Journal
NATURE
Volume 587, Issue 7832, Pages 78-+Publisher
NATURE PORTFOLIO
DOI: 10.1038/s41586-020-2824-5
Keywords
-
Categories
Funding
- National Science Foundation [OCI-0725070, ACI1238993]
- State of Illinois
- AXA post-doctoral research grant
- DFF Sapere Aude grant [9064-00049B]
- Lichtenberg Professorship of the Volkswagen Foundation
- ANR [ANR-10-LABX-25-01, TULIP: ANR-10-LABX-0041]
- Villum Foundation through the project 'Deep Learning and Remote Sensing for Unlocking Global Ecosystem Resource Dynamics' (DeReEco)
- European Research Council (ERC) under the European Union [853222 FORESTDIET]
Ask authors/readers for more resources
A large proportion of dryland trees and shrubs (hereafter referred to collectively as trees) grow in isolation, without canopy closure. These non-forest trees have a crucial role in biodiversity, and provide ecosystem services such as carbon storage, food resources and shelter for humans and animals(1,2). However, most public interest relating to trees is devoted to forests, and trees outside of forests are not well-documented(3). Here we map the crown size of each tree more than 3 m(2) in size over a land area that spans 1.3 million km(2) in the West African Sahara, Sahel and sub-humid zone, using submetre-resolution satellite imagery and deep learning(4). We detected over 1.8 billion individual trees (13.4 trees per hectare), with a median crown size of 12 m(2), along a rainfall gradient from 0 to 1,000 mm per year. The canopy cover increases from 0.1% (0.7 trees per hectare) in hyper-arid areas, through 1.6% (9.9 trees per hectare) in arid and 5.6% (30.1 trees per hectare) in semi-arid zones, to 13.3% (47 trees per hectare) in sub-humid areas. Although the overall canopy cover is low, the relatively high density of isolated trees challenges prevailing narratives about dryland desertification(5-7), and even the desert shows a surprisingly high tree density. Our assessment suggests a way to monitor trees outside of forests globally, and to explore their role in mitigating degradation, climate change and poverty.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available