Biomass functions were established to estimate above-ground biomass of Siberian larch (Larix sibirica) in the Altai Mountains of Mon- golia. The functions are based on biomass sampling of trees from 18 different sit...Biomass functions were established to estimate above-ground biomass of Siberian larch (Larix sibirica) in the Altai Mountains of Mon- golia. The functions are based on biomass sampling of trees from 18 different sites, which represent the driest locations within the natural range ofL. sibirica. The best performing regression model was found for the equations y = (D2 H)/(a+bD) for stem biomass, y = aDb for branch biomass, and y=aDb Hc for needle biomass, where D is the stem diameter at breast height and H is the tree height. The robustness of the biomass functions is assessed by comparison with equations which had been previously published from a plantation in Iceland. There, y=aDb Hc was found to be the most significant model for stem and total above-ground biomasses. Applying the equations from Iceland for estimating the above-ground biomass of trees from Mongolia resulted in the underesti- mation of the biomass in large-diameter trees and the overestimation of the biomass in thin trees. The underestimation of thick-stemmed trees is probably attributable to the higher wood density, which has to be ex- pected under the ultracontinental climate of Mongolia compared to the euoceanic climate of Iceland. The overestimation of the biomass in trees with low stem diameter is probably due to the high density of young growth in the not systematically managed forests of the Mongolian Altai Mountains, which inhibits branching, whereas the plantations in Iceland are likely to have been planted in lower densities.展开更多
The research was carried out on sandy natural forest ecosystems in sandy forest-steppe ecotone in the northern area of China from 1980’s. In this paper, we introduced the concept and origin, distribution and actu- al...The research was carried out on sandy natural forest ecosystems in sandy forest-steppe ecotone in the northern area of China from 1980’s. In this paper, we introduced the concept and origin, distribution and actu- ality,types and succession of sandy natural forests in the northern area of China. The conservation value and strategy for sandy natural forests were also discussed. We hope to supply some scientific basis for performing "the Natural Forest Protection Program" reasonably in China.展开更多
Background:Forest distribution in the forest-steppe of Mongolia depends on relief,permafrost,and climate,and is highly sensitive to climate change and anthropogenic disturbance.Forest fires and logging decreased the f...Background:Forest distribution in the forest-steppe of Mongolia depends on relief,permafrost,and climate,and is highly sensitive to climate change and anthropogenic disturbance.Forest fires and logging decreased the forest area in the forest-steppe of Mongolia.The intention of this study was to identify the geoecological parameters that control forest distribution and living-tree biomass in this semi-arid environment.Based on these parameters,we aimed to delineate the area that forest might potentially occupy and to analyse the spatial patterns of actual and potential tree biomass.Methods:We used a combination of various geographic methods in conjunction with statistical analyses to identify the key parameters controlling forest distribution.In several field campaigns,we mapped tree biomass and ecological parameters in a study area within the Tarvagatai Nuruu National Park(central Mongolia).Forest areas,topographic parameters and vegetation indices were obtained from remote sensing data.Significant correlations between forest distribution and living-tree biomass on one hand,and topographic parameters,climate data,and environmental conditions on the other hand,were used to delineate the area of potential forest distribution and to estimate total living-tree biomass for this area.Results:Presence of forest on slopes was controlled by the factors elevation,aspect,slope,mean annual precipitation,and mean growing-season temperature.Combining these factors allowed for estimation of potential forest area but was less suitable for tree-biomass delineation.No significant differences in mean living-tree biomass existed between sites exposed to different local conditions with respect to forest fire,exploitation,and soil properties.Tree biomass was reduced at forest edges(defined as 30m wide belt),in small fragmented and in large forest stands.Tree biomass in the study area was 20×10^(9) g(1,086 km^(2) forest area),whereas the potential tree biomass would reach up to 65×10^(9) g(>3168 km^(2)).Conclusions:The obtained projection suggests that the potential forest area and tree biomass under the present climatic and geoecological conditions is three times that of the present forest area and biomass.Forest fires,which mostly affected large forest stands in the upper mountains,destroyed 43% of the forest area and 45% of the livingtree biomass in the study area over the period 1986-2017.展开更多
