落叶松、水曲柳、樟子松和农田土壤指标差异及其综合比较

摘要

东北地区以大森林和大农业为主要特色,主要造林树种落叶松、水曲柳、樟子松及农田对土壤肥力、物理指标、盐碱度、碳截获等的影响差异是本文研究目的.选择秀水林场和帽儿山林场的4种植被类型进行0-60cm分层土壤采样,对根系密度、土壤pH、电导率、全氮、全磷、全钾、碱解氮、速效磷、速效钾、土壤真菌代谢产物(球囊霉素相关蛋白易提取球囊霉素EEG、总提取球囊霉素TG)、容重、比重、孔隙度、比表面积、SOC、有机碳矿化速率等17个指标进行研究.主要结论如下:植被类型间的差异在不同土层之间表现一致的指标所占比例很大,其中秀水林场13个指标,帽儿山林场全部17个指标.尽管不同地点间土壤差异较大,但也存在树种差异一致性.土壤物理性质(容重、比重、孔隙度、比表面积)维持方面,两个林场均显示水曲柳综合得分最高,说明其具有更好的土壤物理性质维持能力,且多通过土壤容重下降来实现.土壤固碳能力得分最高的也是水曲柳,并且两个研究地点结果类似,主要与其高根系密度有关.综合土壤肥力维持能力(N、P、K及其有效态及真菌代谢产物球囊霉素相关蛋白),不同地点间植被类型差异排序不同.降低土壤盐碱能力(pH和电导率)方面,樟子松得分最高,尽管不同地点不尽一致.不同植被类型对土壤影响尽管不同地点、不同土壤深度多不相同,但总体上存在规律性,特别是土壤物理性质维持和土壤固碳能力方面.进行造林绿化时应该根据造林目的进行树种选择,提升土壤物理性质应该考虑种植更能够维持良好土壤物理性质的树种(如水曲柳、樟子松等),而提升土壤碳截获则要考虑根系密度大的树种(如水曲柳).相关研究结果对国家重大生态工程(三北防护林、退耕还林)工程生态功能评价以及后续管理、树种选择具有支撑作用.%The main characteristics of Northeast China are large forests and agriculture.The effect of the primary afforestation species (larch:Larix gmelinii,ash:Fraxinus mandschurica,Scots pine:Pinus sylvestris var.mongolica) and farmland on soil fertility,physical properties,salinity,and carbon sequestration were analyzed.In the present study,four vegetation types were selected from Xiushui Forest and Maoershan Forest Farms,and samples from 0-60 cm soils were collected for measuring 17 parameters,including root density,soil pH,electrical conductance (EC),alkali-hydrolyzed nitrogen (AN),total nitrogen (TN),available phosphorus (AP),total phosphorus (TP),available potassium (AK),total potassium(TK),glomalin related soil protein (GRSP) (including easily extracted GRSP (EEG) and total GRSP (TG)),soil bulk density,soil specific gravity,soil porosity,soil specific surface area,soil organic carbon (SOC),and organic carbon mineralization rate.The main conclusions were as follows:inter-species differences between most of the measured indicators were consistent in different soil layers,including 13 indicators in the Xiushui Forest Farm and all 17 indicators in the Maoershan Forest Farm samples.Although there were considerable differences in soil between different locations,the inter-species differences were consistent.Through comprehensive analyses,standardized comprehensive scores of two forest farm-related indicators showed that ash had the highest scores regarding its ability to maintain the physical properties of soil.Therefore,ash had the greatest ability of all the trees and farmland to maintain the physical properties of soil,and depended primarily on decreased soil bulk density.Ash also showed the highest scores for soil carbon sequestration,with similar results at both locations,mainly related to its higher root density.The comprehensive soil fertility (N,P,K,and its effective state,and fungal metabolic product GRSP) indicated inter-species differences between the different locations.Scots pine had the highest scores for reducing the soil salinity (pH and EC).The effects of different vegetation types on the soil were not the same in different locations and soil depths,but there was a general regularity,especially regarding the soil physical properties and carbon sequestration.Therefore,the selection of tree species for afforestation should be planned depending on the particular purpose of afforestation.To improve the physical properties of soil,plant species with the ability to maintain the physical properties effectively (e.g.,ash,Scots pine) should be considered;and to enhance soil carbon sequestration,plant species with large root densities (e.g.,ash) should be considered.The findings in this paper will enhance the evaluation of the national ecological projects of the Three-North Shelterbelt Project and Returning Farmland to Forest Project,and forest management including tree species selections.