Aims The Mongolian Altai is an old settlement area,which is populated by pastoral nomads since 2000–3000 years.Forests in this region(at ca.2300 m a.s.l.)are highly fragmented and border on steppe and alpine grasslan...Aims The Mongolian Altai is an old settlement area,which is populated by pastoral nomads since 2000–3000 years.Forests in this region(at ca.2300 m a.s.l.)are highly fragmented and border on steppe and alpine grasslands,which are used for mobile livestock husbandry.The climate in Central Asia is warming to levels clearly above the global average,which affects the vegetation.Furthermore,the transition from planned to market economy and the decollectivization of livestock 20 years ago has strongly changed land use practices in Mongolia,especially resulting in an increase in recent logging activities.We were interested in the question how climate warming and selective logging influence the annual stem growth and the stand structure.Methods The impact of climate and land use by the pastoral nomads on the annual stem increment of more than 1800 trees of Siberian larch(Larix sibirica)was analyzed.Different groups of trees with divergent growth trends depending on the social position and stand history were identified by non-metric multidimensional scaling and analysis of similarities.Long-term trends in the annual stem increment were analyzed by establishing separate regional growth curves for trees of different age classes.Important Findings Instrumental climate data substantiate an increase of temperature by 2.1°C since 1940 at constant precipitation.Trees benefit from the increased temperatures.Climate–response analysis revealed that radial stem increment was promoted by the temperature in early summer,but also high precipitation in spring and in the year before tree-ring formation.Forest dynamics is also strongly influenced by anthropogenic activities.In addition to the natural forest dynamics,logging resulted in divergent growth trends within given age classes and habitats(forest interior and forest edge);overall,22 groups of trees with different characteristics in the annual radial stem increment were identified.A tree-ring series-based reconstruction of logging intensity since 1935 suggests that moderate sele展开更多
Degradation of land/water ecotones in China is a serious problem and it is often neglected by people. The types of ecotone degradation are described and analyzed. The degradation of land/water ecotones enhanced the wa...Degradation of land/water ecotones in China is a serious problem and it is often neglected by people. The types of ecotone degradation are described and analyzed. The degradation of land/water ecotones enhanced the water quality reduction, bank erosion, desasters such as landslide, flood and drought, biodiversity reduction, lost of fertilized lands, decrease of the resource value of water scenic beauty and many others. The paper analyzes how these problems are related with each other.展开更多
This paper studied the biomass distribution patterns of Lanix olgensis/swamp ecotones and Betula platyphlla/swamp ecotones in Changbai Mountain so as to provide theory foundation for the management of these natur...This paper studied the biomass distribution patterns of Lanix olgensis/swamp ecotones and Betula platyphlla/swamp ecotones in Changbai Mountain so as to provide theory foundation for the management of these nature resources, by setting up sample belts, investigating initial data along the environmental gradients change, and establishing regression models. By means of regression models, the biomass of communities, layers, tree species and organs was calculated. In this system, it was found that the community biomass inreased gradually along the environmental gradients change from swamp to forest in Changbai Mountain. Furthermore, the ecotoneal biomass distributed mainly over tree layer. The tree biomass distributed mainly in two or three dominate tree species.展开更多
Climate constitutes the main limiting factor for tree-ring growth in high-elevation forests, and the relationship between tree-ring growth and climate is complex. Based on tree-ring chronology and meteorological data,...Climate constitutes the main limiting factor for tree-ring growth in high-elevation forests, and the relationship between tree-ring growth and climate is complex. Based on tree-ring chronology and meteorological data, the influence of precipitation, mean temperature and mean minimum temperature at yearly, seasonal and monthly scales on the tree-ring growth of Picea crossifolia was studied at treeline ecotones in the Qilian Mountains, northwestern China. The results show that growing season temperatures of previous and current years are important limiting factors on tree-ring growth, particularly June mean temperature and mean minimum temperature of current year. The precipitations in the previous winter and current spring have a positive correlation, and in the current fall has a negative correlation with tree-ring growth, but these correlations are not significant. Our results suggest that temperature controls tree-ring growth more strongly than precipitation at treeline ecotones in the Qilian Mountains.展开更多
