紫金山栓皮栎林凋落物特性及其对土壤性状的作用

发布时间：2018-03-24 06:31

本文选题：紫金山栓皮栎林　切入点：凋落物分解　出处：《南京林业大学》2015年硕士论文

【摘要】：凋落物作为森林生态系统的重要组成部分,对于森林发挥生态服务功能至关重要。凋落物可以固土保水,还能够通过分解进行物质循环和养分的流动。本文以紫金山次生栓皮栎林为研究对象,从凋落物的分解特性、持水特性、截留降水、阻滞地表径流、抑制土壤蒸发及其对土壤理化性质的影响等方面,对凋落物的水文特性及改土功能展开研究。结果发现:(1)凋落物分解速率与C/N、C/P关系密切,其失重率分别与C/N、C/P呈负相关关系(P0.01);与有机C释放率(P0.01)、N释放率(P0.05)呈显著正相关关系。凋落物分解率及养分、有机C释放率用修正后的Olson指数衰减模型拟合发现,紫金山次生栓皮栎林凋落物半衰期为12个月,分解95%所需时间为58.24个月;除去K的拟合度较低外,各营养元素释放率半衰期PMgNCa有机C,且差异显著,其中Ca、N半衰期较为接近,P、Mg半衰期相差不大,各养分元素及有机C分解95%所需时间也表现为差异显著,表现为PMgN有机CCa。(2)通过室内浸水饱和试验发现,凋落物持水率与时间符合对数函数方程递增,并且持水率半分解凋落物全层未分解层;而凋落物吸水速率随时间呈幂指数函数递减,并且吸水速率始终半分解层凋落物全层未分解层。(3)凋落物对降水的截留与其自然持水率及现存量有关。凋落物降水前后自然含水率差值越大、现存量越大,截留降水的能力越强。凋落物最大能够拦截其自身重量1.23倍的降水。此外,由于凋落物在自然环境下,降水到达地面容易入渗到土壤,或者形成地表径流,所以最大自然含水率与浸水试验得到的最大持水率相差较大,百分差达到126.15%。凋落物阻滞径流与凋落物覆盖厚度、径流深及坡度有关,研究发现,凋落物覆盖厚度相同时,径流深影响着产流时间与坡度的关系,随着径流深的增大,产流时间与坡度的关系逐渐从幂函数递减过渡到递减关系。凋落物抑制土壤蒸发主要与凋落物覆盖厚度及土壤含水率有关,土壤含水率越高,覆盖层越厚,抑制作用越强。(4)凋落物分解对土壤理化性质及养分含量存在一定影响。研究发现,凋落物分解能够降低土壤容重与pH,但是降低程度不明显。研究未发现凋落物分解与土壤总孔隙度、毛管孔隙度和非毛管孔隙度存在相关性。凋落物分解过程中的N、P元素的释放,分别与土壤中全N、有效P的含量显著相关(P0.05)。
[Abstract]:Litter is an important part of forest ecosystem, the forest ecosystem services play a crucial. Litter can soil and water conservation, but also through the decomposition of the material circulation and nutrient flow. In this paper, the purple mountain of Quercus variabilis forest as the research object, from the decomposition of litter, water holding characteristics, interception block precipitation, surface runoff, soil evaporation and its inhibiting effect on soil physicochemical properties, and change the function of soil hydrological characteristics of litter were studied. Results showed that: (1) the rate of litter decomposition and C/N, C/P is closely related to the rate of weight loss, respectively with C/N, C/P showed negative correlation (P0.01); release rate of C and organic (P0.01), the release rate of N (P0.05) showed a significant positive correlation. The rate of litter decomposition and nutrient release rate, organic C by the modified Olson exponential decay model fitting showed that the purple Kimama Jiki of Quercus variabilis forest litter The half-life of 12 months, 95% decomposition time required for 58.24 months; the removal of K fitting degree is low, the nutrient release rate of half-life of PMgNCa organic C, and the difference was significant, including Ca, N P, Mg is close to the half-life, the half-life of less, nutrient elements and organic C solution 95% time also showed significant difference, performance for the PMgN organic CCa. (2) by indoor water saturation test showed that the litter water holding rate and time with increasing logarithmic equation, and the water holding rate of semi decomposed litter layer without decomposition; and water absorption rate of litter was decreasing with time exponential function, and water absorption rate of semi decomposed litter has the whole layer of non decomposed layer. (3) the litter on rainfall interception and natural water holding rate and biomass. Litter precipitation before and after the natural water content difference is greater, the greater the amount of existing, the rainfall interception ability is stronger. The litter Can intercept 1.23 times its weight of precipitation. In addition, the litter in the natural environment, the precipitation infiltration into the soil to reach the ground, or the formation of surface runoff, so get the maximum natural moisture content and immersion test of the maximum water holding rate is larger, up to 126.15%.% of litter and litter blocking runoff cover thickness, depth of runoff and slope, the study found that the litter cover thickness is the same, the runoff depth affects the relationship between the time of runoff and slope, with the increase of runoff depth, runoff time and the slope of the relationship of power function decreasing gradually from the transition to the litter decreased. Inhibition of soil evaporation and litter coverage the thickness and the soil moisture content, soil moisture content is higher, the thicker the coating is, the stronger the inhibition. (4) decomposition has certain influence on soil physical and chemical properties and nutrient contents of litter. The study found that. Litter decomposition can reduce soil bulk density and pH, but lower level is not obvious. The research found no litter decomposition and the correlation between soil total porosity, capillary porosity and non capillary porosity. N in the process of litter decomposition, P elements were released, and total N in soil was significantly related to content of effective P (P0.05).

【学位授予单位】：南京林业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S714

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