| The inefficient plantation hinders the ecological function of plantation and restricts the development of forestry.Planting the native broadleaf trees with forest gap disturbance is an effective way to improve the forest structure and forest quality and enhance the ecosystem service function of the plantation forest.The C,N,P elements and their ratios indicate the growth and physiological effects of plant.The ecological stoichiometry characteristics of litter and soil are important indicator of forest quality,elemental cycle and nutrient use efficiency.Both of them are of great significance to maintain the stability of forest structure and the balance of forest ecosyste-m.By studying the relationship of nutrient stoichiometric between plants,litter and soil in a Kobayashi inefficient forest after forest gap transform,It can provide scientific basis for the sustainable management of plantation,nutrient management,forest land maintenance and the formulate of management measures.In this study,we take an inefficient forest of P Hragmites funebris in the hilly area of central Sichuan as research object,after the transformation of forest gap(50?100?150 m2 and 200 m2)by three years,through analyzing nutrient distribution pattern(C?N?P)and stoichiometric ratio(C:N?C:P?N:P)of replanting Toona sinensis and Cinnamomum septentrionale in the growth season(April,July,October,December),we studied the effect of those changes on forest gap.The results are as follows:(1)The forest gap treatment significantly improved the cotent of C,N,P in the leaves of Toona sinensis and Cinnamomum septentrionale.With the increase of forestgap area,the content of Na nd P in the leaves of Toona sinensis and Cinnamomum septentrionale increased gradually.Toona sinensis>Cinnamomum septentrionale>Cupressus funebris.By the way,the cotent of C increased,too.Cupressus funebris>Cinnamomum septentrionale>Toona sinensis.In different treatment,there was a very significant difference(P<0.01)in N,P content in the leaves of Toona sinensis in April and July,and there was a very significant difference(P<0.01)in N,P content in the leaves of Cinnamomum septentrionale in October,December and Apirl.The difference in N content in the leaves of Cinnamomum septentrionale was very signi:ficant(P<0.01),and the difference of P content was not significant(P>0.05).In the same season,there was no significant difference in the content of C in the leaves of Toona sinensis and Cinnamomum septentrionale in different treatment(P>0.05).During the growing season,the C content in the leaves of Cupressus funebris showed a trend of "decreasing-increasing-decreasing",and the C content in the leaves of Toona sinensis and Cinnamomum septentrionale showed a trend of "rising-decreasing-decreasing".The contents of N and P in leaves of three species were "Decreasing-decreasing-decreasing",and the seasonal variation trend of the cotent of Pand N of tree leaves was consistent.(2)The forest gap treatment significantly improved the content of C,N,P in the litter of Toona sinensis and Cinnamomum septentrionale.With the increase of forest gap area,the content of N and P in the litter of Toona sinensis and Cinnamomum septe-ntrionale increased gradually.The C content:Cupressus funebris>Cinnamomum seplentrionale>Toona sinensis.The N content:Cinnamomum septentrionale>Toona sinensis>Cupressus funebris.in addition to forest gap of 200 m2.The P content:Toona sinensis>Cinnamomum septentrionale>Cupressus funebris.There was a very significant difference(P<0.01)in N,P content in the litter of Toona sinensis between different treatment in October.And the content of C was not significant(P>0.05),There was no significant difference(P>0.05)in N content in the litter of Toona sinensis between different treatment in December,and the difference of P content was very significant(P<0.01),and the difference of C content was significant(P<0.05).There was a very significant difference(P<0.01)in N and P content in the litter of Cinnamomum septentrionale between different treatment in April,July,October and December,and the difference of C content was not significant(P>0.05),the content of C,N,P in the litter of tree was consistent with the seasonal variation and leaves trend.(3)The forest gap treatment significantly improved the content of C,P in the soil of 0-40cm.There was a very significant difference(P<0.01)in C,N,P content in the soil of 0-40cm between different treatment in April,July,October and December,And the N content in the gap was lower than that in the control.From the point of view of the annual mean value,the maximum content of C in soil appeared in the gap of 200m2,and the maximum content of N and P in soil appeared at 150m2.The Soil of 0-5 cm(?):There was a very significant difference(P<0.01)in C,P content in the soil between different treatment in April,July.October and December.In April,there was no difference in content of P in soil of Toona sinensis and Cinnamomum septentrionale(P>0.05).The content of C and N has reached a very significant difference(P<0.01).The Soil of 5-20 cm(?):There was a very significant difference(P<0.01)in C.N content in the soil of Toona sinensis between different treatment in October,the content of P was significantly different(P<0.05),The content of C,N and P in the soil of Toona sinensis has reached very significant level between different treatments in April,July and december(P<0.01).The content of C,N and P in the soil of Cinnamomum septentrionale has reached very significant level between different treatments(P<0.01)in April,July,October and december(P<0.01).The soil of 20-40 cm(?):the contents of C,N and P in the soil of Toona sinensis and Cinnamomum septentrionale were different in April,July,October and December.During the growing season,the trend of C content was "decreasing-increasing-decreasing" in ?,?,? and 0-40cm soil layer of under forest and manual update forest gap.The trend of N,Pwas "decreasing-increasing-smoothing" The content of C,N and P in the soil nucted a litter from month to month.