Monsoon Evergreen Broad-leaved Forest Research Articles

Effects of litter manipulation on litter decomposition in a successional gradients of tropical forests in southern China.

Global changes such as increasing CO2, rising temperature, and land-use change are likely to drive shifts in litter inputs to forest floors, but the effects of such changes on litter decomposition remain largely unknown. We initiated a litter manipulation experiment to test the response of litter decomposition to litter removal/addition in three successional forests in southern China, namely masson pine forest (MPF), mixed coniferous and broadleaved forest (MF) and monsoon evergreen broadleaved forest (MEBF). Results showed that litter removal decreased litter decomposition rates by 27%, 10% and 8% and litter addition increased litter decomposition rates by 55%, 36% and 14% in MEBF, MF and MPF, respectively. The magnitudes of changes in litter decomposition were more significant in MEBF forest and less significant in MF, but not significant in MPF. Our results suggest that change in litter quantity can affect litter decomposition, and this impact may become stronger with forest succession in tropical forest ecosystem.

Available Phosphorus in Forest Soil Increases with Soil Nitrogen but Not Total Phosphorus: Evidence from Subtropical Forests and a Pot Experiment

This paper aims to establish evidence for available phosphorous (AP) binding with total nitrogen (N) in subtropical forest soils. Soil organic carbon (SOC), total N, total phosphorous (P) and AP concentration were measured for three contrasting forest types in southern China: Masson pine forest (MPF), coniferous and broadleaved mixed forest (CBMF) and monsoon evergreen broadleaved forest (MEBF). A pot experiment with N addition was conducted to confirm the dominant factor to affect on soil AP concentration. The results showed that mean soil total N concentration in 0–10 cm soil layer was 440±50 for MPF, 840±80 for CBMF and 1020±50 mg kg−1 for MEBF, respectively. The mean soil AP concentration in 0–10 cm soil layer was 2.67±0.87 for MPF, 2.65±0.58 for CBMF, 4.10±0.29 mg kg−1 for MEBF, respectively. The soil total N concentration could explain about 70% of the variations in soil AP concentration in the top 20 cm soil layers in the three forest types. A pot experiment with N addition also showed an increase of AP concentration from 2.56 to 5.63 mg kg−1, when N addition increased from 5 g to 17 g NH4NO3. Our results therefore suggested that N addition significantly increased soil AP concentration, which might be beneficial for stabilizing the net primary production of subtropical forests that were limited by soil AP. This finding may provide a theory basis for tropical and subtropical forests management.

Responses of soil respiration and its temperature/moisture sensitivity to precipitation in three subtropical forests in southern China

Abstract. Both long-term observation data and model simulations suggest an increasing chance of serious drought in the dry season and extreme flood in the wet season in southern China, yet little is known about how changes in precipitation pattern will affect soil respiration in the region. We conducted a field experiment to study the responses of soil respiration to precipitation manipulations – precipitation exclusion to mimic drought, double precipitation to simulate flood, and ambient precipitation as control (abbr. EP, DP and AP, respectively) – in three subtropical forests in southern China. The three forest sites include Masson pine forest (PF), coniferous and broad-leaved mixed forest (MF) and monsoon evergreen broad-leaved forest (BF). Our observations showed that altered precipitation strongly influenced soil respiration, not only through the well-known direct effects of soil moisture on plant and microbial activities, but also by modification of both moisture and temperature sensitivity of soil respiration. In the dry season, soil respiration and its temperature sensitivity, as well as fine root and soil microbial biomass, showed rising trends with precipitation increases in the three forest sites. Contrarily, the moisture sensitivity of soil respiration decreased with precipitation increases. In the wet season, different treatments showed different effects in three forest sites. The EP treatment decreased fine root biomass, soil microbial biomass, soil respiration and its temperature sensitivity, but enhanced soil moisture sensitivity in all three forest sites. The DP treatment significantly increased soil respiration, fine root and soil microbial biomass in the PF only, and no significant change was found for the soil temperature sensitivity. However, the DP treatment in the MF and BF reduced soil temperature sensitivity significantly in the wet season. Our results indicated that soil respiration would decrease in the three subtropical forests if soil moisture continues to decrease in the future. More rainfall in the wet season could have limited effect on the response of soil respiration to the rising of temperature in the BF and MF.

