scholarly journals Impact of Mikania micrantha H.B.K. Invasion on Diversity and Abundance of Plant Species of Chitwan National Park, Nepal

2015 ◽  
Vol 19 (2) ◽  
pp. 30-36 ◽  
Author(s):  
Binoj Kumar Shrestha ◽  
Dharma Raj Dangol

This research investigated the invasion of the alien plant Mikania micrantha H.B.K. and its impact on plant species richness and abundance in Chitwan National Park (CNP) forest. Stratified sampling technique was used to collect the information using the nested quadrats in the Mikania invaded and not invaded sites in July 2011. The study revealed that the invasion highly related with the vegetation structure of the habitat; higher the tree crown cover lower the invasion. On the other hand, the invasion in terms of cover percent of Mikania irrespective of the biomass (fresh weight) decreased plant species richness. Species richness showed unimodal response to the Mikania cover percent with the decrease after 35% of Mikania cover. Journal of Institute of Science and Technology, 2014, 19(2): 30-36

2007 ◽  
Vol 85 (3) ◽  
pp. 273-284 ◽  
Author(s):  
L. Dennis Gignac ◽  
Mark R.T. Dale

Forty-one remnants of the aspen-dominated upland forest in three subregions of the dry boreal mixed-wood in Alberta were studied to determine effects of fragment size and shape on native and alien plant species richness and abundance in agro-environments. The percent cover of all vascular plant species was visually estimated in 5 m diameter circular plots along transects that covered the length and the width of each fragment. A subset of 12 of the largest fragments (>900 m2) that had distinct interiors (portions of the fragment >15 m from any edge) was used to measure edge effects on the vegetation. Regression analyses revealed significant positive relationships between species richness and area regardless of the subregion. Species richness stabilized in fragments that were larger than 11 ha. Edges did not affect shrub species richness and only affected herbaceous species richness on west- and south-facing aspects. Shrub abundance decreased and herb abundance increased up to 20 m from the edges regardless of orientation. Edges did not support a different suite of species than interiors, although several species occurred more frequently in the interior than along the edges. Alien species richness and abundance reached their highest values between 5 and 15 m from the edge, and some of those species could be found up to 40 m from the edge. Although larger fragments generally supported more alien species than smaller fragments, the smallest fragments had the greatest number of species per metre squared. Results from this study indicated that it would be preferable to conserve larger woodlots rather then several smaller woodlots on the landscape.


2017 ◽  
Vol 601-602 ◽  
pp. 461-468 ◽  
Author(s):  
Panayiotis G. Dimitrakopoulos ◽  
Sotirios Koukoulas ◽  
Alexandros Galanidis ◽  
Pinelopi Delipetrou ◽  
Dimitris Gounaridis ◽  
...  

Koedoe ◽  
2013 ◽  
Vol 55 (1) ◽  
Author(s):  
Helga Van Coller ◽  
Frances Siebert ◽  
Stefan J. Siebert

Understanding relationships between large herbivores and plant species diversity in dynamic riparian zones is critical to biodiversity conservation. The Nkuhlu exclosures in the Kruger National Park (KNP) provided opportunity to investigate spatial heterogeneity patterns within riparian zones, as well as how these patterns are affected by fire and herbivory. A monitoring project was initiated to answer questions about the dynamics of the herbaceous layer and was aimed at determining, (1) whether there exists meaningful variance in herbaceous plant species richness and diversity across different treatments in the ecologically sensitive sodic zone and (2) whether an increase in herbaceous biomass, an artefact of herbivory and fire exclusion, suppresses herbaceous plant species diversity and richness. Herbaceous vegetation was sampled in two 1 m2 circular sub-plots in the eastern and western corners of 81 fixed plots. The biomass of each plot was estimated with a disc pasture meter (DPM) diagonally with the plot. DPM-readings were converted to kg/ha, according to the latest conversions for the Lowveld Savanna. Species richness and biomass showed significant variance across treatments, whereas no significant variation in herbaceous species diversity was perceived. Combined treatment of fire absence and herbivore presence contributed to higher forb species richness in the sodic zone. Biomass is significantly higher in fully fenced areas where herbivores are excluded, as opposed to the open and partially fenced areas. Although no significant variation was recorded for diversity across treatments, lowest diversity was recorded in the absence of all herbivores, especially in combination with fire treatment. Therefore herbivores are essential in sustaining herbaceous plant species richness in the sodic zone, whilst no significant results were found with regard to their effect on species diversity. Although statistically non-significant, fire seems to suppress species richness.Conservation implications: This study could be used as framework to advance and develop science-based management strategies for, at least, the sodic zones of the KNP. Research in these exclosures will create better understanding of these landscapes, benefit ecosystem conservation planning of national parks and also provide valuable long-term information on key ecological processes.


2015 ◽  
Vol 37 (3) ◽  
pp. 309 ◽  
Author(s):  
Suman Aryal ◽  
Geoff Cockfield ◽  
Tek Narayan Maraseni

Grazing systems in the high Himalayas are changing in response to socioeconomic factors and policy decisions. As well as effects on livelihood of herders, such changes may have significant impacts on plant species richness and composition. The objectives of this study were to explore how plant species richness and composition respond to livestock grazing in the high Himalayan rangelands. The study was conducted in three mountainous Protected Areas of Nepal viz. Sagarmatha (Mt Everest) National Park, Gaurishankar Conservation Area and Khaptad National Park. Species and environmental data were collected along perpendicular transects outwards from goths (semi-permanent stopping and camping points). It was found that the distance from goths generally represents a grazing disturbance gradient. The core areas near goths had low species richness per plot (α-diversity) where nitrophilous and grazing-tolerant species were commonly found. However, the highest species richness, total numbers of species and occurrences of rare species at mid- and farther distances from goths within 800 m suggest that negative effects of summer livestock grazing were small and confined to limited areas near goths. Altitude, soil moisture content, percentage shrub cover and distance from goths were the variables significantly correlated with species composition, although the relative importance of these factors varied across study sites. This research can be used to inform decision-making about seasonal livestock grazing in the Himalayan rangelands, which should incorporate both ecological as well as socioeconomic considerations.


2011 ◽  
Vol 2011 ◽  
pp. 1-7 ◽  
Author(s):  
David H. Branson

A continuing challenge in orthopteran ecology is to understand what determines grasshopper species diversity at a given site. In this study, the objective was to determine if variation in grasshopper abundance and diversity between 23 sites in western North Dakota (USA) could be explained by variation in plant species richness and diversity. In this system with relatively low plant diversity, grasshopper species richness and abundance were not significantly associated with plant species richness in either year. Although a number of significant associations between plant diversity and grasshopper diversity were found through regression analyses, results differed greatly between years indicating that plant species richness and diversity did not lead to strong effects on grasshopper diversity metrics. Plant species richness appears to be too coarse grained to lead to accurate predictions of grasshopper species richness in this system dominated by generalist grasshopper species.


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