Picea mongolica is an endemic but endangered species in China. The spruce forest is only found in sandy forest-steppe ecotones. In this study, we examined the initial response of the quantity and refilling process of ...Picea mongolica is an endemic but endangered species in China. The spruce forest is only found in sandy forest-steppe ecotones. In this study, we examined the initial response of the quantity and refilling process of free roots in an artificial canopy gap with a diameter of 36 m in a P. mongolica forest. Under the canopy, the fine root length densities of trees, shrubs and herbs were 2,622, 864 and 3,086 m·m^- 2, respectively. The free root biomass of trees, shrubs and herbs were 148, 62 and 65 g·m^- 2, respectively. In the gap, the fine root length density of trees was 151 m·m^- 2. The mean fine root densities of shrubs and herbs in the gap were 756 and 2,568 m·m^- 2. The fine root biomass of trees, shrubs and herbs were 9, 52 and 47 g·m^- 2, respectively. Two growing seasons after the gap creation, hardly any fine tree roots were found in the middle of the gap. The living tree roots in the gap edge zone were mainly located within a 4.5 m distance from the standing trees. Indices developed to show the influence of trees on free root length density clearly revealed the effect of the vicinity of living trees on fine root length density. The root densities of shrubs and herbs did not show a clear response to gap creation despite the increase of their foliage. Our results suggest that in P mongolica forests a gap disturbance creates a distinct tree root gap and that the gap edge trees do not extend their root systems rapidly into the formed root gap.展开更多
The biodiversity of natural or semi-natural native,old oak woodlands have high conservation importance,especially in landscapes of monocultural forest plantations and arable fields.With a wider variety of microhabitat...The biodiversity of natural or semi-natural native,old oak woodlands have high conservation importance,especially in landscapes of monocultural forest plantations and arable fields.With a wider variety of microhabitats and foraging sources,such old oak forests can provide essential habitat for native forest bird communities.We conducted a study using bird point counts to compare the forest bird communities of old pedunculate oak(Quercus robur)remnants with native and non-native plantations in central Hungary in a landscape of mostly arable fields,settlements,and monocultural plantations.Avian surveys were carried out in old oak forest remnants,middle-aged oak,white poplar(Populus alba),hybrid poplar(Populus×euramericana),black locust(Robinia pseudoacacia),and pine(Pinus spp.)plantations.Fieldwork has been carried out in nine study sites,where all six habitat types were represented(with a few exceptions),to determine total abundance,species richness,Shannon–Wiener diversity,species evenness,dominant and indicator species,and guild abundances.We found that old oak forest remnants were the most diverse habitats among the studied forest types,while hybrid poplar and pine plantations exhibited the lowest avian biodiversity.The avian guilds most sensitive to the loss of old oak forest remnants were ground foragers,bark foragers,cavity-nesters,residents,and Mediterranean migratory birds.Native habitats were more diverse than non-native plantations.Our results suggest that it is important to conserve all remaining high biodiversity old oak stands and to avoid clear-cutting of monocultural plantations in favour of practices such as mixed-species plantations,longer rotation lengths,or retention forestry.展开更多
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 selective logging occurred throughout the study period.However,selective logging was strongly intensified after 1990 as the result of the breakdown of the Communist regime in Mongolia and the transition from centrally planned to market economy.Because tree stump densities showed that the ratio of felled to live trees was 2:1 in the interior or even 0.9:1 at the edges of the forests and most logging occurred during the past 20 years,it must be concluded that the forests of the Mongolian Altai are presently exploited far beyond the level of sustainability.A close correlation of the ratio of felled to live trees with the density of summer camps of pastoral nomads in the vicinity suggests that trees are primarily felled by the local population.展开更多
