[Objective]The aim was to study on the characteristics of soil organic carbon and nitrogen in rubber （Hevea brasiliensis Muell-Arg） plantations at different age stages in the western region of Hainan Island,so as to...[Objective]The aim was to study on the characteristics of soil organic carbon and nitrogen in rubber （Hevea brasiliensis Muell-Arg） plantations at different age stages in the western region of Hainan Island,so as to evaluate the ecological benefits of rubber plantations and provide basic data for studying the effect of tropical land utilization/cover change on the global carbon and nitrogen cycle. [Method]The situs was in Danzhou city,western region of Hainan Island,and the samples were four kinds of rubber plantations soil at different ages and one kind of control check （pepper,Piper nigrum L.） soil. In this research,four quadrats were set up in each sample,and the size of each was 20 cm×20 cm. Four specimens were gathered from four layers of 0-15,15-30,30-45,45-60,and the average of them was the last analysis result of each sample. Soil density was measured by cutting ring method,soil containing and hygroscopic water was detected by oven drying method,soil organic carbon （SOC） was measured by low temperature heated outside potassium dichromate oxidation-colorimetry method,and soil total nitrogen （STN） was detected by semimicro Kjeldahl method. [Result]SOC contents of different layers in rubber plantations soil at different age stages （including the CK pepper soil,the same as below） varied little,and the content of SOC in surface layer （0-15 cm） was higher,while the underlayer （45-60 cm） was lower than the average value; there was significant difference in SOC content among different kinds of soil,and the content was of 6.03-7.78 g/kg,tapping young trees （7 years） CK pepper mature age trees （30 years） prophase of young trees （2 years） tapping trees （16 years）; there was no significant difference in SOC storage among different kinds of soil,and the storage was of 61.33-74.29 t/hm2,mature age trees （30 years） tapping young trees （7 years） prophase of young trees （2 years） CK pepper tapping trees （16 years）; there was significant difference in STN content among rubber plantations soil at different age stages,the content was of 410.86-664.14 mg/kg2,CK pepper tapping young trees （7 years） prophase of young trees （2 years） mature age trees （30 years） tapping trees （16 years）,and STN content of tapping trees （16 years） soil was extremely lowest; there was significant difference in C/N ratio among different kinds of soil,the ratio was of 10.94-14.47,and the ratio of tapping trees （16 years） mature age trees （30 years） tapping young trees （7 years） CK pepper prophase of young trees （2 years）. [Conclusion]There wasn＇t unhealthy effect of rubber trees planted in tropical area on the content and storage of SOC,the content of STN and the ratio of C/N. there was no significant difference between rubber plantations and CK pepper soil,and the effects of rubber plantation on soil carbon-nitrogen was similar to that of other tropical crops （such as pepper）.展开更多
The soil respiration rates （Rh） in 6-year-old （young）, 17-year-old （middle-age）, 31-year-old （mature） Casuarina equisetifolia coastal plantations were measured using an LICOR-8100 automated soil CO2 flux syste...The soil respiration rates （Rh） in 6-year-old （young）, 17-year-old （middle-age）, 31-year-old （mature） Casuarina equisetifolia coastal plantations were measured using an LICOR-8100 automated soil CO2 flux system from May 2006 to April 2007. Results show that Rh displayed an obvious seasonal pattern across the observed years. The maximum values of Rh occurred at June and July and the minimum at December and January. Soil temperature and soil moisture as well as their interaction had significant effects on the monthly dynamics of Rh. The analysis by one-way ANOVA showed that Rh had a significantly exponential relation （p〈0.05） to soil temperature at soil depth of 5 cm, and had a linear relation （p〈0.05） to soil water content of the upper 20 cm. The result estimated by the two-factor model shows that soil temperature at soil depth of 5 cm and soil moisture at soil depth of 20 cm could explain 68.9%-91.9% of seasonal variations in Rh. The or- der of Rh rates between different stand ages was middle-age plantation〉mature plantation〉young-age plantation. With the increase of growth age of plantation, the Q10 of Rh increased. The contribution of Rh to total soil surface CO2 flux was 71.89%, 71.02% and 73.53% for the young, middle-age and mature plantation, respectively. It was estimated that the annual CO2 fluxes from Rh were 29.07, 38.964 and 30.530 t.ha^-1.a^-1 for the young, middle-age and mature plantation, respectively.展开更多
Using complete and orthogonal design, fertilization trials were conducted for the young growth of Populus deltoids cv. Zhonghua hongye in the fluviogenic soil in Xindu District, Chengdu City. The results showed that t...Using complete and orthogonal design, fertilization trials were conducted for the young growth of Populus deltoids cv. Zhonghua hongye in the fluviogenic soil in Xindu District, Chengdu City. The results showed that the application ef- fect of the single nutrient elements ranked as K〉N〉P, and that of the fertilization combinations ranked as N＋P＋K〉N＋K〉N＋P, P＋K. The optimum fertilization formula was urea [（NH2）2CO, 150 g/plant] ＋ calcium superphosphate [Ca（H2PO4）2.H20, 220 g/plant] ＋ potassium sulphate （K2SO4, 75 g/plant）.展开更多
