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Community Structure along Timberline Ecotone in Relation to Micro-topography and Disturbances in Western Himalaya  [cached]
Ishwari D. RAI,Bhupendra S. ADHIKARI,Gopal S. RAWAT,Kiran BARGAL
Notulae Scientia Biologicae , 2012,
Abstract: Four communities, formed as a result of locally varying site conditions, were identified and studied along the timberline ecotone in part of Kedarnath Wildlife Sanctuary (KWS). Communities on the vicinity of pilgrimage site and along gentler slopes were highly disturbed having sharp timberlines, while those located far and in the steep slopes were less affected, forming a little broader transition. The tree density ranged from 340 to 780 trees/ha, while the basal cover of communities varied greatly and ranged from 6.4 to 55.1 m2/ha. Birch dominated community had lowest basal area among all the communities, while mixed community had the highest. In all the respective communities, from subalpine zone, density and basal area was higher than that of timberline zone. The Importance Value Index (IVI), which used to determine the overall importance of each species in the community structure, of dominant species at timberline was more than 200 in all the communities, except in the mixed community. Influence of the anthropogenic disturbances was apparent on the regeneration performance of all the studied tree species. Rhododendron campanulatum was the dominant shrub species of the area and formed krummholz, while distribution of other species varies greatly with forest type. The shrub density decreased from high to low disturbance, while the herbaceous species density increased with prevalence of a few species favoring the high disturbance (grazing). The shrub and herb species richness was higher in the ecotone zone. Some uncommon species like Balanophora involucrata and Aralia cissifolia were also found at timberline. Three species of Lady’s Slipper orchid were reported together from Betula utilis community at timberline ecotone.
The soil properties of the subalpine timberline ecotone and adjacent vegetations in Western Sichuan
川西亚高山林线过渡带及邻近植被土壤性质

qizemin,
齐泽民
,王开运,张远彬,谢玉华

生态学报 , 2009,
Abstract: The upper or alpine timberline(AT) can be either a transitional zone or an abrupt border between continuous forest and herb, shrub and high mountain cushion communities. At present, Although there have been more reports on their positions and dynamics which may be controlled by limitations imposed by abiotic environmental conditions such as low temperature, aridity, wind and snow on the production of viable pollen, viable seeds, seed germination and the survival of saplings and adults, but there is lack of information to understand the effects each other between changing vegetations and their soil properties in this geographical region. Therefore, in a short distance, the physical, chemical and biological properties of the soil mainly taken place in residual deposits in subalpine timberline ecotone, scree meadow and fir forest, were investigated in Wanglang National Nature Reserve in this paper. The results show that from scree meadow to timberline ecotone then to fir forest, with the changement of vegetation some physical structure parameters such as the content of scree, silt, clay and physical clay, aggregate degree, structure coefficient, and some chemical parameters such as the content of soil water, hydrolyzed acid, organic matter, total P, total K, available N, available P and soluble K, exchangeable base content, cation exchangeable capacity content, base saturation percentage and so on in the topsoil(0-30 cm) all were increasing slowly, showing that the soil physical structure and chemical properties were improved but developing slowly on the residual deposits. Furthermore, in the topsoil of the subalpine timberline ecotone, the microbe quantities of bacteria, fungi and actinomyces, enzymatic activities of acid phosphatases, neutra phosphatase, urease, invertase, catalase and polyphenol oxidase were highest among three vegetations, implying that as a ecotone, the soil biological and chemical activities in subalpine timberline ecotone were more active than them in the adjacent vegetations.
Species-abundance relation of herb communities in subalpine timber-line ecotone of Wolong Natural Reserve,Sichuan Province,China
四川卧龙亚高山林线生态交错带群落的种多度关系

