Yusheng Yang

Fujian Normal University, Fujiang, Heilongjiang Sheng, China

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Publications (19)53.2 Total impact

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    ABSTRACT: • Context Coarse woody debris (CWD, ≥10 cm in diameter) is an important structural and functional component of forests. There are few studies that have estimated the mass and carbon (C) and nitrogen (N) stocks of CWD in subtropical forests. Evergreen broad-leaved forests are distributed widely in subtropical zones in China. • Aims This study aimed to evaluate the pools of mass, C and N in CWD in five natural forests of Altingia gracilipes Hemsl., Tsoongiodendron odorum Chun, Castanopsis carlesii (Hemsl.) Hayata, Cinnamomum chekiangense Nakai and Castanopsis fabri Hance in southern China. • Methods The mass of CWD was determined using the fixed-area plot method. All types of CWD (logs, snags, stumps and large branches) within the plot were measured. The species, length, diameter and decay class of each piece of CWD were recorded. The C and N pools of CWD were calculated by multiplying the concentrations of C and N by the estimated mass in each forest and decay category. • Results Total mass of CWD varied from 16.75 Mg ha−1 in the C. fabri forest to 40.60 Mg ha−1 in the A. gracilipes forest; of this CWD, the log contribution ranged from 54.75 to 94.86 %. The largest CWD (≥60 cm diameter) was found only in the A. gracilipes forest. CWD in the 40–60 cm size class represented above 65 % of total mass, while most of CWD accumulations in the C. carlesii, C. chekiangense and C. fabri forests were composed of pieces with diameter less than 40 cm. The A. gracilipes, T. odorum, C. carlesii and C. chekiangense forests contained the full decay classes (from 1 to 5 classes) of CWD. In the C. fabri forest, the CWD in decay classes 2–3 accounted for about 90 % of the total CWD mass. Increasing N concentrations and decreasing densities, C concentrations, and C:N ratios were found with stage of decay. Linear regression showed a strong correlation between the density and C:N ratio (R 2 = 0.821). CWD C-stock ranged from 7.62 to 17.74 Mg ha−1, while the N stock varied from 85.05 to 204.49 kg ha−1. The highest overall pools of C and N in CWD were noted in the A. gracilipes forest. • Conclusion Differences among five forests can be attributed mainly to characteristics of the tree species. It is very important to preserve the current natural evergreen broad-leaved forest and maintain the structural and functional integrity of CWD.
    Annals of Forest Science 07/2014; 71(5). · 1.63 Impact Factor
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    ABSTRACT: To fully understand how soil respiration is partitioned among its component fluxes and responds to climate, it is essential to relate it to belowground carbon allocation, the ultimate carbon source for soil respiration. This remains one of the largest gaps in knowledge of terrestrial carbon cycling. Here, we synthesize data on gross and net primary production and their components, and soil respiration and its components, from a global forest database, to determine mechanisms governing belowground carbon allocation and their relationship with soil respiration partitioning and soil respiration responses to climatic factors across global forest ecosystems. Our results revealed that there are three independent mechanisms controlling belowground carbon allocation and which influence soil respiration and its partitioning: an allometric constraint; a fine-root production vs. root respiration trade-off; and an above- vs. belowground trade-off in plant carbon. Global patterns in soil respiration and its partitioning are constrained primarily by the allometric allocation, which explains some of the previously ambiguous results reported in the literature. Responses of soil respiration and its components to mean annual temperature, precipitation, and nitrogen deposition can be mediated by changes in belowground carbon allocation. Soil respiration responds to mean annual temperature overwhelmingly through an increasing belowground carbon input as a result of extending total day length of growing season, but not by temperature-driven acceleration of soil carbon decomposition, which argues against the possibility of a strong positive feedback between global warming and soil carbon loss. Different nitrogen loads can trigger distinct belowground carbon allocation mechanisms, which are responsible for different responses of soil respiration to nitrogen addition that have been observed. These results provide new insights into belowground carbon allocation, partitioning of soil respiration, and its responses to climate in forest ecosystems and are, therefore, valuable for terrestrial carbon simulations and projections.
