A study of the storage dynamics in the mixed broadleaved and Korean pine forests was carried out in the Changbai Mountains, Jilin Province, P. R. China. The modifying law of fallen trees was the storage dynamics of th...A study of the storage dynamics in the mixed broadleaved and Korean pine forests was carried out in the Changbai Mountains, Jilin Province, P. R. China. The modifying law of fallen trees was the storage dynamics of the existing fallen trees and the annual input in the mixed broadleaved and Korean pine forest. The current storage of fallen trees was 16.25 t昲m-2 in the initially, but after 100 years, 85% of the storage in dry weight was decomposed, and little material was left after 300 years. The average annual input of fallen trees was 0.6 t昲m-2and it increased with time to 31.0 t昲m-2after 200 years, which was maintained until the climax community ended. The total storage of fallen trees increased in the early stage. The decomposition of fallen trees eventually reached equilibrium with storage being identical with the annual input of fallen trees.展开更多
Eco-physiological responses of seedlings of eight species, Pinus koraiensis, Picea koraiensis, Larix olgensis, Populus ussuriensis, Betula platyphylla, Tilia amurensis, Traxinus mandshurica and Acer mono from broadlea...Eco-physiological responses of seedlings of eight species, Pinus koraiensis, Picea koraiensis, Larix olgensis, Populus ussuriensis, Betula platyphylla, Tilia amurensis, Traxinus mandshurica and Acer mono from broadleaved/Korean pine forest, to elevated CO2 were studied by using open-top chambers under natural sunlight in Changbai Mountain, China in two growing seasons (1998-1999). Two concentrations of CO2 were designed: elevated CO2 (700 祄olmol-1) and ambient CO2 (400 祄olmol-1). The study results showed that the height growth of the tree seedlings grown at elevated CO2 increased by about 10%-40% compared to those grown at ambient CO2. And the water using efficiency of seedlings also followed the same tendency. However, the responses of seedlings in transpiration and chlorophyll content to elevated CO2 varied with tree species. The broad-leaf tree species were more sensitive to the elevated CO2 than conifer tree species. All seedlings showed a photosynthetic acclimation to long-term elevated CO2.展开更多
This paper deals with a study on the effects of Chinese fir, loblolly pine and deciduous oak forests on thenutrient status of soils in northern subtropics of China, adopting the principle of forest ecology in the case...This paper deals with a study on the effects of Chinese fir, loblolly pine and deciduous oak forests on thenutrient status of soils in northern subtropics of China, adopting the principle of forest ecology in the caseof similar climate and soil type. The experimental area was situated in the Xiashu Experimental Centre ofForest, where the soil is yellow-brown soil derived from siliceous slope wash. Sample plots of these 3 standswere established to study the nutrient status in litter, the amount of nutrient uptake by roots, the quantityof nutrient output by percolating water outside the deep layer of soil, and the seasonal dynamics of availablenutrient in surface soil. It was shown that the intensity of nutrient cycling in soil under deciduous oak wasthe highest, and the effect of oak in improving soil fertility was the best. The result of improving soil fertilityby Chinese fir was the most inferior, though the intensity of nutrient cycling under that stand was higherthan that under loblolly pine stand. The influence of loblolly pine on the improvement of soil fertility wasbetter than that of Chinese fir, in spite of its lowest intensity of nutrient cycling.展开更多
Natural seedling regeneration and tree establishment are affected by various environmental factors. In this study, we established eight, eight, six, and four independent forest stands （each stand was further divided ...Natural seedling regeneration and tree establishment are affected by various environmental factors. In this study, we established eight, eight, six, and four independent forest stands （each stand was further divided into five subplots） respectively based on the altitudinal gradient, stand density, slope location, and slope aspect to investigate the effects of environmental factors on tree seedling regeneration in a pine-oak mixed forest. The results indicated that the seedling density was significantly higher at altitudes of 1,283 m to 1,665 m, whereas the sapling density did not differ with altitudes. The seedling and sapling density decreased significantly at 1,835 m. The seedling densities on the upper slopes were much higher than those on the middle and lower slopes, whereas the sapling density had no difference. The sapling density decreased southwest （20°-75°） whereas gradually from the it increased on the shady slopes to the northeast （40°）. The seedling density increased from southwest （20°） to northeast （40°The seedling and sapling densities increased with the stand density （850 trees ha-1 to 1,525 trees ha-1） whereas the sapling density was significantly lower in stands （1,9oo trees ha-O. Principal components analysis showed that the slope aspect and stand density had more important roles in tree regeneration in this study region compared with the other two factors. Therefore, our findings suggest that it will be beneficial to keep stands at a moderate density on shady slopes. Appropriate thinning of higher density stands is also expected to promote the natural regeneration of pine-oak mixed forest.展开更多
Cedar forests area in northeastern Algeria （Aures） is decreasing by the massive tree mortality. In some localities more than 95% of the trees have recently died （e.g. Boumerzoug in Belezma National Park）. Three re...Cedar forests area in northeastern Algeria （Aures） is decreasing by the massive tree mortality. In some localities more than 95% of the trees have recently died （e.g. Boumerzoug in Belezma National Park）. Three reported episodes of massive tree mortality in 1880, 1980, and 2000 were attributed to drought at least as the triggering factor. Our main objective was to reconstruct drought events that could be linked to Atlas cedar tree mortality using tree-ring series. We developed a Cedrus atlantica tree-ring width chronology in Chelia with a reliable period spanning from 1502 to 2008. Based on the relationship between chronology indices and instrumental precipitation data, we reconstructed total October-June precipitation. Dry events were identified using a threshold of 90% of the October-June mean instrumental precipitation. The unique drought event of 3-year period （1877-1879） could explain the tree mortality occurred in 1880. In terms of severity and frequency of droughts, the later half of the twentieth century seems to be the worst and may be responsible for the recent tree mortality.展开更多
基金Supported by NKBRSF (Grant No. G1999043407) the Institute of Applied Ecology (grant No. SCXZD0101)+2 种基金 CAS the National Natural Science Foundation of China (NSFC39970123) and by the Changbai Mountain Open Research Station.