A climate change‐induced threat to the ecological resilience of a subtropical monsoon evergreen broad‐leaved forest in Southern China

Recent studies have suggested that tropical forests may not be resilient against climate change in the long term, primarily owing to predicted reductions in rainfall and forest productivity, increased tree mortality, and declining forest biomass carbon sinks. These changes will be caused by drought-induced water stress and ecosystem disturbances. Several recent studies have reported that climate change has increased tree mortality in temperate and boreal forests, or both mortality and recruitment rates in tropical forests. However, no study has yet examined these changes in the subtropical forests that account for the majority of China's forested land. In this study, we describe how the monsoon evergreen broad-leaved forest has responded to global warming and drought stress using 32 years of data from forest observation plots. Due to an imbalance in mortality and recruitment, and changes in diameter growth rates between larger and smaller trees and among different functional groups, the average DBH of trees and forest biomass have decreased. Sap flow measurements also showed that larger trees were more stressed than smaller trees by the warming and drying environment. As a result, the monsoon evergreen broad-leaved forest community is undergoing a transition from a forest dominated by a cohort of fewer and larger individuals to a forest dominated by a cohort of more and smaller individuals, with a different species composition, suggesting that subtropical forests are threatened by their lack of resilience against long-term climate change.

模拟酸沉降对鼎湖山季风常绿阔叶林地表径流水化学特征的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 模拟酸沉降对鼎湖山季风常绿阔叶林地表径流水化学特征的影响 DOI: 10.5846/stxb201209111279 作者: 作者单位: 中国科学院华南植物园 广州,中国科学院华南植物园 广州,中国科学院华南植物园 广州,中国科学院华南植物园 广州,中国科学院华南植物园 广州 作者简介: 通讯作者: 中图分类号: 基金项目: 国家重点基础研究发展计划(973)项目(2009CB421101);中国科学院战略性先导科技专项(XDA05050205))资助 Effect of simulated acid deposition on chemistry of surface runoff in monsoon evergreen broad-leaved forest in Dinghushan Author: Affiliation: South China Botanical Garden,,,,South China Botanical Garden Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:通过模拟酸沉降实验,研究了旱季期间(10-3月份)鼎湖山季风常绿阔叶林在4种不同pH模拟酸雨处理(对照、pH 4.0、pH 3.5、pH 3.0)下地表径流水化学输出特征。结果显示:(1)地表径流pH随酸处理强度增强呈"U"型变化模式,酸沉降对地表径流pH的影响不显著(P>0.05),表明模拟酸沉降尚未引起地表水的酸化。(2)地表径流中NO3-、SO42-浓度随酸处理强度增强略有增加;HCO3-浓度的变化模式与地表径流pH类似。酸根离子浓度与地表径流pH相关性分析表明,SO42-、HCO3-有助于提高地表水抗酸化能力而NO3-则有助于促进地表水酸化。(3)地表径流中盐基离子对酸沉降的响应不尽相同。pH 3.0处理显著提高地表径流中Ca2+、Na+浓度;Mg2+浓度具有随酸处理梯度增强而增加的趋势;K+受模拟酸度的影响小。表明强酸(pH 3.0)处理将导致土壤Na+ 、Ca2+、Mg2+盐基离子流失。(4)酸沉降具有诱发土壤可溶性有机碳(DOC)流失的倾向,增加地表水受有机污染的风险。 Abstract:The effects of simulated acid deposition on chemical properties of surface runoff were studied in a monsoon evergreen broad-leaved forest in Dinghushan Nature Reserve. Four gradients of simulated acid rain treatments with three replications were designed: control (natural lake water, pH 4.5±0.3), pH 4.0, pH 3.5 and pH 3.0. The surface runoff pH, nitric acid (NO3-), sulfuric acid (SO42-), bicarbonate (HCO3-), base cations (K+, Na+, Ca2+, Mg2+) and dissolved organic carbon (DOC) were detected from October 2011 to March 2012. The result showed that the surface runoff pH was not significantly different among treatments, which exhibited "U" patterns with increasing acid intensity. This suggested the pH was unlikely to decline in a short time. The NO3- and SO42- concentrations increased with acid increment, while HCO3- exhibited the same pattern as the surface runoff pH. According to the correlation between acid ions concentrations and the surface runoff pH, we found that SO42- and HCO3- promoted the ability of anti-acidification, while NO3- was adverse. Base cations responded differently to simulated acid treatments. Ca2+ and Na+ were very sensitive to acid deposition, and their concentrations at pH 3.0 treatment were significantly higher than at other acid treatments. Mg2+ concentration increased with the simulated acid intensity, however, there were not significant differences among different acid treatments. K+, however, was not sensitive to acid treatment. These results indicated that pH 3.0 treatment led to the loss of Na+, Ca2+ and Mg2+ from the soil. In addition, acid treatments tended to cause dissolved organic carbon (DOC) loss, increasing the risk of organic contamination in the surface runoff. 参考文献 相似文献 引证文献

