Dendrochronology-Based Normalized Difference Vegetation Index Reconstruction in the Qinling Mountains, North-Central China

Jin Qin,Xiaoyue Huang,Yuanlin Xiang,Hongying Bai,Shu Fang,Pei Zhao

doi:10.3390/f13030443

Jin Qin, Xiaoyue Huang + Show 4 more

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https://doi.org/10.3390/f13030443

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Abstract

Larix chinensis Beissn., as a native, dominant and climate-sensitive coniferous species at Mount Taibai timberline, Qinling mountains, is rarely disturbed by anthropogenic activities; thus, it is an ideal proxy for the investigation of climate change or vegetation evolution. In this study, we applied dendrochronological methods to the L. chinensis tree-ring series from Mt. Taibai and investigated the relationships between tree-ring widths and NDVI/climate factors using Pearson correlation analysis. On the basis of the remarkable positive correlations (r = 0.726, p < 0.01, n = 23) between local July normalized difference vegetation indices (NDVI) and tree-ring width indices, the regional 146-year annual maximum vegetation density was reconstructed using a regression model. The reconstructed NDVI series tracked the observed data well, as the trans-function accounted for 52.8% of observed NDVI variance during AD 1991–2013. After applying an 11-year moving average, five dense vegetation coverage periods and six sparse vegetation coverage periods were clearly presented. At a decadal scale, this reconstruction was reasonably and negatively correlated with a nearby historical-record-based dryness/wetness index (DWI), precisely verifying that local vegetation cover was principally controlled by hydrothermal variations. Spectral analysis unveiled the existence of 2–3-year, 2–4-year, 5–7-year and 7–11-year cycles, which may potentially reflect the connection between local NDVI evolution and larger-scale circulations, such as the El Niño–Southern Oscillation (ENSO) and solar activity. This study is of great significance for providing a long-term perspective on the dynamics of vegetation cover in the Qinling mountains, and could help to guide expectations of future forest variations.

Highlights

Terrestrial ecosystems have undergone significant changes with the intensification of global warming; the response of terrestrial ecosystems to global climate change has become one of the major concerns of various scientific communities [1]
We examined the coherence of the reconstructed normalized difference vegetation index (NDVI) series with the adjacent (Baoji city (Figure 1)) dryness/wetness index (DWI); this was based on historical documents and used to assess the humid conditions of a specific region, as well as the conditions of flood, water logging, normal, dry and severely dry as degrees of 1, 2, 3, 4 and 5, respectively [29]
To verify the reconstructed annual maximum NDVI, we investigated the consistency between the reconstructed seriesperiods and environmental in with northern by comparing the dense and sparse discovered inevolution this study threeChina, NDVI

Summary

Introduction

Terrestrial ecosystems have undergone significant changes with the intensification of global warming; the response of terrestrial ecosystems to global climate change has become one of the major concerns of various scientific communities [1]. As an essential component of terrestrial ecosystems, vegetation sensitively responds to climate change, but is a comprehensive indicator for monitoring land-surface ecosystems and environments [2]. With the development of remote sensing in the past decades, there has been significant growth in research involving the monitoring of vegetation coverage variation and land-cover change [3,4]. In China, NDVI was used to detect phenological changes, classify largescale vegetation and estimate vegetation biomass in response to climate change and its feedback [8]. Further understanding historical vegetation dynamics is critical for local environmental management

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