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Drylands occupy over 40% of the Earth’s land surface but there are many challenges to organisms colonizing these environments, such as aridity and extreme weather conditions. Despite these challenges, drylands support a high level of biodiversity that has developed many different adaptations for survival in harsh environments. This biodiversity also has a major role in many biogeochemical cycles, which together with their wide geographical extent makes drylands a key part of the biosphere. However, the expansion of agriculture and other human activities are having a large impact on fragile dryland ecosystems, altering their functioning and jeopardizing the delivery of the many ecosystem services they provide.
This Collection compiles research devoted to understanding the ecological and evolutionary patterns and processes of dryland biodiversity. Such research ranges from the description of genetic and phylogenetic diversity or the use of new methods and remote sensing for biodiversity monitoring, to the development of a more functional understanding of the ecological dynamics and resilience of these ecosystems, including the role of keystone species and the relationships between biodiversity, ecosystem functioning and ecosystem services. The Collection also focuses on the new challenges that global change is imposing on these ecosystems, including the impacts of climate change, extreme events, land degradation and desertification. The development of specific conservation strategies for threatened dryland species, the incorporation of plant-soil feedbacks in dryland biodiversity conservation and the restoration or sustainable management of dryland biodiversity are also crucial for dryland research.
This Collection supports and amplifies research directly related to SDG 15, SDG 13, and with significant impacts on SDG 2 and SDG 6.
Large-scale and abrupt forest decline occurred in Central Chile in response to acute drought. The extreme conditions, unprecedented in the recent history of all Mediterranean-type ecosystems, are akin to those projected for the second half of the century.
A database and viewer is described, resulting from the assessment of the carbon stock of over 9 billion individual trees in semi-arid sub-Saharan Africa using field data, machine learning, satellite data and high-performance computing.
Changes in vegetation responses to precipitation may be hydroclimate dependent. Here the authors reveal contrasting trends of vegetation sensitivity to precipitation in drylands vs. wetter ecosystems over the last 4 decades and identify increased CO2 as a major contributing factor.
In drylands, there are unique mechanisms that influence multiple ecosystem processes. In this Perspective, the authors identify these dryland mechanisms and show that they could become more important in non-dryland regions or areas that will become drier in the future.
Combining very high-resolution imagery of dryland forests worldwide with climate and aquifer data from the mid-Holocene period, this paper illustrates how geological forces of the past shaped today’s forests.
A cost–benefit analysis of land restoration in the African Great Green Wall shows that, under a range of assumptions, the investment makes economic sense at a regional level, despite the differences across countries and biomes.
Global drylands are threatened by a combination of anthropogenic climate change and human activities, putting some locations at high risk of desertification. This Review details changes observed in the drylands of China, and the mitigating impact of large-scale restoration and conservation programmes designed to reverse them.
Estimates of global dryland changes are often conflicting. This Review discusses and quantifies observed and projected aridity changes, revealing divergent responses between atmospheric and ecohydrological metrics that can be explained by plant physiological responses to elevated CO2.
Deep learning was used to map the crown sizes of each tree in the West African Sahara, Sahel and sub-humid zone using submetre-resolution satellite imagery, revealing a relatively high density of trees in arid areas.
Drylands cover nearly half of Earth’s surface, yet how they will fare in light of anthropogenic climate change is debated. Here the authors find that over the past 40 years climate change has pushed ~13% of drylands towards desertification threatening hundreds of millions of people in developing nations.
Earth’s drylands are expected to expand due to climate change, but how this will affect vegetation remains unclear. Here the authors use models to show that despite expansion, primary productivity in drylands is likely to increase through the 21st Century.
Charles Lee, Daniel Laughlin et al. use structural equation modeling to analyze ecological data from more than 500 sites in the Antarctic Dry Valleys. They find that although abiotic factors are the primary drivers of biodiversity variation, biotic interactions are needed to explain the data fully and may play previously underestimated roles.
Low-frequency passive microwave data (L-VOD) allow quantification of biomass change in sub-Saharan Africa between 2010 and 2016, revealing climate-induced carbon losses, particularly in drylands.
By analysing the abundance distributions of two key plant functional traits in global dryland communities, the authors identify a scaling relationship that quantifies how much trait diversity is required to maximize local ecosystem multifunctionality.
Climate change is causing drylands to expand and this work shows that they will cover half of the land surface by 2100 under a moderate emissions scenario.
Soil samples collected from 224 dryland sites around the world show that aridity affects the concentration of organic carbon and total nitrogen differently from the concentration of inorganic phosphorus, suggesting that any predicted increase in aridity with climate change could uncouple the carbon, nitrogen and phosphorus cycles in drylands and negatively affect the services provided by these ecosystems.
For many years, the extreme environment of the Antarctic Dry Valleys was thought to play host to just a few viable microorganisms. However, as Cary and colleagues explain, recent work has led to the identification of a complex community structure that is able to survive in one of the coldest and driest places on Earth.