Responses of Soil Acid Phosphomonoesterase Activity to Simulated Nitrogen Deposition in Three Forests of Subtropical China

Soil acid phosphomonoesterase activity (APA) plays a vital role in controlling phosphorus (P) cycling and reflecting the current degree of P limitation. Responses of soil APA to elevating nitrogen (N) deposition are important because of their potential applications in addressing the relationship between N and P in forest ecosystems. A study of responses of soil APA to simulated N deposition was conducted in three succession forests of subtropical China. The three forests include a Masson pine (Pinus massoniana) forest (MPF)pioneer community, a coniferous and broad-leaved mixed forest (MF)transition community and a monsoon evergreen broad-leaved forest (MEBF)climax community. Four N treatments were designed for MEBF: control (without N added), low-N (50 kg N ha−1 year−1), and medium-N (100 kg N ha−1 year−1) and high-N (150 kg N ha−1 year−1), and only three N treatments (i.e., control, low-N, medium-N) were established for MPF and MF. Results showed that soil APA was highest in MEBF, followed by MPF and MF. Soil APAs in both MPF and MF were not influenced by low-N treatments but depressed in medium-N treatments. However, soil APA in MEBF exhibited negative responses to high N additions, indicating that the environment of enhanced N depositions would reduce P supply for the mature forest ecosystem. Soil APA and its responses to N additions in subtropical forests were closely related to the succession stages in the forests.

Leaf trait patterns of monsoon evergreen broad-leaved forest in relation to growth form

Recent studies into the interrelationships of plant traits have generated important insights into plant form and function. However, knowledge of the relationships between leaf area, leaf shape and plant height remains poorly resolved. We explored the relationships between leaf traits by testing differences in leaf area (LA), specific leaf area, specific leaf weight, leaf nitrogen content, leaf phosphorus content (leaf P), and leaf construction cost between species and growth forms. The leaf characteristics were compared among different growth forms in monsoon evergreen broad-leaved forests in Southwest China for trees, shrubs, and lianas. The results showed significant differences exist for the mean of all leaf traits except for LA and leaf P, while we did find significant differences for the weighted mean of LA and leaf P among trees, shrubs, and lianas. At the species scale, six leaf traits and the first principal component (PC1) were unrelated to plant height. PC1 captured 50.92% of the variation contained in all six leaf traits at the species scale. PC1 captured 67.91% of the variation contained in all six leaf traits at the growth form scale. Relationships among leaf traits differed by growth form indicating leaf traits were affected by growth form. Key words: Coefficient of variation, leaf construction cost, leaf N content, leaf P content, specific leaf area, vertical gradient.