    Global Change Biology 04/2014; · 8.22 Impact Factor
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    ABSTRACT: Burned and unburned mineral soils (0–10 cm) from a 40-year-old Chinese fir (Cunninghamia lanceolata) forest in Nanping, Fujian, China were incubated for 90 days at different temperatures (25 °C and 35 °C) and humidity [25%, 50%, and 75% of water holding capacity (WHC)] conditions. Carbon (C) mineralization of all soils was determined using CO2 respiration method. The results showed that CO2 evolution rates of the burned and control soils exhibited similar temporal patterns, and similar responses to temperature and moisture. CO2 evolution rates for all soil samples decreased with incubation time. At different humidity conditions, average rate of C mineralization and cumulative mineralized C from burned and control soils were significantly higher at 35 °C than at 25 °C. This implied that C mineralization was less sensitive to soil moisture than to temperature. In both soils at 25 °C or 35 °C, the amount of soil evolved CO2 over the 90 days incubation increased with increasing moisture content from 25% to 75% WHC. A temperature coefficient (Q10) varied with soil moisture contents. The maximum values recorded for Q10 were 1.7 in control soil and 1.6 in burned soil both at 25% WHC. However, there were no significant differences in Q10 values between the control and burned soils over all moisture ranges (P > 0.05). The data of cumulative C–CO2 released from control and burned soils were fitted to two different kinetic models. The two simultaneous reactions model described mineralization better than the first-order exponential model, which reflected the heterogeneity of substrate quality. Based on these results, it is possible to conclude that temperature and moisture are important in the controls of C mineralization, and the combined effects of these variables need to be considered to understand and predict the response of CO2 release in subtropical ecosystems to climate change.
    Acta Ecologica Sinica 01/2014; 34(1):66–71.
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    ABSTRACT: Understanding the allocation of gross primary production (GPP) and its response to climate is essential for improving terrestrial carbon (C) modelling. Here, we synthesize data on component GPP fluxes from a worldwide forest database to determine the allocation patterns of GPP across global gradients in climate and nitrogen deposition (Ndep ). Our results reveal that allocation of GPP is governed in an integrated way by allometric constraints and by three trade-offs among GPP components: wood production (NPPwood ) vs fine-root production (NPPfroot ), NPPwood vs foliage production (NPPfoliage ), and autotrophic respiration (Ra ) vs all biomass production components. Component fluxes were explained more by allometry, while partitioning to components was related more closely to the trade-offs. Elevated temperature and Ndep benefit long-term woody biomass C sequestration by stimulating allometric partitioning to wood. Ndep can also enhance forest C use efficiency by its effects on the Ra vs biomass production trade-off. Greater precipitation affects C allocation by driving the NPPwood vs NPPfoliage trade-off toward the latter component. These results advance our understanding about the global constraints on GPP allocation in forest ecosystems and its climatic responses, and are therefore valuable for simulations and projections of ecosystem C sequestration.
    New Phytologist 07/2013; · 6.74 Impact Factor
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    ABSTRACT: Research on the effects of urban sprawl on carbon stocks within urban forests can help support policy for sustainable urban design. This is particularly important given climate change and environmental deterioration as a result of rapid urbanization. The purpose of this study was to quantify the effects of urban sprawl on dynamics of forest carbon stock and density in Xiamen, a typical city experiencing rapid urbanization in China. Forest resource inventory data collected from 32,898 patches in 4 years (1972, 1988, 1996 and 2006), together with remotely sensed data (from 1988, 1996 and 2006), were used to investigate vegetation carbon densities and stocks in Xiamen, China. We classified the forests into four groups: (1) forest patches connected to construction land; (2) forest patches connected to farmland; (3) forest patches connected to both construction land and farmland and (4) close forest patches. Carbon stocks and densities of four different types of forest patches during different urbanization periods in three zones (urban core, suburb and exurb) were compared to assess the impact of human disturbance on forest carbon. In the urban core, the carbon stock and carbon density in all four forest patch types declined over the study period. In the suburbs, different urbanization processes influenced forest carbon density and carbon stock in all four forest patch types. Urban sprawl negatively affected the surrounding forests. In the exurbs, the carbon stock and carbon density in all four forest patch types tended to increase over the study period. The results revealed that human disturbance played the dominant role in influencing the carbon stock and density of forest patches close to the locations of human activities. In forest patches far away from the locations of human activities, natural forest regrowth was the dominant factor affecting carbon stock and density.
