摘要:作物物候期受气候条件和人为耕作的共同影响，而水热气候条件又直接影响着人为耕作时间。全球变暖背景下温度增加的趋势在近年来出现了停滞现象，针对这一新的气候变化特征，本研究选取作物物候观测和气象观测的站点数据，利用经典的统计学方法分析2000-2013年中国夏玉米和冬小麦主要物候期的变化趋势和空间分布，及作物生育期与对应水热条件的相关关系。研究发现：夏玉米和冬小麦各主要物候期均呈现一定程度的延后，其中64%的站点显示夏玉米成熟期延后，冬小麦成熟期延后的站点数比例达78%。研究期间，夏玉米和冬小麦的生育期历时对温度和降水变化均比较敏感，88%和64%的站点分别显示出夏玉米和冬小麦的生育期历时与平均温度之间呈负相关关系，而71%和77%的站点显示夏玉米和冬小麦生育期历时与年均降水量呈正相关关系。本研究时段内的气温变化也不同于一般性认为的单调升温，夏玉米生育期对应的平均温度呈增加和降低趋势的站点数基本相同，但显示降水量增加的站点较多，达到总站点数的68%；而冬小麦整个生育期显示冷干化趋势的站点居多，显示温度降低和降水量下降的站点数均占总站点数的60%以上。此外，本研究还用轮作站点探讨说明了可以利用年值气候数据替代生育期气候数据分析夏玉米和冬小麦轮作的物候和生育期特征。本研究通过站点数据证实了作物生长发育过程对气候变化的敏感性，新的气候条件下我国夏玉米和冬小麦的物候也对应产生了新的特征。
关键词:物候/
夏玉米/
冬小麦/
轮作/
生长期/
气温/
降雨/
增温停滞
Abstract:Crop phenology is influenced by both climatic and agronomic conditions, especially temperature and precipitation, which directly affect tillage schedule. A climatic phenomenon of warming hiatus has been noted since 2000. This phenomenon differs with the popular views of global warming. From the perspective of crop phenology, numerous studies have been conducted to assess the changes in growth periods of summer maize and winter wheat in the past decades. A relatively clear linkage of phenology and climatic conditions has been confirmed. As necessary climatic variables for crop growth, both temperature and precipitation influence the processes of crop growth, including the time of occurrence of the main phenology and length of the growth period. However, the relationship between phenology and climatic condition in recent years has been hindered by the lack of specific analysis that corresponds this relationship with the warming hiatus. For this specific period therefore, analyzing inter-annual changes of main phenological events and exploring the relationship between phenology and temperature as well as precipitation have become necessary for assessing current and future impacts of climatic conditions on crop growth and food security. Using observed phenological and meteorological data for 2000-2013, this study focused on analyzing of phenological characteristics and variations in growth periods of summer maize and winter wheat. Corresponding matches were built among hydrothermal conditions during the growth periods of the two crops and then the relationships between the length of growth period and hydrothermal conditions were analyzed. Spatial analysis method was used to find the proximal meteorological stations to phenological stations. Also, classical statistic was used to analyze the trends in phenology of the two crops and the relationships between phenology and hydrothermal conditions. The results showed delays in the main phenological events of summer maize and winter wheat. About 64% of the observed data stations showed that maturity of summer maize had delayed and the proportion of station with delayed trends in winter wheat was 78%. For the period covered in the study, the growth periods of summer maize and winter wheat were more sensitive to temperature and precipitation changes. About 88% of the stations used for summer maize and 64% of the stations used for winter wheat showed negative correlation between growth period length and temperature. While 71% of the stations used for summer maize and 77% of the stations used for winter wheat showed positive correlation between growth period length and precipitation. The reason for these tends was attributed to climate change. Different from the general understanding of global warming, average temperature during the growth period of summer maize did not show an obvious increase or decrease in trend, but precipitation obviously increased in most of the stations. The proportion of the stations with increasing trends in precipitation was more than 68%, while both cold and dry trends were observed during the whole growth period of winter wheat. The proportion of the stations with decreasing trend in temperature or precipitation all was more than 60%. In addition, analysis of the crop rotation stations revealed that annual climate data could be used in place of climate data for the growth periods to analyze for phenology and growth of rotational crops.
Key words:Phenology/
Summer maize/
Winter wheat/
Rotational crop/
Growth period/
Temperature/
Precipitation/
Warming hiatus
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