scholarly journals Grazing elevates litter decomposition but slows nitrogen release in an alpine meadow

2018 ◽  
Author(s):  
Yi Sun ◽  
Xiong Zhao He ◽  
Fujiang Hou ◽  
Zhaofeng Wang ◽  
Shenghua Chang
Keyword(s):  
Tibetan Plateau ◽  
Species Composition ◽  
Litter Decomposition ◽  
Nutrient Cycle ◽  
Nitrogen Release ◽  
Alpine Ecosystems ◽  
Grazing Exclusion ◽  
N Release ◽  
Palatable Species

Abstract. Nutrient cycling is a key ecosystem function whereby the processes of litter decomposition and N release in the soil-plant interface are vitally important but still not clear in the alpine ecosystems. We carried out a 3-year study to improve our understandings in nutrient cycle and develop strategies for restoring the degraded grasslands on the Qinghai-Tibetan Plateau. We established the grazing (GP) and grazing exclusion paddocks (GEP), then identified litter species composition and analyzed litter and soil chemical characteristics. Litter decomposition and N release were monitored by incubating litter in situ and across paddocks over 799 days. We found that grazing did not change plant species composition, but increased litter N; while grazing exclusion increased litter mass of palatable species and promoted soil organic carbon. Litter decomposed faster in GP, while N release was faster in GEP. Incubation site environment had more but litter source had less impact on litter decomposition and N release. Therefore, grazing and grazing exclusion had different impacts on litter decomposition and N release but both elevated nutrient cycle. The implications of our findings in restoring the degraded grasslands on the Qinghai-Tibetan Plateau were discussed.

scholarly journals Grazing increases litter decomposition rate but decreases nitrogen release rate in an alpine meadow

2018 ◽  
Vol 15 (13) ◽  
pp. 4233-4243 ◽  
Author(s):  
Yi Sun ◽  
Xiong Z. He ◽  
Fujiang Hou ◽  
Zhaofeng Wang ◽  
Shenghua Chang
Keyword(s):  
Nutrient Cycling ◽  
Community Composition ◽  
Litter Decomposition ◽  
Plant Community ◽  
Litter Quality ◽  
Plant Community Composition ◽  
Short Term ◽  
Grazing Exclusion ◽  
Mixed Litter ◽  
N Release

Abstract. Litter decomposition and N release are the key processes that strongly determine the nutrient cycling at the soil–plant interface; however, how these processes are affected by grazing or grazing exclusion in the alpine grassland ecosystems on the Qinghai-Tibetan Plateau (QTP) is poorly understood. So far few studies have simultaneously investigated the influence of both litter quality and incubation site on litter decomposition and N release. Moreover, previous studies on the QTP investigating how grazing exclusion influences plant abundance and biodiversity usually lasted for many years, and the short-term effects have rarely been reported. This work studied the short-term (6 months) effects of grazing and grazing exclusion on plant community composition (i.e., plant species presented) and litter quality and long-term (27–33 months) effects on soil chemical characteristics and mixed litter decomposition and N release on the QTP. Our results demonstrate that (1) shorter-term grazing exclusion had no effect on plant community composition but increased plant palatability and total litter biomass; (2) grazing resulted in higher N and C content in litter; and (3) grazing accelerated litter decomposition, while grazing exclusion promoted N release from litter and increased soil organic carbon. In addition, incubation site had significantly more impact than litter quality on litter decomposition and N release, while litter quality affected decomposition in the early stages. This study provides insights into the mechanisms behind the nutrient cycling in alpine ecosystems. We suggest that periodic grazing and grazing exclusion is beneficial in grassland management on the QTP.

scholarly journals Photosynthetic parameters of a sedge-grass marsh as a big-leaf: effect of plant species composition

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Markéta Mejdová ◽  
Jiří Dušek ◽  
Lenka Foltýnová ◽  
Lenka Macálková ◽  
Hana Čížková
Keyword(s):  
Species Composition ◽  
Plant Species ◽  
Photosynthetic Parameters ◽  
Acorus Calamus ◽  
Dominant Plant Species ◽  
Local Plant ◽  
Rate Of Photosynthesis ◽  
Carex Acuta ◽  
Leaf P

AbstractThe study estimates the parameters of the photosynthesis–irradiance relationship (PN/I) of a sedge-grass marsh (Czech Republic, Europe), represented as an active “green” surface—a hypothetical “big-leaf”. Photosynthetic parameters of the “big-leaf” are based on in situ measurements of the leaf PN/I curves of the dominant plant species. The non-rectangular hyperbola was selected as the best model for fitting the PN/I relationships. The plant species had different parameters of this relationship. The highest light-saturated rate of photosynthesis (Asat) was recorded for Glyceria maxima and Acorus calamus followed by Carex acuta and Phalaris arundinacea. The lowest Asat was recorded for Calamagrostis canescens. The parameters of the PN/I relationship were calculated also for different growth periods. The highest Asat was calculated for the spring period followed by the summer and autumn periods. The effect of the species composition of the local plant community on the photosynthetic parameters of the “big-leaf” was addressed by introducing both real (recorded) and hypothetical species compositions corresponding to “wet” and “dry” hydrological conditions. We can conclude that the species composition (or diversity) is essential for reaching a high Asat of the “big-leaf ”representing the sedge-grass marsh in different growth periods.

scholarly journals Effects of grazing on plant species diversity and above ground biomass in a Trans- Himalayan Rangeland

1970 ◽  
Vol 17 (1) ◽  
pp. 25-31 ◽  
Author(s):  
Anita Pokharel ◽  
Madhu Chhetri ◽  
Chiranjibi P Upadhyaya
Keyword(s):  
Species Diversity ◽  
Species Composition ◽  
Plant Species ◽  
Diversity Index ◽  
Livestock Grazing ◽  
Above Ground Biomass ◽  
Ground Biomass ◽  
Grazing Effect ◽  
Significant Difference ◽  
Palatable Species

Limited information is available on the species composition, above ground biomass and its relations to grazing in a trans-Himalayan rangeland. Its assessment is essential for long term conservation and management. In the present study, we compared species composition, phenology, diversity index and biomass between controlled (without grazing) and open (free grazing) plots to assess the effects of grazing in the selected experimental sites of Upper Mustang during July and November 2005. Species encountered were classified as high, medium, low and non palatable and in three life form categories-grasses, shrubs and forbs. The experimental sites are dominated by forbs (80%) followed by grasses (15%) and shrubs (5%). Disturbance caused by grazing affects the phenological characteristics of the plant community. Result also reveals that species diversity, maximum possible diversity, evenness and species richness was higher in the grazed plots during July and November. A comparison of the aboveground biomass in July showed that mean percentage biomass of high, medium and low palatable species is higher in ungrazed plots. In November, the percentage biomass of only medium palatable species was higher in ungrazed plots and rest of the category is higher in grazed plots. Significant difference in July, a peak growing seasons for most of the plant species in the region reveals that the pasture has impact of livestock grazing. Keywords: Biomass, diversity, grazing effect, rangeland, species Banko Janakari: A journal of forestry information for Nepal Vol.17(1) 2007 pp.25-31

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