In order to promote the growth of mid-aged Pinus elliottii plantation, the effects of different fertilizing amounts of formula fertilizer were studied on the growth, the soil and cost-benefit of 9 year-old Pinus el/io...In order to promote the growth of mid-aged Pinus elliottii plantation, the effects of different fertilizing amounts of formula fertilizer were studied on the growth, the soil and cost-benefit of 9 year-old Pinus el/iottii plantations in the north- ern part of Hunan, China. Three years after fertilization, the results showed that the increments of DBH, height, individual volume and stock volume of stand, and the fertilizer benefit of the different fertilization treatments were higher than the control to varying degrees, and among them, 700 g/tree was the best for promoting the growth of Pinus elliottii. Two years fertilization, the soil nutrients were improved compared with before, pH values of different layers decreased, organic matter and rapid available K contents increased, and rapid available N content increased dra- matically with the upper layer having an increase higher than the lower one; rapid available P decreased at different levels with the upper layer having a decrease lower than the lower one; and proper application of fertilizer could promote the growth of Pisolithus tinctofius, and 7 months after fertilization, the number of Pisolithus fruiting body generally increased with the increase of the fertilizer within 100-800 g/tree. The yield and benefit per unit area could be increased by fertiliza- tion for 1 time in middle-aged Pinus elliottii plantations, and the best fertilizing amount was N-P-K fertilizer 700 g/tree.展开更多
In this research,the contents of organic carbon in soil profiles in rubber forests in west of Hainan were measured and storage quantity of oganic carbon was estimated.The results indicated that contents of organic car...In this research,the contents of organic carbon in soil profiles in rubber forests in west of Hainan were measured and storage quantity of oganic carbon was estimated.The results indicated that contents of organic carbon in soils of ecosystem of rubber forests at different ages were 6.20-14.36 g/kg;organic carbon in soils of rubber forests reduced upon soil depth;the contents differed signigicantly in soils at 0-60 cm in rubber forest at 33 a,but differed little in soils in rubber forests at other ages;the contents were of significant differences in soils in rubber forests at different ages;organic carbon concentrated in soils at 0-30 cm;the storage quantities of organic carbon in rubber forests at 5,10,19 and 33 a were 76.85,74.48,81.74 and 85.31 t/hm^2.Climate,soil property,accumualtion and decomposition of fallen materials,forest age and management are dominant factors influencing accumulation of organic carbon in soils of rubber forest.展开更多
Soil respiration from decomposing aboveground litter is a major component of the terrestrial carbon cycle. However, variations in the contribution of aboveground litter to the total soil respiration for stands of vary...Soil respiration from decomposing aboveground litter is a major component of the terrestrial carbon cycle. However, variations in the contribution of aboveground litter to the total soil respiration for stands of varying ages are poorly understood. To assess soil respiration induced by aboveground litter, treatments of litter and no litter were applied to 5-, l0-, and 20-year-old stands of Populus davidiana Dode in the sandstorm source area of Beijing-Tianjin, equations were applied to China. Optimal nonlinear model the combined effects of soil temperature and soil water content on soil respiration. Results showed that the monthly average contribution of aboveground litter to total soil respiration were 18.46% ± 4.63%, 16.64% ± 9.31%, and 22.37% ± 8.17% for 5-, 10-, and ao-year-old stands, respectively. The relatively high contribution in 5- and 20-year-old stands could be attributed to easily decomposition products and high accumulated litter, resoectivelv. Also. it fluctuated monthly for all stand ages due to substrate availability caused by phenology and environmental factors. Litter removal significantly decreased soil respiration and soil water content for all stand ages （P 〈 0.05） but not soil temperature （P 〉 0.05）. Variations of soil respiration could be explained by soil temperature at 5-cm depth using an exponential equation and by soil water content at lo-cm depth using a quadratic equation, whereas soil respiration was better modeled using the combined parameters of soil temperature and soil water content than with either soil temperature or soil water content alone. Temperature sensitivity （Q10） increased with stand age in both the litter and the no litter treatments. Considering the effects of aboveground litter, this study provides insights for predicting future soil carbon fluxes and for accurately assessing soil carbon budgets.展开更多
Polymetallic iron ore sulphate deposits of marine volcanic rock have been developed in the Fangniugou area,Jilin Province,China,but the division of volcanic ore-bearing strata has not been specifically elucidated and ...Polymetallic iron ore sulphate deposits of marine volcanic rock have been developed in the Fangniugou area,Jilin Province,China,but the division of volcanic ore-bearing strata has not been specifically elucidated and there is disagreement about the division.The sampling and SHRIMP U-Pb zircon dating of volcanic rock for Daheishan in the Fangniugou area and the northeast slope of the Duanjiadian were described.The volcanic rock formation period and recorded the volcanic events in the Daheishan mountains were systematically researched.Two samples of high-precision U-Pb zircon dating were used to represent the volcanic rock fomation period of the Late Silurian.The measured data reflect that multiple volcanic activities occurred during the Middle Silurian,Early Silurian,Middle Ordovician and Silurian,and Late Ordovician,probably matching volcanic events in the Songnan Basin identified from zircon dating.At the same time,it is confirmed that a controversial "conglomerate of Daheishan" did in fact develop in the Late Silurian,and those sections of both the Dazigou and Xinlitun-Taoshan with graptolite had been reversed.展开更多
