Changes Of Woody Plants Phenophase And Its Response Tomicro-Scale Temperature Variation In Central And Eastern Regions Of Hetao Plain

With the acceleration of urbanization in the Hetao plain region of Inner Mongolia, the change of urban plant phenology is more and more obvious in recent years. At present, Few researches were carried out to study the response of plants phenology to micro-scale temperature variation in central and eastern region of Hetao plain. In this study, to understanding the response of plant phenology to micro-scale temperature variation, we set seven fixed observation points in central and eastern regions of Hetao plain, including Chilechuan Park, Inner Mongolia University, Northern Suburb Park, Trees Park and Wusutu Park in Hohhot, Baotou city and Urad Front Banner, and selected Populus bolleana, P. canadensis, P. cathayana, P. simonii, Salix matsudana and S. babylonica as the observation tree species. We carried out phenological observation of each plant and recorded temperature by temperature sensor in real time. Combined with the phenological and meteorological data of Hohhot station at Chinese phenology observation network in the past years, we discussed the effect of micro-scale temperature variation and local temperature change induced by urbanization construction process on plant phenology by statistically analyzing the temperature and plant phenological data, The main conclusions are as follows:1. The temperature data obtained by iButton sensor from seven observation points showed that the variation trend of active accumulated temperature great er than or equalto10? in 2014 was:Baotou (4419?)>Wulashan(3948?)>Su burb Park (3777?)>Chilechuan Park (3620?)>IMU(3585?)>Trees Park (351 8?)>Wusutu Park (3351?). The data of average temperature of July showed that the temperature of the observation points in Baotou and Wulashan was significantly higher than that in Hohhot, and the temperature of the observati on point in the northern suburbs of Hohhot was significantly higher than the other 4points. In winter and early spring between February and March, there was no significant difference in monthly mean temperature among each observ ation point. The annual temperatur variation in the northern suburbs of Hohh ot is larger than other observation points with a lower winter temperature and a higher temperature in summer2. The phenological period of Salix plant S. matsudana and S. babylonica showed better consistency with that of Populus plant P. bolleana, P. Canadensis and P. simonii. There was significant correlation between phenological period of different plant species according correlation analysis of historical observation data with good continuity for the fixed observation plants with the same phonological period, such as between S. matsudana and S. babylonica (r=0.989, p=0.000), P. bolleana and P. canadensis (r=0.997,p=0.000), P. canadensis and P. simonii (r=0.996,p=0.000), P. simonii and P. bolleana (r=0.994,p=0.000). Meanwhile, the phenology of the plants do not exist significant differences (p<0.05).3. Differences in the phenological period of woody plants in small scale range reflected the response of phenology to urban heat island effect. For the spring phenology of bud opening period of each observation point in Hohhot City, the observation plants in Northern Suburb Park was significantly later than those in IMU, Chilechuan and Wusutu Park (p<0.05). However, for the autumn phenology of leaf falling period, the plants in Wusutu and Tree Park were significantly sooner than those in Northern Suburb Park, IMU and Chilechuan Park.4. The temperature showed a more significant effect on the phenological period in the spring and autumn season of the same year, and had a disparate influential process to each phonological period of different plants. There was a significant negative correlation between the spring phenology and the temperature in the previous period, and it indicated that the higher the temperature was, the earlier the phonological features appeared. The bud opening period of populous plants was significantly negatively correlated with previous monthly mean temperature of December and January. The initial flowering period of populus plants showed significantly negative correlation with the lowest daily mean temperature in winter and the monthly mean temperature from November to early March. The leaf expansion period of populous plants was significantly negatively correlated with the previous average temperature from November to March and the lowest daily mean temperature in winter. For the Salix plants, only the leaf expansion period was significantly negatively correlated with the previous monthly average temperature from November to late February. There was a significant positive correlation between the autumn phenology and autumn monthly average temperature, which indicated that a higher temperature was, the later the phonological features appeared. For example, the leaf falling period of the Salix plants was significantly positively correlated with the average temperature of late September and of late October of the first year to late February, indicating that the autumn temperature in last year also had certain effect on autumn phenological period in next year.