Regeneration of Treeline Birch (Betula utilis D. Don) Forest in a Trans-Himalayan Dry Valley in Central Nepal

Shrestha, Bharat Babu; Ghimire, Balkrishna; Lekhak, Hari D; Jha, Pramod Kumar

doi:10.1659/mrdd.0784

Cited by 105 publications

(81 citation statements)

References 15 publications

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“…For all our transects, we see that the densities of seedlings and saplings were higher below the treeline than above. This is in line with other studies (Ninot et al 2008;Shrestha et al 2007), although it contrasts with findings from Bell et al (2014) who note an upshift of range for juveniles and from Shrestha et al (2014) who found more seedlings of A. spectabilis above the treeline in Laurebinayak area in Langtang National Park, Nepal. There could be many factors to cause these patterns, such as orography, soil moisture, pH, community interaction and chance events; some are likely to be quite site specific.…”

Section: Discussionsupporting

confidence: 87%

Land-use change under a warming climate facilitated upslope expansion of Himalayan silver fir (Abies spectabilis (D. Don) Spach)

Suwal

Shrestha²,

Guragain³

et al. 2016

Plant Ecol

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Global warming is triggering some species to shift towards the poles or higher elevations, but spatial translocation is also influenced by land-use regime or intensity. The Himalayan climate is getting warmer and land use has changed, reducing in intensity in some areas. We estimated the upper species limit (USL) and tree limit of Abies spectabilis (D. Don) Spach and assessed whether these have changed over recent years. We hypothesise an upslope shift in response to enhanced temperature and changes in land-use intensity. Our four transects were located in treeline ecotones of two protected areas in Nepal, namely Manaslu Conservation Area (3 transects) and Gaurishankar Conservation Area (1 transect). Transects (20 m wide) ran from the USL of A. spectabilis down towards the treeline and beyond to the forest line. Length of each transect varied depending on local conditions. Co-ordinates, elevation, height and age of each A. spectabilis individual along the transects were recorded. We noted an upward shift of both the USL and the tree limit. The rate of shift was ca. 20 m per decade for the USL and 12 m per decade for the tree limit in the area of reduced land-use intensity and in the area with no change in land use, 5 m per decade for the USL, but almost nil for tree limit. The seedling density was higher below the treeline than above. Reduced intensity of land use was the dominant factor in upslope shift of A. spectabilis at both the USL and the tree limit.

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Section: Discussionsupporting

confidence: 87%

Land-use change under a warming climate facilitated upslope expansion of Himalayan silver fir (Abies spectabilis (D. Don) Spach)

Suwal

Shrestha²,

Guragain³

et al. 2016

Plant Ecol

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“…Distribution of Betula utilis up to higher altitude is seen in Himalaya as it is adapted well in cold climate. Lower belt of the forest was occupied by Abies spectabilis and Larix himalaica in our study site but in the dry Manang valley, central Nepal, lower belt was dominated by Abies spectabilis and Pinus wallichiana Lekhak 2007, Shrestha et al 2007). In a study, Gaire et al (2010) recorded six tree species from treeline ecotone of Langtang National Park, which is greater than our observation from Himalayan treeline.…”

Section: Community Structurecontrasting

confidence: 61%

“…Present studied tree species richness (four species) is equitable to the tree species richness (three species) at tree line in Manang area of Trans-Himalayan dry valley in Central Nepal reported by Shrestha et al (2007). The observation of various forests of the subalpine region of Manang revealed that the tree species such as Betula utilis generally preferred moist northern slope.…”

Section: Community Structurementioning

confidence: 52%

Forest Structure and Regeneration Pattern of Betula Utilis D. Don in Manaslu Conservation Area, Nepal

