| The karst ecosystem is widely distributed in the southwestern part of China.The complexity and heterogeneity of karst habitat determines that we can not use the conventional method to study the relevant characteristics of litter in the karst area,and we must study it with the niche.Based on the interfacial systems appearing in the karst area due to the appearance of rocks,this paper studies the characteristics of litter and discusses the characteristics of nutrient utilization and the influence of interface system on the karst area.The results are as follows:(1)According to the characteristics of karst ecosystem habitat,the karst ecosystem interface is divided into three types: soil and stone interface,soil interface and stone interface.The interface area of the study area is calculated as: 9.64%,59.62% and 30.74% of the total area of the soil and stone interface,soil interface and stone interface,respectively.(2)Among the three vegetation types of tropical rain forest,tropical monsoon forest and subtropical evergreen broad-leaved forest,the maximum thickness of litter was the tropical monsoon forest(0.38cm),May be related to its high temperature and rainy weather,community life structure and biodiversity.The maximum thickness of the semi-decomposed layer is subtropical evergreen broad-leaved forest(0.40cm),which is related to the low decomposition rate.The largest humus thickness is tropical rain forest(0.52cm).In the three different successional stages of primary forest,secondary forest and shrub,the thickness of litter was the largest(0.60cm),which was related to the sampling site terrain.The thickness of litter was the largest(0.96cm),May be due to less precipitation,litter decomposition rate is low;humus layer thickness is the largest native forest(1.01cm).The interface has a significant effect on the litter thickness: the increase of the interface area of the stone will cause the litter thickness to decrease and the decomposition rate decrease,and the increase of the interface area will cause the litter thickness to increase and the decomposition rate increase.(3)The decomposition rate of litter in the three sites of Guqingqing,Ailao Mountain and Shilin was studied.Guqingqing(60.6±0.012%)> Ailao Mountain(42.03±0.032%)>Shilin(33.69±0.129%).Guilinqing belongs to the tropical rain forest climate,rainfall is more,the temperature is higher,the microorganism is active,the litter decomposition rate is quick;Ailao Mountain belongs to the subtropical Zhongshan humid climate,but the decomposition rate is faster than the stone forest,mainly because of the rain More relevant.The annual decomposition rate of litter was significantly different among the three climatic types(P <0.05).(4)Tropical rainforest,tropical monsoon forest and subtropical evergreen broad-leaved forest.The highest nutrient content of litter in the three types of vegetation was tropical monsoon forest because the climatic types were dry and wet,And the highest amount of litter was higher.The highest content of semi-decomposed layer was subtropical evergreen broad-leaved forest,which was mainly due to the low decomposition rate of litter.The highest nutrient content of the fresh layer of litter was the main forest,which was mainly related to the higher biological diversity of the original forest.The highest nutrient content of the semi-decomposed layer was secondary forest,The rate of low litter residue is greater.In the karst area,the interface type had an effect on the nutrient content of the litter.The interface between the soil interface and the soil interface had a great influence on the contents of ammonium nitrogen,nitrogen,potassium and phosphorus in litter and semi-decomposed layers.Magnesium content of the outstanding impact.(5)Tropical rain forest,tropical monsoon forest and subtropical evergreen broad-leaved forest.The highest content of soil humus in the three types of vegetation is tropical rain forest,which is related to the nutrient supply of litter;Is the tropical monsoon forest,the main reason is the decomposition rate of litter is low,the supply of soil nutrients less,while the dry season rainfall will reduce the nutrient transport efficiency.The highest content of soil humus in the five vegetation successional stages of primary forest,secondary forest and shrub,grass and bare ground is the highest in the original forest,the lowest is the grass and bare land;the soil leaching layer has the highest nutrient content,The grass and bare land.The interfacial structure has a great effect on soil nutrient content,especially the soil interface playsa key role in the accumulation of soil nutrients.(6)Tropical monsoon forest,tropical monsoon forest and subtropical evergreen broad-leaved forest have the highest nutrient cycling efficiency in tropical monsoon forest.The rain and rain environment of tropical monsoon forest is worse than that of tropical rain forest,The nutrient content of the vegetation is lower than that of the vegetation,and the nutrient efficiency is the highest in the three vegetation successional stages of the primary forest,the secondary forest and the shrub,and the vegetation is degraded with the ecosystem,Plants in the absence of sufficient nutrients,will choose to improve the efficiency of nutrient use to adapt to the coercive environment.In the karst area the soil interface basically occupies large proportion,while the nutrient circulation plays a key role.(7)Vegetation type,vegetation succession stage,interface type had some influence on nutrient content of litter,soil nutrient content and nutrient cycling rate in karst area. |
PDF Full Text Request