RELATIONSHIP BETWEEN PHENOLOGY, PRODUCTIVITY, AND METEOROLOGICAL FACTORS IN RECENT 15 YEARS IN THE PASTORAL AREA OF QINGHAI, CHINA

Abstract

Through studying vegetation phenology and its relation to meteorological factors in a representative region, we can get the responsiveness of vegetation phenophase in different sites to climate changes and how it affects vegetation productivity by the changes of growing season. It is crucial to enhance the accuracy of carbon sequestration estimate. We use phenological observation data and corresponding meteorological data from weather stations of six counties in Qinghai province. The conclusions are (1) In the background of global climate change, the temperature of the pastoral area of Qinghai takes a significantly increasing trend. The precipitation also takes an increasing trend, but only the site of Qumalai is significant. (2) The green-up dates of forages in every site are not significant, but the withered dates of forages are significantly put off. In the sites of Gande and Haiyan, the major forages put off in withered dates are Gramineae, in the site of Henan, Cyperaceae is significantly put off. Significantly extended growing season of representative forages of Gramineae, Cyperaceae and other broad-leaved herb exist in the pastoral area of Qinghai. (3) In terms of relations between green-up date and temperature, the influence of site scale is greater than the influence of different species, and advanced green-up dates of forages in the sites of Henan and Haiyan are longer than the dates of the same forages in the site of Gande. Overall, green-up dates of forages advanced in the site of Henan (Avg3.67 days/[Formula: see text]C) are longer than the dates in the site of Gande (Avg1.31 days/[Formula: see text]C). In terms of relations between green-up date and precipitation, divergences of sites and species exist. The green-up dates of forages in the sites of both Qumalai and Tongde have significant negative correlation with precipitation. In the site of Haiyan, the green-up dates of some forages advance, and the green-up dates of some forages put off. On the whole, Gramineae is best responded, then Cyperaceae and broad-leaved herb show hardly any responsiveness. (4) The responsiveness of temperature is less than precipitation in the pastoral area of Qinghai. Forages in Tongde and Qumalai have significantly positive correlation with the accumulation precipitation from August to September. The differences are the delayed dates of the withered dates of Cyperaceae (2.97 days/10[Formula: see text]mm) which are longer than the delayed dates of the withered dates of Gramineae (2.02 days/10[Formula: see text]mm) in the site of Qumalai. Conversely, the delayed dates of the withered dates of Gramineae (3.13 days/10[Formula: see text]mm) are longer than the delayed dates of the withered dates of Cyperaceae (1.68 days/10[Formula: see text]mm) in the site of Tongde. (5) Only parts of sites in the pastoral area of Qinghai have the tendency of significant increment of forage yield. The precipitations in the sites of Gande, Qumalai and Xinghai can significantly increase the forage yield. (6) The main vegetation phenology and productivity changes are affected by the drivers of climate factors. The response patterns of vegetation phenology of different functional groups and forage yield of different regions are inconsistent with the climate factors which are related to the biologic characteristics of different kinds of vegetations and climate sensitivities.