Ecotones have received great attention due to its critical function in energy flux, species harbor, global carbon sequestration, and land-atmosphere interaction. This study investigated land use pattern and spatial he...Ecotones have received great attention due to its critical function in energy flux, species harbor, global carbon sequestration, and land-atmosphere interaction. This study investigated land use pattern and spatial heterogeneity of the ecotones among agricultural land, forest land, and grassland of the southeastern Da Hinggan Mountains in the northeastern China. The change of these delineated ecotones under different slopes and aridity conditions was analyzed by two landscape indices, edge density(ED) and core area percentage of landscape(CPL), to explore the inter-linkage between spatial structure of ecotones and socioeconomic development and land management. Specifically, the ecotones such as agriculture-forest(AF) ecotone, forest-grassland(FG) ecotone, and agriculture-forestgrassland(AFG) ecotone moved from the arid southeast to the humid northwest. The flat area with small slope is more edge-fragmented than the steep area since the ED decreases as the slope increases. The AF ecotone mostly found in the humid region is moving to more humid areas while the agriculture-grassland(AG) ecotone mostly found in the dry region is moving towards the drier region.展开更多
An ecotone is a transition area between two biomes or two different ecosystems and are often fragile, sensitive and variable. Since the 1970s, the study of the ecotone has increasingly gained notoriety as an important...An ecotone is a transition area between two biomes or two different ecosystems and are often fragile, sensitive and variable. Since the 1970s, the study of the ecotone has increasingly gained notoriety as an important facet of ecological research. China, with a vast complex geology, climate and vegetation, is home to a variety of ecotones. This variety is witnessed in breeds, scales and sizes. This vast array has not only laid a solid foundation for scientific research but also enhanced China’s economic development, social development and cultural diversity conservation. According to the geographical distribution and ecological features of China’s large scale ecotone, ＂The trinity index system＂ has been established including land use types, natural climate characteristics and agricultural economic development to classify and define the spatial distribution of typical ecotones in China. Based on this classification, the natural environmental characteristics, environmental fragility and the existing problems of five kinds of typical ecotones have been studied. This study will lead to a comprehensive understanding of the evolutionary patterns of ecotones.展开更多
During last decades, new trends appeared in the ecotones of the upper boundary of forests at the ridges surroundingLakeBaikal(Khamar-Daban and Baikal’sky Ridge): ones to advance of wood species (Pinus sibirica Du Tou...During last decades, new trends appeared in the ecotones of the upper boundary of forests at the ridges surroundingLakeBaikal(Khamar-Daban and Baikal’sky Ridge): ones to advance of wood species (Pinus sibirica Du Tour, Abies sibirica Ledeb., Larix sibirica Ledeb., Larix dahurica Lawson) out of timber stands into the area of subgoltsy with Pinus pumila (Pallas) Regel. up to mountain tundras. In average, this is from 100 to 200 - 300 meters (maximum up to500 m) in linear distance from the margin of dense timber stand. A burst of forests renewal occurred in 1989-1995, it resulted probably from a high productivity of the seeds of wood species due to warmer winters in 1980ies-1990ies which favoured the formation of favourable climate-edaphic conditions for the development of forest communities above the forests boundary on the ridges surrounding Lake Baikal.展开更多
Changes in vegetation structure in environments contact community characterize the ecotones and paragenese inside zonal vegetation site or altitude belt as of concrete environments while differences of cenotic structu...Changes in vegetation structure in environments contact community characterize the ecotones and paragenese inside zonal vegetation site or altitude belt as of concrete environments while differences of cenotic structures of communities between zones or between altitude belts as well. The aim of this work was research of structural-dynamic organization of phytocenoses forming under the conditions of environments contact and mountain tundra, forests (zonal taiga) and extrazonal steppes, zonal forest steppes of some areas at the Baikalian Siberia, Eastern Siberia of Russia.展开更多
Aims Several mechanistic hypotheses have been developed to explain the existence of alpine treelines worldwide.The reproduction limita-tion hypothesis(RLH)postulates that reproductive processes such as seed production...Aims Several mechanistic hypotheses have been developed to explain the existence of alpine treelines worldwide.The reproduction limita-tion hypothesis(RLH)postulates that reproductive processes such as seed production and dispersal are restricted in treeline envi-ronments,thereby limiting the establishment of new individuals in advance of extant treelines.Despite its popularity,no study has tested this hypothesis in a comprehensive fashion.In this experi-ment,we attempted to answer whether there are enough viable seeds being dispersed beyond treeline for sexually mediated tree-line advance,and what the implications of climate change might be on these processes.Methods We established 30 plots across two aspects(north vs.south)and three elevational