Estimation of fire cycle has been conducted by using the negative exponential function as an approximation of time-since-fire distribution of a landscape assumed to be homogeneous with respect to fire spread processes...Estimation of fire cycle has been conducted by using the negative exponential function as an approximation of time-since-fire distribution of a landscape assumed to be homogeneous with respect to fire spread processes. The authors imposed predefined fire cycles on a virtual landscape of 100 cell×100 cell, and obtained a mosaic composing of patches with different stand ages （i.e. time since fire）. Graphical and statistical methods （Van Wagner 1978; Reed et al. 1998） were employed to derive fire cycle from the virtual landscape. By comparing the predefined and the derived fire cycles, the two methods and tested the effects of sample size and hazard of burning （i.e., stand＇s susceptibility to fire in relation to its stand age） were evaluated on fire cycle deviation. The simulation results indicated a minimum sample size of l0 times of the annual burnt area would be required for.partitioning time-since-fire distribution into homogeneous epochs indicating temporal change in fire cycle. Statistically, there was significant difference among the imposed and the derived fire cycle, regardless of sample sizes with or without consideration of hazard of burning. Both methods underestimated the more recent fire cycle without significant difference between them. The results imply that deviation of fire cycle based on time-since-fire distribution warrants cautious interpretation, especially when a landscape is spatially partitioned into small units and temporal changes in fire cycle are involved.展开更多
Taking Hainan Eucalyptus plantation as the research object with 4 other kinds of plantations or natural forest as reference plots, the effects of different forest land types on soil nutrient contents were analyzed, an...Taking Hainan Eucalyptus plantation as the research object with 4 other kinds of plantations or natural forest as reference plots, the effects of different forest land types on soil nutrient contents were analyzed, and the differences of soil properties were discussed. The results showed that: (1) Eucalyptus plantations were relatively helpful to reduce soil bulk density and enhance the stability of water-stable aggregates;(2) Eucalyptus plantations can improve the content of soil organic matter;(3) Soil pH showed an overall acidi fication trend under forest land conditions in Hainan;total nitrogen and alkali-hydrolyzed nitrogen content of Eucalyptus plantations showed a downward trend with the deepening of soil layer;total phosphorus and available phosphorus content showed a downward trend, while organic matter, total potassium and available K showed an upward trend. (4) The contents of total phosphorus and available phosphorus in the soil of Eucalyptus plantations of different ages did not change significantly, whereas the contents of other nutrients decreased gradually with the increase of soil depth.展开更多
Aims Mosses are dominant in many ecosystems where nutrients from deposition are one of the main nutrient sources.However,it is difficult to evaluate mosses’role in nutrient cycling without knowledge of how mosses use...Aims Mosses are dominant in many ecosystems where nutrients from deposition are one of the main nutrient sources.However,it is difficult to evaluate mosses’role in nutrient cycling without knowledge of how mosses use deposited nutrient inputs.To fill this gap,the present study aims to investigate:(i)how nitrogen(N)and phosphorus(P)concentrations of new-grown segments change along a gradient of N or P amount in a pulse treatment?(ii)how do a pulse of major nutrient(N or P)affect N or P translocation rate along a moss shoot?and(iii)to what extent do N or P translocation rates link to nutrient status of the new-grown segments of mosses?Methods We measured N and P concentrations of segments with different ages in two dominant forest floor mosses,Actinothuidium hookeri and Hylocomium splendens,on 8 days and 1 year after N and P pulse treatment with an in situ experiment in a subalpine fir forest in eastern Tibetan Plateau.Important Findings Both mosses were efficient in taking up nutrients from a pulse of either N or P.Nitrogen and P concentrations of new-grown segments were affected by nutrient pulse treatments.These N and P concentration changes were attributed to the initial N and P concentration of the young segments harvested 8 days after nutrient pulse treatments,suggesting that the captured nutrients were reallocated to the new-grown segments via translocation,which was largely controlled by a source-sink relationship.While no significant relationship was found between N translocation rate and N:P ratio of the new-grown segments,P translocation rate explained 21%-23%of the variance of N:P ratio of the new-grown segments,implying importance of P transport in supporting the new-grown sections.These results suggest that nutrient(N,P)translocation is a key process for mosses to utilize intermittent nutrient supply,and thus make mosses an important nutrient pool of the ecosystem.展开更多
This study analyzes change in carbon storage by applying forest growth models and final cutting age to actual and potential forest cover for six major tree species in South Korea. Using National Forest Inventory data,...This study analyzes change in carbon storage by applying forest growth models and final cutting age to actual and potential forest cover for six major tree species in South Korea. Using National Forest Inventory data, the growth models were developed to estimate mean diameter at breast height, tree height, and number of trees for Pinus densiflora, Pinus koraiensis, Pinus rigida, Larix kaernpferi, Castanea crenata and Quercus spp. stands. We assumed that actual forest cover in a forest type map will change into potential forest covers according to the Hydrological and Thermal Analogy Groups model. When actual forest cover reaches the final cutting age, forest volume and carbon storage are estimated by changed forest cover and its growth model. Forest volume between 2010 and 2110 would increase from 126.73 to 157.33 m^3 hm^-2. Our results also show that forest cover, volume, and carbon storage could abruptly change by 2060. This is attributed to the fact that most forests are presumed to reach final cutting age. To avoid such dramatic change, a regeneration and yield control scheme should be prepared and implemented in a way that ensures balance in forest practice and yield.展开更多