普洱季风常绿阔叶林次生演替中木本植物幼苗更新特征

PDF HTML阅读 XML下载 导出引用 引用提醒 普洱季风常绿阔叶林次生演替中木本植物幼苗更新特征 DOI: 10.5846/stxb201108101174 作者: 作者单位: 中国林业科学研究院资源昆虫研究所,中国林业科学研究院资源昆虫研究所,中国林业科学研究院资源昆虫研究所,中国林业科学研究院资源昆虫研究所,普洱市林业科学研究所 作者简介: 通讯作者: 中图分类号: 基金项目: 中国林业科学研究院中央级公益性科研院所基本科研业务费专项资金资助项目(CAFYBB2008001, riricaf 201002M) Woody seedling regeneration in secondary succession of monsoon broad-leaved evergreen forest in Puer, Yunnan, Southwest China Author: Affiliation: Research Institute of Resource Insects,Chinese Academy of Forestry,Research Institute of Resource Insects,Chinese Academy of Forestry,Research Institute of Resource Insects,Chinese Academy of Forestry,Research Institute of Resource Insects,Chinese Academy of Forestry,Forestry Research Institute of Pu''er Municipality Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:以时空替代的方法,将针阔混交林、季风常绿阔叶林的次生林与成熟林等3个处于同一空间下的群落作为次生演替进程中的3个阶段,研究云南普洱地区次生演替过程中的木本植物幼苗更新特征,分析了次生演替过程中木本植物幼苗的物种组成、密度、高度级及与环境因子的相关性。结果表明:在8个共144 m2的幼苗样地中调查木本植物幼苗101种2014株,其中乔木幼苗是主要组成。随着次生演替的进行,木本植物幼苗、乔木与藤本幼苗密度逐渐增加,灌木幼苗密度无显著变化;藤本植物幼苗的物种丰富度随着次生演替进行而增加,乔木与灌木幼苗则无显著变化,成熟季风常绿阔叶林中木本植物幼苗Shannon-Wiener指数要显著小于针阔混交林与次生季风常绿阔叶林。次生与成熟季风常绿阔叶林木本植物幼苗多度随高度级增加而减少,针阔混交林则呈现偏峰曲线,幼苗密度均集中分布在高度20 cm以内,3个群落演替阶段木本植物幼苗物种丰富度随高度级增加呈现偏锋曲线。相似性系数反映出乔木和藤本幼苗的更新来源与群落的物种组成存在着紧密的联系。乔木幼苗密度分布与样地坡度之间存在着显著的负相关,灌木幼苗密度与土壤pH值之间存在着显著正相关。 Abstract:Seedling, made up of small individuals of woody plant species in the understorey, is an important component of many forests and considered as an important source for natural restoration in forest ecosystems. Simultaneously seedling plays an important role in the regeneration of numerous tree species. Based on space-for-time substitution method, we treated coniferous and broad-leaved mixed forest, secondary monsoon evergreen broad-leaved forest (MEBF), primary MEBF in the same area as three different stages of secondary succession of MEBF. Eight sampling plots representing the three different stages distribute in Caiyanghe nature reserve, surrounding the areas of Meizihu and Xinfang reservoir of Puer, in Yunnan Province, the southwest of China. We investigated seedling regeneration characteristics of woody plants of MEBF during secondary succession by looking at species composition, density, height level and the relationship with environmental factors. Overall, we found 2014 individuals of woody seedlings belonging to 101 species (dominated by understory tree species) in the eight plots covering 144-m2 area. The species richness of tree seedling, shrub seedling and liana seedling were 50, 29 and 22 respectively, and their corresponding individuals were 1499, 299 and 216. Tree seedling was the main component of woody plant seedling, such as Castanopsis echidnocarpa. Pinus kesiya var. langbianensis are dominant species in coniferous and broad-leaved mixed forest, however, their seedlings rarely appeared in the understory. The pine seedling stages need more light than shade-tolerant species which can conserve seedling bank in understory and waited for appropriate chance to regeneration. The woody plant seedling density of coniferous and broad-leaved mixed forest, secondary and mature MEBF was 183±5.69, 240±20.31 and 372.5±4.5 individuals per 18m2. As succession progresses, the density of total woody seedlings, tree seedlings and liana seedlings all increased, while the density of shrub seedlings did not change significantly. Celastrus virens as a liana was particularly conspicuous in mature MEBF. Species richness of liana seedlings tended to increase, while species richness of tree seedlings and shrub seedlings remained relatively stable along the succession gradient. The Shannon-Wiener index of woody seedlings was significantly lower in primary MEBF than those in mixed forest and secondary MEBF. The abundance of woody seedlings in secondary and primary MEBF decreased with the increase of height level, while in mixed forest, the abundance of woody seedlings form a unimodal pattern with peak at 20 cm. Species richness, however, showed consistent (increasing or decreasing) pattern with the increase of height level in all these forest types. Distribution of woody seedlings abundance concentrated in 0-20 cm in the three community types. Woody seedlings species richness of mature MEBF was significantly lower than coniferous and broad-leaved mixed forest when height level was at Ⅰand Ⅱ. Sørensen index indicated a close link between tree and liana seedlings and the species composition of the community. Moreover, tree seedling density distribution was significantly negatively correlated with the slope of the plot, while shrub seedling density was significantly positively related to soil pH. 参考文献 相似文献 引证文献