2014

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Forest structure and regeneration of Betula utilis (D. Don) was studied in birch forest located in Samagaun valley (3500 -4000 m) of Manaslu Conservation Area. Vegetation sampling was done by quadrat method. Altogether 40 quadrats were sampled to determine the Importance Value Index (IVI) of tree species, and distribution pattern of seedlings and saplings. Regeneration was assessed by density -diameter curve. Four tree species were recorded from the forest. Betula utilis was the dominant tree species with the highest Importance Value Index (173.22) in mixed Betula forest and 262.96 in pure Betula forest and Abies spectabilis was the co -dominant species (65.95) in mixed Betula forest while Rhododendron campanulatum was the co-dominant species (37.03) in pure Betula forest. Density of Betula utilis increased with increase in elevation where as density of other tree species decreased with increase in elevation. Mixed Betula forest at lower elevation was young. The density diameter curve of the tree population of Betula utilis, both on mixed and pure forests, deviated slightly from the typical reverse J shaped structure and hence did not show the sustainable regeneration. The sapling density was higher than seedling density. The distribution of seedlings and saplings were not uniform among the sampling plots.

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“…The majority of studies on seedbased regeneration have been carried out in Nepal. Shrestha et al (2007) found Betula utilis treeline forests in Manang Valley, Annapurna Conservation Area, sufficiently generating with a reverse J-shaped diameter distribution. Along vertical transects, Betula seedlings and saplings were common up to an altitudinal distance of 50 m above the treeline.…”

Section: Seed-based Regenerationmentioning

confidence: 86%

“…Abrupt treelines do occur (e.g. Betula treelines in Manang Valley, Nepal), but they are caused by land use (Shrestha et al, 2007). The vast majority of less disturbed or near-natural Himalayan treelines, mainly confined to north-facing slopes, should be categorized as krummholz treelines (cf.…”

Section: Susceptibility Of Treeline Types and Treeline Formsmentioning

confidence: 99%

Do Himalayan treelines respond to recent climate change? An evaluation of sensitivity indicators

et al. 2015

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Abstract. Climate warming is expected to induce treelines to advance to higher elevations. Empirical studies in diverse mountain ranges, however, give evidence of both advancing alpine treelines and rather insignificant responses. The inconsistency of findings suggests distinct differences in the sensitivity of global treelines to recent climate change. It is still unclear where Himalayan treeline ecotones are located along the response gradient from rapid dynamics to apparently complete inertia. This paper reviews the current state of knowledge regarding sensitivity and response of Himalayan treelines to climate warming, based on extensive field observations, published results in the widely scattered literature, and novel data from ongoing research of the present authors.Several sensitivity indicators such as treeline type, treeline form, seed-based regeneration, and growth patterns are evaluated. Since most Himalayan treelines are anthropogenically depressed, observed advances are largely the result of land use change. Near-natural treelines are usually krummholz treelines, which are relatively unresponsive to climate change. Nevertheless, intense recruitment of treeline trees suggests a great potential for future treeline advance. Competitive abilities of seedlings within krummholz thickets and dwarf scrub heaths will be a major source of variation in treeline dynamics. Tree growth-climate relationships show mature treeline trees to be responsive to temperature change, in particular in winter and pre-monsoon seasons. High pre-monsoon temperature trends will most likely drive tree growth performance in the western and central Himalaya. Ecological niche modelling suggests that bioclimatic conditions for a range expansion of treeline trees will be created during coming decades.

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Regeneration of Treeline Birch (Betula utilis D. Don) Forest in a Trans-Himalayan Dry Valley in Central Nepal

Cited by 105 publications

References 15 publications

Land-use change under a warming climate facilitated upslope expansion of Himalayan silver fir (Abies spectabilis (D. Don) Spach)

Land-use change under a warming climate facilitated upslope expansion of Himalayan silver fir (Abies spectabilis (D. Don) Spach)

Forest Structure and Regeneration Pattern of Betula Utilis D. Don in Manaslu Conservation Area, Nepal

Do Himalayan treelines respond to recent climate change? An evaluation of sensitivity indicators

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