Study On The Litter And Soil Ecological Stoichiometry In Castanopsis Kawakamii Natural Forest Gaps

Castanopsis kawakamii Hayata is a proper precious and endangered species.The range of its natural distribution is limited,which is almost pure forest above 700 hm2 area in Xiaohu religion,Sanming city,Fujian province of China.C.kawakamii have been high endangered according to the human disturbance,biological characteristics,natural environment and other factors.At present,the number of gaps in C.kawakamii forest is increasing,the number of C.kawakamii population decreasing and it is difficult for seedlings to update.Therefore,how to promote the regeneration of C.kawakamii becomes a top priority.And the size of the gap affects the decomposition of litter material,litter nutrients and soil nutrients,etc.,for the study of C.kawakamii update problem provides an opportunity.At the same time,the ecological stoichiometry mainly studied the proportion of chemical elements in ecological process,which provided a comprehensive method for studying the coupling relationship between litter and soil chemical elements.So the gap is divided into large(>150 m2),medium(50?100 m2),small(30?50 m2),and set in different positions in the forest gaps.Study of decomposable and resistant plant material for the litter and soil ecological stoichiometry in different gap sizes and directions of the forest gaps,in order to understand the distribution of litter and soil nutrient in the gaps and reveal the relationship between litter and soil ecological stoichiometry,which provide a reference for the cultivation of C.kawakamii and soil fertility management.(1)Forest gap sizes had a significant effect on the litter ecological stoichiometry.Litter C and N contents in the large gap size were significantly higher when compared with the medium and small gap sizes.Litter P and K contents were significantly higher in the small gap size than in the large and medium gap sizes.The litter C:N,C:P and N:P in large and medium gap were significantly higher than small gap.The litter C:K and N:K in the large gap size were significantly higher when compared with the medium and small gap sizes,while P:K was significantly higher than large and medium gap sizes.The distribution patterns of nutrient contents in litter were not obvious in different directions of gaps and non-gap,the high value areas of ecological stoichiometry mostly distributed in the gap center.As the lower N:P was accelerate the litter decomposition,the litter decomposition was rapid in the medium gaps,small gaps and at the gap center,which increased the soil fertility and promoted nutrient cycling of underground soil ecosystem.(2)The result showed that the ethanol solution 70%,extraction temperature 80 ? and volume of ethanol-water solution were the optimum conditions in tannin extraction.The extraction content of the tannin was 30.58 g·kg-1.The litter cellulose,lignin,tannin and total phenol contents in the large gap size were significantly higher when compared with the medium and small gap sizes.The resistant plant materials of litter were mostly concentrated in the west(W)direction of gap,while 'the gap center(O direction)was low.The resistant plant materials of litter were more concentrated in the northwest(NW)direction of non-gap,while the north(N)direction was low.Therefore,the resistant plant materials contents of litter were low in the gap center and north(N)direction of non-gap,which had a greater potential for nutrient supply.Simultaneously,we will take measures to promote the resistant plant materials degradation and maintain the nutrient balance in the forest.(3)The soil C,N,P,K contents and C:N in the large gap size were significantly higher when compared with the medium and small gap sizes.The soil C:P,C:K,N:P,N:K and P:K in small gap size were significantly higher when compared with the large and medium gap sizes.The high value area of C and N contents were mostly concentrated in southeast of gaps and non-gap,while soil P and K contents were generally higher in the gap center.The variety of C:P and N:P had the same patterns,the low value area of C:P and N:P mostly concentrated in gap center(O direction).The variety of C:K and N:K had the same patterns,the value of C:K and N:K had not significantly difference in directions.Therefor,the soil fertility were high in large gap size,medium gap size and gap center,which provided high nutrient supply for plant growth.(4)The result of Pearson correlation analysis and Redundancy analysis(RDA)between the decomposable and resistant plant material for the litter and soil ecological stoichiometry showed that the cellulose and tannin contents in litter had a positive significant correlation with soil C and N contents in the large gap size.Moreover,the litter C:P and N:P had a positive significant correlation with soil P and K contents,while had a negative significant correlation with soil C:P,C:K,N:P and N:K in the large gap size.The litter C,tannin and total phenol contents had a positive significant correlation with soil C,N,P and K contents,while had a negative significant correlation with soil C:N,C:P,C:K,N:P,N:K and P:K in different directions,especially the gap center was more obvious.Therefore,the decomposable and resistant plant material contents of litter were low in the large gap size,medium gap size and gap center,indicated that the litter decomposition was rapid and the soil fertility was high,which provided the best location for the plant growth and development.