Global Distribution and Local Variation of Pre-Rain Green-Up in Tropical Dryland

Pre-rain green-up is a distinctive phenological phenomenon observed in arid and semi-arid regions, featuring the sprouting of plants before the onset of the rainy season. This phenomenon indicates the intricate controls of vegetation phenology other than precipitation, yet its global distribution pa...

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Main Authors: Shuyi Huang, Yirong Sang, Zhanzhang Cai, Feng Tian
Format: Article
Language:English
Published: MDPI AG 2025-04-01
Series:Remote Sensing
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Online Access:https://www.mdpi.com/2072-4292/17/8/1377
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author Shuyi Huang
Yirong Sang
Zhanzhang Cai
Feng Tian
author_facet Shuyi Huang
Yirong Sang
Zhanzhang Cai
Feng Tian
author_sort Shuyi Huang
collection DOAJ
description Pre-rain green-up is a distinctive phenological phenomenon observed in arid and semi-arid regions, featuring the sprouting of plants before the onset of the rainy season. This phenomenon indicates the intricate controls of vegetation phenology other than precipitation, yet its global distribution patterns and underlying causes remain unclear. In this study, we used remotely sensed phenology and rainfall data to map the global distribution of pre-rain green-up vegetation for the first time in arid and semi-arid savanna areas. The results revealed that over one-third of pre-rain green-up vegetation is in mountainous regions. Furthermore, to explore the potential effect of groundwater accessibility on pre-rain green-up, we employed high-resolution imagery to quantify phenological parameters and analyzed the relationship between pre-rain green-up and elevation at the watershed scale in a typical mountainous pre-rain green-up region in Africa. We found that within the pre-rain green-up area, 60.64% of sub-watersheds show a significant negative correlation (<i>p</i> < 0.05) between the start of the season (SOS) and elevation, indicating that the SOS occurs earlier at higher elevations despite the complex spatial variability overall. Our study provides a global picture of the pre-rain green-up phenomenon in tropical drylands and suggests that tree internal water regulation mechanisms rather than groundwater accessibility control the pre-rain green-up.
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spelling doaj-art-62cbf3f2ef994c2cb753e591b28f27f92025-08-20T02:18:04ZengMDPI AGRemote Sensing2072-42922025-04-01178137710.3390/rs17081377Global Distribution and Local Variation of Pre-Rain Green-Up in Tropical DrylandShuyi Huang0Yirong Sang1Zhanzhang Cai2Feng Tian3Hubei Key Laboratory of Quantitative Remote Sensing of Land and Atmosphere, School of Remote Sensing and Information Engineering, Wuhan University, Wuhan 430072, ChinaHubei Key Laboratory of Quantitative Remote Sensing of Land and Atmosphere, School of Remote Sensing and Information Engineering, Wuhan University, Wuhan 430072, ChinaDepartment of Physical Geography and Ecosystem Science, Lund University, 22100 Lund, SwedenHubei Key Laboratory of Quantitative Remote Sensing of Land and Atmosphere, School of Remote Sensing and Information Engineering, Wuhan University, Wuhan 430072, ChinaPre-rain green-up is a distinctive phenological phenomenon observed in arid and semi-arid regions, featuring the sprouting of plants before the onset of the rainy season. This phenomenon indicates the intricate controls of vegetation phenology other than precipitation, yet its global distribution patterns and underlying causes remain unclear. In this study, we used remotely sensed phenology and rainfall data to map the global distribution of pre-rain green-up vegetation for the first time in arid and semi-arid savanna areas. The results revealed that over one-third of pre-rain green-up vegetation is in mountainous regions. Furthermore, to explore the potential effect of groundwater accessibility on pre-rain green-up, we employed high-resolution imagery to quantify phenological parameters and analyzed the relationship between pre-rain green-up and elevation at the watershed scale in a typical mountainous pre-rain green-up region in Africa. We found that within the pre-rain green-up area, 60.64% of sub-watersheds show a significant negative correlation (<i>p</i> < 0.05) between the start of the season (SOS) and elevation, indicating that the SOS occurs earlier at higher elevations despite the complex spatial variability overall. Our study provides a global picture of the pre-rain green-up phenomenon in tropical drylands and suggests that tree internal water regulation mechanisms rather than groundwater accessibility control the pre-rain green-up.https://www.mdpi.com/2072-4292/17/8/1377savannasspring phenologyrainy seasonelevation gradientSentinel-2MODIS
spellingShingle Shuyi Huang
Yirong Sang
Zhanzhang Cai
Feng Tian
Global Distribution and Local Variation of Pre-Rain Green-Up in Tropical Dryland
Remote Sensing
savannas
spring phenology
rainy season
elevation gradient
Sentinel-2
MODIS
title Global Distribution and Local Variation of Pre-Rain Green-Up in Tropical Dryland
title_full Global Distribution and Local Variation of Pre-Rain Green-Up in Tropical Dryland
title_fullStr Global Distribution and Local Variation of Pre-Rain Green-Up in Tropical Dryland
title_full_unstemmed Global Distribution and Local Variation of Pre-Rain Green-Up in Tropical Dryland
title_short Global Distribution and Local Variation of Pre-Rain Green-Up in Tropical Dryland
title_sort global distribution and local variation of pre rain green up in tropical dryland
topic savannas
spring phenology
rainy season
elevation gradient
Sentinel-2
MODIS
url https://www.mdpi.com/2072-4292/17/8/1377
work_keys_str_mv AT shuyihuang globaldistributionandlocalvariationofpreraingreenupintropicaldryland
AT yirongsang globaldistributionandlocalvariationofpreraingreenupintropicaldryland
AT zhanzhangcai globaldistributionandlocalvariationofpreraingreenupintropicaldryland
AT fengtian globaldistributionandlocalvariationofpreraingreenupintropicaldryland