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Journal of forestry Research 2024年第3期35卷 175-188页

作者： Niu Zhu Jinniu Wang Dongliang Luo Xufeng Wang Cheng Shen Ning Wu Ning Zhang Binghui Tian Aihong Gai Chengdu Institute of Biology Chinese Academy of SciencesChengdu 610041People's Republic of China College of Resources and Environmental Sciences Gansu Agricultural UniversityLanzhou 730070People's Republic of China Mangkang Ecological Monitoring Station Tibet Ecological Security Barrier Ecological Monitoring NetworkQamdo 854500People's Republic of China Northwest Institute of Eco Environmental Resources Chinese Academy of SciencesLanzhou 730000People's Republic of China

Evapotranspiration is an important parameter used to characterize the water cycle of ecosystems.To under-stand the properties of the evapotranspiration and energy balance of a subalpine forest in the southeastern Qinghai-Tibet Plateau,an open-path eddy covariance system was set up to monitor the forest from November 2020 to October 2021 in a core area of the Three Parallel Rivers in the Qing-hai-Tibet Plateau.The results show that the evapotranspira-tion peaked daily,the maximum occurring between 11:00 and 15:00.Environmental factors had significant effects on evapotranspiration,among them,net radiation the greatest(R^(2)=0.487),and relative humidity the least(R^(2)=0.001).The energy flux varied considerably in different seasons and sensible heat flux accounted for the main part of turbulent energy.The energy balance ratio in the dormant season was less than that in the growing season,and there is an energy imbalance at the site on an annual time scale.

关键词： Evapotranspiration Energy balance subalpine forest Three Parallel Rivers region Southeast Qinghai-Tibet Plateau

Gap edge canopy buffering of throughfall deposition in a subalpine natural forest

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forest Ecosystems 2022年第4期9卷 503-510页

作者： Siyi Tan Qing Dong Xiangyin Ni Kai Yue Shu Liao Fuzhong Wu Key Laboratory for Humid Subtropical Eco-Geographical Processes of the Ministry of Education School of Geographical SciencesFujian Normal UniversityFuzhou350007China Ecological Security and Protection Key Laboratory of Sichuan Province Mianyang Teachers'CollegeMianyang621000China

Base cation loads are rarely considered in forest gap edge canopies,but they can play critical roles in capturing or buffering atmospheric deposition in forests with frequent gap disturbances,such as subalpine forests.We selected an expanded gap edge canopy and a closed canopy in a subalpine natural forest on the eastern Tibetan Plateau.The throughfall deposition and canopy exchange processes of common base cations(K^(+),Ca^(2+),Na^(+),and Mg^(2+))were continuously studied over two years.The results showed that the enrichment ratio and fluxes had lower levels of base cations in the gap-edge canopy than in the closed canopy,which indicated that base cations were concentrated more in the closed canopy than in the gap-edge canopy.Although Ca^(2+)in the gap-edge canopy showed a higher net throughfall flux,the annual net throughfall fluxes of K^(+),Na^(+) and Mg^(2+) within the gap-edge canopy were 1.83,6.75 and 2.95 times lower than those in the closed canopy,respectively.Moreover,dry deposition fluxes of base cations significantly decreased in the gap edge canopy compared to those in the closed canopy,and the decreasing tendency was more significant during the snowy season than during the rainy season.Overall,these results suggest that the amount of base cations in subalpine natural forest ecosystems may be overestimated when the throughfall deposition of ions in gap edge canopies is ignored.

关键词： Canopy exchange Dry deposition Throughfall subalpine forest Precipitation deposition

Once upon a time biomass burning in the western Alps: Nesting effects of climate and local drivers on long-term subalpine fires

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forest Ecosystems 2022年第2期9卷 257-266页

作者： Christopher Carcaillet Benjamin Boulley Frederique Carcaillet Univ Lyon Universite Claude Bernard Lyon 1CNRSENTPE(UMR LEHNA)F-69622VilleurbanneFrance Paris Sciences&Lettres University(PSL) Ecole Pratique des Hautes Etudes(EPHE)F-75014ParisFrance NaturCom Chair Universite de MontpellierF-34000MontpellierFrance MARBEC(Universite de Montpellier CNRSIfremerIRD)F-34000MontpellierFrance

