论文部分内容阅读
高山林线对气候变化反应敏感,是研究气候变化的理想场所。本文以秦岭太白山林线树种太白红杉为研究对象,利用2000—2015年MODIS NDVI数据集和气温数据,研究了太白红杉对气温变化的响应特征并试图揭示其响应机理。结果表明:太白红杉区年均NDVI与年均气温呈正相关,呈正相关的像元数占96.30%,达显著正相关的像元数占31.42%,即在年尺度上气温升高有利于太白红杉的生长;月尺度上,太白红杉区月均NDVI对月均气温的响应大多为正响应,既具有同期性,也存在滞后性,滞后期约为1~3个月;但8月NDVI与前期、同期气温及积温均为负相关,且大多数为显著负相关;太白红杉区年最大NDVI与前期不同时段气温均呈负相关,表明气温升高在一定程度上不利于太白红杉年最大NDVI的增长;年最大NDVI与前一年8月至当年7月平均气温相关性分析中,负相关像元数远高于正相关像元数,且当前一年8月至当年7月年均温在-0.4~0.8℃范围内,太白红杉年最大NDVI对气温的响应达到最佳状态,当气温低于-0.4℃或高于0.8℃时,负相关比例增多,太白红杉的生长在一定程度上会受到影响。
Alpine timberline is sensitive to climate change and is an ideal place to study climate change. In this paper, Taibai Redwoods, a species of Pinus densiflora in the Qinling Mountains, was studied. Based on the MODIS NDVI dataset and temperature data from 2000 to 2015, the response characteristics of Taibai Sequoia to temperature changes were studied and the response mechanism was revealed. The results showed that the average annual NDVI of Taizai Sequoia was positively correlated with the annual mean temperature, with positively correlated pixels accounting for 96.30%, and the number of significant positive correlation pixels accounting for 31.42%, that is, Sequoia growth; on the monthly scale, monthly average NDVI monthly mean NDVI response to monthly mean temperature is mostly positive, both with the same period, but also lag, lag period of about 1 to 3 months; but in August NDVI was negatively correlated with temperature and accumulated temperature in the previous period and in the same period, and most of them were significantly negatively correlated. The annual maximum NDVI in the Taibai Sequoia area was negatively correlated with the temperature in different periods of the previous period, indicating that the temperature increase is not conducive to Taibaihong In the analysis of the correlation between the maximum annual NDVI and the average temperature in August from the previous year to July, the number of negative correlation pixels is much higher than that of positive correlation pixels, and the current year from August to the current year The monthly mean annual temperature was in the range of -0.4 ~ 0.8 ℃. The maximum NDVI response to air temperature reached its optimum. When the air temperature was lower than -0.4 ℃ or higher than 0.8 ℃, the negative correlation increased, To some extent, the growth will be affected.