habitats(forest,treeline and tundra)in a white spruce(Picea glauca)boreal forest-alpine tundra ecotone in south-west Yukon,Canada.In each plot,tree characteristics,seed produc-tion and predispersal damage were measured.Additionally,eight dispersal trays were positioned in each plot to measure seed rain,and germination trials with and without predation exclosures were constructed in a subset of plots to quantify dispersal and germina-tion success.Important Findings Results were highly variable both temporally and spatially.In 2014,a mast year,69%of adult trees produced cones compared to 0.4%in the following year.Higher density of trees in forest plots compared to treeline and tundra resulted in greater seed production at lower elevations.Across all plots,88%of seeds were damaged before dispersal or were not viable.Treeline plots had significantly greater predispersal damage.Seed rain was greater in south-facing plots than north-facing plots.Less than 2%of seeds produced on the landscape were dispersed into Tundra plots,located 50 m above treeline.There was a net movement of seeds from the north-facing slope to the south at our study site,likely due to prevailing winds during the dispersal period.Germination counts were more than double on north-facing slopes and one-third展开更多
Nutrient retention capacity by the land/water ecotone soil of Lake Baiyangdian was studied by means of simulation in situ. The results from column experiments suggested that the standard capacity for phosphorus adsorp...Nutrient retention capacity by the land/water ecotone soil of Lake Baiyangdian was studied by means of simulation in situ. The results from column experiments suggested that the standard capacity for phosphorus adsorption be less than P14 mg·kg -1 soil in order to meet the lake water quality regulation (P 0.1 mg·L -1 ). Thus the 9,333 hectares of ecotone around the lake could retain 1,245 tons phosphorus in the upper 50-cm soil without degrading the water quality. The amount was nearly 24 times large as that of taken by annual reed harvesting. The maximum capacity for phosphorus was measured as P 774 mg·kg -1 soil. The isothermal equation of phosphorus was also obtained. It was found that temperature had a significant effect on the transformation of nitrogen, and higher temperature would accelerated the nitrification rate. Nitrogen retention was conducted by the microbial activities in the soil and the uptake through aquatic vegetation. The research will benefit for better utilization of local ecotone and design of the planning project which aims to water eutrophication control.展开更多
基金The study was supported by a grant of the Volkswagen Foundation to M.H.,C.D.and C.L.for the project‘Forest regeneration and biodiversity at the forest-steppe border of the Altai and Khangai Mountains under contrasting developments of livestock numbers in Kazakhstan and Mongolia’.
文摘Aims The Mongolian Altai is an old settlement area,which is populated by pastoral nomads since 2000–3000 years.Forests in this region(at ca.2300 m a.s.l.)are highly fragmented and border on steppe and alpine grasslands,which are used for mobile livestock husbandry.The climate in Central Asia is warming to levels clearly above the global average,which affects the vegetation.Furthermore,the transition from planned to market economy and the decollectivization of livestock 20 years ago has strongly changed land use practices in Mongolia,especially resulting in an increase in recent logging activities.We were interested in the question how climate warming and selective logging influence the annual stem growth and the stand structure.Methods The impact of climate and land use by the pastoral nomads on the annual stem increment of more than 1800 trees of Siberian larch(Larix sibirica)was analyzed.Different groups of trees with divergent growth trends depending on the social position and stand history were identified by non-metric multidimensional scaling and analysis of similarities.Long-term trends in the annual stem increment were analyzed by establishing separate regional growth curves for trees of different age classes.Important Findings Instrumental climate data substantiate an increase of temperature by 2.1°C since 1940 at constant precipitation.Trees benefit from the increased temperatures.Climate–response analysis revealed that radial stem increment was promoted by the temperature in early summer,but also high precipitation in spring and in the year before tree-ring formation.Forest dynamics is also strongly influenced by anthropogenic activities.In addition to the natural forest dynamics,logging resulted in divergent growth trends within given age classes and habitats(forest interior and forest edge);overall,22 groups of trees with different characteristics in the annual radial stem increment were identified.A tree-ring series-based reconstruction of logging intensity since 1935 suggests that moderate sele
文摘Degradation of land/water ecotones in China is a serious problem and it is often neglected by people. The types of ecotone degradation are described and analyzed. The degradation of land/water ecotones enhanced the water quality reduction, bank erosion, desasters such as landslide, flood and drought, biodiversity reduction, lost of fertilized lands, decrease of the resource value of water scenic beauty and many others. The paper analyzes how these problems are related with each other.