SHI Pei Li,
石培礼

生态学报 , 2000,
Abstract: By using species abundance distribution models Broken Stick,Geometric Serices,Log Series and Truncated Log Normal,percent cover of every species was used as indicator of abundance to study species abundance relations of herb communities along transects across subalpine timberline ecotone of Abies faxoniana forest in Balang Mountain of Wolong Natural Reserve,Sichuan Province,southwestern China.The results showed that Truncated Log Normal and Log Series distribution models can well fit to the species a...
Treeline advance - driving processes and adverse factors  [PDF]
F.-K. Holtmeier,G. Broll
Landscape Online , 2007,
Abstract: The general trend of climatically-driven treeline advance is modified by regional, local and temporal variations. Treelines will not advance in a closed front parallel to the shift of any isotherm to higher elevations and more northern latitudes. The effects of varying topography on site conditions and the after-effects of historical disturbances by natural and anthropogenic factors may override the effects of slightly higher average temperatures. Moreover, the varying treeline-forming species respond in different ways to a changing climate. Forest advance upwards and northwards primarily depends on successful regeneration and survival of young growth rather than on increasing growth rates of mature trees. Every assessment of treeline response to future climate change must consider the effects of local site conditions and feedbacks of in-creasing tree population in modulating the climatically-driven change. Treeline-shift will influence regional and local climates, pedogenesis, plant communities, animal populations and biodiversity as well as having a considerable effect on economic changes in primary production. A better understanding of the functional relationships between the many treeline-relevant factors and treeline dynamics can be achieved only by extensive research at different scales within different climatic regions supported by as many as possible experimental studies in the field together with laboratory and remote sensing techniques.
Contrasting short-term performance of mountain birch (Betula pubescens ssp. czerepanovii) treeline along a latitudinal continentality-maritimity gradient in the southern Swedish Scandes  [cached]
Lisa ?berg,Leif Kullman
Fennia : International Journal of Geography , 2012,
Abstract: Positional treeline shift is a fundamental aspect and indicator of high-mountain vegetation response to climate change. This study analyses treeline performance during the period 2005/2007 -2010/2011 in the Swedish Scandes. Focus is on mountain birch (Betula pubescens ssp. czerepanovii) along a regional climatic maritimity-continentality gradient. Treeline upshift by 3.0 yr-1 in the maritime part differed significantly from retreat by 0.4 m yr-1 in the continental part of the transect. This discrepancy is discussed in terms of differential warming-induced snow cover phenology patterns and their influence on soil moisture conditions. In the continental area, earlier and more complete melting of prior relatively rare late-lying snow patches, even high above the treeline, has progressed to a state when melt water irrigation ceases. As a consequence, soil drought sets back the vigor of existing birches and precludes sexual regeneration and upslope advance of the treeline. In the maritime area, extensive and deep snow packs still exist above the treeline and constrain its position, although some release is taking place in the current warm climate. Thereby, the birch treeline expands upslope as the alpine snow patches shrink, but continue to provide sufficient melt water throughout the summer. Treeline rise appears to have been based primarily on seed regeneration over the past few decades. This is a novelty, since prior (1915-2007) treeline advance was accomplished mainly by in situ shifts in growth form of relict krummholz birches, in some cases millennial-old, prevailing above the treeline. By the snow phenology mechanism, birch can benefit from climate warming in the maritime region, which contrasts with the situation in the continental region. This discrepancy should be accounted for in projective models. In a hypothetical case of sustained warming, the subalpine birch forest belt may expand less extensively than often assumed, although advance may continue for some time in snow rich maritime areas.
Global change and upward shift of treeline in the Alps: genetic consequences of pastures colonization
Piotti A,Piovani P,Scalfi M,Leonardi S
Forest@ , 2007,
Abstract: In the Alps global warming and change in land use, in particular the drastic reduction in cattle grazing, are causing a progressive treeline ecotone upwards shift. The colonization dynamics of woody species are modulated by high selective pressure on seedlings due to the extreme ecological conditions of this habitat. We studied the colonization dynamics of Norway spruce in a treeline plot, at the upper limit of the Paneveggio forest (Trentino, Italy). We have exhaustively sampled the study stand, collecting needle tissue from all the adults and the juveniles detected, and we have genotyped all the samples (376) with 4 SSR markers. Parentage relationships between the few adults presents in the stand (23) and the juveniles were established. Our results indicate that, in spite of extreme ecological condition of the treeline environment, local adaptations do not seem to favour local parents: only 4% of juveniles have both parents among local adult trees, while 96% of juveniles are completely or partially sired outside the sampling area. Assessing parentage relationship also allowed the estimation of relative reproductive success of local adult trees. Out of a total of 23 adult trees, 5 trees were involved in the 59% of successful reproductive events detected inside the sampling area.
Seasonal dynamics in soil microbial biomass carbon and nitrogen and microbial quantity in a forest-alpine tundra ecotone,Eastern Qinghai-Tibetan Plateau,China
青藏高原东缘高山森林-苔原交错带土壤微生物生物量碳、氮和可培养微生物数量的季节动态

