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Guo J.,Fujian Normal University | Guo J.,Key Laboratory for Subtropical Mountain Ecology | Chen G.,Fujian Normal University | Chen G.,Key Laboratory for Subtropical Mountain Ecology | And 6 more authors.
Annals of Forest Science | Year: 2014

• 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. © 2014 INRA and Springer-Verlag France.

Guo J.,Fujian Normal University | Guo J.,Key Laboratory for Subtropical Mountain Ecology | Chen G.,Fujian Normal University | Chen G.,Key Laboratory for Subtropical Mountain Ecology | And 6 more authors.
Plant and Soil | Year: 2014

Background and aims: Carbon (C) loss from coarse woody debris (CWD) may be important in forest ecosystem C budgets, yet few studies have assessed CWD respiration in natural evergreen broad-leaved forests in subtropical China. The objectives of this study were (1) to quantify the respiration rates of downed logs (Rlog) and Q10 of different tree species at various stages of decay, (2) to assess the effect of microclimatic (log temperature and moisture) variables on Rlog and (3) to estimate annual C flux of the CWD logs in four natural evergreen broad-leaved forest types of Altingia gracilipes Hemsl. (ALG), Tsoongiodendron odorum Chun (TSO), Castanopsis carlesii (Hemsl.) Hayata (CAC) and Cinnamomum chekiangense Nakai (CIC) in southern China.Methods: A dynamic chamber method was used to measure Rlog in four decay classes (DCs) (ranging from freshly felled logs in DC 1 to highly decomposed logs in DC 4). The effects of changes in log temperature (Tlog) and log moisture content (Mlog) on Rlog were determined and annual Rlog estimated.Results: The Rlog exhibited a distinct seasonal pattern, and it was predominantly controlled by the log temperature. The temperature sensitivity of Rlog to log temperature as indicated by Q10 ranged from 1.82 to 2.86 and was variable among decay classes and forests. Significant relationships between moisture content of logs and Rlog were only observed for logs in the ALG (P = 0.001), TSO (P = 0.002) and CIC (P < 0.001). The log temperature in combination with the moisture of logs explained over 60 % of the variation in Rlog. The effects of decay class (F = 3.707, df = 3, P = 0.013) and tree species (F = 8.705, df = 3, P < 0.001) on Rlog were significant. Annual C fluxes ranged from 652 kg C ha−1 year−1 in the CIC to 1,243 kg C ha−1 year−1 in the TSO, with varying contributions from each decay class.Conclusions: At these subtropical natural forests, Rlog was a significant component of overall heterotrophic respiration (about 10–20 % on the annual basis). With increasing climate change-associated tree mortality in our mature forests, CWD respiration is expected to increase. The results indicate that species, decay stage and microclimatic conditions should be considered when predicting CWD decay rates. © 2014, Springer International Publishing Switzerland.

Chen G.-S.,Fujian Normal University | Chen G.-S.,Key Laboratory for Subtropical Mountain Ecology | Yang Z.-J.,Fujian Normal University | Yang Z.-J.,Key Laboratory for Subtropical Mountain Ecology | And 10 more authors.
Forest Ecology and Management | Year: 2013

Tree plantations established on the natural forest lands increasingly expand globally but their significance in sequestering atmospheric carbon (C) is rarely examined. We investigated changes of C stocks in Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) plantations converted from a natural broadleaved forest, based on a typical chronosequence in mountainland of subtropical China, which includes six first-generation Chinese fir stands at different development stages: 2- (recently regenerated), 7- (sapling), 16- (middle-aged), 21- (pre-mature), 40- (mature), and 88-year-old (over-mature), with a natural evergreen broadleaved forest (NF) as a comparison. The tree biomass C pool increased linearly from 2 to 40. years old, with no further significant increase from 40 to 88. years old. Compared with that in the NF forest, the mineral soil organic C (SOC) pool in Chinese fir plantation was decreased by 38.9% to a minimum at 16. years old. The soils reaccumulated C only between 16 and 21. years old, and then became neutral to C till to the over-mature stage, attaining an equilibrium SOC pool 30% lower than the pre-harvest level. The contribution of subsoil (below 20. cm depth) to total profile SOC loss ranged from 53.2% in the recently regenerated stand to 81.1% in the 16-year-old stand, emphasizing the importance of subsoil for the SOC balance. Both litterfall and fine-root biomass of Chinese fir trees exhibited a decreasing trend during late stand development, while the stand fine-root biomass remained relatively constant due to an increased contribution from understory vegetations. The stagnancy in stand fine-root biomass during late stand development might prevent the accruement of total profile SOC. However, the reduction of tree roots and the increase of understory roots did change the vertical distribution of soil C at the over-mature stage: the surface 0-20. cm soils accumulated C while the 20-40. cm soils lose C. It is concluded that over-mature tree plantations had a limited role in continuously sequestering C as old-growth unmanaged forests did, and that the SOC pools of tree plantations can be hardly recovered to those of natural forests due to a large initial loss and a low late gain in SOC following tree plantation establishment. © 2012 Elsevier B.V.

Xie J.,Fujian Normal University | Xie J.,Key Laboratory for Subtropical Mountain Ecology | Guo J.,Fujian Normal University | Guo J.,Key Laboratory for Subtropical Mountain Ecology | And 8 more authors.
Forest Ecology and Management | Year: 2013

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±7.2MgCha-1) was 10 times higher than in BL (13.0±1.3MgCha-1), and 22% lower than that in SF (166.7±7.0MgCha-1) (p<0.05). The above ground biomass carbon pool was 91.9±4.8MgCha-1 in PM, similar to 98.2±5.5MgCha-1 in SF. The soil organic carbon (SOC) pool (to 1m depth) in PM (38.2±3.4MgCha-1) was 2.9 times higher than that in BL (13.0±1.3Mg C ha-1), but was significantly lower than that in SF (68.5±2.5Mg C ha-1). About 70% of the organic C to 1m depth was stored in the top 40cm in the two forests. The storage of light fraction organic carbon (LFOC) at the 0-60cm 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±0.09MgCha-1yr-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. © 2012 Elsevier B.V.

