Papers by Bharat Shrestha
Located in the Himalayas, and situated at the highest altitude worldwide, the subalpine 21 forest... more Located in the Himalayas, and situated at the highest altitude worldwide, the subalpine 21 forests have come under human pressure through means of timber logging, livestock 22 farming and tourism, which has brought about the progress of degradation. Thus, it is 23 essential to quantify how forest structure is determined by environmental factors over the 24 range of subalpine zone for better management planning. We investigated the subalpine 25 forest dominated by Abies spectabilis in Langtang National Park, Nepal Himalaya, by 26 setting 80 plots of 10-by-10 m scattered over the range of subalpine forest from 3170 to 27 3810 m a.s.l. on a north-facing slope, and examined the relationship between topographic 28 factors (e.g. altitude and slope inclination), anthropogenic factors (e.g. number of cut 29 stumps and trampling intensity), and forest stand variables (e.g. woody species richness 30 and composition, tree and juvenile density, basal area, and topsoil C/N content). Species 31 richness was decreased with altitude, number of fallen logs, and trampling intensity while 32 at the same time, it was increased with slope inclination and cut stump density. Stands in 33 higher altitude showed lower tree density and basal area, while higher juvenile density of 34 A. spectabilis. Juvenile density was decreased with high basal area. Stands on steeper 35 slopes had higher tree density with smaller maximum size on poorer soil. With increasing 36 cut stumps, basal area and soil carbon content were decreased while woody species 37 richness and tree density were increased, suggesting enhanced stand recovery in response 38 to canopy removal. We conclude that Abies population is vulnerable to topsoil removal by 39 trampling and cutting, and that altitude-dependent management is needed. 40 41 Key-words: detrended correspondence analysis, disturbance, generalized linear model, 42 species richness. * All forest stand variables except DCA axis are log-transformed. Bold values are significant (P = 0.05).
Mountain Research and Development, 2010
Parthenium (Parthenium hysterophorus L.) is an invasive alien species of global significance whic... more Parthenium (Parthenium hysterophorus L.) is an invasive alien species of global significance which is rapidly expanding in Nepal and other Asian countries with negative impacts on species diversity, health of human and livestock, and productivity of pasture and agriculture. To understand the invasive success of this weed, we analysed soil of its invaded sites, morphological traits, biomass allocation, leaf attributes, and phenology in the Kathmandu valley. The roadside soil, which is loamy sand in the valley is highly suitable for the growth and proliferation of the parthenium weed where its density has become double in less than a decade. An average size plant was 112 cm tall with 12 cm long tap root and produced 2637 achene per plant (max. 3865 per plant). A combination of different leaf traits enables the parthenium to grow under diverse habitats such as resouces poor condition (due to low specific leaf area, SLA), disturbed habitats (due to low leaf dry matter content, LDMC) as well as productive sites (due to high leaf nitrogen content). During rainy season it completes lifecycle in 16-18 weeks. Relatively long (12-16 weeks) reproductive period with high output of small seeds and their capacity to germinate and flower anytime in the year make parthenium a successful invasive weed in the Kathmandu valley.
International Journal of Biodiversity and Conservation, Apr 1, 2010
Community forests management in Nepal has been exemplified as one of the most successful programs... more Community forests management in Nepal has been exemplified as one of the most successful programs for participatory resource management. The success of community forestry is described in terms of restoring degraded land and habitats, conserving biodiversity, increasing supply of forest products, empowering women and disadvantaged groups, generating rural incomes, and developing human resources. However, the contribution of existing community forest management practices to biodiversity conservation in the form of enhancing species diversity and ecosystem functioning is questionable. We reviewed the role of community forest management practices to biodiversity conservation based on published materials and our own observations. Practices such as seedling plantation; controlling wildlife hunting, forest fire and grazing; regulating forest encroachment; protecting soil erosion prone area and water resource area assist biodiversity conservation, paradoxically other practices such as species selection; removal of unwanted species during silvicultural activities; leaf litter collection; elite dominance in decision making; and traditional knowledge depletion have detrimental impact on biological diversity and ecosystem function of community managed forest.
Tropical Ecology, 2011
Lack of biological information is a major constraint to the development of the medicinal plant se... more Lack of biological information is a major constraint to the development of the medicinal plant sector in Nepal. We monitored phenology, population structure, and regeneration strategies of Curculigo orchioides, a threatened medicinal herb of tropical to subtropical Asia, for 1 year at five sites in the inner Terai, Central Nepal. Only 20 -26 % of mature individuals were in the reproductive phase during the phenologically most active months (June -July), and about 55 % of flowering individuals developed fruits. Soil moisture, stored reserves, and biotic pressure appeared to govern phenological patterns. Fruiting frequency was high under conditions of a partially open canopy and a thin litter layer. Seeds showed physiological dormancy and germinated 10 -12 months after dispersal in natural habitats. Clonal propagation from leaves was induced by mild mechanical damage, high soil moisture, and humidity. Low regenerative potential through sexual reproduction and high vulnerability to habitat disturbance appear to be the major constraints to maintaining natural populations of C. orchioides.
