Species Richness, Diversity and Density of Understory Vegetation along Disturbance Gradients in the Himalayan Conifer Forest

We investigated whether species richness, diversity and density of understory herbaceous plants differed along logging（gap） and grazing（primarily by cattle） disturbance gradients, and sought to identify drivers of richness, diversity and density of understory vegetation of logged sites. A factorial...

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Bibliographic Details
Published inJournal of mountain science Vol. 11; no. 5; pp. 1182 - 1191
Main Authors Wangchuk, Kesang, Darabant, András, Rai, Prem Bahadur, Wurzinger, Maria, Zollitsch, Werner, Gratzer, Georg
Format Journal Article
LanguageEnglish
Published Heidelberg Science Press 01.09.2014
Springer Nature B.V
Subjects
Cattle
Community ecology
Coniferous forests
Coniferous trees
Earth and Environmental Science
Earth Sciences
Ecology
Environment
Forest management
Forests
Geography
Grazing
Herbivores
Land use
Logging
Mixed forests
Nutrients
Plant populations
Species diversity
Species richness
Understory
Vegetation
品种
喜马拉雅
干扰梯度
林下植被
物种丰富度
物种多样性
相对密度
针叶林
Species diversity
Soil nutrients
Grazing
Relative density
Species richness
Forest gap
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Summary:We investigated whether species richness, diversity and density of understory herbaceous plants differed along logging（gap） and grazing（primarily by cattle） disturbance gradients, and sought to identify drivers of richness, diversity and density of understory vegetation of logged sites. A factorial experiment was conducted in the mixed conifer forest of Gidakom in Western Bhutan. Levels of the logging treatment included small（0.15 - 0.24 ha）, medium（0.25 - 0.35 ha） and large（0.36 - 1.31 ha） gaps. The grazing treatment included grazed（primarily by cattle） and ungrazed（where herbivores were excluded by a fence） plots nested within each gap. Data were collected from 12 gaps（4 replicates at each level of logging） using the point intercept method. Shannon Weaver Diversity and Margalef＇s indices were used to estimate species diversity and describe species richness, respectively. Soil samples were analyzed for pH and nutrients. The interaction effect of logging and grazing was significant（p≤0.001） only on species diversity. Relative to ungrazed areas, species diversity was significantly higher（0.01≤p≤0.05） in medium grazed gaps. Under grazed conditions, soil P was negatively correlated with gap size and species diversity. While species diversity was positivelycorrelated（0.01≤p≤0.05） with soil N in grazed plots species richness was positively correlated（0.001≤p≤0.01） with soil N in ungrazed plots. Relative density of Yushania microphylla and Carex nubigena were higher under ungrazed conditions. Our study suggests that the combined effect of cattle grazing and logging results in higher species diversity of understory vegetation in medium and grazed gaps in mixed conifer forests of Bhutan,whereas increase or decrease in relative density of major species is determined primarily by the independent effects of grazing and logging. From management perspective, forest managers must refrain from creating large gaps to avoid loss of nutrients（mainly P and N）, which may eventually affect tree regeneration. Managers intending to maintain understory vegetation diversity must consider the combined effects of grazing and logging, ensuring low to moderate grazing pressure.
Bibliography:Forest gap Grazing Relative density Soil nutrients Species diversity Species richness
51-1668/P
We investigated whether species richness, diversity and density of understory herbaceous plants differed along logging（gap） and grazing（primarily by cattle） disturbance gradients, and sought to identify drivers of richness, diversity and density of understory vegetation of logged sites. A factorial experiment was conducted in the mixed conifer forest of Gidakom in Western Bhutan. Levels of the logging treatment included small（0.15 - 0.24 ha）, medium（0.25 - 0.35 ha） and large（0.36 - 1.31 ha） gaps. The grazing treatment included grazed（primarily by cattle） and ungrazed（where herbivores were excluded by a fence） plots nested within each gap. Data were collected from 12 gaps（4 replicates at each level of logging） using the point intercept method. Shannon Weaver Diversity and Margalef＇s indices were used to estimate species diversity and describe species richness, respectively. Soil samples were analyzed for pH and nutrients. The interaction effect of logging and grazing was significant（p≤0.001） only on species diversity. Relative to ungrazed areas, species diversity was significantly higher（0.01≤p≤0.05） in medium grazed gaps. Under grazed conditions, soil P was negatively correlated with gap size and species diversity. While species diversity was positivelycorrelated（0.01≤p≤0.05） with soil N in grazed plots species richness was positively correlated（0.001≤p≤0.01） with soil N in ungrazed plots. Relative density of Yushania microphylla and Carex nubigena were higher under ungrazed conditions. Our study suggests that the combined effect of cattle grazing and logging results in higher species diversity of understory vegetation in medium and grazed gaps in mixed conifer forests of Bhutan,whereas increase or decrease in relative density of major species is determined primarily by the independent effects of grazing and logging. From management perspective, forest managers must refrain from creating large gaps to avoid loss of nutrients（mainly P and N）, which may eventually affect tree regeneration. Managers intending to maintain understory vegetation diversity must consider the combined effects of grazing and logging, ensuring low to moderate grazing pressure.
ISSN:1672-6316
1993-0321
1008-2786
DOI:10.1007/s11629-013-2942-8