(4)The forest gap treatment significantly reduced the C:N and C:P in the leaves of Toona sinensis,Cinnamomum septentrionale,with the increase of the gap area,the C:N and C:P in the leaves of Toona sinensis,Cinnamomum septentrionale decreased gradually,Cupressus funebris>Cinnamomum septentrionale>Toona sinensis,the N:P in the leaves of Toona sinensis and Cinnamomum septentrionale reached the maximum at the 150m2 gap,in addition to the 150m2 forest gap,Toona sinensis>Cupressus funebris>Cinnamomum septentrionale:the C:N.C:P.N:P in the leaves of Toon sinensis in October was not significant(P>0.05)between different treatment.the C:N,C:P in leaves of Toona sinensis in April was significant(P<0.01)between different treatment,but the N:P in leaves of Toona sinensis in April was not significant(P>0.05)between different treatment,there was a very significant difference(P<0.01)in C:N in the leaves of Toona sinensis in July between different treatment,and there was a significant difference(P<0.05)in C:P in the leaves of Toona sinensis in July between different treatment,but the N:P in the leaves of Toona sinensis in July between different treatment was not significant(P>0.05);there were significant differences(P<0.05)in C:N in the leaves of Cinnamomum septentrionale in October and December between different treatments,the C:P in the leaves of Cinnamomum septentrionale in October and December between different treatments were very significant(P<0.01),the N:had a insignificant difference(P>0.05)in the leaves of Cinnamomum sptentrionale in October,December,April between different treatments,the C:N and C:P had significant difference(P<0.05)in the leaves of Cinnamomum septentrionale,there was a significant difference(P<0.0])in C:N in the leaves of Cinnamomum septentrionale between dif-ferent treatments,but there was no significant difference(P>0.05)in C:P and N:P in the leaves of Cinnamomum septentrionale.During the growing season,the trend of C:N,C:P was:"increasing-increasing-increasing" in the leaves of Cupressus funebris,Toona sinensis and Cinnamomum septentrionale,the trend of N:P was:"increasing-increasing-decreasing "in the leaves of three trees.(5)The forest gap treatment significantly reduced the C:N and C:P in the litter of Toona sinensis,Cinnamomum septentrionale,with the increase of the gap area,the C:N,C:P and N:P in the litter of Toona sinensis,Cinnamomum septentrionale decreased gradually,C:N and C:P:Cupressus funebris>Cinnamomum septentrionale>Toona sinensis,N:P:in addition to the 50m2 forest gap,Cupressus funebris>Cinnamomum septentrionale>Toona sinensis.There was a significant difference in C:N,C:P in the litter of Toona sinensis in October between different treatments,but a insignificant difference in N:P in the litter of Toona sinensis in October between different treatments,there was a insignificant difference in C:N,C:P,N:P in the litter of Toona sinensis in December between different treatments.The C:N in the litter of Cinnamomum septentrionale was not significant in October(P>0.05)between different treatments,but the C:P,N:P in the litter of Cinnamomum septentrionale was very significant in October(P<0.01)between different treatments;the C:N in the litter of Cinnamomum septentrionale was very significant in December(P<0.01)between different treatments,the C:P in the litter of Cinnamomum septentrionale was significant in December(P<0.05)between different treatments,the N:P in the litter of Cinnamomum septentrionale was not significant in December(P>0.05)between different treatments;there was a significant difference in C:N in the litter of of Cinnamomum septentrionale in April,July between different treatments,the C:P in the litter of Cinnamomum septentrionale was very significant(P<0.01)in April,July between different treatments,the N:P in the litter of Cinnamomum septentrionale was not significant(P>0.05)in April.July between different treatments.The seasonal variation of C:N,C:P and N:P in three trees was consistent with leaf.(6)The forest gap treatment significantly increased the C:N in the soil(0-40cm)of Toona sinensis,Cinnamomum septentrionale,reduced the C:P.N:P in the soil(0-40 cm)of Toona sinensis,Cinnamomum septentrionale.There was a significant difference(P<0.01)in C:N.C:P,N:P in the soil(0-40cm)in April,July,October,December betw-een different treatments,the maximum C:N value of annual average angle was in the 50m2 forest gap,and the maximum value of C:P and N:P appeared in the 100m2 forest gap.The significant difference of C:N,C:P,N:P in the soil(?,?,III)of CK,artificial regeneration forest gap in April.July,October,December were different.During the growing season,the trend of C:N,C:P in the soil was:"increasing-increasing-decreasing",the C:N in the soil of forest gap is higher than CK,but the C:P,N:P in the soil of forest gap is lower than CK.The analysis of variance showed that the seasonal difference of soil C:N was different in each forest gap.The seasonal variation of soil N:P under artificial regeneration forest gap is stable.