Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.), a fast-growing, ever-green conifer tree with high yield and excellent quality, is the most important tree species of timber plantations in subtropical China. We inv...Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.), a fast-growing, ever-green conifer tree with high yield and excellent quality, is the most important tree species of timber plantations in subtropical China. We investigated the characteristics of biomass, litterfall and nutrient fluxes in the 8, 14 and 24 year-old stands, representing the young, middle-aged and mature stands. The results showed that Chinese fir plantations in central Fujian province had high productivity, and the proportion of stem mass in total biomass was between 50%-70%. Chinese fir was low nutrient-return tree species with litterfall. Nutrient withdrawal from senescing needles was a strong age-dependence for nitrogen, phosphorous and potassium in Chinese fir. With a management system of such short-rotation and continuously pure-crop planting, harvesting timber can lead to great nutrient loss, which may be one of the causes for site degradation.展开更多
The effects of different types of Chinese fir stand, including those with various composition (pure andmixed), in various cropping systems (first and continuous cropping system) and at different ages, on thenutrient s...The effects of different types of Chinese fir stand, including those with various composition (pure andmixed), in various cropping systems (first and continuous cropping system) and at different ages, on thenutrient status of soils in the hilly regions of southern Anhui Province were studied by means of ecologicalsequential comparison on the basis of similar climate and soil type. The work was carried out in the XiaoxiForest Farm of Jingxian County and the Caijiaqiao Forest Farm of Jingde County, where the soil is parayellowsoil derived from phyllite and sandstone. The results revealed that with the increase of age, Chinese fir purestand could accumulate organic matter and nitrogen in the soil but it resulted in decreasing of soil PH and baseions (especially Ca￣(2+)) compared to its mixed stand with broad-leaf trees such as Chinese sassafra.s. In orderto improve the soil fertility, it would be better to mix Chinese fir with broad-leaf trees when afforestation.In the management of Chinese fir pure stand, base compounds and phosphates should be added to the soilfor maintaining soil fertility and raising forest productivity.展开更多
Forest management is expected to influence soil CO2 effiux （FCO2） as a result of changes in microenvironmental conditions, soil microclimate, and root dynamics. Soil EGO2 rate was measured during the growing season ...Forest management is expected to influence soil CO2 effiux （FCO2） as a result of changes in microenvironmental conditions, soil microclimate, and root dynamics. Soil EGO2 rate was measured during the growing season of 2006 in both thinning and non-thinning locations within stands ranging from 0 to 8 years after the most recent thinning in Chinese fir （Cunninghamia lanceolata （Lamb.） Hook） plantations in Huitong Ecosystem Research Station, Hunan, China. Soil temperature and moisture were also measured to examine relationships between FCO2 and soil properties. Forest thinning resulted in huge changes in FCO2 that varied with time since cutting. Immediately following harvest （year 0） FCO2 in thinning area increased by about 30%, declined to 20%-27% below pre-cutting levels during years 4-6, and recovered to pre-cutting levels at 8 years post-cutting. A similar temporal pattern, but with smaller changes, was found in non-thinning locations. The initial increase in FCO2 could be attributed to a combination of root decay, soil disturbance, and increased soil temperature in gaps, while the subsequent decrease and recovery to the death and gradual regrowth of active roots. Strong effects of soil temperature and soil water content on FCO2 were found. Forest thinning mainly influenced FCO2 through changes in tree root respiration, and the net result was a decrease in integrated FCO2 flux through the entire felling cycle.展开更多
Data selection and methods for fitting coefficients were considered to test the self-thinning law. TheChinese fir (Cunninghamia lanceolata) in even-aged pure stands with 26 years of observation data were applied tofit...Data selection and methods for fitting coefficients were considered to test the self-thinning law. TheChinese fir (Cunninghamia lanceolata) in even-aged pure stands with 26 years of observation data were applied tofit Reineke's (1933) empirically derived stand density rule (No∝d^-1.605, N = numbers of stems, d= mean diameter),Yoda's (1963) self-thinning law based on Euclidian geometry (v ∝ N^-3/2, v= tree volume), and West, Brown andEnquist's (1997, 1999)(WBE) fractal geometry (w ∝ d^-8/3). OLS, RMA and SFF algorithms provided observedself-thinning exponents with the seven mortality rate intervals (2%--80%, 5%--80%, 10%- 80%, 15%--80%,20%- 80%, 25%--80% and 30%- 80%), which were tested against the exponents, and expected by the rules con-sidered. Hope for a consistent allometry law that ignores species-specific morphologic allometric and scale differ-ences faded. Exponents a of N ∝ d^α, were significantly different from -1.605 and -2, not expected by Euclidianfractal geometry;exponents β of w ∝ N^β varied around Yoda's self-thinning slope - 3/2, but was significantly differentfrom - 4/3;exponent Y of w ∝ d^γ tended to neither 8/3 nor 3.展开更多
基金This research was sponsored by National Natural Science Foundation of China (Grant No. 39630240 and 3000132).
