贵阳木本植物始花期对温度变化的敏感度

植物物候期的温度敏感度反映了植物是怎样及在何种程度上响应气候变化,研究不同物种物候期的温度敏感度有利于鉴别易受气候变化影响的物种。现有关于始花期的温度敏感度研究主要集中在温带地区,在亚热带地区研究仍较少。本文以位于亚热带的贵阳为研究区,利用1980-2014年60种典型木本植物的始花期观测资料,分析了该地区植物始花期变化趋势及对气温变化的敏感度,评估了样本量大小对敏感度估计稳定性的影响。结果表明：①研究时段内贵阳发生了明显的气候变化,年平均气温显著升高,其中春、秋季的增温比夏、冬季显著。②绝大多数植物(88.3%)的始花期在研究时段内呈提前趋势,其中显著提前的占物种总数的21.7%(P<0.05);60种植物始花期总体的提前趋势为2.89 d/10 a。③绝大多数(88.3%)植物始花期的年际变化与最优时段内平均气温呈显著负相关(P<0.05),所有植物始花期的总体敏感度为-5.75 d/℃。④样本量大小对温度敏感度估计的稳定性有显著影响,15年长序列能将敏感度估计结果的波动范围以99%的概率控制在2 d/℃之内。

Sensitivity of first flowering dates to temperature change for typical woody plants in Guiyang City,China

Temperature sensitivity of phenophases can reflect how and to what degree plants could tract climate change, and is related to the ability of plants to adapt to climate change. Investigating the temperature sensitivity of phenophases of different plant species could help us to identify species that are sensitive to climate change. To date, the studies about temperature sensitivity of first flowering date (FFD) mainly focused on the temperate area, and fewer studies focused on the subtropical area. We selected Guiyang City, located in subtropical China, as the study area, and analyzed the temporal changes in FFD of plants and their temperature sensitivities based on phenological observation data of 60 typical woody plants from 1980 to 2014. In addition, we evaluated the impact of the length of time series on the stability of the estimates of temperature sensitivity. The results show that: (1) Guiyang City experienced notable climate change with significantly increased annual mean temperature during the study period. The warming of spring and autumn was stronger than summer and winter. (2) FFD of 53 species (88.3%) advanced during the study period with 13 species (21.7%) significantly advancing (P<0.05). Most trends of FFD were between -4 and -2 d/decade. The overall advancing trend for FFD of 60 species was 2.89 d/decade. (3) FFD was significantly and negatively correlated with mean temperature during the optimum period for most species (88.3%). Most temperature sensitivities of FFD ranged from -8 to -4 d/°C. The overall temperature sensitivity for FFD of all species was -5.75 d/°C. (4) Sample size clearly affected stability of the estimates of temperature sensitivity. The time series of 15 years could make the difference of estimates less than 2 d/°C with a probability of 99%. Thus, time series should be as long as possible to be used in estimating the temperature sensitivity of flowering phenology with a stability that is sufficient for interspecific comparisons.