In this paper, secondary forest of Pinus massoniana , coniferous-broad-leaved mixed forest and broad-leaved evergreen forest were taken as research objects, to explore carbon reserve of arbor layer and its spatial dis...In this paper, secondary forest of Pinus massoniana , coniferous-broad-leaved mixed forest and broad-leaved evergreen forest were taken as research objects, to explore carbon reserve of arbor layer and its spatial distribution characteristics. At different succession stages, the sequence of organic carbon content in each organ was secondary forest of P. massoniana > coniferous-broad-leaved mixed forest> broad-leaved evergreen forest. Carbon reserve of arbor layer was the highest in broad-leaved evergreen forest, which was 129.34 t/hm 2, followed by coniferous-broad-leaved mixed forest (95.83 t/hm 2), and the minimum was 85.27 t/hm 2 in secondary forest of P. massoniana . In each stand type, the sequence of carbon reserve of each organ in arbor layer was trunk>root>branch>leaf>bark. Carbon reserve of arbor layer mainly concentrated in trunk, and the proportion to carbon reserve of arbor layer declined from secondary forest of P. massoniana to broad-leaved evergreen forest, while it had increasing relationship in root. In secondary forest of P. massoniana , coniferous-broad-leaved mixed forest and broad-leaved evergreen forest, individual with the diameter more than 20 cm accounted for the majority of carbon reserve in the arbor layer.展开更多
Seed dispersal is a key process within community dynamics. The spatial and temporal variations of seed dispersal and the interspecific differences are crucial for understanding species coexistence and community dynami...Seed dispersal is a key process within community dynamics. The spatial and temporal variations of seed dispersal and the interspecific differences are crucial for understanding species coexistence and community dynamics. This might also hold for the mixed evergreen broadleaved and deciduous forests in the mountains of subtropical China, but until now little existing knowledge is available for this question. In 2001, we chose to monitor the seed rain process of our mixed evergreen broad-leaved and deciduous forest communities in Mount Dalaoling National Forest Park, Yichang, Hubei Province, China. The preliminary analyses show obvious variations in seed rain density, species compositions and timing of seed rain among four communities. The average seed rain densities of the four communities are 2.43 ± 5.15, 54.13 ±182.75, 10.05 ±19.30 and 24.91 ± 58.86 inds/m^2, respectively; about one tenth the values in other studies in subtropical forests of China. in each community, the seed production is dominated by a limited number of species, and the contributions from the others are generally minor. Fecundity of evergreen broadleaved tree species is weaker than deciduous species. The seed rain of four communities begins earlier than September, and stops before December, peaking from early September to late October. The beginning date, ending date and peak times of seed rain are extensively varied among the species, indicating different types of dispersal strategies. According to the existing data, the timing of seed rain is not determined by the climate conditions in the same period, while the density of seed rain may be affected by the disturbances of weather variations at a finer temporal resolution.展开更多
In this paper, the Pinus massoniana forest in the early stage of succession, the coniferous broad-leaved mixed forest in the middle stage of succession, and the evergreen broad-leaved forest in the late stage of succe...In this paper, the Pinus massoniana forest in the early stage of succession, the coniferous broad-leaved mixed forest in the middle stage of succession, and the evergreen broad-leaved forest in the late stage of succession were studied, and the biomass and its spatial distribution characteristics of the tree layer in different succession stages of the ecosystem were discussed. The results showed that the biomass of the arbor layer was the highest in the evergreen broad-leaved forest, which was 292.51 t/ hm2, followed by the coniferous and broad-leaved mixed forest, which was 206.87 t/hm2, and the Pinus massoniana forest, which was 171.76 t/hm2. The biomass of trunks accounted for the largest proportion in the total biomass of the arbor layer, which reduced from the Pinus massoniana forest to the evergreen broad-leaved forest. The proportion of the biomass of roots in the total biomass of the arbor layer increased from the Pinus massoniana forest to the evergreen broad-leaved forest. The biomass of the diameter class above 20 cm in the Pinus massoniana forest, the coniferous and broad-leaved mixed forest and the evergreen broad-leaved forest accounted for a large proportion of total biomass.展开更多
Forest disturbance and recovery are critical ecosystem processes,but the temporal patterns of disturbance have not been studied in subtropical China.Using a tree-ring analysis approach,we studied post-logging above-gr...Forest disturbance and recovery are critical ecosystem processes,but the temporal patterns of disturbance have not been studied in subtropical China.Using a tree-ring analysis approach,we studied post-logging above-ground(ABG)biomass recovery dynamics over a 26-year period in four plots with different degrees of logging disturbance.Before logging,the ABG biomass ranged from 291 to 309 t ha-1.Soon after logging,the plots in primary forest,secondary forest,mixed forest and singlespecies forest had lost 33,91,90 and 100%of their initial ABG biomass,respectively.Twenty-six years after logging,the plots had regained 147,62,80 and 92%of their original ABG biomass,respectively.Over the 26 years following logging,the mean CAI(Current annual increment)were 10.1,5.5,6.4 and 10.8 t ha^-1 a^-1 and the average MAI(Mean annual increment)8.7,2.5,5.6 and 7.8 t ha^-1 a^-1 for the four forest types,respectively.The results indicate that subtropical forests subjected to moderate logging or disturbances do not require intensive management and single-species plantings can rapidly restore the above-ground biomass to levels prior to heavy logging.展开更多