文摘Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.), a fast-growing, ever-green conifer tree with high yield and excellent quality, is the most important tree species of timber plantations in subtropical China. We investigated the characteristics of biomass, litterfall and nutrient fluxes in the 8, 14 and 24 year-old stands, representing the young, middle-aged and mature stands. The results showed that Chinese fir plantations in central Fujian province had high productivity, and the proportion of stem mass in total biomass was between 50%-70%. Chinese fir was low nutrient-return tree species with litterfall. Nutrient withdrawal from senescing needles was a strong age-dependence for nitrogen, phosphorous and potassium in Chinese fir. With a management system of such short-rotation and continuously pure-crop planting, harvesting timber can lead to great nutrient loss, which may be one of the causes for site degradation.
文摘The effects of different types of Chinese fir stand, including those with various composition (pure andmixed), in various cropping systems (first and continuous cropping system) and at different ages, on thenutrient status of soils in the hilly regions of southern Anhui Province were studied by means of ecologicalsequential comparison on the basis of similar climate and soil type. The work was carried out in the XiaoxiForest Farm of Jingxian County and the Caijiaqiao Forest Farm of Jingde County, where the soil is parayellowsoil derived from phyllite and sandstone. The results revealed that with the increase of age, Chinese fir purestand could accumulate organic matter and nitrogen in the soil but it resulted in decreasing of soil PH and baseions (especially Ca￣(2+)) compared to its mixed stand with broad-leaf trees such as Chinese sassafra.s. In orderto improve the soil fertility, it would be better to mix Chinese fir with broad-leaf trees when afforestation.In the management of Chinese fir pure stand, base compounds and phosphates should be added to the soilfor maintaining soil fertility and raising forest productivity.
基金Project supported by the State Forestry Special Fund for non-profit industries of China (Nos.2007-4-15 and 20080430)the Key Program of the State Forestry Administration of China (No.2006-11)+2 种基金the Introducing Advance TechnologyProgram (948 Program) from the State Forestry Administration of China (No.2007-4-19)the Provincial Fund for Distin-guished Young Scholars of Hunan, China (No.07JJ1004)the Key Project of Science and Technology Department of Hunan Province, China (Nos.06FJ3083 and 2007SK4030).
文摘Forest management is expected to influence soil CO2 effiux （FCO2） as a result of changes in microenvironmental conditions, soil microclimate, and root dynamics. Soil EGO2 rate was measured during the growing season of 2006 in both thinning and non-thinning locations within stands ranging from 0 to 8 years after the most recent thinning in Chinese fir （Cunninghamia lanceolata （Lamb.） Hook） plantations in Huitong Ecosystem Research Station, Hunan, China. Soil temperature and moisture were also measured to examine relationships between FCO2 and soil properties. Forest thinning resulted in huge changes in FCO2 that varied with time since cutting. Immediately following harvest （year 0） FCO2 in thinning area increased by about 30%, declined to 20%-27% below pre-cutting levels during years 4-6, and recovered to pre-cutting levels at 8 years post-cutting. A similar temporal pattern, but with smaller changes, was found in non-thinning locations. The initial increase in FCO2 could be attributed to a combination of root decay, soil disturbance, and increased soil temperature in gaps, while the subsequent decrease and recovery to the death and gradual regrowth of active roots. Strong effects of soil temperature and soil water content on FCO2 were found. Forest thinning mainly influenced FCO2 through changes in tree root respiration, and the net result was a decrease in integrated FCO2 flux through the entire felling cycle.
基金The 12th and 13th Five-Year Plan of the National Scientific and Technological Support Projects(2015BAD09B01,2016YFD0600302)Jiangxi Scientific and Technological innovation plan(201702)National Natural Science Foundation of China(31570619,31370629)
文摘Data selection and methods for fitting coefficients were considered to test the self-thinning law. TheChinese fir (Cunninghamia lanceolata) in even-aged pure stands with 26 years of observation data were applied tofit Reineke's (1933) empirically derived stand density rule (No∝d^-1.605, N = numbers of stems, d= mean diameter),Yoda's (1963) self-thinning law based on Euclidian geometry (v ∝ N^-3/2, v= tree volume), and West, Brown andEnquist's (1997, 1999)(WBE) fractal geometry (w ∝ d^-8/3). OLS, RMA and SFF algorithms provided observedself-thinning exponents with the seven mortality rate intervals (2%--80%, 5%--80%, 10%- 80%, 15%--80%,20%- 80%, 25%--80% and 30%- 80%), which were tested against the exponents, and expected by the rules con-sidered. Hope for a consistent allometry law that ignores species-specific morphologic allometric and scale differ-ences faded. Exponents a of N ∝ d^α, were significantly different from -1.605 and -2, not expected by Euclidianfractal geometry;exponents β of w ∝ N^β varied around Yoda's self-thinning slope - 3/2, but was significantly differentfrom - 4/3;exponent Y of w ∝ d^γ tended to neither 8/3 nor 3.