基金Chinese Academy of Sciences and National Education Committee
文摘This paper studied the biomass distribution patterns of Lanix olgensis/swamp ecotones and Betula platyphlla/swamp ecotones in Changbai Mountain so as to provide theory foundation for the management of these nature resources, by setting up sample belts, investigating initial data along the environmental gradients change, and establishing regression models. By means of regression models, the biomass of communities, layers, tree species and organs was calculated. In this system, it was found that the community biomass inreased gradually along the environmental gradients change from swamp to forest in Changbai Mountain. Furthermore, the ecotoneal biomass distributed mainly over tree layer. The tree biomass distributed mainly in two or three dominate tree species.
基金supported by the Major Research Plan of National Natural Science Foundation of China (No. 91025014),the National Natural Science Foundation of China (No. 30800147)
文摘Climate constitutes the main limiting factor for tree-ring growth in high-elevation forests, and the relationship between tree-ring growth and climate is complex. Based on tree-ring chronology and meteorological data, the influence of precipitation, mean temperature and mean minimum temperature at yearly, seasonal and monthly scales on the tree-ring growth of Picea crossifolia was studied at treeline ecotones in the Qilian Mountains, northwestern China. The results show that growing season temperatures of previous and current years are important limiting factors on tree-ring growth, particularly June mean temperature and mean minimum temperature of current year. The precipitations in the previous winter and current spring have a positive correlation, and in the current fall has a negative correlation with tree-ring growth, but these correlations are not significant. Our results suggest that temperature controls tree-ring growth more strongly than precipitation at treeline ecotones in the Qilian Mountains.
基金Under the auspices of'Strategic Priority Research Program-Climate Change:Carbon Budget and Relevant Issues'of Chinese Academy of Sciences(No.XDA05090310)
文摘Ecotones have received great attention due to its critical function in energy flux, species harbor, global carbon sequestration, and land-atmosphere interaction. This study investigated land use pattern and spatial heterogeneity of the ecotones among agricultural land, forest land, and grassland of the southeastern Da Hinggan Mountains in the northeastern China. The change of these delineated ecotones under different slopes and aridity conditions was analyzed by two landscape indices, edge density(ED) and core area percentage of landscape(CPL), to explore the inter-linkage between spatial structure of ecotones and socioeconomic development and land management. Specifically, the ecotones such as agriculture-forest(AF) ecotone, forest-grassland(FG) ecotone, and agriculture-forestgrassland(AFG) ecotone moved from the arid southeast to the humid northwest. The flat area with small slope is more edge-fragmented than the steep area since the ED decreases as the slope increases. The AF ecotone mostly found in the humid region is moving to more humid areas while the agriculture-grassland(AG) ecotone mostly found in the dry region is moving towards the drier region.
基金Specific Research on Public Service of Environmental Protection in China (No. 201109025, No. 200909021)the National Special Commonweal Study on Environmental Protection of China (No. 201209027)
文摘An ecotone is a transition area between two biomes or two different ecosystems and are often fragile, sensitive and variable. Since the 1970s, the study of the ecotone has increasingly gained notoriety as an important facet of ecological research. China, with a vast complex geology, climate and vegetation, is home to a variety of ecotones. This variety is witnessed in breeds, scales and sizes. This vast array has not only laid a solid foundation for scientific research but also enhanced China’s economic development, social development and cultural diversity conservation. According to the geographical distribution and ecological features of China’s large scale ecotone, ＂The trinity index system＂ has been established including land use types, natural climate characteristics and agricultural economic development to classify and define the spatial distribution of typical ecotones in China. Based on this classification, the natural environmental characteristics, environmental fragility and the existing problems of five kinds of typical ecotones have been studied. This study will lead to a comprehensive understanding of the evolutionary patterns of ecotones.