Soil CO2 concentration and efflux from three forests in subtropical China

Measurements of soil CO2 efflux and soil CO2 concentration concurrently are important for understanding the mechanism and regulation of CO2 in the soil. We have analysed CO2 concentration in a soil profile and soil CO2 efflux in three typical forests in subtropical China: monsoon evergreen broad-leaved forest (BF, 400 years old), pine and broad-leaved mixed forest (MF, 80 years old), and pine forest (PF, 70 years old). A portable soil CO2 sampler of simple sample operation was designed and used. The seasonal patterns of soil surface CO2 efflux and soil CO2 concentration were observed, and were positively correlated with rainfall, soil temperature, and moisture. The mean values of soil CO2 concentrations at the 15, 30, 45, and 60 cm soil depth were higher in BF (3368–9243 μL L–1) than in MF (1495–7662 μL L–1) and PF (1566–5730 μL L–1), while the mean values of soil surface CO2 efflux (Rsurface) were 0.55 ± 0.11 g m–2 h–1 in BF, 0.52 ± 0.10 g m–2 h–1 in MF, and 0.45 ± 0.07 g m–2 h–1 in PF. Soil CO2 concentration and Rsurface increased gradually with the age of the forests, but the incremental increase in soil CO2 concentration will be greater than that of Rsurface in MF and PF compared with BF. The data suggested that, although older forests have more C, younger forests probably will sequester C as CO2 faster than older forests.

Effects of Precipitation Change and Nitrogen Addition on Organic CarbonMineralization and Soil Microbial Carbon of the Forest Soils in Dinghushan,Southeastern China

Soil organic carbon(SOC) mineralization and soil microbial carbon(SMBC) play an important role in global C cycle.With method of incubation and chloroform fumigation extraction,the effects of precipitation change and nitrogen(N) addition on the SOC mineralization and SMBC were studied along a forest succession series including pine forest(PF),mixed pine and broadleaved forest(MF) and monsoon evergreen broadleaved forest(MEBF) at Dinghushan,Southestern China.The results showed that:(1) Increased precipitation could improve the mineralization of SOC in the late-successional forest plots,but the effect in the early-successional forest plots were not significant(P0.05).(2) Less precipitation(drought) resulted in lower content of SMBC in the monsoon forest soil(0～10 cm),while the doubled precipitation treatment had no significant effect on the SMBC content.(3) N deposition did not affect SMBC mineralization and SMBC in all of the three forests.It is important to take the quality of organic matter,C/N ratio,exogenous nitrogen and many other combined effects into consideration in the future studies on the responses of SOC mineralization and SMBC to climate change.Fig 4,Tab 2,Ref 37

Controlling action of soil organic matter on soil moisture retention and its availability

Aims Assessment of the ecological benefits of forest in soil water retention based on conventionally monitored factors and exploration of the relation between forest carbon-sink function and hydrological benefits has special meaning in Millennium Ecosystem Assessment.Our objectives were to 1) characterize the spatial and temporal variations of soil moisture in three subtropical forests and 2) determine the controlling action of soil organic matter on soil moisture retention during vegetation succession.Methods Standard plots were established in Pinus massonniana coniferous forest(PF),mixed Pinus massonniana-broad-leaved forest(PBF) and monsoon evergreen broad-leaved forest(MBF).We measured soil water content every 10 days from 2002 to 2008 using neutron probes and analyzed soil organic matter content in the laboratory by the potassium dichromate oxidation method.Important findings With natural succession from planted PF to climax MBF,soil water content(0–30 cm soil layer) increased significantly;soil water content was highest in MBF and lowest in PBF.The distribution patterns of soil moisture in the three forests were different: the soil moisture of MBF decreased with soil depth,was more homogeneous in the soil profile in PBF and was lower at the surface than in deeper layers in PF.The soil water characteristic curves showed that under the same matrix suction the magnitude of soil water content(0–40 cm soil layer) was: MBF PBF PF;the soil of MBF was the most retentive.Further analysis indicated that soil porosity had the greatest impact on soil moisture,followed by saturated soil water content and soil organic matter content,while soil bulk density had a minimal impact.In the process of natural succession,soil moisture was significantly correlated with the soil organic matter content(p = 0.014),as the soil organic matter could affect soil moisture holding(p = 0.030).Accordingly,we recommend soil organic matter as an effective and integrated index for appraising forest ecosystem services.