LIU Yang,ZHANG Jian,YAN Bang-Guo,HUANG Xu,XU Zhen-Feng,WU Fu-Zhong,
刘洋
,张健,闫帮国,黄旭,徐振锋,吴福忠

植物生态学报 , 2012,
Abstract: Aims The forest-alpine tundra ecotone is one of the most conspicuous climate-driven ecological boundaries.However,dynamics of soil microbial biomass and quantity during different stages of the growing season in the ecotone remain unclear.Our objective was to understand the temporal and spatial variations of microbial biomass and quantity to explore the main drivers in the ecotone.Methods We collected soil samples in a forest-alpine tundra ecotone(dark-conifer forest,timberline,treeline,dense shrub,sparse shrub and alpine meadow) during early,mid and late growing season(EGS,MGS and LGS).The number and species composition of soil microorganisms were determined by means of the plate count method.Soil microbial biomass carbon(MBC) and nitrogen(MBN) were measured by the chloroform fumigation leaching method.Important findings Vegetation and seasonality significantly influence MBC,MBN and microbial community structure.Microbial biomass distribution among vegetation types was different in the three stages of the growing season.MBC above treeline was higher than below during EGS and MGS.The MBC of dark-conifer forest,timberline and treeline during LGS was significantly increased,and MBC differences among different vegetation types decreased.There were significant differences in measured soil microbial quantity between above-and below-treeline vegetation types;bacteria of dense shrub were highest among vegetation types.The amount of cultivated microorganisms was LGS>EGS>MGS.The ratio of MBC to MBN was the highest and the quantity of fungi increased largely late in the growing season.Statistical analysis showed that there were significant correlations between MBN and bacteria,fungi and actinomyces quantity,while only MBC and fungi quantity weresignificantly correlated(p < 0.05).Litter input and snow cover late in the growing season were external factors of microbial seasonal variation.Soil microbes and alpine plants competing for nitrogen may be internal factors.Plant nitrogen absorption early in the growing season and microorganisms’ nitrogen fixation late in the growing season enhanced the alpine ecosystem’s nitrogen fixation and utilization.Climate warming may extend the growing season of alpine plants,increasing the alpine soil microbial biomass,and accelerate the decomposition of soil organic matter,which may change soil carbon sequestration rates in the alpine ecosystem.
Stability of alpine timberline ecotone on Taibai Mountain, China
Stability of alpine timberline ecotone on Taibai Mountain,China

Cui Hai-ting,Dai Jun-hu,Tang Zhi-yao,Huang Yong-mei,Cao Yan-li,
Cui Hai ting
,Dai Jun hu,Tang Zhi yao,Huang Yong mei,Cao Yan li