Ye S.L.,Fujian Normal University | Qi X.H.,Fujian Normal University | Qi X.H.,Key Laboratory for Subtropical Mountain Ecology | Chen Y.,Fujian Normal University | And 2 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2015

Climate change is characterized by warming trends, consequences of which are heat waves. These major meteorological disasters have severely threatened ecosystems, social and economic development, and human survival. At present, research on heat waves focuses on their description, causation, and consequences. Currently, little research describes the public perception of heat waves, even as this perception forms the social foundation of human response and adaptation to this phenomenon and has aroused interests of scholars both domestic and abroad. Our survey of 585 residents of Fuzhou, an urban area severely affected by heat waves, shows that: (1) most Fuzhou residents (75.56%) were able to correctly discern the local warming trend and 85.81% believes that this trend has become more severe since 2000, in accordance with meteorological data; (2) most Fuzhou residents (79.83%) have experienced heat waves and noticed their impact: 85.81% believed that heat waves significantly affected daily life, while 14.02% reported no effects. (3) ANOVA revealed that perceptions differed among subgroups. The perception of the warming trend differs significantly across age groups, increasing at first and then decreasing. Moreover, the perception of the impact of heat waves correlates with health, gradually decreasing with improved health levels. No correlation was found with gender, education, or occupational factors, consistent with previous reports. In addition, the results demonstrate that local residents spontaneously adopt a variety of adaptive behaviors during heat waves; these include increasing water intake, making dietary adjustments, installing air-conditioning, wearing cooler clothing, and using shading devices. Factors determining the adaptive measures chosen include income and convenience. Although air conditioning can effectively mitigate heat wave impact, because widespread use of this technology enhances the urban heat island effect and the risk of future heat waves, measures should be taken to reduce it. In the context of global warming, most metropolitan areas in China have been heavily affected by heat waves. Perceptions of heat waves among urban residents, which will guide them in taking measures to alleviate negative impacts, is a crucial area requiring further study, the results of which can serve as a valuable resource for local governments. © 2015 Ecological Society of China. All rights reserved.

Jin X.X.,Fujian Normal University | Ye S.L.,CAS Nanjing Institute of Geography and Limnology | Wu X.Y.,Fujian Normal University | Wang Y.,Fujian Normal University | And 2 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2016

In the 21st century, the strategic importance of islands is greatly highlighted. The quality of human settlements is one of the necessary indicators of island cities. However, until recently there have been few reports on quality evaluations of human settlements in island cities. Therefore, based on the theory of human settlements, a comprehensive quality evaluation system on the human settlements of island cities was conducted in the present study. Two typical island cities of the Xiamen and Pingtan Comprehensive Experimental Zone were chosen and their human settlement qualities during different periods were carefully explored and compared respectively. The results show that:(1) the human settlement quality of the two island cities is relatively stable, whereas the livability of Xiamen was higher than that of Pingtan and the gap between them gradually increased; (2) the urban human settlements were correlated with urban economic systems and the degree of correlation between them varied in different stages; (3) the human settlements of the two island cities was comprehensively affected by the subsystems, such as natural, human, social, residential, and support systems, respectively, and the roles of each subsystem were obviously different. The human settlements of Pingtan, which is at the early stage, presented some significant characteristics:the natural system aligned to some extent with the human system and changed to a small degree, whereas the contribution of the social, residential and support systems steadily increased. The human settlements of Xiamen, which is in a more developed stage, presented different characteristics; the natural system was relatively stable, whereas the variations in the human system increased slightly, and the contribution of the social, residential, and support systems were relatively high. The present study provides valuable references for the sustainable development of human settlements of Xiamen and Pingtan Comprehensive Experimental Zone and other similar island cities. Simultaneously, it enriches the empirical cases and human settlement theory. © 2016, Ecological Society of China. All rights reserved.

Li X.-F.,Key Laboratory of Geographic Information Science | Li X.-F.,East China Normal University | Li X.-F.,Key Laboratory for Subtropical Mountain Ecology | Li X.-F.,Fujian Normal University | And 4 more authors.
Environmental Earth Sciences | Year: 2014

Accumulations of rare earth elements (REEs) in human body through multiple pathways including food ingestion, air inhalation and dermal absorption have received considerable attention due to their chronic toxicity to human health. The distribution and fractionation of 14 REEs were conducted in soil, well water, human blood and hair in the vicinity of a large-scale mining site in southwest Fujian Province, China. The LREEs/HREEs ratios were 9.17 for soil, 2.18 for water, 36.93 for human blood and 7.24 for human hair, respectively. The distribution patterns of REEs in soil, human blood and hair samples were characterized by LREEs enrichment and HREEs depletion, but LREEs depletion and HREEs enrichment in water sample. LaN/YbN values of these samples ranged from 0.41 to 1.83, LaN/SmN values from 0.43 to 4.92, and GdN/YbN values from 0.81 to 4.71. Soil and human blood showed enrichments of Ce, Gd and Er, but water showed a depletion of Ce. In addition, the normalized patterns showed a weak negative anomaly of Eu in soil and a weak negative anomaly of Nd in human blood and hair. Consequently, enrichment and depletion of REEs differ significantly among soil, water and human blood and hair, thus the REEs after entering into human body can undergo fractionation effects. © 2014, Springer-Verlag Berlin Heidelberg.

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