    Journal of Environmental Management 11/2012; · 3.06 Impact Factor
  • Chengchao Wang, Yusheng Yang, Yaoqi Zhang
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    ABSTRACT: This paper systematically analyzes the driving forces and mechanism of fuelwood substitution and related ecological consequences in an under-developed county in rural Southeast China. Based on 358 respondents from rural households in Changting County, as well as additional statistical data, we present strong evidence in support of the argument that changes in the livelihoods of rural households lead to fuelwood substitution and finally, hilly ecosystem restoration. Important factors influencing fuelwood substitution are closely linked with changes in rural livelihoods: off-farm employment and agricultural specialization. Therefore, these changes are argued to be the primary driving force of fuelwood substitution. Reasons include the increasing opportunity costs of fuelwood collection, increases in household income, and decreases in household energy consumption for cooking, feeding and heating. Such changes have unexpectedly caused significant progress in hilly ecosystem restoration, particularly in mitigation of soil erosion and forest degradation. Thus, it is suggested that the progressive change and improvement in the livelihoods of rural households should be included in the mix of policies intended to restore hilly ecosystems.
    Renewable and Sustainable Energy Reviews. 06/2012; 16(5).
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    Chengchao Wang, Yusheng Yang, Yaoqi Zhang
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    ABSTRACT: This article uses a case study in Southeast China to demonstrate how the substantial changes in rural livelihoods have been driven by a combination of "pull" forces from external economic development, and "push" forces from local areas, leading to a shift in rural household economic activities: household outmigration and de-population of the countryside, changes in energy consumption, and most importantly, changes in land uses and eventually, ecological restoration. Such dramatic changes are becoming common across the Chinese countryside. It is pointed out that economic development has generally caused a deterioration of the environment at least at the early period of economic growth, but the positive impacts, especially in some ecosystem in rural areas, have become more apparent.
    AMBIO A Journal of the Human Environment 02/2011; 40(1):78-87. · 2.30 Impact Factor
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    ABSTRACT: To gain insight into fine roots decomposition in subtropical China, the litter bag method was used to examine the decomposition dynamics of dry mass, N, P, K, and organic fractions in six natural forests and a Chinese fir plantation over a 2-year period in the Wanmulin Nature Reserve, Fujian. The seven tree species examined, representative of this area, differed significantly in their initial chemical quality and were used to determine the best substrate quality parameters to predict decomposition dynamics. Dry mass loss varied significantly among the different roots, which showed fast decomposition in the first year, with mass loss regulated by extractive and acid-soluble fraction, followed by a low rate in the second year, with mass loss dominated by acid-insoluble fraction. Net N release was constantly slower than the mass loss of acid-insoluble fractions, while K release was the other way around. Release of P seemed to be independent of disappearance of acid-insoluble fraction. Not all the very fine roots (0–1mm) decomposed faster than the fine ones (1–2mm), and decomposition rates of coniferous roots were not always lower than broadleaved species. Correlation analysis demonstrated that dry mass loss and net N and P release rates were not correlated with initial N concentration, but with acid-insoluble organic fraction and P related parameters at the end of a 2-year decomposition period. Our results suggest that N is a limiting factor of fine root decomposition. Additionally, P could also be an important driver of fine root decomposition and N and P dynamics in this low soil P availability area. KeywordsFine root decomposition-Substrate quality-Organic fraction-Nutrient release-Subtropical ecosystem
    Plant and Soil 01/2011; 338(1):311-327. · 3.24 Impact Factor
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    ABSTRACT: Given lawns cultivation are expanding rapidly with urbanization in China and plays an important role in regional carbon cycle, but little is know about its carbon cycling. In this study, soil CO2 efflux (soil respiration, Rs) was partitioned into root (Rr) and microbial (Rh) components by using a deep-collar insertion method in Zoysia matrella lawns. Results indicated that both Rr and Rh presented pronounced seasonal patterns and were highly dependent on soil temperature and biomass. The annual Rr and Rh were 435 gC/(m 2 ·y) and 1249 gC/(m 2 ·y), respectively, thus the annual value of RC was 25.8%. These results suggest that the Rs of lawns in subtropical China is mainly microbe- derived.