基金funded by the Asian Research Center (ARC) based in the National University of Mongolia (Ulan Bator) The work was done in association with 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" funded by the Volkswagen Foundation
文摘Biomass functions were established to estimate above-ground biomass of Siberian larch (Larix sibirica) in the Altai Mountains of Mon- golia. The functions are based on biomass sampling of trees from 18 different sites, which represent the driest locations within the natural range ofL. sibirica. The best performing regression model was found for the equations y = (D2 H)/(a+bD) for stem biomass, y = aDb for branch biomass, and y=aDb Hc for needle biomass, where D is the stem diameter at breast height and H is the tree height. The robustness of the biomass functions is assessed by comparison with equations which had been previously published from a plantation in Iceland. There, y=aDb Hc was found to be the most significant model for stem and total above-ground biomasses. Applying the equations from Iceland for estimating the above-ground biomass of trees from Mongolia resulted in the underesti- mation of the biomass in large-diameter trees and the overestimation of the biomass in thin trees. The underestimation of thick-stemmed trees is probably attributable to the higher wood density, which has to be ex- pected under the ultracontinental climate of Mongolia compared to the euoceanic climate of Iceland. The overestimation of the biomass in trees with low stem diameter is probably due to the high density of young growth in the not systematically managed forests of the Mongolian Altai Mountains, which inhibits branching, whereas the plantations in Iceland are likely to have been planted in lower densities.
基金Chinese Academy of Sciences and National Nature Science Foundation of China!(No.39900019)
文摘The research was carried out on sandy natural forest ecosystems in sandy forest-steppe ecotone in the northern area of China from 1980’s. In this paper, we introduced the concept and origin, distribution and actu- ality,types and succession of sandy natural forests in the northern area of China. The conservation value and strategy for sandy natural forests were also discussed. We hope to supply some scientific basis for performing "the Natural Forest Protection Program" reasonably in China.
基金funded by the Volkswagen Foundation(project-no.871759)by the German Research Council(Deutsche Forschungsgemeinschaft,DFG),(project no.385460422).
文摘Background:Forest distribution in the forest-steppe of Mongolia depends on relief,permafrost,and climate,and is highly sensitive to climate change and anthropogenic disturbance.Forest fires and logging decreased the forest area in the forest-steppe of Mongolia.The intention of this study was to identify the geoecological parameters that control forest distribution and living-tree biomass in this semi-arid environment.Based on these parameters,we aimed to delineate the area that forest might potentially occupy and to analyse the spatial patterns of actual and potential tree biomass.Methods:We used a combination of various geographic methods in conjunction with statistical analyses to identify the key parameters controlling forest distribution.In several field campaigns,we mapped tree biomass and ecological parameters in a study area within the Tarvagatai Nuruu National Park(central Mongolia).Forest areas,topographic parameters and vegetation indices were obtained from remote sensing data.Significant correlations between forest distribution and living-tree biomass on one hand,and topographic parameters,climate data,and environmental conditions on the other hand,were used to delineate the area of potential forest distribution and to estimate total living-tree biomass for this area.Results:Presence of forest on slopes was controlled by the factors elevation,aspect,slope,mean annual precipitation,and mean growing-season temperature.Combining these factors allowed for estimation of potential forest area but was less suitable for tree-biomass delineation.No significant differences in mean living-tree biomass existed between sites exposed to different local conditions with respect to forest fire,exploitation,and soil properties.Tree biomass was reduced at forest edges(defined as 30m wide belt),in small fragmented and in large forest stands.Tree biomass in the study area was 20×10^(9) g(1,086 km^(2) forest area),whereas the potential tree biomass would reach up to 65×10^(9) g(>3168 km^(2)).Conclusions:The obtained projection suggests that the potential forest area and tree biomass under the present climatic and geoecological conditions is three times that of the present forest area and biomass.Forest fires,which mostly affected large forest stands in the upper mountains,destroyed 43% of the forest area and 45% of the livingtree biomass in the study area over the period 1986-2017.
