Vegetation Response to Recent Trends in Climate and Landuse Dynamics in a Typical Humid and Dry Tropical Region under Global Change

Kayode Adepoju,Samuel Adelabu,Olutoyin Fashae

doi:10.1155/2019/4946127

Kayode Adepoju, Samuel Adelabu + Show 1 more

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https://doi.org/10.1155/2019/4946127

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Abstract

The influence of global change on vegetation cover and processes has drawn increasing attention in the past few decades. In this study, we used remotely sensed rainfall and land surface temperature to investigate the spatiotemporal pattern and trend in vegetation condition using NDVI as proxy from 2001 to 2017 in a humid and dry tropical region. We also determined the partial correlation coefficient of temperature and rainfall with NDVI and the response of NDVI to changes in landcover categories due to human activities. We found that the mean annual maximum NDVI was 0.42, decreasing at a rate of 0.06 per decade. About 27.4% of the area was found to have experienced a significant negative trend in vegetation cover, while only 0.34% exhibited significant increasing vegetation vigour. Land surface temperature increased at a mean rate of 0.75°C/decade, with higher rates in agriculture, savanna, settlements, woodlands, and riparian vegetation than in forest and mangrove vegetations. Precipitation also reduced at a mean rate of 58.69 mm/decade, with higher rates in agriculture savanna and riparian vegetation than in sahelian grasslands, mangrove, forest, and woodlands. NDVI was negatively correlated with temperature in savanna, settlements, degraded forest, and sahelian grasslands providing confirmation of ongoing land degradation. It was concluded that vegetation vigour will continue to decline under rainfall and increasing temperature conditions especially in dryer regions. The use of land surface temperature in this study is particularly valuable in highlighting areas where changes in NDVI occurred as a result of synergistic action between climate and human-induced landcover changes. Our findings underscore the importance of landuse policies that account for spatial variation in synergistic relationships between the nexus of climate and land conversion processes that influence vegetation cover change in different landcover types in tropical regions.

Highlights

Vegetation is considered as an important intermediate link in the earth’s atmosphere and hydrosphere, and its dynamics plays a crucial role in maintaining the functioning of the earth’s diverse ecosystems and their services provision [1, 2]
To show the impact of anthropogenic activities on Normalized Difference Vegetation Index (NDVI), we investigated the dynamics of landuse change from 2001 to 2017 in the study area. e major landuse types in the study area were savanna, agriculture, sahelian grassland, woodland, swamp forest, and degraded forest, which combined to account for 76.44%, 78.23%, and 78.91% of the total area of the region in 2000 and 2017, respectively (Figure 9)
We investigated the potential impacts of anthropogenic landcover change on vegetation change during this period by fitting a stack of remote sensing-based climate and landuse covariates to a regression model using the R software package. e annual maximum NDVI was 0.42, decreasing at a rate of 0.06 per decade

Summary

Introduction

Vegetation is considered as an important intermediate link in the earth’s atmosphere and hydrosphere, and its dynamics plays a crucial role in maintaining the functioning of the earth’s diverse ecosystems and their services provision [1, 2]. A growing number of studies have shown that vegetation growth has been strongly influenced by global change in recent decades [4, 5]. Climate variability and landuse change have been recognized as two important factors influencing vegetation dynamics under global change [4]. While landuse changes are more or less linked to changes in the hydrological processes and biodiversity loss, climate variability, especially precipitation and temperature, is more closely associated with changes in phenology, respiration, and ecological balance [1,2,3,4]. Satellite remote sensing which depends primarily on reflected or emitted electromagnetic signals from specific targets on the earth’s surface has emerged as an important tool for vegetation assessment and monitoring owing to its ability to provide spatially continuous observations and environmental proxies across geographical boundaries and over wide areas [6]

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