羌塘国家级自然保护区地表土壤冻结天数时空变化特征  

Spatial and temporal variations of surface soil freezing days in Chang Tang Natural Reserve of Tibet during 1981-2018

作　　者：杜军 周刊社[2] 次旺顿珠 DU Jun;ZHOU Kan-she;Ciwangdunzhu(Tibet Institute of Plateau Atmospheric and Environmental Science Research,Lhasa 850001,China;Tibet Autonomous Region Climate Centre,Lhasa 850001,China)

机构地区：[1]西藏高原大气环境科学研究所,拉萨850001 [2]西藏自治区气候中心,拉萨850001

出　　处：《生态学杂志》2020年第4期1121-1129,共9页Chinese Journal of Ecology

基　　金：国家自然科学基金项目(41765011);2019年西藏自治区科技重点研发计划“西藏主要地表特征科学考察及研究”共同资助。

摘　　要：利用1981—2018年羌塘自然保护区周边5个气象台站的地表逐日最低温度和平均气温资料,采用线性回归和Mann-Kendall非参数检验方法,分析了近38 a以及全球变暖1.5℃和2℃阈值时羌塘自然保护区地表土壤冻结天数的时空变化特征。结果表明:(1)近38 a近地表土壤冻结开始日期呈推迟趋势,变化率为7.72 d·10 a^-1,冻结终止日期以8.17d·10 a^-1的速率显著提早;冻结持续时间和冻结天数均呈显著缩短趋势,平均每10年分别缩短14.69和11.19 d;同时段内,自然保护区大部分土壤冻结参数的变化率均大于青藏高原。(2)在年代际变化上,自然保护区呈现土壤冻结开始日期推迟、冻结终止日期提前、冻结持续时间和冻结天数缩短的变化特征。(3)土壤冻结参数在21世纪初均发生了气候突变,较青藏高原土壤冻融时间的突变点偏晚。(4)在全球变暖1.5℃时,RCP4.5和RCP8.5情景下的自然保护区土壤冻结参数变化值相同,冻结开始日期推迟25 d,冻结终止日期提早22 d,冻结持续时间和冻结天数分别缩短46和28 d;变暖2.0℃时,RCP4.5和RCP8.5情景下的土壤冻结开始日期推迟35和33 d,冻结终止日期提早30和29 d,冻结持续时间减少64和62 d,冻结天数缩短40和39 d。The near-surface soil freezing/thawing status is an important indicator of climate change.Based on the daily minimum surface soil temperature and air temperature data in the period 1981-2018 from five meteorological stations in Chang Tang Natural Reserve of Tibet(CTNRT),the spatiotemporal distribution of the number of freezing days for the ground surface under the scenarios of 1.5℃and 2℃warming were analyzed with the methods of linear regression method and Mann-Kendall test.The results showed that:(1)In the past 38 years,the first date of near-surface soil freeze had been significantly postponed at a rate of 7.72 d·10 a^-1,and the last date of near-surface freeze had been advanced at a rate of 8.17 d·10 a^-1.The duration days and freeze days exhibited declining trends,with a rate of 14.69 and 11.19 d·10 a^-1,respectively.The average rate of change for most near-surface freezing variables in CTNRT was generally higher than that over the Qinghai-Tibet Plateau.(2)In terms of inter-decadal variation,the first date had been delayed,as opposed to the advanced last date,while the duration days and freeze days had been shortened in CTNRT.(3)The trend reversal for the near-surface freeze parameters occurred in the early 21 st century,with the abrupt point being later than that over Qinghai-Tibet Plateau.(4)The values of near-surface freeze parameters in CTNRT are similar under the RCP4.5/RCP8.5 scenarios of 1.5℃warming:the first date is delayed by 25 days,the last date becomes earlier by 22 days,and the duration and freeze days are shortened by 46 and 28 days,respectively.Under the RCP4.5/RCP8.5 scenarios of 2.0℃warming,the first date is postponed by 35 and 33 d,the last date is advanced by 30 and 29 d,the duration is shortened by 64 and 62 d,and the number of days is reduced by 40 and 39 d.

关 键 词：土壤冻结天数 变化趋势 气候突变 全球变暖 羌塘国家级自然保护区 

分 类 号：S152[农业科学—土壤学]