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Ming A.,Chinese Academy of Forestry | Ming A.,Guangxi Youyiguan Forest Ecosystem Research Station | Jia H.,Chinese Academy of Forestry | Jia H.,Guangxi Youyiguan Forest Ecosystem Research Station | And 3 more authors.
PLoS ONE | Year: 2014

More than 60% of the total area of tree plantations in China is in subtropical, and over 70% of subtropical plantations consist of pure stands of coniferous species. Because of the poor ecosystem services provided by pure coniferous plantations and the ecological instability of these stands, a movement is under way to promote indigenous broadleaf plantation cultivation as a promising alternative. However, little is known about the carbon (C) stocks in indigenous broadleaf plantations and their dependence on stand age. Thus, we studied above- and below-ground biomass and C stocks in a chronosequence of Mytilaria laosensis plantations in subtropical China; stands were 7, 10, 18, 23, 29 and 33 years old. Our assessments included tree, shrub, herb and litter layers. We used plot-level inventories and destructive tree sampling to determine vegetation C stocks. We also measured soil C stocks by analyses of soil profiles to 100 cm depth. C stocks in the tree layer dominated the above-ground ecosystem C pool across the chronosequence. C stocks increased with age from 7 to 29 years and plateaued thereafter due to a reduction in tree growth rates. Minor C stocks were found in the shrub and herb layers of all six plantations and their temporal fluctuations were relatively small. C stocks in the litter and soil layers increased with stand age. Total above-ground ecosystem C also increased with stand age. Most increases in C stocks in below-ground and total ecosystems were attributable to increases in soil C content and tree biomass. Therefore, considerations of C sequestration potential in indigenous broadleaf plantations must take stand age into account.

Ming A.-G.,Chinese Academy of Forestry | Ming A.-G.,Guangxi Youyiguan Forest Ecosystem Research Station | Zheng L.,Chinese Academy of Forestry | Zheng L.,Guangxi Youyiguan Forest Ecosystem Research Station | And 4 more authors.
Beijing Linye Daxue Xuebao/Journal of Beijing Forestry University | Year: 2015

Based on the quadrat survey and actual biomass measurement in a 28-year-old Mesua ferrea plantation in Experimental Center of Tropical Forestry located at Pingxiang City of Guangxi Zhuang Autonomous Region, the carbon stock and its allocation characteristics were studied by the allometric method. The results showed that carbon contents in different organs of M. ferrea ranged between 452.4 and 524.5 g/kg, following the order of leaf > stem > branch > root > bark. Soil carbon content in the surface layer was the highest, and it reduced with the increase of soil depth. The biomass and carbon stock of tree layer in M. ferrea plantation were 165.8 and 79.3 t/hm2, and the allocation of biomass ranked as stem > branch > root > leaf > bark, the same as the allocation of the carbon stock in the tree layer. The biomass of M. ferrea plantation ecosystem was 173.5 t/hm2 and carbon stock 203.1 t/hm2, the biomass in the plantation was mainly distributed in the tree layer (95.6%), and the allocation of carbon stock in different components was soil layer (59.3%) > tree layer (39.0%) > ground layer (1.7%). The carbon content aboveground was greater than that underground in shrub layer and herb layer; however, the biomass and carbon stock aboveground were less than those underground. ©, 2015, Beijing Forestry University. All right reserved.

Hao J.,Chinese Academy of Forestry | Hao J.,Guangxi Youyiguan Forest Ecosystem Research Station | Mo H.-H.,Chinese Academy of Forestry | Mo H.-H.,Guangxi Youyiguan Forest Ecosystem Research Station | And 4 more authors.
Forest Research | Year: 2016

Objective: To study the decomposition dynamics of leaf litter and its relationship with soil chemical properties in two young plantation stands (monocultures of Betula alnoides and Eucalyptus urophylla × E. grandis) in subtropical China. Method: The decomposition processes of leaf litter were measured using mesh nylon bag method. Result: The decomposition coefficients of leaf litter of B. alnoides and E. urophylla × E. grandis were 0.96 a-1 and 0.88 a-1, respectively. During the 12-month decomposition, the organic carbon contents declined gradually in the two leaf litter. The total K and C/N ratio rapidly decrease at the early stage, and tended towards stability thereafter. The total N and total P in the two leaf litter increased gradually, whereas the N/P ratio increased at first and then decreased throughout the entire decomposition. In both early and late phase of decomposition, the dry mass loss of the leaf litter was correlated positively with the N contents (R=0.877 and 0.855, respectively), and a negative relation was observed with C/N ratio (R=-0.735 and-0.697, respectively). Compared with the E. urophylla × E. grandis stand, the B. alnoides had significantly higher contents of soil organic carbon (SOC), total N, total P, total K as well as higher N/P ratio in 0-10 and 10-20 cm soil depth. However, the litter decomposition had no significant effects on SOC, total K, pH, C/N ratio and N/P ratio in 20-30 cm soil depth. The correlation analysis revealed that the organic C of leaf litter was significantly related to SOC, total N, total P, total K and N/P ratio, whereas the total N of leaf litter was significantly related to soil total N, pH and C/N ratio. Conclusion: The nutrient contents of leaf litter were found to be significantly correlated with the soil nutrient condition. Compared with the E. urophylla × E. grandis, the nutrient contents of leaf litter were significantly higher in B. alnoides, and subsequently, faster decomposition rate of leaf litter resulted in higher soil nutrient contents. © 2016, Chinese Academy of Forestry. All right reserved.