The response and recovery mechanisms of forests to damage from freezing rain and snow events are a key topic in forest research and management. However, the relationship between the degree of damage and tree age, i.e....The response and recovery mechanisms of forests to damage from freezing rain and snow events are a key topic in forest research and management. However, the relationship between the degree of damage and tree age, i.e., whether seedlings, young trees, or adult trees are most vulnerable, remains unclear and is rarely reported. We investigated the effect of tree age on the degrees of vegetation damage and subsequent recovery in three subtropical forest types-coniferous, mixed, and broad-leaved —in the Tianjing Mountains, South China, after a series of rare icy rain and freezing snow events in 2008. The results showed that damage and recovery rates were both dependent on tree age, with the proportion of damaged vegetation increasing with age(estimated by diameter at breast height, DBH) in all three forest types and gradually plateauing. Significant variation occurred among forest types. Young trees in the coniferous forest were more vulnerable than those in the broad-leaved forest. The type of damage also varied with tree age in different ways in the three forest types. The proportion of young seedlings that were uprooted(the most severe type of damage) was highest in the coniferous forest. In the mixed forest, young trees were significantly more likely to be uprooted than seedlings and adult trees, while in the broad-leaved forest, the proportion of uprooted adult trees was significantly higher than that of seedlings and young trees. There were also differences among forest types in how tree age affected damage recovery. In the coniferous forest, the recovery rate of trees with broken trunks or crowns(DBH > 2.5 cm) increased with tree age. However, in the mixed and broad-leaved forests, no obvious correlation between the recovery rate of trees with broken trunks or crowns and tree age was observed. Trees with severe root damage did not recover; they were uprooted and died. In these forests, vegetation damage and recovery showed tree age dependencies, which varied with tree shape, forest type, and damage type. Understanding this dependency will guide restoration after freezing rain and snow disturbances.展开更多
Aims Litterfall is a key parameter in forest biogeochemical cycle and fire risk prediction.However,considerable uncertainty remains regarding the litterfall variations with forest ages.Quantifying the interannual vari...Aims Litterfall is a key parameter in forest biogeochemical cycle and fire risk prediction.However,considerable uncertainty remains regarding the litterfall variations with forest ages.Quantifying the interannual variation of forest litterfall is crucial for reducing uncertainties in large-scale litterfall prediction.Methods Based on the available dataset(N=318)with continuous multi-year(≥2 years)measurements of litterfall in Chinese planted and secondary forests,coefficient of variation(CV),variation percent(V_(P)),and the ratio of next-year litterfall to current-year litterfall were used as the indexes to quantify the interannual variability in litterfall.Important Findings The interannual variations of litterfall showed a declining trend with increasing age from 1 to 90 years.The litterfall variations were the largest in 1-10 years(mean CV=23.51%and mean V_(P)=−28.59%to 20.89%),which were mainly from tree growth(mean ratio of next-year to current-year=1.20).In 11-40 years,the interannual variations of litterfall gradually decreased but still varied widely,mean CV was~18%and mean V_(P) ranged from−17.69%to 21.19%.In 41-90 years,the interannual variations minimized to 8.98%in mean CV and~8%in mean V_(P).As a result,forest litterfall remained relatively low and constant when stand age was larger than 40 years.This result was different from the previous assumptions that forest litterfall reached relatively stable when stand age was larger than 30,20 or even 15 years.Our findings can improve the knowledge about forest litter ecology and provide the groundwork for carbon budget and biogeochemical cycle models at a large scale.展开更多
Aims There are different components of carbon(C)pools in a natural forest ecosystem:biomass,soil,litter and woody debris.We asked how these pools changed with elevation in one of China’s ecologically important forest...Aims There are different components of carbon(C)pools in a natural forest ecosystem:biomass,soil,litter and woody debris.We asked how these pools changed with elevation in one of China’s ecologically important forest ecosystem,i.e.beech(Fagus L.,Fagaceae)forests,and what were the underlying driving factors of such variation.Methods The four C pools in nine beech forests were investigated along an elevational gradient(1095–1930 m)on Mt.Fanjingshan in Guizhou Province,Southwest China.Variance partitioning was used to explore the relative effects of stand age,climate and other factors on C storage.In addition,we compared the four C pools to other beech forests in Guizhou Province and worldwide.Important Findings The total C pools of beech forest ecosystems ranged from 190.5 to 504.3 Mg C ha^(–1),mainly attributed to biomass C(accounting for 33.7–73.9%)and soil C(accounting for 23.9–65.5%).No more than 4%of ecosystem C pools were stored in woody debris(0.05–3.1%)and litter(0.2–0.7%).Ecosystem C storage increased significantly with elevation,where both the biomass and woody debris C pools increased with elevation,while those of litter and soil exhibited no such trend.For the Guizhou beech forests,climate and stand age were found to be key drivers of the elevational patterns of ecosystem and biomass C storage,while for beech forests globally,stand age was the most important predictor.Compared to beech forests worldwide,beech forests in Guizhou Province displayed a relatively higher biomass C accumulation rate,which may be explained by a much higher precipitation in this area.The present study provides basic data for understanding the C budgets of Chinese beech forests and their possible roles in regional C cycling and emphasizes the general importance of stand age and climate on C accumulation.展开更多
