The Guiana Shield rainforests—overlooked guardians of South American climate

Abstract

Tropical forests are global climate regulators through their interaction with hydrological and biogeochemical cycles. Despite extensive research on deforestation in South America and its global impact, the role of the largely intact Guiana Shield forests, north of the Amazon, has not yet been considered as part of this climate system. We use a regional climate model with a realistic deforestation scenario to test the impact of deforestation in the Guiana Shield on climate throughout South America. We show that replacing ∼28% of the current Guiana Shield rainforest with savannah leads to multi-scale impacts across South America, through vegetation-land-atmosphere interactions that disrupt the initial phase of two major 'atmospheric rivers': the Caribbean low-level Jet and the South American low-level jet (SALLJ). Our climate simulations suggest that following deforestation, locally, precipitation and runoff would more than double in lowland forests, whilst mean annual temperatures would increase by up to 2.2• C in savannahs. Regionally, significant wetting is simulated in northern South America (April−September) and the western Amazon (October-March), while temperatures increase up to 2• C in central and eastern Amazon, causing more dry months in up to 64% of the Amazon basin. Reduction of moisture transfer by the SALLJ of 2.2% of total annual flow causes noticeable and highly diverse spatial changes in simulated monthly rainfall in la plata basin (LPB). These results highlight the potential consequences of land cover change in a sensitive hot-spot with hydro-climatic impacts 1000 km west and 4000 km south. Such multi-scale perturbations can severely impact biodiversity and ecosystem services across South America, including agriculture in LPB. Recognition of the far field effects of localised deforestation in key areas is urgently needed to improve development plans for a sustainable future. Significance statementThe Guiana Shield, at the northern boundary of Amazonia, is located at the start of two atmospheric rivers which carry moisture across South America. We show that deforesting less than a third of the Guiana Shield, in areas currently under threat from mining, logging and agricultural activities, could result in significant changes in the water cycle across the continent. This includes large variations in temperature and precipitation affecting areas 4000 km away, impacting ecosystems and economies, with consequences for society. The study demonstrates how land-use change, even if small in spatial scale, but occurring in particularly sensitive hot-spots, can alter the flow of atmospheric rivers, with large consequences. This pan-continental cascade must be considered when designing trans-national management plans for a sustainable future.

How REDD+ governs: Multiple forest environmentalities in Guyana and Suriname

“…Few scholars have examined how REDD+ operates in the Guiana Shield, representing a significant absence given that these forests are central to maintaining the biodiversity and ecosystem functions of the wider Amazon ecosystem (Bovolo et al., 2018). In attempting to remedy this absence, I analyse REDD+ through a multi-sited ethnography (Marcus, 1995) of REDD+ in Guyana and Suriname conducted from January 2014 to January 2015, including an analysis of over 80 development and policy documents, four week-long field visits, two internships with REDD+ related international governmental organizations and approximately 60 in-depth interviews with actors identified as related to REDD+ identified in the national REDD+ Readiness Preparation Proposals.…”

Effect of CO2 increase on ecological parameters of plant ecosystems of Central and South America countries

“…Also, it supports the payments to rainforest countries like Guyana for its storage of forest carbon under the REDD + mechanism (Reduce Emissions from Deforestation and Degradation). As a conceptual basis of the applied methods in the framework of REDD, it can be designate the theory of "forest transition", which implies a transition from reducing forests to increasing forest cover, which means an increase in the area of natural absorbers of greenhouse gases, and thus the prevention of emissions [24]. For Suriname, Brazil and Guyana there is a decrease in humus between 2000 and 2020.…”

Importance of succession in estimating biomass loss: Combining remote sensing and individual-based forest models

“…The resulting map of biomass mortality rates indicates that more biomass is dying in the central, southern and eastern regions than in the northern parts of French Guiana. The forest areas in the north and north-east are more used for timber production, agricultural activities and housing (Bovolo et al, 2018;Stach et al, 2009), whereas the forest areas in the south are predominantly natural rainforests (Hammond, 2005).…”