The Dinghushan flux observation site, as one of the four forest sites of ChinaFLUX, aims to acquire long-term measurements of CO2 flux over a typical southern subtropical evergreen coniferous and broad-leaved mixed fo...The Dinghushan flux observation site, as one of the four forest sites of ChinaFLUX, aims to acquire long-term measurements of CO2 flux over a typical southern subtropical evergreen coniferous and broad-leaved mixed forest ecosystem using the open path eddy covariance method. Based on two years of data from 2003 to 2004, the characteristics of temporal variation in CO2 flux and its response to environmental factors in the forest ecosystem are analyzed. Provided two-dimensional coordinate rotation, WPL correction and quality control, poor energy-balance and underestimation of ecosystem respiration during nighttime implied that there could be a CO2 leak during the nighttime at the site. Using daytime (PAR 】 1.0μmol-1·m-2·s-1) flux data during windy conditions (u* 】 0.2 m·s-1), monthly ecosystem respiration (Reco) was derived through the Michaelis-Menten equation modeling the relationship between net ecosystem CO2 exchange (NEE) and photosynthetically active radiation (PAR). Exponential function was employed to describe the relationship between Reco and soil temperature at 5 cm depth (Ts05), then Reco of both daytime and nighttime was calculated respectively by the function. The major results are: (i) Derived from the Michaelis-Menten equation, the apparent quantum yield (α) was 0.0027±0.0011 mgCO2·μmol-1 photons, and the maximum photosynthetic assimilation rate (Amax) was 1.102±0.288 mgCO2·m-2·s-1. Indistinctive seasonal variation of o or Amax was consistent with weak seasonal dynamics of leaf area index (LAI) in such a lower subtropical evergreen mixed forest. (ii) Monthly accumulated Reco was estimated as 95.3±21.1 gC·m-2 mon-1, accounting for about 68% of the gross primary product (GPP). Monthly accumulated NEE was estimated as -43.2±29.6 gC·m-2·mon-1. The forest ecosystem acted as carbon sink all year round without any seasonal carbon efflux period. Annual NEE of 2003 and 2004 was estimated as -563.0 and -441.2 gC·m-2·a-1 respectively, accounting for about 32% of GPP.展开更多
基金Sponsored by Forestry Science and Technology Plan of Hunan Province(XLK201806,XLK201925)National Forestry Science and Technology Development Project(KJZXSA2018011,KJZXSA2019009)Operational Subsidy Project of National Forestry Science and Technology Innovation Platform(2019132068)
文摘In this paper, secondary forest of Pinus massoniana , coniferous-broad-leaved mixed forest and broad-leaved evergreen forest were taken as research objects, to explore carbon reserve of arbor layer and its spatial distribution characteristics. At different succession stages, the sequence of organic carbon content in each organ was secondary forest of P. massoniana > coniferous-broad-leaved mixed forest> broad-leaved evergreen forest. Carbon reserve of arbor layer was the highest in broad-leaved evergreen forest, which was 129.34 t/hm 2, followed by coniferous-broad-leaved mixed forest (95.83 t/hm 2), and the minimum was 85.27 t/hm 2 in secondary forest of P. massoniana . In each stand type, the sequence of carbon reserve of each organ in arbor layer was trunk>root>branch>leaf>bark. Carbon reserve of arbor layer mainly concentrated in trunk, and the proportion to carbon reserve of arbor layer declined from secondary forest of P. massoniana to broad-leaved evergreen forest, while it had increasing relationship in root. In secondary forest of P. massoniana , coniferous-broad-leaved mixed forest and broad-leaved evergreen forest, individual with the diameter more than 20 cm accounted for the majority of carbon reserve in the arbor layer.
基金the National Natural Science Foundation of China(30000024,30470313).
文摘Seed dispersal is a key process within community dynamics. The spatial and temporal variations of seed dispersal and the interspecific differences are crucial for understanding species coexistence and community dynamics. This might also hold for the mixed evergreen broadleaved and deciduous forests in the mountains of subtropical China, but until now little existing knowledge is available for this question. In 2001, we chose to monitor the seed rain process of our mixed evergreen broad-leaved and deciduous forest communities in Mount Dalaoling National Forest Park, Yichang, Hubei Province, China. The preliminary analyses show obvious variations in seed rain density, species compositions and timing of seed rain among four communities. The average seed rain densities of the four communities are 2.43 ± 5.15, 54.13 ±182.75, 10.05 ±19.30 and 24.91 ± 58.86 inds/m^2, respectively; about one tenth the values in other studies in subtropical forests of China. in each community, the seed production is dominated by a limited number of species, and the contributions from the others are generally minor. Fecundity of evergreen broadleaved tree species is weaker than deciduous species. The seed rain of four communities begins earlier than September, and stops before December, peaking from early September to late October. The beginning date, ending date and peak times of seed rain are extensively varied among the species, indicating different types of dispersal strategies. According to the existing data, the timing of seed rain is not determined by the climate conditions in the same period, while the density of seed rain may be affected by the disturbances of weather variations at a finer temporal resolution.