Age and body size are two important demographic traits that determine the life history strategies of populations and species. We measured these two parameters ofRana amurensis, at a 900 m and a 500 m altitude site in ...Age and body size are two important demographic traits that determine the life history strategies of populations and species. We measured these two parameters ofRana amurensis, at a 900 m and a 500 m altitude site in northeastern China. At the two sites, age at first reproduction was 2 years for males and 3 years for females. The maximum age of males and females at the high-altitude site was 6 and 7 years, and 5 and 7 years at the low-altitude population, respectively. Females were significantly larger than males in both populations, due to greater age in both the high- and low-altitude sites, Body size of either males or fe- males did not differ significantly between populations; only males showed increased body size at the high-altitude site when age effect was statistically controlled for. The increased cline of male body size may be attributable to delayed maturation of the sex due to a shorter growing season at high altitudes展开更多
基金Supported by the Project of the Basic Research Operation Cost of State Level Research Institutes "Long-term Location Investigation of Basic Data for Rubber Production " ( XJSYWFZX-2008-14 and XJSYWFZX-2007-2)the Project Natural Sciences Fund of Hainan Province (807045)~~
文摘[Objective]The aim was to study on the characteristics of soil organic carbon and nitrogen in rubber （Hevea brasiliensis Muell-Arg） plantations at different age stages in the western region of Hainan Island,so as to evaluate the ecological benefits of rubber plantations and provide basic data for studying the effect of tropical land utilization/cover change on the global carbon and nitrogen cycle. [Method]The situs was in Danzhou city,western region of Hainan Island,and the samples were four kinds of rubber plantations soil at different ages and one kind of control check （pepper,Piper nigrum L.） soil. In this research,four quadrats were set up in each sample,and the size of each was 20 cm×20 cm. Four specimens were gathered from four layers of 0-15,15-30,30-45,45-60,and the average of them was the last analysis result of each sample. Soil density was measured by cutting ring method,soil containing and hygroscopic water was detected by oven drying method,soil organic carbon （SOC） was measured by low temperature heated outside potassium dichromate oxidation-colorimetry method,and soil total nitrogen （STN） was detected by semimicro Kjeldahl method. [Result]SOC contents of different layers in rubber plantations soil at different age stages （including the CK pepper soil,the same as below） varied little,and the content of SOC in surface layer （0-15 cm） was higher,while the underlayer （45-60 cm） was lower than the average value; there was significant difference in SOC content among different kinds of soil,and the content was of 6.03-7.78 g/kg,tapping young trees （7 years） CK pepper mature age trees （30 years） prophase of young trees （2 years） tapping trees （16 years）; there was no significant difference in SOC storage among different kinds of soil,and the storage was of 61.33-74.29 t/hm2,mature age trees （30 years） tapping young trees （7 years） prophase of young trees （2 years） CK pepper tapping trees （16 years）; there was significant difference in STN content among rubber plantations soil at different age stages,the content was of 410.86-664.14 mg/kg2,CK pepper tapping young trees （7 years） prophase of young trees （2 years） mature age trees （30 years） tapping trees （16 years）,and STN content of tapping trees （16 years） soil was extremely lowest; there was significant difference in C/N ratio among different kinds of soil,the ratio was of 10.94-14.47,and the ratio of tapping trees （16 years） mature age trees （30 years） tapping young trees （7 years） CK pepper prophase of young trees （2 years）. [Conclusion]There wasn＇t unhealthy effect of rubber trees planted in tropical area on the content and storage of SOC,the content of STN and the ratio of C/N. there was no significant difference between rubber plantations and CK pepper soil,and the effects of rubber plantation on soil carbon-nitrogen was similar to that of other tropical crops （such as pepper）.
基金supported by Key Projects in the National Science & Technology Pillar Program during the EleventhFive-year Plan Period (Nos. 2006BAD03A14-01)Important Science & Technology Specific Projects of Fujian province (2006NZ0001-2)supported by the Key Laboratory of south mountain timber culti-vation, state forestry administration, P. R. China
文摘The soil respiration rates （Rh） in 6-year-old （young）, 17-year-old （middle-age）, 31-year-old （mature） Casuarina equisetifolia coastal plantations were measured using an LICOR-8100 automated soil CO2 flux system from May 2006 to April 2007. Results show that Rh displayed an obvious seasonal pattern across the observed years. The maximum values of Rh occurred at June and July and the minimum at December and January. Soil temperature and soil moisture as well as their interaction had significant effects on the monthly dynamics of Rh. The analysis by one-way ANOVA showed that Rh had a significantly exponential relation （p〈0.05） to soil temperature at soil depth of 5 cm, and had a linear relation （p〈0.05） to soil water content of the upper 20 cm. The result estimated by the two-factor model shows that soil temperature at soil depth of 5 cm and soil moisture at soil depth of 20 cm could explain 68.9%-91.9% of seasonal variations in Rh. The or- der of Rh rates between different stand ages was middle-age plantation〉mature plantation〉young-age plantation. With the increase of growth age of plantation, the Q10 of Rh increased. The contribution of Rh to total soil surface CO2 flux was 71.89%, 71.02% and 73.53% for the young, middle-age and mature plantation, respectively. It was estimated that the annual CO2 fluxes from Rh were 29.07, 38.964 and 30.530 t.ha^-1.a^-1 for the young, middle-age and mature plantation, respectively.
基金Supported by Special Scientific Research Fund of Forestry Public Welfare Profession of China(201104026)~~
文摘Using complete and orthogonal design, fertilization trials were conducted for the young growth of Populus deltoids cv. Zhonghua hongye in the fluviogenic soil in Xindu District, Chengdu City. The results showed that the application ef- fect of the single nutrient elements ranked as K〉N〉P, and that of the fertilization combinations ranked as N＋P＋K〉N＋K〉N＋P, P＋K. The optimum fertilization formula was urea [（NH2）2CO, 150 g/plant] ＋ calcium superphosphate [Ca（H2PO4）2.H20, 220 g/plant] ＋ potassium sulphate （K2SO4, 75 g/plant）.