Partitioning soil respiration in lower subtropical forests at different successional stages in southern China

Aims Quantifying forest soil respiration(RS) components is vital to accurately evaluate carbon sequestration of forest ecosystems.Our objectives were to determine(1) seasonal variations in RS and its components of autotrophic(RA) and heterotropic respiration(R H) in subtropical forests,(2) the relative contributions of RA and RH to RS in the three subtropical forests and(3) relationships between RS and temperature and water content.Methods We used the trenching-plot and infrared gas exchange analyzer approaches to determine RA and R H in the soil surface CO2 flux for monsoon evergreen broad-leaved forest(MEBF) and its early succession communities,coniferous and broad-leaved mixed forest(MF) and coniferous masson pine forest(MPF) in southern China.Rate of RS was measured twice a month in the hot,humid season(April-September) and once a month in the cool,dry season(October-March).Soil temperature and soil water content were measured at the same time.Important findings RS,RA and R H varied markedly during the year with high rates in the hot,humid season and low rates in the cool,dry season.RS rate measured in the trenched plots(R H) at these forests showed an increasing trend with succession,but the change was not statistically significant.RS and RA followed a similaRSeasonal trend and were highest in MEBF and lowest in MF.Contribution of RA to RS was(39.48±15.49)%,(33.29±17.19)% and(44.52±10.67)% in MPF,MF and MEBF,respectively.Repeated measurement ANOVA indicated that soil temperature was the main factor that affected RS and its components,and there was a significant exponential relationship between them.While there was no significant relationship between soil water content and soil respiration flux,there appears to be a mild inhibition phenomenon.Soil Q10 values increased with succession,whereas autotrophic respiration(RA) is more sensitive to temperature in all stands.

Effects of precipitation on soil acid phosphatase activity in three successional forests in southern China

Abstract. Phosphorus (P) is often a limiting nutrient for plant growth in tropical and subtropical forests. Global climate change has led to alterations in precipitation in the recent years, which inevitably influences P cycling. Soil acid phosphatase plays a vital role in controlling P mineralization, and its activity reflects the capacity of organic P mineralization potential in soils. In order to study the effects of precipitation on soil acid phosphatase activity, an experiment with precipitation treatments (no precipitation, natural precipitation and doubled precipitation) in three successional forests in southern China was carried out. The three forests include Masson pine forest (MPF), coniferous and broad-leaved mixed forest (MF) and monsoon evergreen broad-leaved forest (MEBF). Results showed that driven by seasonality of precipitation, changes in soil acid phosphatase activities coincided with the seasonal climate pattern, with significantly higher values in the wet season than in the dry season. Soil acid phosphatase activities were closely linked to forest successional stages, with enhanced values in the later stages of forest succession. In the dry season, soil acid phosphatase activities in the three forests showed a rising trend with increasing precipitation treatments. In the wet season, soil acid phosphatase activity was depressed by no precipitation treatment in the three forests. However, doubled precipitation treatment exerted a significantly negative effect on it only in MEBF. These results indicate that the potential transformation rate of organic P might be more dependent on water in the dry season than in the wet season. A decrease in organic P turnover would occur in the three forests if there was a drought in a whole year in the future. More rainfall in the wet season would also be adverse to organic P turnover in MEBF due to its high soil moisture.

Nitrogen and phosphorus status and their influence on aboveground production under increasing nitrogen deposition in three successional forests

Compared with temperate ecosystems, tropical ecosystems will respond differently to increasing nitrogen (N) deposition due to indirect effects on the availability of phosphorus (P). Data in this study were collected from the long-term research plots and controlled experiments in a succession series, including 50-year-old pine forest (PF), 80-year-old mixed pine and broadleaved forest (MF), and more than 400-year-old monsoon evergreen broadleaved forest (MEBF), in southern China to study growth patterns and biogeochemical processes. The results showed that soil total N and available N were significantly higher in MEBF than in the other two forests. Soil available P was significantly lower in MEBF than in PF though the total P was the same. The N/P ratios in living leaves were increasing with succession stages. The standing biomass and productivity of MEBF have been declining over the last 30 years. Our findings suggest that the high N stock in soil pools through atmospheric deposition and self-accumulation in MEBF would require more available P to prevent deficiency that would limit plant growth. However, as more organic matter accumulated and thus, more P was bound in MEBF, there was much less available P in soils. These processes result in significantly higher N/P ratios in living leaves of the old-growth forest, which may be responsible for the decline.