Background:The present article questions the relative importance of local-and large-scale processes on the long-term dynamics of fire in the subalpine belt in the western Alps.The study is based on soil charcoal dating and identification,several study sites in contrasting environmental conditions,and sampling of soil charcoal along the elevation gradient of each site.Based on local differences in biomass combustion,we hypothesize that local-scale or landscape-scale processes have driven the fire history,while combustion homogeneity supports the hypothesis of the importance of large-scale or macro-ecological processes,especially climate.Results:Biomass burning during the Holocene resulted from the nesting effects of climate,land use,and altitude,but was little influenced by slope exposure(north versus south),soil(dryness,pH,depth),and vegetation.The mid-Holocene(6500–2700 cal BP)was an important period for climate-driven biomass burning in the subalpine ecosystems of the western Alps,while fires over the last 2500 years appear much more episodic,prompting us to speculate that human activity has played a vital role in their occurrence.Conclusion:Our working hypothesis that the strength of local drivers should offset the effects of regional climate is not validated.The homogeneity of the fire regime between sites thus underscores that climate was the main driver during the Holocene of the western Alps.Long-term subalpine fires are controlled by climate at the millennial scale.Local conditions matter for little in determining variability at the century scale.The mid-Holocene was a chief period for climatic biomass burning in the subalpine zone,while fires during the late Holocene appear much more episodic,suggesting that social drivers has exercised key function on their control.

关键词： Biomass burning subalpine forest Climate Landscape Pedoanthracology Radiocarbon dating Pyrogenic carbon

Soil seed banks along elevational gradients in tropical, subtropical and subalpine forests in Yunnan Province, southwest China

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Plant Diversity 2017年第5期39卷 273-286页

作者： Xiaqin Luo Min Cao Min Zhang Xiaoyang Song Jieqiong Li Akihiro Nakamura Roger Kitching Key Laboratory of Tropical forest Ecology Xishuanghanna Tropical Botanical GardenChinese Academy of Sciences666303 YunnanChina University of Chinese Academy of Sciences 100049BeijingChina Griffith School of Environment and Environmental Futures Research Institute Griffith UniversityNathan QLD 4111BrisbaneAustralia

Soil seed banks are a vital part of ecosystems and influence community dynamics and regeneration.Although soil seed banks in different habitats have been reported, how soil seed banks vary with elevational gradients in different climatic zones is still unknown. This paper investigates seed density,species composition and nonconstituent species of forest soil seed banks in Yunnan Province, southwest China. Similarity between the soil seed bank and standing vegetation was also examined. We collected soil samples from sites spanning 12 elevations in tropical rain forests, subtropical evergreen broadleaved forests and subalpine coniferous forests, and transported them to a glasshouse for germination trials for species identification. The soil seed banks of tropical and subtropical forests had much higher seed densities and species richness than those of subalpine forests. Seeds of woody species dominated the soil seed banks of tropical and subtropical forests, while herbs dominated those of subalpine forests.The nonconstituent species in the soil seed banks were all herbs and were most abundant in tropical forests, followed by subtropical forests but were completely absent from subalpine forests.

关键词： Elevational gradient Soil seed bank Standing vegetation subalpine forest Subtropical forest Tropical forest

Population structure and regeneration patterns of tree species in climate-sensitive subalpine forests of Indian western Himalaya

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Journal of forestry Research 2014年第2期25卷 343-349页

作者： Sanjay Gairola R. S. Rawal N. P. Todaria Arvind Bhatt School of Agricultural Earth and Environmental SciencesUniversity of KwaZulu-NatalWestville Campus G.B. Pant Institute of Himalayan Environment and Development Department of forestry and Natural Resources H.N.B. Garhwal University School of Life Sciences University of KwaZulu-NatalWestville Campus

The population structure of tree species has been explored in order to elucidate regeneration potential of the subalpine forests of Indian western Himalaya. For this study, the subalpine forest area was divided into three strata, i.e., lower altitude （〈3000 m）; mid-altitude （3000-3200 m）; and high altitude （〉3200m）. Considering the major compositional attributes, an increase in altitude came with a significant decline in tree density and the total basal area for all the sites. However, no such clear trends were observed for recruits （i.e., seedlings and saplings）. Seedling density did not exhibit uniform patterns for sites and altitude strata. In general, overall seedling density was greater at the Pindari site compared to the Lata and Tungnath sites. By comparison, significant variation in seedling density along the altitude strata was recorded for the Tungnath and Pindari sites only. Likewise, sapling density patterns varied across the sites and altitude strata, and significant variation in sapling density along the altitude strata was recorded only for the Lata site. At the Pin- daft site, the continuous increase in sapling density along with increasing altitude was revealing. The Pindari forests of exhibited expanding population structure. In contrast, greater accumulation of individuals in the sapling class and sharp decline toward both higher tree classes and lower seedling classes was generally apparent for the Lata and Tungnath sites. This indicates that the replacement in tree size classes from sapling stage is not proportional and the population may decline in the long-term. Considerable variation in patterns of forest and dominant species popula- tion structure were evident across altitude strata. But in all cases irrespective of sites, we found growth at the high-altitude stratum, in the form of entire forests or dominant species. This trend deserves further investigation to explore its relevance under changing climate scenarios.

关键词： population structure regeneration subalpine forest altitude