(7)According to the study of analysis of nutrient elements and stoichiometry in leaf and soil,the C:N and N content,C:P and P content in the leaf of three trees were negatively correlated,C:N,C:P decreasing with the increasing of N,P content,fitting the relationship between them by linear equation.There was a positive correlation between soil N and P content,but also showed a negative correlation,which is different from previous studies,this may be due to geographical reasons.Soil C:N and N content,soil C:P and P content in the linear regression equation showed a negative correlation,indicating that the soil C:N,C:P,respectively,with the increase of soil N,P content decreased.There was no significant correlation between the ecological stoichiometry characteristics of leaf,litter and soil in the samespecies.In addition,the ecological stoichiometric characteristics of the three trees were different for the gap treatment,and the C,N and P elements in the 200m2 gap were best,the N:P in the leaf of three trees was less than 14,indicating that its growth by the N restrictions,in the subsequent management of technical measures or new afforestation,it is recommended that adding appropriate amount of N fertilizer in the sum-mer,priority is given to the selection of alternative tree species,such as native broadleaf or solid tree species(Alnus cremastogyne,Coriaria nepalensis Wall.,etc.).The C and P content were higher than those in the forest(CK),and the maximum value of C and P content were appear in 150m2 forest gap,and the 200m2 forest was the second,which indicated that the artificial regeneration forest gap improved the soil fertility of inefficient cypress forest,and the effect in 150m2 and 200m2 forest gap is ide-al.With the increase of the gap,the C:N,C:P in the leaf and litter were decreased,which indicated that the utilization efficiency of N and P was decreased with the increase of the gap;the N:P maximum in the leaf appeared in the 150m2 gap,indicating that the growth of trees in 150m2 forest gap was less limited by N.The C:N maximum in soil appears in 50m2 gap,100m2 gap was second,The C:P maximum in soil appears in 100m2 gap,200m2 gap was second,indicating that the utilization efficiency of N,P in soil in 200m2 gap were better.The contents of C,N and P in leaves andsoils of the three trees changed with the seasons,but the trend was not the same,which indicated that the content of nutrient elements in the leaves of plants was influenced mainly by their geneticfactors.The season al variation of Toona sinensis and Cinnamomum septentrionale is similar which may be related to the biological habits of the tree species,since they are all broadleaved species.The C:N,C:P in th e leaf Cupressus funebris>Cinnamomum septentrionale>Toona sinensis,indicatingthat Cupressus f unebrisand Cinnamomum septentrionale had higher utilization efficiency of N,P,Toona sinensis h ad low utilization efficiency of N,P;in addition to 150m2 gap,the N:P in the leaf:Toona sinen sis>Cupressus funebris>Cinnamomum septentrionale,indicating that the Toona sinensis w as restrictted by N was smaller.The seasonal variation trend of soil and leaf of three trees was di fferent,which indicated that leaf nutrient was.from soil and had some coupling relationship with s oil nutrient.The forestland productivity of Cinnamomum septentrionale is higherthan Toona sinensis,and Cinnamomum septentrionale retains higher N and P nutrient reservoirs.From an annual p erspective,the overall soil quality is in the middle and lower levels comparedwith the national a verage soil nutrient level.The contents of C and N in ineffient cypress treeswere as follows:1 eaf?litte>soil,and there was a certain coupling relationship between the three reservo irs,C,N and P elements were transported between the three reservoirs.The content of C,N,P and the ecological stoichiometry ratio of leaves,litter and soil were different under different t reatments,which indicated that the forest gap affects the nutrient allocationpattern and stoichi ometric characteristics of Cupressus funebris inefficient forest ecosystem.There isno significant co rrelation of ecological stoichiometry in leaf,litter and soil in the same tree species,which is r elated to the selective absorption of nutrients by tree species.As an important way to update the plantation,the gap can affect the morphological and physiological functions of the plant by changing the effective soil resources,and also affect the distribution pattern and stoichiometric characteristics of the plant soil.The research on this can reveal the plant litter soil response to the gap mechanism,the scientific management of plantations:(1)Broadleaf tree-soil ecological chemical balance internal balance maintenance mechanism and influencing factors were affected by forest gap;(2)The chemical metrological mechanism of the quality of timber in broadleaved trees was closely related to the gap;(3)Broadleaf-soil interaction chemometrics quantitative differences in the process in different gaps;(4)Develop fertilization measures based on nutrient diagnosis-ecological chemical balance;(5)According to the ecological chemical measurement can optimize the broadleaved forest ecological system management.Through the conservation of "stoichiometric stability" and "growth rate" regulation,the biological processes such as growth and physiological functions of broadleaf trees are affected,and the ecological processes such as wood quality,yield,community dynamics and environmental effects are also affected.With the growth of high quality,high utilization of resources,continuous utilization of resources and environmental friendliness,this paper should learn from the latest research achievements in the field of ecological chemistry metrology,and focus on the interaction mechanism between the native plantation and the important elements of life,Plant forest ecosystems and wood quality and yield formation process,and to strengthen the long-term monitoring and research on the dynamic process of "fertile balance-nutrient management-plantation production-environmental effect" of native broadleav-ed tree plantation ecosystem. |
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