文摘During last decades, new trends appeared in the ecotones of the upper boundary of forests at the ridges surroundingLakeBaikal(Khamar-Daban and Baikal’sky Ridge): ones to advance of wood species (Pinus sibirica Du Tour, Abies sibirica Ledeb., Larix sibirica Ledeb., Larix dahurica Lawson) out of timber stands into the area of subgoltsy with Pinus pumila (Pallas) Regel. up to mountain tundras. In average, this is from 100 to 200 - 300 meters (maximum up to500 m) in linear distance from the margin of dense timber stand. A burst of forests renewal occurred in 1989-1995, it resulted probably from a high productivity of the seeds of wood species due to warmer winters in 1980ies-1990ies which favoured the formation of favourable climate-edaphic conditions for the development of forest communities above the forests boundary on the ridges surrounding Lake Baikal.
文摘Changes in vegetation structure in environments contact community characterize the ecotones and paragenese inside zonal vegetation site or altitude belt as of concrete environments while differences of cenotic structures of communities between zones or between altitude belts as well. The aim of this work was research of structural-dynamic organization of phytocenoses forming under the conditions of environments contact and mountain tundra, forests (zonal taiga) and extrazonal steppes, zonal forest steppes of some areas at the Baikalian Siberia, Eastern Siberia of Russia.
文摘Aims Several mechanistic hypotheses have been developed to explain the existence of alpine treelines worldwide.The reproduction limita-tion hypothesis(RLH)postulates that reproductive processes such as seed production and dispersal are restricted in treeline envi-ronments,thereby limiting the establishment of new individuals in advance of extant treelines.Despite its popularity,no study has tested this hypothesis in a comprehensive fashion.In this experi-ment,we attempted to answer whether there are enough viable seeds being dispersed beyond treeline for sexually mediated tree-line advance,and what the implications of climate change might be on these processes.Methods We established 30 plots across two aspects(north vs.south)and three elevational habitats(forest,treeline and tundra)in a white spruce(Picea glauca)boreal forest-alpine tundra ecotone in south-west Yukon,Canada.In each plot,tree characteristics,seed produc-tion and predispersal damage were measured.Additionally,eight dispersal trays were positioned in each plot to measure seed rain,and germination trials with and without predation exclosures were constructed in a subset of plots to quantify dispersal and germina-tion success.Important Findings Results were highly variable both temporally and spatially.In 2014,a mast year,69%of adult trees produced cones compared to 0.4%in the following year.Higher density of trees in forest plots compared to treeline and tundra resulted in greater seed production at lower elevations.Across all plots,88%of seeds were damaged before dispersal or were not viable.Treeline plots had significantly greater predispersal damage.Seed rain was greater in south-facing plots than north-facing plots.Less than 2%of seeds produced on the landscape were dispersed into Tundra plots,located 50 m above treeline.There was a net movement of seeds from the north-facing slope to the south at our study site,likely due to prevailing winds during the dispersal period.Germination counts were more than double on north-facing slopes and one-third
文摘Nutrient retention capacity by the land/water ecotone soil of Lake Baiyangdian was studied by means of simulation in situ. The results from column experiments suggested that the standard capacity for phosphorus adsorption be less than P14 mg·kg -1 soil in order to meet the lake water quality regulation (P 0.1 mg·L -1 ). Thus the 9,333 hectares of ecotone around the lake could retain 1,245 tons phosphorus in the upper 50-cm soil without degrading the water quality. The amount was nearly 24 times large as that of taken by annual reed harvesting. The maximum capacity for phosphorus was measured as P 774 mg·kg -1 soil. The isothermal equation of phosphorus was also obtained. It was found that temperature had a significant effect on the transformation of nitrogen, and higher temperature would accelerated the nitrification rate. Nitrogen retention was conducted by the microbial activities in the soil and the uptake through aquatic vegetation. The research will benefit for better utilization of local ecotone and design of the planning project which aims to water eutrophication control.