Luo D.,Chinese Academy of Forestry | Shi Z.M.,Chinese Academy of Forestry | Wang W.X.,Chinese Academy of Forestry | Liu S.R.,Chinese Academy of Forestry | And 6 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2015

Carbon sequestration in forest ecosystems is recognized as a key mechanism for mitigating the accumulation of atmospheric carbon dioxide. However, both forest carbon pools and sequestration vary according to tree species, age of the stand, soil types, climate, environmental disturbances, and management practices. Tree species composition and management practices are important tools for increasing carbon storage in forest ecosystems. Plantation is becoming a key component of the world’s forest resources and is playing an important role in sustainable forest management. Well-designed, multi-purpose plantations can reduce the pressure on natural forests and complement some ecological resources provided by natural forests in addition to mitigating climate change through direct carbon sequestration. Afforestation and reforestation are important measures for managing commercial forests in subtropical China. However, the large-scale development of monoculture plantations of coniferous species (e.g., Pinus massoniana and Cunninghamia lanceolata) and exotic species (Eucalyptus spp.) has caused a number of problems, such as the loss of biodiversity, degradation of soil fertility, reduction of ecosystem stability, and loss of ecological resources. Thus, some broad-leaved tree species with different functions (e.g., indigenous valuable broad-leaved species and nitrogen-fixing species) have been developed for restructuring the plantations. In this study, three young plantation stands (monoculture of Erythrophleum fordii, monoculture of P. massoniana and a mixed stand of the two species) were selected to study carbon and nitrogen storage in these ecosystems and their spatial distribution. The results showed that the total carbon storage of the mixed plantation stand was 137.75 t/ hm2, higher than that of monoculture stands of E. fordii (134.07 t/ hm2) and P. massoniana (131.10 t/ hm2). Nitrogen storage was highest in E. fordii (10.19 t/ hm2), followed by the mixed plantation (8.68 t/ hm2), and then P. massoniana stands (7.01 t/ hm2). The spatial distribution of carbon and nitrogen was identical in the three plantation stands, with the majority found in the 0—100 cm soil (occupying an average 81.49% and 96.91% of the total storage, respectively), followed by the above- ground biomass represented by the trees (17.52% and 2.69%, respectively), and the understory vegetation and litterfall. Soil organic carbon was mainly distributed in the top-soil, while soil nitrogen was irregularly distributed. Average organic carbon storage in 0—30 cm soil was 52.52 t/ hm2(47.99% of the total 0—100 cm soil storage). The mixed plantation stands showed a greater capacity for carbon storage in comparison to the other two monoculture stands. The above-/ underground ratio of carbon and nitrogen suggested that these three young plantation stands had a high potential for carbon and nitrogen sequestration. The results are significant in that they provide scientific references for tree species selection and plantation management to enhance productivity and carbon sequestration in subtropical China. © 2015 Ecological Society of China. All rights reserved.

Sun D.-J.,Guangxi University | Sun D.-J.,Chinese Academy of Forestry | Wen Y.-G.,Guangxi University | Wen Y.-G.,Guangxi Youyiguan Forest Ecosystem Research Station | And 8 more authors.
Forest Research | Year: 2015

The study was conducted in a Cunninghamia lanceolata stand under close-to-nature management, with three different thinning densities (75%, 55%, and 35%) and three repetitions, in the Experimental Center of Tropical Forestry, Pingxiang, Guangxi. Four broad-leaved species Castanopsis hystrix, Mytilaria laosensis, Castanopsis fissa and Machilus pingii were randomly inter-planted into the Cunninghamia lanceolata stand. The impact of close-to-nature management with different thinning densities on community composition, species diversity and growth status were studied. The results showed that after five years of the close-to-nature management, the number of species in tree layer, shrub layer and herb layer highly increased. The dominant species in shrub layer and herb layer varied before and after thinning operation, but they were mostly the same in different thinning intensities. In the shrub layer, there was no significant difference in diversity indexes between the thinning stands and the unthinned pure stands. In the herb layer, the diversity indexes in the thinning stands were higher than that of the unthinned pure stands, while the Simpson index and Pielous evenness index were significantly higher than the pure stand. The average DBH of Cunninghamia lanceolata was significantly increased with the thinning intensities, but no significant difference was found in tree height. The DBH and height of the broad-leaved trees grew as the thinning density increasing. Significant differences were found in the DBH and height of Castanopsis fissa and Castanopsis hystrix in different thinning intensities. Intolerant species such as Castanopsis fissa and Mytilaria laosensis, as well as neutral species Castanopsis hystrix were good for inter-planted in high thinning intensity during close-to-nature management in Cunninghamia lanceolata plantation, while the shade tolerant species like Machilus pingii performed better in medium thinning stands. ©, 2015, Chinese Academy of Forestry. All right reserved.

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