    01/2011;
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    ABSTRACT: Soil respiration (Rs) was measured over 2years in mature, clear-cut, and clear-cut with slash burnt stands of Cunninghamia lanceolata Lamb. (Chinese fir) (CF) and secondary evergreen broadleaved forest (BF) located in Fujian Province, southeastern China from late October 2001 to 2003. Rs was measured as CO2 evolved in situ using the soda lime absorption method. Soil temperature and moisture content at 10cm depth were monitored in treatments of clear-cut (CC) and slash burnt (SB) and undisturbed controls. Respiration levels varied seasonally with maximum rates observed from May to July. Both, CC and SB plots showed increase in Rs for the first 3months after treatments but for the subsequent 2years the Rs in the CC and SB stands fell below that of controls. There were no significant difference in soil temperature among treatments in each forest, while the CC and SB treatments resulted in reduced soil moisture contents. Relationships between Rs and soil environmental variables were examined via a regression analysis. A combination of soil temperature and soil moisture content proved to be a reliable predictor of CO2 evolution in control plots, but not in CC and SB plots. We concluded that the effect of forest management on Rs is a combined result of changes in other factors rather than soil temperature and moisture. This study contributes to our understanding of how common forestry management practices might affect soil carbon sequestration, as Rs is a major component of ecosystem respiration. KeywordsClear-cutting-Slash burning-Soil respiration-Chinese fir (CF)-Evergreen broadleaved forest (BF)
    Plant and Soil 01/2010; 333(1):249-261. · 3.24 Impact Factor
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    ABSTRACT: Assessing the impact of land-use changes on soil respiration (RS) is of vital significance to understand the interactions between belowground metabolism and regional carbon budgets. In this study, the monthly in situ RS was examined between 09:00 and 12:00 hours over a 3-year period within a representative land-use sequence in the subtropical region of China. The land-use sequence contained natural forest (control treatment), secondary forest, two plantations, citrus orchard and sloping tillage land. Results showed that the RS exhibited a distinct seasonal pattern, and it was dominantly controlled by the soil temperature. After the land-use conversion, the apparent temperature sensitivity of RS (Q10) was increased from 2.10 in natural forest to 2.71 in sloping tillage land except for an abnormal decrease to 1.66 in citrus orchard. Contrarily, the annual RS was reduced by 32% following the conversion of natural forest to secondary forest, 46–48% to plantations, 63% to citrus orchard and 50% to sloping tillage land, with the average reduction of 48%. Such reduction of annual RS could be explained by the decrease of topsoil organic carbon and light-fraction organic carbon storages, live biomass of fine root (<2 mm) and annual litter input, which indirectly/directly correlated with plant productivity. Our results suggest that substrate availability (e.g., soil organic carbon and nutrients) and soil carbon input (e.g., fine root turnover and litterfall) through plant productivity may drive the RS both in natural and managed ecosystems following strong disturbance events.
