Abstract: Using the data of the livestock-losing-weight period (defined as the daily mean temperature≤-5℃) including the starting date, ending date, and duration, and the data of the negative accumulated temperature, mean temperature, mean maximum and minimum temperatures in the period of livestock-losing-weight from 1971 to 2005 in Nakchu district of Tibet, the variation trends of various temperatures in this region were analyzed by climatic linear trend method. The main findings can be summarized as follows: in the past 35 years, the starting date postponed at an average rate of (2.1-4.9) d/10a in various pastoral areas in northern Tibet; the ending date showed no significant changes, and the duration displayed an obvious shortening tendency. In addition, during the period of the livestock-losing-weight in the 35 years, the mean temperature exhibited an increasing trend, and the negative accumulated temperature (≤-5℃) a decreasing trend in pastoral areas. In the 1990s, the period of livestock-losing-weight was shorter, and therefore there is advantage in husbandry production.

Key words: period of livestock-losing-weight, temperature, negative accumulated temperature, linear trend, anomalous years