基金Supported by Basic Scientific Research Business Expense Project for Public-interest Scientific Institute of Sichuan Province(ZL2014-13)~~
文摘In order to promote the growth of mid-aged Pinus elliottii plantation, the effects of different fertilizing amounts of formula fertilizer were studied on the growth, the soil and cost-benefit of 9 year-old Pinus el/iottii plantations in the north- ern part of Hunan, China. Three years after fertilization, the results showed that the increments of DBH, height, individual volume and stock volume of stand, and the fertilizer benefit of the different fertilization treatments were higher than the control to varying degrees, and among them, 700 g/tree was the best for promoting the growth of Pinus elliottii. Two years fertilization, the soil nutrients were improved compared with before, pH values of different layers decreased, organic matter and rapid available K contents increased, and rapid available N content increased dra- matically with the upper layer having an increase higher than the lower one; rapid available P decreased at different levels with the upper layer having a decrease lower than the lower one; and proper application of fertilizer could promote the growth of Pisolithus tinctofius, and 7 months after fertilization, the number of Pisolithus fruiting body generally increased with the increase of the fertilizer within 100-800 g/tree. The yield and benefit per unit area could be increased by fertiliza- tion for 1 time in middle-aged Pinus elliottii plantations, and the best fertilizing amount was N-P-K fertilizer 700 g/tree.
基金Supported by Strategic Priority Research Program,CAS(XDA05050601-01-25)Basic Scientific Research Project of Central Science and Technology Institute(163002-2011013)Project of Danzhou Investigation&Experiment Station of Tropical Crops Ministry of Agriculture~~
文摘In this research,the contents of organic carbon in soil profiles in rubber forests in west of Hainan were measured and storage quantity of oganic carbon was estimated.The results indicated that contents of organic carbon in soils of ecosystem of rubber forests at different ages were 6.20-14.36 g/kg;organic carbon in soils of rubber forests reduced upon soil depth;the contents differed signigicantly in soils at 0-60 cm in rubber forest at 33 a,but differed little in soils in rubber forests at other ages;the contents were of significant differences in soils in rubber forests at different ages;organic carbon concentrated in soils at 0-30 cm;the storage quantities of organic carbon in rubber forests at 5,10,19 and 33 a were 76.85,74.48,81.74 and 85.31 t/hm^2.Climate,soil property,accumualtion and decomposition of fallen materials,forest age and management are dominant factors influencing accumulation of organic carbon in soils of rubber forest.
基金funded by the National Natural Science Foundation of China (Grant No.31170414)the 100 Talents Program of Chinese Academy of Sciences,and the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No.XDA05060600)
文摘Soil respiration from decomposing aboveground litter is a major component of the terrestrial carbon cycle. However, variations in the contribution of aboveground litter to the total soil respiration for stands of varying ages are poorly understood. To assess soil respiration induced by aboveground litter, treatments of litter and no litter were applied to 5-, l0-, and 20-year-old stands of Populus davidiana Dode in the sandstorm source area of Beijing-Tianjin, equations were applied to China. Optimal nonlinear model the combined effects of soil temperature and soil water content on soil respiration. Results showed that the monthly average contribution of aboveground litter to total soil respiration were 18.46% ± 4.63%, 16.64% ± 9.31%, and 22.37% ± 8.17% for 5-, 10-, and ao-year-old stands, respectively. The relatively high contribution in 5- and 20-year-old stands could be attributed to easily decomposition products and high accumulated litter, resoectivelv. Also. it fluctuated monthly for all stand ages due to substrate availability caused by phenology and environmental factors. Litter removal significantly decreased soil respiration and soil water content for all stand ages （P 〈 0.05） but not soil temperature （P 〉 0.05）. Variations of soil respiration could be explained by soil temperature at 5-cm depth using an exponential equation and by soil water content at lo-cm depth using a quadratic equation, whereas soil respiration was better modeled using the combined parameters of soil temperature and soil water content than with either soil temperature or soil water content alone. Temperature sensitivity （Q10） increased with stand age in both the litter and the no litter treatments. Considering the effects of aboveground litter, this study provides insights for predicting future soil carbon fluxes and for accurately assessing soil carbon budgets.
基金Project(2009GYXQ02-06) supported by the National Oil and Gas Resources of Strategic Project Selection Survey and Evaluation Fund from Land and Natural Resources Ministry,ChinaProject(2652013099) supported by the Fundamental Research Funds of Central Universities,China
文摘Polymetallic iron ore sulphate deposits of marine volcanic rock have been developed in the Fangniugou area,Jilin Province,China,but the division of volcanic ore-bearing strata has not been specifically elucidated and there is disagreement about the division.The sampling and SHRIMP U-Pb zircon dating of volcanic rock for Daheishan in the Fangniugou area and the northeast slope of the Duanjiadian were described.The volcanic rock formation period and recorded the volcanic events in the Daheishan mountains were systematically researched.Two samples of high-precision U-Pb zircon dating were used to represent the volcanic rock fomation period of the Late Silurian.The measured data reflect that multiple volcanic activities occurred during the Middle Silurian,Early Silurian,Middle Ordovician and Silurian,and Late Ordovician,probably matching volcanic events in the Songnan Basin identified from zircon dating.At the same time,it is confirmed that a controversial "conglomerate of Daheishan" did in fact develop in the Late Silurian,and those sections of both the Dazigou and Xinlitun-Taoshan with graptolite had been reversed.