基金We thank Mr. Liu Guangtian and the staff of Baiyinaobao Nature Reserve. This study was funded by the National Natural Science Foundation of China (Grant Nos. 39900019 and 30070129). We thank Prof. Liao Liping for English corrections.
文摘Picea mongolica is an endemic but endangered species in China. The spruce forest is only found in sandy forest-steppe ecotones. In this study, we examined the initial response of the quantity and refilling process of free roots in an artificial canopy gap with a diameter of 36 m in a P. mongolica forest. Under the canopy, the fine root length densities of trees, shrubs and herbs were 2,622, 864 and 3,086 m·m^- 2, respectively. The free root biomass of trees, shrubs and herbs were 148, 62 and 65 g·m^- 2, respectively. In the gap, the fine root length density of trees was 151 m·m^- 2. The mean fine root densities of shrubs and herbs in the gap were 756 and 2,568 m·m^- 2. The fine root biomass of trees, shrubs and herbs were 9, 52 and 47 g·m^- 2, respectively. Two growing seasons after the gap creation, hardly any fine tree roots were found in the middle of the gap. The living tree roots in the gap edge zone were mainly located within a 4.5 m distance from the standing trees. Indices developed to show the influence of trees on free root length density clearly revealed the effect of the vicinity of living trees on fine root length density. The root densities of shrubs and herbs did not show a clear response to gap creation despite the increase of their foliage. Our results suggest that in P mongolica forests a gap disturbance creates a distinct tree root gap and that the gap edge trees do not extend their root systems rapidly into the formed root gap.
基金supported financially by the projects(LIFE16NAT/IT/000245)(Oe AD-Gmb H-ICM-2020-00204)GINOP-2.3.2-15-2016-00019。
文摘The biodiversity of natural or semi-natural native,old oak woodlands have high conservation importance,especially in landscapes of monocultural forest plantations and arable fields.With a wider variety of microhabitats and foraging sources,such old oak forests can provide essential habitat for native forest bird communities.We conducted a study using bird point counts to compare the forest bird communities of old pedunculate oak(Quercus robur)remnants with native and non-native plantations in central Hungary in a landscape of mostly arable fields,settlements,and monocultural plantations.Avian surveys were carried out in old oak forest remnants,middle-aged oak,white poplar(Populus alba),hybrid poplar(Populus×euramericana),black locust(Robinia pseudoacacia),and pine(Pinus spp.)plantations.Fieldwork has been carried out in nine study sites,where all six habitat types were represented(with a few exceptions),to determine total abundance,species richness,Shannon–Wiener diversity,species evenness,dominant and indicator species,and guild abundances.We found that old oak forest remnants were the most diverse habitats among the studied forest types,while hybrid poplar and pine plantations exhibited the lowest avian biodiversity.The avian guilds most sensitive to the loss of old oak forest remnants were ground foragers,bark foragers,cavity-nesters,residents,and Mediterranean migratory birds.Native habitats were more diverse than non-native plantations.Our results suggest that it is important to conserve all remaining high biodiversity old oak stands and to avoid clear-cutting of monocultural plantations in favour of practices such as mixed-species plantations,longer rotation lengths,or retention forestry.
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 selective logging occurred throughout the study period.However,selective logging was strongly intensified after 1990 as the result of the breakdown of the Communist regime in Mongolia and the transition from centrally planned to market economy.Because tree stump densities showed that the ratio of felled to live trees was 2:1 in the interior or even 0.9:1 at the edges of the forests and most logging occurred during the past 20 years,it must be concluded that the forests of the Mongolian Altai are presently exploited far beyond the level of sustainability.A close correlation of the ratio of felled to live trees with the density of summer camps of pastoral nomads in the vicinity suggests that trees are primarily felled by the local population.