气候变暖背景下西藏中南部苹果物候期变化及其气候影响因子分析

Phenological Change and Its Climatic Impact Factors of Apple under the Background of Climate Warming in South-Central Tibet

利用2001-2020年西藏泽当农业气象站苹果物候期和逐日平均气温(T_(m))、最高气温(T_(max))、最低气温(T_(min))、气温日较差(DTR)、相对湿度(RH)、降水量(P_(r))、日照时数(S)和≥0℃积温(∑T_(0))等资料,采用线性回归、Pearson相关系数和逐步回归等方法,分析近20a西藏中南部苹果物候期及生长期长度的变化趋势,以及影响的主导气候因子,以期揭示西藏高原苹果物候期变化特征及其对气候变暖的响应。结果表明:2001-2020年西藏中南部苹果除可采成熟期以1.28d·a^(-1)的速率呈提前趋势外,其它物候期平均每年推迟2.83~7.64d;果实生长发育期长度、花期长度平均每年分别缩短8.92d和5.98d,而果树全生育期长度略有延长,速率为0.65d·a^(-1)。各物候期T_(max)趋于升高,T_(min)呈降低趋势,DTR显著增大;多数物候期RH、S呈显著减少趋势;Pr在可采成熟期前以增加为主,之后趋于减少。春季物候期主要受温度影响,而秋季物候期主要受降水影响。影响物候期长度的主导气候因子,可采成熟期-叶变色末期和果树全生育期长度为T_(m),叶变色末期-落叶末期为S,其它物候期长度均为∑T_(0)。研究区3月上旬T_(m)每升高1℃,苹果开花始期提前2.32d;10月下旬Pr每增加10mm,苹果落叶末期提前8.55d。

To reveal the characteristics of apple phenology changes and its response to climate warming on the Tibetan plateau,with a view to providing basic scientific and technological support for local apple cultivation,management,breeding and coping with climate change.Both phenological data and meteorological items measured in the period of apple growth in Tsedang agrometeorological station from 2001 to 2020 were analyzed,which include phenological dates and the daily mean value of several meteorological factors such as mean temperature(T_(m)),maximum temperature(T_(max)),minimum temperature(T_(min)),diurnal temperature range(DTR),precipitation(Pr),relative humidity(RH),sunshine duration(S),and accumulated temperature above 0℃(∑T_(0))et al.Statistical methods,including linear regression,Pearson correlation coefficient and stepwise regression,were used to reveal the trends and identify the leading factors caused the changes in apple phenology in south-central Tibet in the past 20years.The results indicated that:(1)all of the apple phenological dates were postponed in a range from 2.83 to7.64d·y^(-1) in south-central Tibet from 2001 to 2020 except for the fruit maturing date(FMD),which exhibited an advanced rate of 1.28d·y^(-1).The length of fruit growing period(LFG)and flowering duration(FD)were shortened by8.92d·y^(-1) and 5.98d·y^(-1),respectively,while the length of tree growing season(LTG)was slightly extended at an increasing rate of 0.65d·y^(-1).These results were different from the main apple producing areas in northern China where the autumn phenophase was delayed and the spring phenophase was advanced,and may be attributed to the reduction of∑T_(0) during the growth seasons.(2)For all of apple phenological stages,the Tmaxhas increased with Tmindecreasing,leading to a significant larger value of DTR.For most of the phenological stages,RH and S have reduced significantly,while Pr increased before FMD and decreased afterwards.(3)In spring,temperature was identified as the dominant factor with negative correlation with the phenophase in south-central Tibet.In contrast,Pr was the leading factor causing changes in autumn phenophases,which was positively correlated with the FMD and negatively correlated with both the end of leaf coloring date(LCD)and the end of leaf fall date(LFD).(4)For most of the phenology,∑T_(0) has been revealed as the leading factor influencing the length of phenological period.However,T_(m) has played the dominant roles influencing the length of the whole period and the period from the FMD to LCD,and S can be viewed as the leading factor influencing the length of the period from the LCD to LFD.It has been identified that the first flowering date was advanced by 2.32 days when T_(max) increased by 1℃ in early March,and the LFD was advanced by 8.55 days when Pr changed with 10mm in late October in this study region.