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根层与表层土壤水分的关系,是由较易获取的表层土壤水分信息去探讨较难获取的深层土壤水分信息的重要桥梁。已有的根层与表层土壤水分关系(简称根表关系)大都基于一种作物或一种生态系统。该文根据我国生态系统研究网络,包括森林、草地、农田、荒漠和沼泽生态系统的31个站点109个观测场2006年全年3437对根层和表层土壤水分数据,研究了根表关系以及生态系统、土壤质地、湿润度、植被、土壤厚度和土壤水分量级对根表关系的影响。研究发现,表层和根层土壤水分存在着线性关系。森林和沼泽的根层与表层土壤水分相关程度较高,无论是率定段还是校核段,其决定系数(R2)均大于0.79。农田和草地生态系统的率定段相关性较好,R2均大于0.80,校核段相关性稍弱,R2分别为0.70和0.50。荒漠生态系统的相关关系最弱,率定段的R2为0.62,校核段的R2为0.49。土壤质地和生态系统因素对根表关系的影响较为一致。半湿润带、半干旱带和干旱带的根表关系空间分异性最强;十分湿润带的根表关系与壤土和森林生态系统的根表关系相对应。湿润带内部的根表关系较为一致。将植被对根表关系的影响分为4类,前两类为根表关系微弱的植被,由植被本身或者植被以外的地域因素导致,不适合用根表关系去由表层推算根层土壤水分;后两类为根表关系良好植被,区别为服从和不服从关系总线,可分别用各自的根表关系或者关系总线从表层土壤水分获取根层土壤水分。表层土壤水分与0–20、0–30、……、0–100cm土层的土壤水分均分别具有较好的相关关系,但二者的相关性随土层厚度的增加而降低。不过,即使是土层厚度抵及100cm,R2仍能维持在0.79。通过将土壤水分分别除以所有观测数据的最大值(“标甲”法)和各个生态系统数据的最大值(“标乙”法),发现根表关系不受土壤水分量级本身的影响。
The relationship between root and topsoil moisture is an important bridge to explore the harder to obtain the deeper soil moisture information from the more accessible topsoil moisture information. The existing root and surface soil moisture (referred to as root surface relations) are mostly based on a crop or an ecosystem. Based on the data of 3437 pairs of soil layers and surface soil moisture data from 109 observational sites in 31 sites of forest, grassland, farmland, desert and swamp ecosystem in China, the relationship between root surface and ecology System, Soil Texture, Moisture, Vegetation, Soil Thickness and Soil Moisture Level on the Root-Surface Relationship. The study found that there is a linear relationship between surface and root soil moisture. The correlation between the root and the surface soil moisture in forest and swamp was high, and the determination coefficients (R2) were both greater than 0.79 in both rate and calibration stages. The correlation between cropland and grassland ecosystem was good, with R2 greater than 0.80 and weak correlation in the calibration segment, with R2 of 0.70 and 0.50 respectively. The correlation between desert ecosystems is the weakest, with R2 of 0.62 for calibration and R2 of 0.49 for calibration. Soil texture and ecosystem factors on the relationship between the root and surface more consistent. The semi-humid zone, the semi-arid zone and the arid zone had the strongest spatial differentiation of root-surface relationships. The root-zone relationships of the most humid zones corresponded with the root-surface relationships of loamy soil and forest ecosystems. The root zone inside the wet zone is more consistent. The effects of vegetation on root-surface relationships are divided into four types. The first two types are vegetation with weak root-surface relationships, which are caused by the vegetation itself or the regional factors other than vegetation. The latter two types are good vegetation with root-surface relationships, the difference being obedience and disobedience relational busses, root-layer soil moisture can be obtained from surface soil moisture with their respective root-surface relationships or relational busses, respectively. The surface soil moisture has a good correlation with the soil moisture in 0-20, 0-30, ..., 0-100cm soil layers respectively, but the correlation between them decreases with the soil thickness increasing. However, even though the thickness of the soil reached 100 cm, R2 remained at 0.79. By dividing the soil moisture by the maximum of all observed data (the “standard” method) and the maximum value of each ecosystem data (“standard B” method), the root surface relationships were found to be independent of soil moisture Its own influence.