|
|
Biological invasion is a major component of global environmental change and it has negative impacts on native biodiversity, ecosystem services, infrastructures, agriculture production, and human and animal health
. Direct and indirect economic costs of biological invasions amount to several hundred billions of dollars annually. Lowlands with high urbanization, industrialization, and other economic activities are adversely affected by biological invasions, whereas mountain regions were considered to be relatively less affected by this phenomenon. However, recent research and meta-analyses have revealed that biological invasions are occurring in mountain regions at an alarming rate. Management of invasive alien species (IAS) is more challenging in mountains due to the rugged topography
Read More
|
|
|
An understanding of the differences in vegetation and soil characteristics between slope aspects in high altitude semiarid environments is fundamentally important for efficient management of these semi-natural systems; however, few studies have quantified these differences
. Here, we analyzed forest stand characteristics, carbon stocks and soil properties of north- and south-facing slopes in a trans-Himalayan semiarid valley. Pinus wallichiana was the dominant and Juniperus indica the co-dominant species in both aspects, whereas Betula utilis and Abies spectabilis were only recorded in north-facing forests. Pinus regenerated in both aspects, whereas Juniperus did not. Carbon stocks did not differ between aspects; 33 t/ha in north-facing and 31 t/ha in south-facing forests. Similarly, soil properties did not vary between slope aspects, expect for potassium (highest in south-facing slopes). These results suggest that topographic factors affect mountain forests through their direct influence on radiation and moisture, but that human disturbance also plays a significant role affecting vegetation and soil characteristics in a semiarid environment. These natural and anthropogenic factors may play in harmony or in discord with each other. Here, the aridity of the region, parent material and land use history led to less pronounced differences between slope aspects, than commonly found in moister habitats
Read 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
Read More
|
|
|
Manfredi, E. C.; Flury, B.; Viviano, G.; Thakuri, S.; Khanal, S. N.; Jha, P. K.; Maskey, R. K.; Kayastha, R. B.; Kafle, K. R.; Bhochhibhoya, S.; Ghimire, N. P.; Shrestha, B. B.; Chaudhary, G.; Giannino, F.; Carten, F.; Mazzoleni, S.; Salerno, F.
The problem of supporting decision- and policy-makers in managing issues related to solid waste and water quality was addressed within the context of a participatory modeling framework in the Sagarmatha National Park and Buffer Zone in Nepal
. We present the main findings of management-oriented research projects conducted within this framework, thus providing an overview of the current situation in the park regarding solid waste and water quality issues. We found that most of the solid waste generated in the park is composed of organic matter, paper, and minor reused waste that is mainly reused for cattle feeding and manure, while disposal of other nondegradable categories of collected waste (glass, metal, and plastic) is not properly managed. Particularly, burning or disposal in open dumps poses a great hazard to environmental, human, and animal health, as most dump sites situated close to water courses are prone to regular flooding during the rainy season, thereby directly contaminating river water. Pollutants and microbiological contamination in water bodies were found and anthropogenic activities and hazardous practices such as solid waste dump sites, open defecation, and poor conditions of existing septic tanks are suggested as possibly affecting water quality. Collection of these data on solid waste and water quality and compilation of management information on the targeted social-ecological system allowed us to develop consensus-building models to be used as management supporting tools. By implementing such models, we were able to simulate scenarios identifying and evaluating possible management solutions and interventions in the park. This work reveals insights into general dynamics that can support the quest for solutions to waste and water quality management problems in other protected areas and mountain landscapes where traditional livelihood and land use patterns are changing under the influence of a growing population, changing consumption patterns, and international tourism
Read More
|
|
|
|
|
|
Distribution and community structure of treeline birch (Betula utilis D
. Don) forest in a trans-Himalayan dry valley was studied in Manang (central Nepal) with the major focus on regeneration. Along five vertical transects, a total of 41 square quadrats (10 m x 10 m) were sampled to determine the importance value index (IVI) of tree species, distribution pattern of seedlings and saplings, and soil attributes. Regeneration was assessed by a density–diameter curve. Moisture plays an important role in spatial (horizontal) distribution of Betula utilis. Pure Betula forest forming the treeline was mature, with high basal area (2.3%), but mixed Betula forest at lower elevations was young. This might have developed after large-scale clear cutting of Abies spectabilis. If not severely disturbed, mixed Betula forest may be replaced by Abies spectabilis. In general, Betula utilis was regenerating, as evident from a reverse J-shaped density–diameter curve for both forests. However, the distribution of seedlings and saplings was spatially heterogeneous and appeared to depend on canopy cover. The stands with highest seedling and sapling densities of Betula utilis had no trees. Betula seedlings were absent where the tree density and basal area (BA) exceeded 20 stems/100 m2 and 1.0% respectively. It was apparent that Betula seedlings could not establish under their own closed canopy even if they produced viable seeds. Partial canopy opening may induce seedling establishment and hence continuous regeneration of Betula utilis at mature stands. The tree-line formed by Betula utilis was abrupt — the anthropo-zoogenic type — without the krummholz zone
Read More
|
|
|
From July to December 2003 the authors studied the impact of forest resource use and management practices on community structure and regeneration of locally managed Shorea robusta (sal) forest in the mid-hills of central Nepal
. They carried out a household survey in two villages (Namjung village of Gorkha and Khari village of Dhading district), and studied the community structure and regeneration of important multipurpose tree species (Shorea robusta Gaertn. and Schima wallichii (DC.) Korth.) in community forests. Dependency on forests has been decreasing due to limited access to resources, decrease in cattle number and the cultivation of more fuelwood and fodder trees in non-forested land. theless, forests remain the major source of fuelwood, supplying 63% of the total. Alternative energy sources (biogas and solar cell) were not significant at the time of their study. S. robusta was the dominant tree in both forests, with high relative density (74%) in Namjung forest (NF) and 50% in Khari forest (KF); its importance value index (IVI) was 171 in NF and 152 in KF. Tree density of sal in NF was the highest (909 tree ha–1) among the reported values in references for the same species. Both forests had comparatively low species diversity (1.09 in NF and 1.30 in KF); local management appears to contribute to reduced diversity. Regeneration of sal was sustainable and fairly high, with a typical reverse-J-shaped size class diagram (in NF), a good predictor of mono-dominant sal forest. Regeneration of S. wallichii was unsustainable in both forests
Read More
|
|
|
Oaks (Quercus spp
.) are among the dominant vascular plants of the Himalayas, ranging from the subtropical to the sub-alpine zones. They play an important role in maintaining ecosystem stability. Oaks in the Himalayan region are intimately linked with subsistence hill agriculture as they protect soil fertility, watershed and local biodiversity. They also supply fodder, leaf litter, firewood and timber. Q. semecarpifolia is a high altitude oak, ranging up to the timberline in the Himalayan region and forming the climax community on the southern aspect; it is considered to be one of the oldest plants of the region. It is also one of the most over-exploited species and fails to regenerate adequately either in disturbed or undisturbed natural habitat. Since plantation has not been successful, it is important to manage natural forest more effectively. This can be done by implementing sustainable methods of lopping the trees for fodder, removing an adequate number of old and dying trees to make the canopy more open, and controlling the population of cattle and wild animals that damage seedlings through browsing and trampling
Read More
|
email alert
or subscribe to the 
RSS feed.