    Global Change Biology 05/2009; 16(3):1107 - 1121. · 8.22 Impact Factor
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    ABSTRACT: Land use/cover change (LUCC) is widely recognized as one of the most important driving forces of global carbon cycles. The influence of converting native forest into plantations, secondary forest, orchard and arable land on stores and quality of soil organic carbon (SOC) was investigated in mid-subtropical mountainous area of southern China. The results showed that LUCC had led to great decreases in SOC stocks and quality. Considerable SOC and light-fraction organic carbon (LFOC) had been stored in the native forest (142.2 t hm−2 and 14.8 t hm−2 respectively). When the native forest was converted to plantations, secondary forest, orchard and arable land, the SOC stocks decreased by 25.6%, 28.7%, 38.0%, 31.8% and 51.2%, respectively. The LFOC stocks decreased by 52.2% to 57.2% when the native forest was converted to woodland plantations and secondary forest, and by 82.1% to 84.2% when converted to economic plantation, orchard and arable land. After the conversion, the ratios of LFOC to SOC (0–60 cm) decreased from 13.3% to about 3.0% to 10.7%. The SOC and LFOC stored at the upper 20 cm were more sensitive to LUCC when compared to the subsurface soil layer. Also, the decline in carbon storage induced by LUCC was greater than the global average level, it could be explained by the vulnerable natural environment and special human management practices. Thus, it is wise to enhance soil carbon sequestration, mitigate elevated atmospheric CO2 and develop ecological services by protecting vulnerable environment, restoring vegetation coverage, and afforesting in mountainous area in mid-subtropics.
    Journal of Geographical Sciences 01/2009; 19(1):49-57. · 0.91 Impact Factor
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    ABSTRACT: Soil labile fractions play an important role in improving soil quality due to its ability of maintaining soil fertility and minimizing negative environmental impacts. The objective of this study was to evaluate the effects of forest transition (conversion of natural broadleaf forests into monoculture tree plantations) on soil labile fractions (light fraction organic carbon, particulate organic carbon, and microbial biomass carbon). Soil samples were collected from a natural forest of Castanopsis kawakamii Hayata (NF) and two adjacent 36-year-old monoculture plantations of C. kawakamii (CK) and Cunninghamia lanceolata Lamb. (Chinese fir) (CF) at Xinkou Experimental Forestry Centre, southeastern China. In the 0–100cm depth, the light fraction organic carbon (LFOC), particulate organic carbon (POC) and microbial biomass carbon (MBC) were significantly lower in the CK and CF than in the NF (P < 0.05). Generally, LFOC, POC and MBC contents declined consistently with profile depth. Significant differences in LFOC, POC and MBC concentrations between the native forest and two plantations were detected at 0–40cm depth, especially the top 10cm, whereas there was less change below 40cm, indicating that labile fraction losses due to forest transition mainly occurred in the surface soils. The three indices of labile organic carbon were closely correlated, suggesting they are interrelated properties. Labile fractions (LFOC, POC and MBC) were more sensitive indicators of SOC change resulting from the forest transition. We also found that forest types significantly affected the water stable aggregate >0.25mm content (WSA) at the 0–10cm depth. It suggested that converting old-growth native forest to intensively-managed plantations would reduce labile organic C, which may be attributed to a combination of factors including quantity of litter materials, microbial activity and management disturbances, which would change greatly with the forest conversion. How long these changes would persist needs the further study. KeywordsNatural forest-Monoculture plantation-Labile fractions-Aggregation
    Plant and Soil 01/2009; 323(1):153-162. · 3.24 Impact Factor
  • Zhanyuan Yu, Yusheng Yang, Guangshui Chen
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    ABSTRACT: This paper studied the carbon storages and carbon sequestration capacities of degraded plantation ecosystems in purple soil area. Using space-time replacement method, four ecological restoration treatments (I, II, III and IV) were selected on the basis of erosion intensions from high to low in Ninghua, Fujian. Treatment I was not treated with any other measures after afforestation. Treatment II adopted engineering soil and water conservation measure after afforestation. In treatment III, the engineering measure associated biological measure was taken after afforestation. As for treatment IV, enclosure was adopted to protect against anthropogenic disturbances after afforestation. We observed that the carbon sequestration potential was increased with weakening erosion degree, i.e., I < II < III < IV. The carbon storage of 4 treatments was 1.4, 8.5, 25.6 and 37.6 t x hm(-2), and the annual assimilation of CO2 was 712.87, 1458.01, 9718.10 and 11,109.56 kg x hm(-2), respectively. It was suggested that the restored forest ecosystem was one of the important carbon sinks in this area. Engineering soil and water conservation measure associated biological measure would be the main means of restoring degraded ecosystem. But presently, the reasonable strategy was to decrease human's disturbances, and hence, the enclosure for reforestation could be used to transform forest ecosystem into carbon sink.