基金Sponsored by Forestry Science and Technology Plan of Hunan Province(XLK201925,XLK201806)National Forestry Science and Technology Development Project(KJZXSA2018011)Operational Subsidy Project of National Forestry Science and Technology Innovation Platform(2018-LYPT-DW-064)
文摘In this paper, the Pinus massoniana forest in the early stage of succession, the coniferous broad-leaved mixed forest in the middle stage of succession, and the evergreen broad-leaved forest in the late stage of succession were studied, and the biomass and its spatial distribution characteristics of the tree layer in different succession stages of the ecosystem were discussed. The results showed that the biomass of the arbor layer was the highest in the evergreen broad-leaved forest, which was 292.51 t/ hm2, followed by the coniferous and broad-leaved mixed forest, which was 206.87 t/hm2, and the Pinus massoniana forest, which was 171.76 t/hm2. The biomass of trunks accounted for the largest proportion in the total biomass of the arbor layer, which reduced from the Pinus massoniana forest to the evergreen broad-leaved forest. The proportion of the biomass of roots in the total biomass of the arbor layer increased from the Pinus massoniana forest to the evergreen broad-leaved forest. The biomass of the diameter class above 20 cm in the Pinus massoniana forest, the coniferous and broad-leaved mixed forest and the evergreen broad-leaved forest accounted for a large proportion of total biomass.
文摘Forest disturbance and recovery are critical ecosystem processes,but the temporal patterns of disturbance have not been studied in subtropical China.Using a tree-ring analysis approach,we studied post-logging above-ground(ABG)biomass recovery dynamics over a 26-year period in four plots with different degrees of logging disturbance.Before logging,the ABG biomass ranged from 291 to 309 t ha-1.Soon after logging,the plots in primary forest,secondary forest,mixed forest and singlespecies forest had lost 33,91,90 and 100%of their initial ABG biomass,respectively.Twenty-six years after logging,the plots had regained 147,62,80 and 92%of their original ABG biomass,respectively.Over the 26 years following logging,the mean CAI(Current annual increment)were 10.1,5.5,6.4 and 10.8 t ha^-1 a^-1 and the average MAI(Mean annual increment)8.7,2.5,5.6 and 7.8 t ha^-1 a^-1 for the four forest types,respectively.The results indicate that subtropical forests subjected to moderate logging or disturbances do not require intensive management and single-species plantings can rapidly restore the above-ground biomass to levels prior to heavy logging.
基金This study was jointly supported by the Knowledge Innovation Program of the Chinese Acad-emy of Sciences (Grant Nos. KZCX1-SW-01-O1A and KSCX2-SW-120) the National Key Fundamental Research Development Layout Project (Grant No. 2002CB412501) the Natural Science Foundation of Guangdong Province (Grant No. 010567).
文摘The Dinghushan flux observation site, as one of the four forest sites of ChinaFLUX, aims to acquire long-term measurements of CO2 flux over a typical southern subtropical evergreen coniferous and broad-leaved mixed forest ecosystem using the open path eddy covariance method. Based on two years of data from 2003 to 2004, the characteristics of temporal variation in CO2 flux and its response to environmental factors in the forest ecosystem are analyzed. Provided two-dimensional coordinate rotation, WPL correction and quality control, poor energy-balance and underestimation of ecosystem respiration during nighttime implied that there could be a CO2 leak during the nighttime at the site. Using daytime (PAR 】 1.0μmol-1·m-2·s-1) flux data during windy conditions (u* 】 0.2 m·s-1), monthly ecosystem respiration (Reco) was derived through the Michaelis-Menten equation modeling the relationship between net ecosystem CO2 exchange (NEE) and photosynthetically active radiation (PAR). Exponential function was employed to describe the relationship between Reco and soil temperature at 5 cm depth (Ts05), then Reco of both daytime and nighttime was calculated respectively by the function. The major results are: (i) Derived from the Michaelis-Menten equation, the apparent quantum yield (α) was 0.0027±0.0011 mgCO2·μmol-1 photons, and the maximum photosynthetic assimilation rate (Amax) was 1.102±0.288 mgCO2·m-2·s-1. Indistinctive seasonal variation of o or Amax was consistent with weak seasonal dynamics of leaf area index (LAI) in such a lower subtropical evergreen mixed forest. (ii) Monthly accumulated Reco was estimated as 95.3±21.1 gC·m-2 mon-1, accounting for about 68% of the gross primary product (GPP). Monthly accumulated NEE was estimated as -43.2±29.6 gC·m-2·mon-1. The forest ecosystem acted as carbon sink all year round without any seasonal carbon efflux period. Annual NEE of 2003 and 2004 was estimated as -563.0 and -441.2 gC·m-2·a-1 respectively, accounting for about 32% of GPP.