环境科学学报(英文版) , 1999,
Abstract: --Landscape boundaries are always indicated by thevegetation boundaries. As an ecotone between closed forest andtreeline, alpine timberline may respond to global climate changessensitively. The stability of timberline and treeline depend notonly on climate change, but also on the interaction of both sidesof the ecosystems. Three natural boundaries existing in thetimberline transitional zone are recognized (1) timberline (upperlimit of closed forest zone); (2) treeline (upper limit of treeislands zone); (3) tree-species line (upper limit of individualtree growth). Paleobotanical and sedimentary evidences suggest thatthere were several times of climate fluctuation during the Holoceneperiod in this area. The timberline of Taibai Mountain must havemoved for four times on the millennium scale. Being a stochasticoscillation boundary, treeline appears in a semi-stable conditionon the century scale. The tree-species line is even more unstable,which appears in an unstable status on the decades scale. Thecomparison of the stability within several landscape boundaries,shed light on the sensibility of these communities to variousperturbation and environmental heterogeneity, i.e., herb community is the most sensitive one, which is followed by shrubs, and forestis the most stable one. Trees and shrubs can adapt to rocky andpoor soils. On the contrary, alpine herbs are able to adapt towetter and cooler soils. Finally, under a scenario of a temperatureof 1.5-4.5℃ increase, the present timberline will be relativelystable but treeline and tree-species line will move upward.
Mass Foliar Damage at Subalpine-Timberline Ecotone in Western Himalaya Due to Extreme Climatic Events  [PDF]
Ishwari Datt Rai, Bhupendra Singh Adhikari, Gopal Singh Rawat
American Journal of Climate Change (AJCC) , 2012, DOI: 10.4236/ajcc.2012.12008
Abstract: Glimpses of unusual climatic conditions such as high summer temperature, heavy rainfall as well as snowfall and low winter temperature were noticed during 2010-2011 in subalpine-timberline (2700 - 3600 m) zones of Western Himalaya. Abundant winter injury to the current year (2010) foliage and shoot of Rhododendron arboretum and Quercus semecarpifolia became apparent in winters of 2010-2011. The foliar and bud mortality both increased with elevation beyond 2800 m and maximum along the edges of forest. Rhododendron campanulatum was another species which also got affected throughout the Western Himalaya. Such events were not reported earlier from the region and current observations indicate the high sensitivity of the plant species to the extreme inter-annual climatic variations.
Litter Production, Decomposition, and Nutrient Release in Subalpine Forest Communities of the Northwest Himalaya  [PDF]
Vinod K. Bisht,Bhagwati P. Nautiyal,Chandra P. Kuniyal,P. Prasad,Rakesh C. Sundriyal
Journal of Ecosystems , 2014, DOI: 10.1155/2014/294867
Abstract: Production, decomposition, and release of nutrients from leaf and nonleaf litter were investigated in four subalpine forests of North-West Himalaya, India. Total annual litter fall in four communities varied from 2950.00 to 4040.00?kg?ha?1 and was found significant (CD0.05 = 118.2). Decomposition of leaf litter varied from 1.82–3.5% during autumn-winter to 36.14–45.51 during summer rainy season in all stands and percent of mass loss was significantly varied in stands (CD6.00). Similarly, decomposition in nonleaf litter was varied from 0.3–1.1% during autumn-winter to 19.59–30.05% during summer rainy season and was significantly varied irrespective of seasons. However, percent decomposition of leaf litter and the values of decay constant () were at par in all stands. Total standing state of nutrients in fresh litter as well as release of total nitrogen (N), phosphorus (P), and potassium (K) in due course of decomposition (12 months) was also varying significantly. The rate of nonleaf litter decomposition was significantly positively correlated with air temperature ( in all communities). The significant correlation was observed only in Rhododendron-Sorbus forest community (PRS). Study indicates that the air temperature is a major determinant for nonleaf litter decomposition in this region. 1. Introduction Subalpine forests represent a transition zone between alpine areas and temperate forest communities [1] and shared floristic components of alpine and lower temperate zone. Thus, subalpine forests are the habitat specialized with key governing factors such as harsh environmental conditions including low soil and air temperatures, massive snowfall, scanty precipitation, and diurnal variations in the temperatures for ecosystem functioning. Notable shift in the vegetational pattern at subalpine region appears in the form of cessation of tree limit and beginning of alpine meadows those harbours herbaceous and complex mosaic of plant communities. Thus, subalpine habitats are indicators for presence of specific environmental and edaphic determinant. Majority of subalpine forests in the Northwestern Himalaya are sensitive to topography, anthropogenic interferences, and abrupt climatic changes [2]. The integrity of an ecosystem is maintained by the transfer of matter and energy between producers, consumers, and decomposers [3]. A major part of the annual gain of energy and matter is shed as litter [4] which enters into the decomposition subsystem as dead organic matter or detritus. The organic matter on the forest floor is a major source of energy for
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