    Ying yong sheng tai xue bao = The journal of applied ecology / Zhongguo sheng tai xue xue hui, Zhongguo ke xue yuan Shenyang ying yong sheng tai yan jiu suo zhu ban 11/2004; 15(10):1837-41.
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    ABSTRACT: The amount of carbon returned through litterfall and its seasonal pattern were studied in a natural forest of Castanopsis kawakamii (NF) and adjacent monoculture plantations of C. kawakamii (CK) and Chinese fir (Cunninghamia lanceolata) (CF) in Sanming, Fujian Province, China. Mean annual carbon return through total litterfall over 3 years (from 1999 to 2001) was 5.097 t·hm−2 in the NF, 4.337 t·hm−2 in the CK and 2.502 t·hm−2 in the CF respectively. Of the total carbon return in the three forests, leaf contribution accounted for 58.96%, 68.53% and 56.12% and twig 24.41%, 22.34% and 26.18%, respectively. The seasonal patterns of carbon return from total litterfall and leaf-litter were quite similar among the three forests. A peak of carbon input from litterfall in the NF and the CK occurred in spring except for the highest annual C return through branch litter of the NF in summer, while the CF showed the maximum C return in summer. The results of this study demonstrate that the natural forest has a greater C return through litterfall than monoculture plantations, which is beneficial to the increase of soil organic matter storage and the maintenance of soil fertility.
    Forestry Studies in China 02/2004; 6(1):33-36.
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    ABSTRACT: We investigated microbial biomass and composition (lipid profile), mineral N pools and soil physicochemical parameters in the top 5-cm soils 19 years after reforestation of Chinese fir (Cunninghamia lanceolata (Lamb.) Hook) woodland with itself or a native broadleaf species, Mytilaria laosensis. The results suggested that tree species transition had a large impact on microbial biomass and a small impact on the composition of the microbial community as indicated by the relative abundance of individual lipid biomarkers. Between November 2011 and October 2012, there was on average 50% greater microbial biomass carbon (C) measured by the fumigation extraction procedure under M. laosensis than under C. lanceolata. A one-time measurement of phospholipid fatty acids in soil samples collected in May 2012 suggested M. laosensis plots had greater content of individual lipid biomarkers than C. lanceolata plots. Using a litter manipulation experiment, we found that the increases in content of lipid biomarkers under M. laosensis can be attributed to changed litter chemistry. Analysis of soil mineral N pools indicated that there were significantly lower +4NHNH4+ and −3NONO3− pools as well as potential net N mineralization rates in M. laosensis soil than in C. lanceolata soil. The relationships among N dynamics, soil chemistry and microbial properties were analysed. The results suggested tree species induced differences in soil N mineralization rates and mineral N pools were related to labile C availability, soil C:N ratio and the composition of the microbial community. Our data of mineral N pools and soil δ15N implied that the transition of land use from C. lanceolata to M. laosensis leads to an enhanced N retention in the plantation.
    Soil Biology and Biochemistry 62:68–75. · 4.41 Impact Factor
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    ABSTRACT: Recovery of carbon stocks after afforestation in degraded lands provides a management practice to mitigate rising atmospheric carbon dioxide concentrations, however carbon accumulation after afforestation of severely eroded lands is poorly understood. Large areas of the red soils in subtropical China suffer from severe erosion and have very low carbon density. We investigated above- and below-ground carbon pools in bare land on a severely eroded red soil (BL), a Pinus massoniana plantation that had been established on bare land in 1981(PM) and a nearby secondary forest (SF) in southeastern China. The ecosystem carbon pool in PM (130.1 ± 7.2 Mg C ha−1) was 10 times higher than in BL (13.0 ± 1.3 Mg C ha−1), and 22% lower than that in SF (166.7 ± 7.0 Mg C ha−1) (p < 0.05). The above ground biomass carbon pool was 91.9 ± 4.8 Mg C ha−1 in PM, similar to 98.2 ± 5.5 Mg C ha−1 in SF. The soil organic carbon (SOC) pool (to 1 m depth) in PM (38.2 ± 3.4 Mg C ha−1) was 2.9 times higher than that in BL (13.0 ± 1.3 Mg C ha–1), but was significantly lower than that in SF (68.5 ± 2.5 Mg C ha–1). About 70% of the organic C to 1 m depth was stored in the top 40 cm in the two forests. The storage of light fraction organic carbon (LFOC) at the 0–60 cm depth in PM was significantly higher than that in BL, but not significantly different from that in SF. PM had significantly higher proportions of LFOC to SOC for all soil depths in comparison with BL and SF (p < 0.05). The mean accumulation rates of ecosystem carbon pools, aboveground biomass carbon pools, and SOC pools in PM were 4.88 ± 0.25, 3.83 ± 0.16, and 1.05 ± 0.09 Mg C ha−1 yr−1, respectively. Our results indicate that afforestation of severely eroded red soils with P. massoniana may be a successful forest management practice to achieve rapid carbon accumulation.
