Abstract
The eastern coastal areas of China span multiple climatic zones, and the impacts of climate warming on their ecological environment show regional differences. This dissertation used the Normalized Difference Vegetation Index(NDVI) as the indicator to characterize the ecological environment, and selected Guangdong, Jiangsu and Liaoning as its typical research areas. In this dissertation, the author selected the NDVI, average temperature and precipitation data of the yearly growth season respectively from 1982 to 2016, and adopted the copula functions model based on Markov Chain Monte Carlo to carry out the research of bivariate joint distribution so as to calculate the joint probability, the joint exceedance probability, the joint return period and the co-occurrence return period. The results showed that: (1) the temperature and precipitation in the three regions were respectively related to the NDVI sequence showing the characteristic that was correlated at the upper tail and asymptotically independent at the lower tail, which demonstrated that the temperature and precipitation had little effect on NDVI when they reached their minimum values, and the temperature and precipitation had obvious effect on NDVI when they reached their maximum values. (2) The shorter the return period was, the wider the ranges of the climate factor and the NDVI were, showing that when the climate factor was constant, the probability of the NDVI having a shorter return period was higher. The greater the climate factor was, the longer the return period was, indicating that the probability of plant growth inhibition was higher when the climate factor exceeded a certain threshold. (3) The suitable temperature and precipitation for vegetation growth in the three regions gradually decreased from south to north. In addition, this research can provide theoretical guidance and scientific foundation for the protection of regional ecological environment and enhance the understanding of the impact of climate change on the ecosystem.
Highlights
As the main body of the terrestrial ecosystem, vegetation is an important part connecting the atmosphere, soil water, and energy cycle (Huryna and Pokorný, 2016; Jin et al, 2017), and has great significance to regional climate regulation, surface energy balance and soil and water conservation, etc. (Li et al, 2016; Duveiller et al, 2018; He et al, 2018)
The mean temperature change rate was the smallest in Guangzhou and the largest in Jiangsu, which may be caused by the fact that climate regulation of sea surface temperature enhanced the stability of a climate system of Guangdong greatly influenced by marine factors
The precipitation in Liaoning Province showed a significant downward trend, which was due to the law that the annual precipitation in Liaoning Province decreases from southeast to northwest at almost equal intervals, and the significant decrease of the precipitation mainly arose from dramatically reduced summer precipitation in southeast and winter precipitation in southern Liaoning
Summary
As the main body of the terrestrial ecosystem, vegetation is an important part connecting the atmosphere, soil water, and energy cycle (Huryna and Pokorný, 2016; Jin et al, 2017), and has great significance to regional climate regulation, surface energy balance and soil and water conservation, etc. (Li et al, 2016; Duveiller et al, 2018; He et al, 2018). (Li et al, 2016; Duveiller et al, 2018; He et al, 2018) Climate resources such as light, heat, and water are the basis of vegetation growth, and a vegetation variation is a key indicator to measure a regional environment and a climate change (Li et al, 2017; Zewdie et al, 2017; Wan et al, 2018). Under the background of climate warming, temperature, precipitation, radiation, and other factors in different regions are obviously different, and the influence of the climate change on the vegetation in different regions varies. The study held that the changes in factors such as temperature, water, and light affect the vegetation by participating in photosynthesis, respiration, and transpiration of the vegetation (Zandalinas et al, 2018; Dusenge et al, 2019). The interaction between the regional climate and the vegetation belongs to a nonlinear category (Wen et al, 2017)
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