Http Dx Doi Org 10 1659 Mrd Journal D 10 00003 1, 2010
Open access article: please credit the authors and the full source.
Natural Product Communications, Jun 1, 2011
Our ongoing studies of Nepalese medicinal plants has led to the isolation and characterization of... more Our ongoing studies of Nepalese medicinal plants has led to the isolation and characterization of five new triterpenes, two known triterpenes and two phenolic derivatives from Abies spectabilis (D.Don) Mirb leaves grown in the high mountain. The structures of the isolated compounds were characterized by means of 1D and 2D NMR spectroscopic and MS techniques.
Global Change Biology, 2015
Modeling the distributions of species, especially of invasive species in non-native ranges, invol... more Modeling the distributions of species, especially of invasive species in non-native ranges, involves multiple challenges. Here, we developed some novel approaches to species distribution modeling aimed at reducing the influences of such challenges and improving the realism of projections. We estimated species-environment relationships with four modeling methods run with multiple scenarios of (1) sources of occurrences and geographically isolated background ranges for absences, (2) approaches to drawing background (absence) points, and (3) alternate sets of predictor variables. We further tested various quantitative metrics of model evaluation against biological insight. Model projections were very sensitive to the choice of training dataset. Model accuracy was much improved by using a global dataset for model training, rather than restricting data input to the species' native range. AUC score was a poor metric for model evaluation and, if used alone, was not a useful criterion for assessing model performance. Projections away from the sampled space (i.e. into areas of potential future invasion) were very different depending on the modeling methods used, raising questions about the reliability of ensemble projections. Generalized linear models gave very unrealistic projections far away from the training region. Models that efficiently fit the dominant pattern, but exclude highly local patterns in the dataset and capture interactions as they appear in data (e.g. boosted regression trees), improved generalization of the models. Biological knowledge of the species and its distribution was important in refining choices about the best set of projections. A post-hoc test conducted on a new Partenium dataset from Nepal validated excellent predictive performance of our "best" model. We showed that vast stretches of currently uninvaded geographic areas on multiple continents harbor highly suitable habitats for Parthenium hysterophorus L. (Asteraceae; parthenium). However, discrepancies between model predictions and parthenium invasion in Australia indicate successful management for this globally significant weed. This article is protected by copyright. All rights reserved.
Banko Janakari
Population structure of Quercus semecarpifolia Sm. (khasru) was studied in mature forest of Shiva... more Population structure of Quercus semecarpifolia Sm. (khasru) was studied in mature forest of Shivapuri Hill (Shivapuri National Park, Kathmandu), Central Nepal from November 2002 to February 2003. A total of 16 quadrats (20 m x 20 m) for trees and 58 (5 m x 5 m) for seedling and sapling were laid from 2200 m to 2500 m on southern face of the hill. The study site had mature forest with comparatively low tree density (203 ha- 1) but high basal area (50 m2 ha-1). The forest had abundant number of small seedlings (density 3807 ha-1) but sapling was very rare (density 62 ha- 1). Survival of large seedling and sapling appear to limit the regeneration of khasru forest. Size class diagram of khasru resembled bell shape with higher density of medium sized trees. So there is lack of continuous regeneration of khasru under its own canopy. Partial canopy opening by thinning of old trees may induce regeneration in old growth and mature khasru forest but long term monitoring of seedling and saplin...
Himalayan Journal of Sciences, 2006
Lack of big funds is not the primary constraint in development of science and technology in Nepal... more Lack of big funds is not the primary constraint in development of science and technology in Nepal. More important and subtle factors -lack of exchange of information between researchers; lack of co-operation and unhealthy competition between professors and among big institutions (although co-operation is essential for integrated study); data manipulation which prevails from beginners to some established researchers; and professors, the highly expert people in university, being enticed away from their research activity by private teaching institutes.
Himalayan Journal of Sciences, 2006
Journal of Sustainable Forestry, 2015
ABSTRACT
Natural product communications, 2011
Our ongoing studies of Nepalese medicinal plants has led to the isolation and characterization of... more Our ongoing studies of Nepalese medicinal plants has led to the isolation and characterization of five new triterpenes, two known triterpenes and two phenolic derivatives from Abies spectabilis (D.Don) Mirb leaves grown in the high mountain. The structures of the isolated compounds were characterized by means of 1D and 2D NMR spectroscopic and MS techniques.
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Papers by Bharat Shrestha