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Accueil du site → Master → Chine → 2009 → Effects of Sheep Rotation Grazing on Soil Respiration and Analysis on Important Impact Factors in Hilly Area of Loess Plateau

Lanzhou Université (2009)

Effects of Sheep Rotation Grazing on Soil Respiration and Analysis on Important Impact Factors in Hilly Area of Loess Plateau

陈俊博;

Titre : Effects of Sheep Rotation Grazing on Soil Respiration and Analysis on Important Impact Factors in Hilly Area of Loess Plateau

Auteur : 陈俊博;

Grade : Master’s Theses 2009

Université : Lanzhou Université

Résumé
The rangeland in Loess Plateau which accounts for 27.3%-67.5% of land area is mainly used for pasture, and plays an important role in livestock production and ecological protection. This research carried on the steppe grassland ecosystem of the eastern Gansu, Loess Plateau, and mainly studied on the characteristic of soil respiration in rotation paddocks under different seasons and different stocking rates, also analyzed the effect of soil, grass and livestock on soil respiration.1 In summer, the diurnal curve of soil respiration of paddocks closely resembled a unimodal curve. The soil respiration rates in warm pastures peaked at around 14:00 h and at around 16:00 h in cold pastures, and then dropped rapidly to its minimum at 01:00-06:00 h. In warm pastures, the soil respiration rate lay in 1.12-1.58μmol·m-2·s-1, and it decreased with the increase of stocking rates. In cold pastures, the soil respiration rate lay in 1.26-1.44μmol·m-2·s-1, and it was positively correlated with stocking rates. The soil respiration rate in exclosure plots was 2.08μmol·m-2·s-1. We simulated the diurnal dynamic of soil respiration by the sine function Rs=a×sin(ωt+φ)+b, and obtained good effect. In warm pastures, the maximum of predicted soil respiration rate is lower than the measured by 0.21%-4.57%, and the minimum of predicted soil respiration rate is lower than the measured by 1.87%-8.34% ; in cold pastures, the maximum of predicted soil respiration rate is lower than the measured by 1.38%-4.60%, and the minimum of predicted soil respiration rate is lower than the measured by 3.13%-10.99% ; and in exclosures, the maximum of predicted soil respiration rate is lower than the measured by 0.82%, and the minimum of predicted soil respiration rate is lower than the measured by 4.99%.2 The pattern of seasonal dynamics of soil respiration was August > May > November, whether in warm pastures or in cold pastures. In warm pastures and cold pastures, the CO2 efflux (in descending order) was as follows : 1.35、0.79、0.43μmolCO2·m-2·s-1 and 1.36、0.78、0.42μmolCO2·m-2·s-1, respectively, and the difference of stocking rate was remarked significant (P<0.01).3 Path analysis was used to assess the effects of important impact factors on soil respiration. Our analysis indicated that the path coefficients of the influence factors affecting soil respiration in warm pastures were as follows (in descending order) : soil moisture (0.52), underground biomass (0.49) and soil temperature (0.42), and the indirect path coefficients of grazing affecting soil respiration in warm pastures were as follows (in descending order) : underground biomass (-0.089), soil moisture (-0.059) and soil temperature (-0.006) ; the path coefficients of the influence factors in cold pastures were as follows (in descending order) : soil temperature (0.67), underground biomass (0.42) and soil moisture (0.39), and the indirect path coefficients of grazing affecting soil respiration in cold pastures were as follows (in descending order) : underground biomass (0.052), soil temperature (0.042) and soil moisture (-0.004). The seasonal variation had great influence on soil respiration than stocking rate whether in warm pastures or in cold pastures, and grazing affected soil respiration manly by changing the underground biomass.In warm pastures, the soil respiration rate decreased with the increase of stocking rates ; but in cold pastures, the soil respiration rate was positively correlated with stocking rates. The warm grazing effected soil respiration mainly by reducing the input of carbon and the cold grazing effected soil respiration mainly by reducing the output of carbon. This research could provide base information for the establishment of reasonable style of management which could estimate the grassland carbon pool and the emissions of CO2 from grassland soil.

Mots clés : Loess Plateau; Rangeland; Grazing; Sheep; Soil respiration; Path analysis; Soil temperature; Soil moisture; Biomass;

Présentation (CNKI)

Page publiée le 14 mars 2018