The Characteristics Of Climatic Productivity And Its Effect On The Climatic Change In The Three-river Headwaters Region From1960to2011

Grassland is the main type of terrestrial ecosystems, natural grassland is thelargest green vegetation cover layer of the earth’s land surface, and grasslandproductivity on temperature, precipitation and other climatic factors have a strongdependence. In recent years, under the background of global warming, regionalgrassland productivity also produced significant changes. Three-River HeadwatersRegion is the birthplace of the Yangtze, Yellow and Lancang rivers. It is located inhumid and semi-humid areas, and basically natural herbage. There are low levels innaturally productivity and economic productivity. The spatiotemporal variations of theclimatic productivity were analyzed in the Three-River Headwaters Region hasimportant theoretical and practical significance for guiding the area of natural herbageproduction. Meanwhile, it can provide a reference value in using climate resourcesreasonably protected the nature grassland and restoring the ecological environment.Based on the air temperature and precipitation data from13meteorologicalstations in the Three-River Headwaters Region in1960-2011, the climaticproductivity in this Region and its three source regions was estimated byThornthwaite Memorial model, the spatiotemporal variations of the air temperatureand precipitation in the Three-River Headwaters Region, the climatic productivity andits response to climate change and prediction in this Region and its three sourceregions were studied. In order to better understanding the potential of grasslandresources in the study area and the natural environment, particularly under thebackground of global climate change, the effects and responses of the grasslandclimatic productivity to climate change. By predicting the future trends, the study areawill be adopted measures to prevent the deterioration of the natural grasslandecosystem, thereby promoting the development of regional husbandry and ecologicalenvironment good circulation.The article mainly divides into the following several parts:(1) In the Three-River Headwaters Region, the mean annual temperature andthe mean temperature in winter and in summer in recent52years were featured by repeated cold and warm fluctuations, but overall, presented an obvious rising trend atstatistical significance level. Summer and annual average temperatures tended to bewarm significantly since the medium-term1990s, but the winter average temperatureexhibited a significant increasing trend since the late1990s. The annual averagetemperature change tendency rate of the Three-River Headwaters Region was0.289℃/10a, and the temperature rising trends of winter was higher than summer, thosechange tendency rate were0.409℃/10a and0.254℃/10a. The annual, summer andwinter average temperatures in the Three-River Headwaters Region had abruptchanges. The annual average temperature abrupt changes was mainly observed in1996~1997, while the summer and winter average temperature abrupt changes mainlyoccurred in1994and1998. Each component of the first eigenvector of EOF analyzedthe annual average temperature was positive and it reflected the spatial distribution ofthe annual average temperature changes had a strong consistency in the Three-RiverHeadwaters Region. Descending from the central region to the east-west direction, theoverall small compared to the eastern part of the western region.(2) In1960~2010, the annual, winter and growth season precipitation in theThree-River Headwaters Region were a slow upward trend in volatility. The annualand growth season precipitation had an increasing trend, especially since2001. Thelargest of winter precipitation was in1990s. The annual, winter and growthprecipitation change tendency rate were4.503mm/10a,0.804mm/10a and1.833mm/10a. The annual and growth season precipitation had not abrupt changes. Thewinter precipitation abrupt change was in1972. The annual precipitation of theThree-River Headwaters Region had an obvious change in different regions. Spatially,the precipitation had opposite variation trend in the east and west as well as in thesouth and north.(3) The climatic productivity in the Three-River Headwaters Region for the past52years exhibited an increasing trend, especially obviously in the21st century. Theannual average climatic productivity change tendency rate of the Three-RiverHeadwaters Region was13.451kg/(hm2·a), while the annual average climaticproductivity change tendency rates of the Yangtze River source region, the YellowRiver source region and the Lancang River source region were16.149kg/(hm2·a), 10.721kg/(hm2·a) and14.894kg/(hm2·a), respectively. The climatic productivity ofthe Yangtze River source region was the greatest increases, followed by the LancangRiver source region and the Yellow River source region was the least. Eachcomponent of the first eigenvector of EOF analyzed the annual average climaticproductivity was positive and it reflected the spatial distribution of the annual averageclimatic productivity changes had a strong consistency in the Three-River HeadwatersRegion.(4) The correlation coefficient of climatic productivity and air temperature waslarger than that of climatic productivity and precipitation, illustrating that airtemperature was the main factor limiting the climatic productivity. The correlationcoefficient of air temperature and precipitation were0.905and0.536. The warm andwet climate increased the climatic productivity by8.67%, but the cold and dry climatedecreased the climatic productivity by8.91%. The climatic productivity of the warmand dry climate than cold and wet climate larger, were3.03%and-4.99%. In thefuture, the regions climate would generally be warm and wet, and thus, the climaticproductivity would be increased, which would be conducive to the improvement ofnatural herbage yield.(5) Regression equation prediction shows that, in the Three-River HeadwatersRegion, average temperature increase or decrease1℃, the climatic productivityincrease or decrease417.782kg/(hm2·a), annual precipitation increase or decrease1mm, the climatic productivity increase or decrease3.038kg/(hm2·a). In the YangtzeRiver source region, average temperature increase or decrease1℃, the climaticproductivity increase or decrease427.342kg/(hm2·a), annual precipitation increase ordecrease1mm, the climatic productivity increase or decrease3.323kg/(hm2·a). In theYellow River source region, average temperature increase or decrease1℃, theclimatic productivity increase or decrease418.203kg/(hm2·a), annual precipitationincrease or decrease1mm, the climatic productivity increase or decrease2.725kg/(hm2·a). In the Lancang River source region, average temperature increase ordecrease1℃, the climatic productivity increase or decrease364.659kg/(hm2·a),annual precipitation increase or decrease1mm, the climatic productivity increase or decrease3.864kg/(hm2·a).