Changes in the Tree-Ring Width-Derived Cumulative Normalized Difference Vegetation Index over Northeast China during 1825 to 2013 CE

Ruoshi Liu,Qiufang Cai,Meng Ren,Changfeng Sun,Xuxiang Li,Yu Liu,Huiming Song,Qiang Li,Lu Wang,Yi Song

doi:10.3390/f12020241

Abstract

Vegetation coverage is very important in terrestrial ecosystems and climate systems. However, the observational record of the normalized difference vegetation index (NDVI), which started in the 1980s when satellites became widely used, is too short to investigate the history of variation in vegetation coverage beyond the modern observation period. Here, we present a 189 y vegetation coverage series based on a total of 349 Mongolian pine (Pinus sylvestris var. mongolica Litv) cores from seven locations from the central–western Da Hinggan Mountains (CW–DHM), northeastern China. We found a significant relationship between tree-ring width and the regional cumulative normalized difference vegetation index (CNDVI). The correlation between the ring-width chronology and the regional June–July CNDVI (CNDVIJJ) was significant, with r = 0.68 (n = 32, p < 0.001) and an explained variance of 45.8% (44.0% after the adjustment for the loss of the degree of freedom). On this basis, we designed a transfer function to reconstruct the CNDVIJJ for the CW–DHM region from 1825 to 2013 CE (Common Era). During the last 189 years, there were 28 years with high CNDVIJJ values, and another 28 years with low values. We also observed CNDVIJJ fluctuations at the inter-annual and decadal time scales, including eight low value periods and nine high value periods. Based on our analysis, the variation in CNDVI is associated with climatic factors, such as temperature, precipitation and the Palmer Drought Severity Index (PDSI), which combines both temperature and precipitation. From 1950 to 2002 CE, the CNDVI showed a noticeable decreasing trend in the CW–DHM region, whereas after 2003 CE, the CNDVI exhibited an apparent increase, which has also been observed in southern Central Siberia, eastern Mongolia and northeastern and eastern China, indicating that the CNDVI change in the CW–DHM is related to climate change in the local region and in some parts of Asia.

Highlights

Vegetation is of great significance worldwide and is a major factor in the exchange of substances and energy among the hydrosphere, atmosphere, pedosphere, and biosphere on the Earth’s surface [1,2]
Since the cumulative normalized difference vegetation index (CNDVI) variation is tightly associated with climate factors, such as the moisture and temperature conditions [34], we investigated the changing trends of various climatic factors in the central–western Da Hinggan Mountains (CW–DHM) region during the periods 1951–1999 CE and 2000–2013
We obtained a CNDVI sequence using 32 y normalized difference vegetation index (NDVI) data recorded by existing satellite observations, combined with tree-ring width data from the CW–DHM

Summary

Introduction

Vegetation is of great significance worldwide and is a major factor in the exchange of substances and energy among the hydrosphere, atmosphere, pedosphere, and biosphere on the Earth’s surface [1,2]. Since the 1980s, with the rapid development of satellite remote sensing technology, remote sensing images and data have been used to estimate vegetation parameters, such as vegetation coverage and biomass [3] and to further explore the relationships between this variation and changes in the climate and environment to assess the response and feedback of vegetation change to climate variation. In the study of surface vegetation, the normalized difference vegetation index (NDVI). Is considered to be the most effective indicator of terrestrial vegetation coverage and growth conditions. The most significant problem at present is that the observational dataset of the NDVI is too short Finding a reliable paleo-vegetation variation proxy in the past has become a priority for terrestrial ecological system research

Methods

Results

Discussion

Conclusion