Controls of litter quality on the carbon sink in soils through partitioning the products of decomposing litter in a forest succession series in South China

Through the long-term measurement and development of a method for partitioning the products of decomposing litter, the impact of chemical components of forest debris on soil organic carbon (SOC) accumulation was studied in a forest succession series in South China. We quantified how litter quality is strongly correlated with the partitioning of respiration, dissolved organic carbon (DOC) and fragments of decomposing litter. In the succession sequence of 60-year-old pine forest (PF), to 80-year-old mixed pine and evergreen broadleaved forest (MF) to more than 400-year-old monsoon evergreen broadleaved forest (MEBF), the litter C/N ratios and lignin contents were gradually decreasing, which in turn were correlated with increasing litter decomposition constants ( k-values), gradually shortening residence times of standing litter pool. And, 53.5%, 65.6% and 76.2% of the gravimetric litter mass losses were going belowground through both DOC and fragmentation. Correspondingly, the SOC accumulation rates in the top 20 cm of mineral soils for the three forests from 1978 to 2008 were 26 ± 4, 33 ± 5 and 67 ± 5 g C m −2 yr −1, respectively. Results of the study support the idea that in order to increase carbon sequestration in soils and long-term functional ability of forest ecosystems to act as carbon sinks, “Kyoto Forests” should be designed and reconstructed with a high diversity of broadleaved species, especially containing nitrogen-fixing trees.

Dynamics of coarse woody debris and decomposition rates in an old-growth forest in lower tropical China

The biomass and decomposition of coarse woody debris (CWD, ≥10 cm in diameter) were studied in a monsoon evergreen broad-leaved old-growth forest in Dinghushan Nature Reserve, Southern China. The study examined the biomass of CWD from 1992 to 2008 and decomposition of three dominant tree species CWD ( Castanopsis chinensis, Cryptocarya concinna, Schima superba) from 1999 to 2008. Changes in the wood density of three tree species’ CWD were used to estimate the decay rates with a single exponential model. The results showed that the biomass of CWD in the old-growth forest was increasing from 17.41 tonnes ha −1 (t ha −1) in 1992 to 38.54 t ha −1 in 2008, and a higher decay constant was observed for C. concinna (0.1570 – 19 years for 95% mass loss); the decay rates of S. superba and C. chinensis were 0.1486 (20 years for 95% mass loss) and 0.1095 (27 years for 95% mass loss), respectively. The difference in decay constant rates may be due to their substrate quality and decomposers. The content of carbon (C) in three species declined after 9 years of decay. Nitrogen (N) content increased in all species with decay. The C/N ratio in the three species declined during the decay process.

Simulating dynamics of managed monsoon evergreen broad-leaved forest in south China

The forest succession model FORDYN is developed based on TREEDEV model. TREEDEV is a process-based tree growth model, that calculates tree growth based on carbon and nitrogen balance, and is calculated using on the photo-production of leaves, respiration, nitrogen content of all organisms and that in soil, and other losses due to respiration, litter and renewal of stems, branches, leaves and roots. In the FORDYN model succession is divided into three phases called early, middle and late succession, and the transition between these three succession phases is distinguished by a difference in leaf area index. As a verification of the model we used the characteristics and available data of a monsoon evergreen broad-leaved forest in Dinghushan Biosphere Reserve (DHS-BR). The model was validated with natural forest data. In addition, a sensitivity analysis was performed in which 30 independent variables were varied and analyzed in connection with their influence on 16 dependent variables describing forest conditions. The simulation results describe the changes in total biomass, carbon and nitrogen change in plant–litter–soil system of an undisturbed monsoon evergreen broad-leaved forest during succession. We compared these findings with simulation in which different logging management strategies were used. The results show that having a longer logging cycle, delaying the first logging time and a smaller logging fraction the scenario can contribute to a sustainable forest development, while still having a positive economic yield.