    Forest Ecology and Management 300:53–59. · 2.77 Impact Factor
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    ABSTRACT: Aims This study aimed to determine the influence of different harvest residue management strategies on tree growth, soil carbon (C) concentrations, soil nitrogen (N) availability and ecosystem C stocks 15 years after replanting second rotation Chinese fir (Cunninghamia lanceolata), an important plantation species in subtropical China. Such information is needed for designing improved management strategies for reforestation programmes in subtropical environments aimed at mitigating CO2 emissions. Methods Four harvest residue management treatments including slash burning, whole tree, stem-only and double residue retention were applied to sixteen 20 m × 30 m plots in a randomized complete block design with four replicates. Tree growth was measured annually and soil properties were measured at 3 year intervals over a 15 year period after re-planting. Results Cumulative diameter growth at age 15 years was significantly smaller in the slash burning than the whole tree and double residue harvest treatments. Hot water extractable N concentrations increased with the increased organic residue retention levels and significant differences were observed between double residue and slash burning treatments. Harvest residue management had no significant effect on the soil C concentrations to 40 cm depth. ANOVA showed that harvest residue management had no significant effect on total biomass carbon at age 15, but the plantation ecosystem (soil C at 0–40 cm depth plus forest biomass C) had significantly lower C mass in the slash burning treatment compared with whole tree, stem only harvest and double residue harvest treatments. Conclusions These observations suggest that organic residue retention during the harvesting could improve the growth and ecosystem C stocks of Chinese fir in second rotation forest plantations in subtropical China and highlight the importance of viewing the ecosystem as a whole when evaluating the impact of harvest residue management on C stocks.
    Plant and Soil 364(1-2). · 3.24 Impact Factor
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    ABSTRACT: The relationship between landscape patterns and functions is the central research theme of landscape ecology and forest management. This study assesses the interactive relationship of landscape heterogeneity with the carbon stock of urban forests in the city of Xiamen, Fujian Province, China, using spatial and statistical analyses. The objectives of this study are to explore the most appropriate scale for studying urban landscape patterns in Xiamen, analyze the dynamics of forested landscape heterogeneity at different scales, and identify suitable landscape metrics that are closely related to and can be used to describe vegetation carbon density. This study is based on data from 31,933 plots measured during the years 1972, 1996, and 2006 and collected as part of the Chinese National Forest Resource Planning and Inventory Program. A total of 12 landscape metrics were used to quantify spatial patterns and were subsequently related to vegetation carbon density. The results show that the most appropriate scale for landscape pattern analysis is 80 km2. With urbanization advancing between 1972 and 1996, landscape heterogeneity at both class and landscape levels showed a significant increase and then remained stable from 1996 to 2006. Shannon’s diversity index was the most sensitive landscape metric among all selected landscape heterogeneity metrics, and its ability to explain the variation of carbon density was better than that of forest types. This study clearly shows that information on spatial patterns of landscape heterogeneity is important for urban forest landscape planning to achieve forest carbon objective.
    Forest Ecology and Management 293:122–131. · 2.77 Impact Factor