The northeast region of Brazil is relatively dry compared to the rest of the country, with unusually irregular rainfall patterns and associated frequent droughts. The soils there tend to be relatively fertile and so, despite crop failures sometimes occurring in drier years, the area is reasonably densely populated with about 15% of Brazil's population living there; but under what are generally impoverished conditions.
This has led to extreme land-use pressures on the natural vegetation and widespread degradation of remaining lands. As in other parts of the world with similar soils and climate, the natural vegetation of the area is a form of deciduous scrub, known locally as Caatinga. Probably because Caatinga typically lacks the complexity and grandeur of moist tropical forests, this vegetation type has been to a large extent neglected to date both in terms of conservation programmes and scientific enquiry.
This neglect has serious consequences given the enormous destruction of the Caatinga, which exceeds that of the neighbouring biomes of Amazonia and the Cerrado. Because of their potential importance in future warmer and drier climates in Brazil, conservation of the plant species of the Caatinga, which are adapted to high temperatures and seasonally erratic rainfall, is vital.
Designed as an integrated research program involving both Brazilian and UK researchers 'Nordeste' will attempt to redress this neglect:
- Through the establishment of a permanent plot network similar to that existing in moist tropical forests, allowing measurements of Caatinga canopy structure and dynamics and both their short- and long-term responses to climate change to be evaluated for the first time.
- With the aid of new DNA barcoding measurements designed to better quantify the biodiversity of the region.
- Through a comprehensive analysis of the biogeochemistry of natural and disturbed ecosystems to develop an understanding of how nutrient cycling processes vary in response to variations in soils and climate and human activity.
- Via a series of detailed structural, physiological measurements across the wide range of different Caatinga sub-types found in the region. These will be made both above- and below-ground and in natural and degraded ecosystems of the region. A special emphasis will be placed on measurements designed to help us understand why it is that under certain circumstances it is that very high biomass stands of Caatinga occur despite the very low rainfall.
- Glasshouse experiments comparing water stress responses of seedlings native to moist forest, savanna and caatinga will also be undertaken in order to try and understand what specific metabolic adaptions are involved in plant adaptions to frequent and/or erratic conditions of extreme soil water deficit.
- Via an integrated modelling program to provide new parameterisations of surface fluxes for semi-aid ecosystems in general and to provide new insights into variations in woody plant shoot: root allocation patterns in response to variation in precipitation regime.
To achieve these aims, the project has been designed as a series of six inter-related field-based work packages, with a seventh work package focussed on modelling of species distributions, ecosystem fluxes and developing a mechanistic understanding of caatinga vegetation functional responses to both variations in climate and soil properties.
Designed with a view to also producing a series of well-defined products to assist both policy makers and local communities to better manage this unique resource - for example, online guides to ecologically dominant and economically useful plants, the study will serve to provide a valuable first step towards a better understanding of Caatinga vegetation and its responses to anthropogenic and land-use change pressures.
Most conservation and science projects in the tropics focus on the rain forest biome, neglecting the fact that 50% of the lowland tropics is covered by dry biomes such as dry forests or savannas. These dry areas are home to 30% of the global population, and are hence massively impacted by human activity.
This project focuses on the dry forests of the Caatinga region of North East Brazil, which have suffered from scientific neglect, destruction, and lack of conservation attention, with only <1% of these forests included in Brazil's National Protected Area Network. Despite this, the dry forests of the Caatinga house a high level of unique (endemic) plant species that are adapted to the region's severe and erratic droughts.
These plants will be a valuable resource as climates change especially for the 15% of Brazil's population that lives in the Caatinga region who depend on these woodlands for ecosystem services and more specific needs such as firewood. Our project will increase our understanding on how dry biomes contribute to global biogeochemical cycles and how their unique species react to environmental changes, expanding ecological and biodiversity monitoring in Brazil beyond Amazonia and into the Caatinga.
The project will build a platform from which Brazil, and Latin America more generally, can monitor more effectively biodiversity and ecosystem services in dry biomes. We aim to develop whole-system knowledge for the Caatinga to inform responsible management of this unique environment at national and regional political level in Brazil. Brazil has an obligation to monitor its biodiversity and carbon stocks under the Convention on Biological Diversity and the Aichi 2020 Biodiversity Targets, but most previous work has been focused on Amazonia.
In particular, this project is relevant to achieving Strategic Goal 3 ('...safeguarding ecosystems, species and genetic diversity through direct interventions such as increasing the coverage, effectiveness and representativeness of protected areas and other area-based conservation measures...') and Strategic Goal 4 ('...safeguarding and enhancement of the benefits of biodiversity and ecosystem services to human societies') of the Aichi targets.
Our project will provide impetus and build capacity for conservation action in the Caatinga. We aim to build bridges between scientists and policy makers who can influence their protection and sustainable management at federal and state level via two policy meetings in Brasilia and Salvador.
We will also build environmental science capacity in Brazil for undergraduate and postgraduate students in cutting edge methodologies in biodiversity and ecological science, and involve local communities in the collection of our biodiversity and ecological data. Our project will therefore build long-term capacity to monitor species composition, carbon stock, biogeochemical cycles, vegetation dynamics, and biodiversity loss in the Caatinga.
The project will also benefit local people in NE Brazil through delivery of user-friendly information about plant species useful for ecological restoration, crop wild relatives, minor crops, and useful plants. In the long-term, our science will provide information essentially to successful restoration of Caatinga, for example by a better understanding of the genetic diversity of its plants.
Such restoration could have major regional and global ecological effects - for example it has been estimated that large scale dry forest restoration in Latin America could generate up to 8Pg of carbon storage. In the long-term, the knowledge of biome-level ecological processes gained during the project will enable the sustainable management of ecosystem services that underlie human wellbeing in Brazil and more widely.