文摘A study of the storage dynamics in the mixed broadleaved and Korean pine forests was carried out in the Changbai Mountains, Jilin Province, P. R. China. The modifying law of fallen trees was the storage dynamics of the existing fallen trees and the annual input in the mixed broadleaved and Korean pine forest. The current storage of fallen trees was 16.25 t昲m-2 in the initially, but after 100 years, 85% of the storage in dry weight was decomposed, and little material was left after 300 years. The average annual input of fallen trees was 0.6 t昲m-2and it increased with time to 31.0 t昲m-2after 200 years, which was maintained until the climax community ended. The total storage of fallen trees increased in the early stage. The decomposition of fallen trees eventually reached equilibrium with storage being identical with the annual input of fallen trees.
基金The project was supported by National Key Basic Development of China (G1999043400) and the grant KZCX-406-4 KZCX1SW01 of the Chinese Academy of Sciences
文摘Eco-physiological responses of seedlings of eight species, Pinus koraiensis, Picea koraiensis, Larix olgensis, Populus ussuriensis, Betula platyphylla, Tilia amurensis, Traxinus mandshurica and Acer mono from broadleaved/Korean pine forest, to elevated CO2 were studied by using open-top chambers under natural sunlight in Changbai Mountain, China in two growing seasons (1998-1999). Two concentrations of CO2 were designed: elevated CO2 (700 祄olmol-1) and ambient CO2 (400 祄olmol-1). The study results showed that the height growth of the tree seedlings grown at elevated CO2 increased by about 10%-40% compared to those grown at ambient CO2. And the water using efficiency of seedlings also followed the same tendency. However, the responses of seedlings in transpiration and chlorophyll content to elevated CO2 varied with tree species. The broad-leaf tree species were more sensitive to the elevated CO2 than conifer tree species. All seedlings showed a photosynthetic acclimation to long-term elevated CO2.
文摘This paper deals with a study on the effects of Chinese fir, loblolly pine and deciduous oak forests on thenutrient status of soils in northern subtropics of China, adopting the principle of forest ecology in the caseof similar climate and soil type. The experimental area was situated in the Xiashu Experimental Centre ofForest, where the soil is yellow-brown soil derived from siliceous slope wash. Sample plots of these 3 standswere established to study the nutrient status in litter, the amount of nutrient uptake by roots, the quantityof nutrient output by percolating water outside the deep layer of soil, and the seasonal dynamics of availablenutrient in surface soil. It was shown that the intensity of nutrient cycling in soil under deciduous oak wasthe highest, and the effect of oak in improving soil fertility was the best. The result of improving soil fertilityby Chinese fir was the most inferior, though the intensity of nutrient cycling under that stand was higherthan that under loblolly pine stand. The influence of loblolly pine on the improvement of soil fertility wasbetter than that of Chinese fir, in spite of its lowest intensity of nutrient cycling.
基金funded by the Special Research Program for Public-Welfare Forestry of State Forestry Administration of China (Grant No. 20100400206)National Natural Science Funds of China (Grant No. 31070570)CFERN & GENE Award Funds on Ecological Paper
文摘Natural seedling regeneration and tree establishment are affected by various environmental factors. In this study, we established eight, eight, six, and four independent forest stands （each stand was further divided into five subplots） respectively based on the altitudinal gradient, stand density, slope location, and slope aspect to investigate the effects of environmental factors on tree seedling regeneration in a pine-oak mixed forest. The results indicated that the seedling density was significantly higher at altitudes of 1,283 m to 1,665 m, whereas the sapling density did not differ with altitudes. The seedling and sapling density decreased significantly at 1,835 m. The seedling densities on the upper slopes were much higher than those on the middle and lower slopes, whereas the sapling density had no difference. The sapling density decreased southwest （20°-75°） whereas gradually from the it increased on the shady slopes to the northeast （40°）. The seedling density increased from southwest （20°） to northeast （40°The seedling and sapling densities increased with the stand density （850 trees ha-1 to 1,525 trees ha-1） whereas the sapling density was significantly lower in stands （1,9oo trees ha-O. Principal components analysis showed that the slope aspect and stand density had more important roles in tree regeneration in this study region compared with the other two factors. Therefore, our findings suggest that it will be beneficial to keep stands at a moderate density on shady slopes. Appropriate thinning of higher density stands is also expected to promote the natural regeneration of pine-oak mixed forest.
文摘Cedar forests area in northeastern Algeria （Aures） is decreasing by the massive tree mortality. In some localities more than 95% of the trees have recently died （e.g. Boumerzoug in Belezma National Park）. Three reported episodes of massive tree mortality in 1880, 1980, and 2000 were attributed to drought at least as the triggering factor. Our main objective was to reconstruct drought events that could be linked to Atlas cedar tree mortality using tree-ring series. We developed a Cedrus atlantica tree-ring width chronology in Chelia with a reliable period spanning from 1502 to 2008. Based on the relationship between chronology indices and instrumental precipitation data, we reconstructed total October-June precipitation. Dry events were identified using a threshold of 90% of the October-June mean instrumental precipitation. The unique drought event of 3-year period （1877-1879） could explain the tree mortality occurred in 1880. In terms of severity and frequency of droughts, the later half of the twentieth century seems to be the worst and may be responsible for the recent tree mortality.
