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Sun F.,Sichuan Agricultural University | Chen W.,Gansu Forestry Science and Technology Research Academy | Liu L.,Sichuan Agricultural University | Liu W.,Sichuan Agricultural University | And 2 more authors.
Grassland Science | Year: 2015

The foraging and burrowing activities of small mammalian herbivores may have either detrimental or beneficial effects on grassland ecosystems; the direction of the effect is determined by the species, population abundances and fluctuations. Twelve survey sites with active burrow of plateau pika were classified into four degrees of density: approximately zero-density, low-density, medium-density and high-density, to evaluate the impact of different pika densities on vegetation, plant biomass, soil organic carbon and nutrients in a whole growing season. We show that pika as a main supplement to livestock activities contributed to a decrease in the number of plant species, vegetation cover, plant height and seasonal mean biomass, while values at medium-density site except above-ground biomass were the lowest. With the exception of available potassium, soil organic carbon, nitrogen, total phosphorus and soil water content, zero-density areas were significantly higher than those of pika occupied areas. However, there were slight or no differences in vegetation characteristics and soil properties between medium-and high-density sites. Our study suggests pika activities with high-density made palatable forage less and soil carbon and nitrogen more than low-density, moreover, plateau pika had greater impacts on above-ground vegetation than on root system. © 2015 Japanese Society of Grassland Science.


Sun F.,Sichuan Agricultural University | Chen W.,Gansu Forestry Science and Technology Research Academy | Liu L.,Sichuan Agricultural University | Liu W.,Sichuan Agricultural University | And 2 more authors.
Biochemical Systematics and Ecology | Year: 2015

Understanding the relationships between plateau pika population and plants biomass is essential for improving small herbivores management in alpine meadow ecosystems. Four degrees of active burrow densities were classified to evaluate pika populations and biomass allocation interactions. Our results showed that plant composition, overall vegetation height and cover, dominant species were significantly different among four sites. Additionally, plant functional groups, above ground, below ground and total biomass, root:shoot ratios and the living roots proportion were the greatest at the zero-density site, and those at the medium-density site were the lowest. We postulate that pika activities may not be the cause of the differences, but a symptom of grassland degradation. Further, pika population fluctuations should be monitored, and when the population exceeds the economic threshold of low-density (110pikas or/and 512activeburrowsha-1) or reaches high-density (200pikas or/and 1360activeburrowsha-1), integrated management strategies should be implemented to protect damage. © 2015 Elsevier Ltd.


Wei Q.,Gansu Forestry Science and Technology Research Academy | Ling L.,Gansu Forestry Science and Technology Research Academy | Zhang G.,Gansu Forestry Science and Technology Research Academy | Yan P.-B.,Administration Bureau of Xinglong Mountain National Nature Reserve | And 3 more authors.
Chinese Journal of Applied Ecology | Year: 2011

By the methods of field survey and laboratory soaking extraction, an investigation was conducted on the accumulation amount, water-holding capacity, water-holding rate, and water-absorption rate of the litters under six main forests(Picea wilsonii forest, P. wilsonii - Betula platyphlla forest, Populus davidiana - B. platyphlla forest, Cotonester multiglorus - Rosa xanthina shrubs, Pinus tabulaeformis forest, and Larix principis-rupprechtii forest) in Xinglong Mountain of Gansu. The accumulation amount of the litters under the forests was 13.40-46.32 t · hm-2, and in the order of P. tabulaeformis forest > P. wilsonii - B. platyphlla forest > L. principis-rupprechtii forest > P. wilsonii forest > C. multiglorus-R. xanthina shrubs > P. davidiana- B. platyphlla forest. The litter storage of coniferous forests was greater than that of broadleaved forests, and the storage percentage of semi-decomposed litters was all higher than that of un-decomposed litters. The maximum water-holding rate of the litters was 185.5%-303.6%, being the highest for L. principis-rupprechtii forest and the lowest for P. tabulaeformis forest. The litters' water-holding capacity changed logarithmically with their soaking time. For coniferous forests, un-decomposed litters had a lower water-holding rate than semi-decomposed litters; whereas for broadleaved forests, it was in adverse. The maximum water-holding capacity of the litters varied from 3.94 mm to 8.59 mm, and was in the order of P. tabulaeformis forest > L. principis-rupprechtii forest > P. wilsonii - B. platyphlla forest > P. wilsonii forest > C. multiglorus - R. xanthina shrubs > P. davidiana - B. platyphlla forest. The litters' water-holding capacity also changed logarithmically with immersing time, and the half-decomposed litters had a larger water-holding capacity than un-decomposed litters. The water-absorption rate of the litters presented a power function with immersing time. Within the first one hour of immersed in water, the water-absorption rate of the litters declined linearly; after the first one hour, the litters' water-absorption rate became smaller, and changed slowly at different immersed stages. Semi-decomposed litters had a higher water-absorption rate than un-decomposed litters. The effective retaining amount(depth) of the litters was in the order of P. wilsonii - B. platyphlla forest(5.97 mm) > P. tabulaeformis forest(5.59 mm) > L. principis-rupprechtii forest(5.46 mm) >P. wilsonii forest(4.30 mm) > C. multiglorus - R. xanthina shrubs(3.03 mm) >P. davidiana - B. platyphlla forest(2.13 mm).

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