed in Tianmu Mountain at the junction of Zhejiang and Anhui Provinces.There is a long cultivation and utilization history of hickory,and continued development and adaption of advanced management practices since 1980s,such as high fertilizer addition and effectively artificial weeding techniques,etc.However,this intensive management for highly economic profit of nut production may lead to soil degradation,and the influence of such intensive management measures on soil organic carbon（SOC） under hickory forest has not yet been reported.So the objectives of this study were to investigate the effects of intensive management on SOC content and distribution of hickory forest,which could provide useful information for sustainable management of hickory forests.The experiment sites located in Lin ’ an City（118°51′-119°52′E,29°56′-30°23′N）,which were the major production base of hickory and the total acreage reached 29 047.1hm 2.Soil samples（0-30cm depth） were collected from 306plots with the areas of 1km by 1km for each plot between July and August in 2008according to the multi-point sampling method.The characteristics of each sample plot were recorded such as altitude,parent rock,soil species and slope,and the soil bulk density,SOC content and other soil nutrients were measured in the laboratory.The results showed that the average SOC content and density were 18.87g / kg and 60.92t / hm 2,which were significantly lower than those under evergreen broad-leaf forest.Multivariate covariance analysis showed that the SOC content of hickory forest was significantly influenced by three factors of altitude,parent rock and township.The SOC content（21.59g / kg） in Daxiagu town was significantly higher than those in Heqiao,Maxiao,Tuankou and Qingliangfeng towns.The SOC content enhanced with the increase of altitude.It was also found that the SOC content in granite rocks was significant higher than those in sandshale rocks.The total storage of SOC on 0-30 cm layers was 1 828.92×10 3 t.Soil pH and bulk density showed significantly negative correlations with SOC content（R 2 =0.187 1-0.207 6,n=306,P0.01）.Furthermore,SOC content was significantly and positively correlated with available nitrogen,available phosphorus,available potassium and available sulfur（R 2 =0.193 10.708 7,n=306,P0.01）.In conclusion,to sustain the soil organic carbon and C.cathayensis production,it is recommended that more organic fertilizers（manures） should be used together with chemical fertilizers.