文摘Estimation of fire cycle has been conducted by using the negative exponential function as an approximation of time-since-fire distribution of a landscape assumed to be homogeneous with respect to fire spread processes. The authors imposed predefined fire cycles on a virtual landscape of 100 cell×100 cell, and obtained a mosaic composing of patches with different stand ages （i.e. time since fire）. Graphical and statistical methods （Van Wagner 1978; Reed et al. 1998） were employed to derive fire cycle from the virtual landscape. By comparing the predefined and the derived fire cycles, the two methods and tested the effects of sample size and hazard of burning （i.e., stand＇s susceptibility to fire in relation to its stand age） were evaluated on fire cycle deviation. The simulation results indicated a minimum sample size of l0 times of the annual burnt area would be required for.partitioning time-since-fire distribution into homogeneous epochs indicating temporal change in fire cycle. Statistically, there was significant difference among the imposed and the derived fire cycle, regardless of sample sizes with or without consideration of hazard of burning. Both methods underestimated the more recent fire cycle without significant difference between them. The results imply that deviation of fire cycle based on time-since-fire distribution warrants cautious interpretation, especially when a landscape is spatially partitioned into small units and temporal changes in fire cycle are involved.
文摘Taking Hainan Eucalyptus plantation as the research object with 4 other kinds of plantations or natural forest as reference plots, the effects of different forest land types on soil nutrient contents were analyzed, and the differences of soil properties were discussed. The results showed that: (1) Eucalyptus plantations were relatively helpful to reduce soil bulk density and enhance the stability of water-stable aggregates;(2) Eucalyptus plantations can improve the content of soil organic matter;(3) Soil pH showed an overall acidi fication trend under forest land conditions in Hainan;total nitrogen and alkali-hydrolyzed nitrogen content of Eucalyptus plantations showed a downward trend with the deepening of soil layer;total phosphorus and available phosphorus content showed a downward trend, while organic matter, total potassium and available K showed an upward trend. (4) The contents of total phosphorus and available phosphorus in the soil of Eucalyptus plantations of different ages did not change significantly, whereas the contents of other nutrients decreased gradually with the increase of soil depth.
文摘Aims Mosses are dominant in many ecosystems where nutrients from deposition are one of the main nutrient sources.However,it is difficult to evaluate mosses’role in nutrient cycling without knowledge of how mosses use deposited nutrient inputs.To fill this gap,the present study aims to investigate:(i)how nitrogen(N)and phosphorus(P)concentrations of new-grown segments change along a gradient of N or P amount in a pulse treatment?(ii)how do a pulse of major nutrient(N or P)affect N or P translocation rate along a moss shoot?and(iii)to what extent do N or P translocation rates link to nutrient status of the new-grown segments of mosses?Methods We measured N and P concentrations of segments with different ages in two dominant forest floor mosses,Actinothuidium hookeri and Hylocomium splendens,on 8 days and 1 year after N and P pulse treatment with an in situ experiment in a subalpine fir forest in eastern Tibetan Plateau.Important Findings Both mosses were efficient in taking up nutrients from a pulse of either N or P.Nitrogen and P concentrations of new-grown segments were affected by nutrient pulse treatments.These N and P concentration changes were attributed to the initial N and P concentration of the young segments harvested 8 days after nutrient pulse treatments,suggesting that the captured nutrients were reallocated to the new-grown segments via translocation,which was largely controlled by a source-sink relationship.While no significant relationship was found between N translocation rate and N:P ratio of the new-grown segments,P translocation rate explained 21%-23%of the variance of N:P ratio of the new-grown segments,implying importance of P transport in supporting the new-grown sections.These results suggest that nutrient(N,P)translocation is a key process for mosses to utilize intermittent nutrient supply,and thus make mosses an important nutrient pool of the ecosystem.
基金supported by"Developing Forest Management Model for Climate Change Adaptation"(FE 0100-2009-01)provided by the Korea Forest Research Institutesupported by"Climate Change Correspondence Program"(2014001310008)provided by Ministry of Environment,Korea
文摘This study analyzes change in carbon storage by applying forest growth models and final cutting age to actual and potential forest cover for six major tree species in South Korea. Using National Forest Inventory data, the growth models were developed to estimate mean diameter at breast height, tree height, and number of trees for Pinus densiflora, Pinus koraiensis, Pinus rigida, Larix kaernpferi, Castanea crenata and Quercus spp. stands. We assumed that actual forest cover in a forest type map will change into potential forest covers according to the Hydrological and Thermal Analogy Groups model. When actual forest cover reaches the final cutting age, forest volume and carbon storage are estimated by changed forest cover and its growth model. Forest volume between 2010 and 2110 would increase from 126.73 to 157.33 m^3 hm^-2. Our results also show that forest cover, volume, and carbon storage could abruptly change by 2060. This is attributed to the fact that most forests are presumed to reach final cutting age. To avoid such dramatic change, a regeneration and yield control scheme should be prepared and implemented in a way that ensures balance in forest practice and yield.
