作 者 ：柏方敏,田大伦*,方晰,闫文德,梁小翠
期 刊 ：生态学报 2010年 30卷 21期 页码：5832~5842
Keywords:Dongting Lake, protective forest, soil, plant, nutrient concentrations,
摘 要 ：洞庭湖西岸区防护林土壤和植物营养元素含量特征
Abstract:Apart from providing wood materials and other forest side-products, forests provide a great deal of protective services, for example in soil and water conservation, in carbon sequestration, and in reducing the risks of impacts of floods, erosion and drought. The effect of forest structure on nutrient status and cycling is fundamental to our understanding of ecosystem function. To determine the influence of forest structure on concentration, distribution and accumulation of mineral elements, nutrient status in soil and plant of four protective forest types (Preserved forests for soil and water conservation on hilly areas along the lake (PF); Replanting preserved forests for soil and water conservation on hilly areas along the lake (RPF); Protective forest bands on plain area (PFB); and Wave-break Forest bands along the shores of the lake (WFB)) were investigated in western bank of Dongting Lake. Our specific objectives were to (1) quantify variation of pH value, bulk density, texture, organic matter content, and macronutrients (N, P, K, Ca, and Mg) and available-nutrient elements (available-N, available-P, and available-K) concentrations in soils in the four forest types; (2) determine distribution of macronutrient elements in different plant organs in the studied forest stands; (3) calculate biological absorption intensity of nutrients by plants from soil systems; and (4) examine effects of forest structure on nutrient status in these four forest communities. Results showed that average soil bulk density was higher in WFB (1.52 g/cm3) than other forest types (ranged 1.21-1.52g/cm3). Soil pH value was acidic (4.54-5.27) in PF, RPF and PFB, but alkaline (8.18) in WFB. Soil organic matter and total N contents were significantly higher in PF due to more litter accumulated on the forest floor when compared with those in other three protective forest types. The concentrations of available N and P in soil were very low and accounted for 1.46%-3.35% of total N and 0.5%-1.6% of total P in PF, respectively. It was found that total K content was adequate in PF, but was considerable deficient in other three forest types. The average concentrations of total Ca and Mg in soils were statistically higher in WFB (16.89 and 5.03 g/kg，respectively) than in other three stand types. The contents of nutrients in plants changed greatly in different forest types and the concentration of same nutrient element in different plant organs varied widely within the same forest type as well. Based on the biological absorption coefficient (A) (calculated using the equation: A=(Cp/Cn)×100, where Cp and Cp are the concentrations of the same nutrient element in plant and soil, respectively), the total of 66 vegetation species (including tree, shrub, and herbaceous species) in the study sites was classified into three groups: strong absorption species (A＞1000), medium absorption species (A 100-1000) and low absorption species (A<100). Our results demonstrated that nutrient status and distribution in forest stands were strongly influenced by forest community structure. The results provided scientific references for studying nutrient biogeochemistry cycling, constructing and managing the protective forest systems, and assessing and maintaining soil fertility in forest ecosystems.
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