Effects of elevated nitrogen deposition on soil microbial biomass carbon in major subtropical forests of southern China

The effects of elevated nitrogen deposition on soil microbial biomass carbon (C) and extractable dissolved organic carbon (DOC) in three types of forest of southern China were studied in November, 2004 and June, 2006. Plots were established in a pine forest (PF), a mixed pine and broad-leaved forest (MF) and monsoon evergreen broad-leaved forest (MEBF) in the Dinghushan Nature Reserve. Nitrogen treatments included a control (no N addition), low N (50 kg N/(hm2·a)), medium N (100 kg N/(hm2·a)) and high N (150 kg N/(hm2·a)). Microbial biomass C and extractable DOC were determined using a chloroform fumigation-extraction method. Results indicate that microbial biomass C and extractable DOC were higher in June, 2006 than in November, 2004 and higher in the MEBF than in the PF or the MF. The response of soil microbial biomass C and extractable DOC to nitrogen deposition varied depending on the forest type and the level of nitrogen treatment. In the PF or MF forests, no significantly different effects of nitrogen addition were found on soil microbial biomass C and extractable DOC. In the MEBF, however, the soil microbial biomass C generally decreased with increased nitrogen levels and high nitrogen addition significantly reduced soil microbial biomass C. The response of soil extractable DOC to added nitrogen in the MEBF shows the opposite trend to soil microbial biomass C. These results suggest that nitrogen deposition may increase the accumulation of soil organic carbon in the MEBF in the study region.

Soil respiration associated with forest succession in subtropical forests in Dinghushan Biosphere Reserve

This paper reports the results of soil respiration (SR, including heterotrophic and autotrophic respiration), in a presumably successional series (early, middle and advanced) of subtropical forests in Dinghushan Biosphere Reserve in Guangdong Province, China. A static chamber method was used to characterize SR in dynamics of diurnal and seasonal patterns. The relationships of SR with soil temperature (ST) at 5 cm depth and with soil moisture (SM) at 0–10 cm depth were studied in order to estimate the annual SR of each of the forests. The annual SR in a climax forest community, monsoon evergreen broad-leaved forest (MEBF) was estimated as 1163.0 g C m −2 year −1 and in its successional communities, coniferous and broad-leaved mixed forest (MF) and the Masson pine forest (MPF) were 592.1 g C m −2 year −1, 1023.7 g C m −2 year −1, respectively. In addition, removal of surface litter led to the reduction of annual SR by 27–45% in those three forests. Analysis of the results indicated that the annual SR was highly correlated with both ST and SM. Furthermore, ST and SM themselves were highly correlated with each other across season in this study area. Thus for seasonal predictive SR model, either ST or SM could be integrated. However, for SR daily change prediction, both ST and SM were required because of confounding effects of ST and SM on a diurnal time scale. The Q 10 values of SR derived from ST dependence function were 2.37, 2.31 and 2.25 in the three forests: MPF, MF and MEBF, respectively, suggesting a decreasing trend of the Q 10 with the degree of forest succession.

Vegetation succession process induced by reforestation in erosion areas

Reforestation is one of the most important and efficient measures of water and soil conservation. Based on field investigations in the Shangyang Soil Conservation and Reforestation Station in Huizhou, Guangdong Province, China, we studied the variation in vegetation development, vegetation succession processes and soil erosion. The regional vegetation consists mainly of monsoon evergreen broad-leaved forests (MEBF). The area was deforested and became a denuded hill area with extremely high soil erosion in the 1960s and 1970s. Then, the area was closed in order to allow recovery of the vegetation. Under natural conditions the vegetation development and succession processes were slow during which soil erosion and strong sunshine and evaporation slowed down the development of the vegetation. About 25 years later, the vegetation cover was still merely 35% or so. The dominant vegetation types were heliophilous herbage and shrubs which formed a poorly developed shrub-herbage community and erosion remained high. In contrast, reforestation with selected tree species dramatically speeded up the vegetation succession process. About 12 years after reforestation, vegetation cover of the Acacia auriculiformis plantations in the Shangyang Station was 90% and erosion was under control. After 23 years, understory vegetation, consisting of indigenous species, had developed in the plantations. The planted trees and naturally developing herbage, shrubs, bamboo, local trees and liana formed a complex vegetation community in three layers. It will take 60 years for the vegetation to succeed from bare land to a secondary growth forest under natural conditions. Reforestation may speed up the vegetation succession process. The time may be reduced to 20 years. Reforestation is the most effective measure of vegetation restoration and erosion control in this area.