基金financially supported by the National Natural Science Foundation of China(31300401,31030015,31100402)the Forestry Science and Technology Innovative Foundation of Guangdong Province(2008KJCX012,2009KJCX015)+1 种基金the Guangdong Natural Science Foundation(S2012040007896)the Fundamental Research Funds for the Central Universities
文摘The response and recovery mechanisms of forests to damage from freezing rain and snow events are a key topic in forest research and management. However, the relationship between the degree of damage and tree age, i.e., whether seedlings, young trees, or adult trees are most vulnerable, remains unclear and is rarely reported. We investigated the effect of tree age on the degrees of vegetation damage and subsequent recovery in three subtropical forest types-coniferous, mixed, and broad-leaved —in the Tianjing Mountains, South China, after a series of rare icy rain and freezing snow events in 2008. The results showed that damage and recovery rates were both dependent on tree age, with the proportion of damaged vegetation increasing with age(estimated by diameter at breast height, DBH) in all three forest types and gradually plateauing. Significant variation occurred among forest types. Young trees in the coniferous forest were more vulnerable than those in the broad-leaved forest. The type of damage also varied with tree age in different ways in the three forest types. The proportion of young seedlings that were uprooted(the most severe type of damage) was highest in the coniferous forest. In the mixed forest, young trees were significantly more likely to be uprooted than seedlings and adult trees, while in the broad-leaved forest, the proportion of uprooted adult trees was significantly higher than that of seedlings and young trees. There were also differences among forest types in how tree age affected damage recovery. In the coniferous forest, the recovery rate of trees with broken trunks or crowns(DBH > 2.5 cm) increased with tree age. However, in the mixed and broad-leaved forests, no obvious correlation between the recovery rate of trees with broken trunks or crowns and tree age was observed. Trees with severe root damage did not recover; they were uprooted and died. In these forests, vegetation damage and recovery showed tree age dependencies, which varied with tree shape, forest type, and damage type. Understanding this dependency will guide restoration after freezing rain and snow disturbances.
基金supported by the National Key Research and Development Program of China(2017YFC0503906)the China Special Fund for Meteorological Research in the Public Interest(GYHY201406034).
文摘Aims Litterfall is a key parameter in forest biogeochemical cycle and fire risk prediction.However,considerable uncertainty remains regarding the litterfall variations with forest ages.Quantifying the interannual variation of forest litterfall is crucial for reducing uncertainties in large-scale litterfall prediction.Methods Based on the available dataset(N=318)with continuous multi-year(≥2 years)measurements of litterfall in Chinese planted and secondary forests,coefficient of variation(CV),variation percent(V_(P)),and the ratio of next-year litterfall to current-year litterfall were used as the indexes to quantify the interannual variability in litterfall.Important Findings The interannual variations of litterfall showed a declining trend with increasing age from 1 to 90 years.The litterfall variations were the largest in 1-10 years(mean CV=23.51%and mean V_(P)=−28.59%to 20.89%),which were mainly from tree growth(mean ratio of next-year to current-year=1.20).In 11-40 years,the interannual variations of litterfall gradually decreased but still varied widely,mean CV was~18%and mean V_(P) ranged from−17.69%to 21.19%.In 41-90 years,the interannual variations minimized to 8.98%in mean CV and~8%in mean V_(P).As a result,forest litterfall remained relatively low and constant when stand age was larger than 40 years.This result was different from the previous assumptions that forest litterfall reached relatively stable when stand age was larger than 30,20 or even 15 years.Our findings can improve the knowledge about forest litter ecology and provide the groundwork for carbon budget and biogeochemical cycle models at a large scale.
基金supported by the National Key Research and Development Program of China(grant no.2017YFA0605101)Ministry of Science and Technology of China(grant no.2015FY210200)National Natural Science Foundation of China(grant nos.31700374,31621091).
文摘Aims There are different components of carbon(C)pools in a natural forest ecosystem:biomass,soil,litter and woody debris.We asked how these pools changed with elevation in one of China’s ecologically important forest ecosystem,i.e.beech(Fagus L.,Fagaceae)forests,and what were the underlying driving factors of such variation.Methods The four C pools in nine beech forests were investigated along an elevational gradient(1095–1930 m)on Mt.Fanjingshan in Guizhou Province,Southwest China.Variance partitioning was used to explore the relative effects of stand age,climate and other factors on C storage.In addition,we compared the four C pools to other beech forests in Guizhou Province and worldwide.Important Findings The total C pools of beech forest ecosystems ranged from 190.5 to 504.3 Mg C ha^(–1),mainly attributed to biomass C(accounting for 33.7–73.9%)and soil C(accounting for 23.9–65.5%).No more than 4%of ecosystem C pools were stored in woody debris(0.05–3.1%)and litter(0.2–0.7%).Ecosystem C storage increased significantly with elevation,where both the biomass and woody debris C pools increased with elevation,while those of litter and soil exhibited no such trend.For the Guizhou beech forests,climate and stand age were found to be key drivers of the elevational patterns of ecosystem and biomass C storage,while for beech forests globally,stand age was the most important predictor.Compared to beech forests worldwide,beech forests in Guizhou Province displayed a relatively higher biomass C accumulation rate,which may be explained by a much higher precipitation in this area.The present study provides basic data for understanding the C budgets of Chinese beech forests and their possible roles in regional C cycling and emphasizes the general importance of stand age and climate on C accumulation.
文摘Age and body size are two important demographic traits that determine the life history strategies of populations and species. We measured these two parameters ofRana amurensis, at a 900 m and a 500 m altitude site in northeastern China. At the two sites, age at first reproduction was 2 years for males and 3 years for females. The maximum age of males and females at the high-altitude site was 6 and 7 years, and 5 and 7 years at the low-altitude population, respectively. Females were significantly larger than males in both populations, due to greater age in both the high- and low-altitude sites, Body size of either males or fe- males did not differ significantly between populations; only males showed increased body size at the high-altitude site when age effect was statistically controlled for. The increased cline of male body size may be attributable to delayed maturation of the sex due to a shorter growing season at high altitudes
