Combined effects of tree plantation expansion and climate change on the hydro-sedimentary functioning of tropical mountain watersheds: aquatic microbial diversity as a proxy land use transition – TecItEasy
Rapid expansion of tree plantations worldwide simplifies landscape mosaics and is suspected to accelerate land degradation (soil and water resources, erosion of microbial functional diversity). In many tropical catchments, the combined effects of economic, demographic and climate pressures are expected to exacerbate the undesirable externalities of this unrestricted land use conversion.
TecItEasy is a 3-year exploratory project whose originality relies on (i) simultaneously collecting data on the interdependent fluxes of water sediment and bacteria, in an observatory for environmental research (SOERE-RBV, EQUIPEX-CRITEX) located in tropical montane Laos, (ii) incrementally analysing and integrating these data through mapping and modelling, and (iii) translating findings into practical guidelines delivered as a management toolbox for practitioners. The project aims to clarify 1) the hydro-sedimentary response of a watershed whose agro-ecosystem is converted to perennial tree plantations, 2) what type of landscape mosaics should be implemented on hillslopes and along waterways, to ensure that sustainability and productivity are optimized and 3) whether a typology of aquatic bacterial assemblages could serve as a proxy of the state of agro-ecosystems and their dynamics.
To tackle this scientific challenge, we formed an inter-disciplinary consortium involving recognized specialists of agronomy, soil science, hydrology, microbiology, and biogeochemistry, from four French and one Laotian partner laboratories: GET (Géosciences Environnement Toulouse); BIOEMCO (Biogéochimie et écologie des milieux continentaux); LEM (Laboratoire d’Ecologie Microbienne) and LSCE (Laboratoire des Sciences du Climat et de l'Environnement); the ALUPC (Agriculture Land Use Planning Center) placed under the authority of the Laotian Ministry of Agriculture and Forestry.
TecItEasy is divided into three research tasks: 1) Integrated analysis of existing hydro-sedimentary and land use datasets (collected by the MSEC catchment long term observatory since 1998); 2) Inter-disciplinary fieldwork on hydro-sedimentary fluxes and associated microbial diversity; 3) Physically-based modelling (i.e. KINEROS2, WEPP and OpenFOAM) and scenario testing of global change and landscape mosaics. Novel tracer-based tools (i.e. radionuclides, stable isotopes, genetic markers…) will be used to study the spatial origin and residence times of water and particle-borne transfers along a network of nested catchments. A specific task is devoted to the project management and results dissemination. ALUPC will liaise with relevant stakeholders at the local (farmers, head of village), regional (provincial and district offices of agriculture and forestry) and national (ministry of agriculture and forestry) levels, to accompany the forest transition.
The main expected outcomes of the project are twofold. First, TecItEasy will generate new integrated knowledge that will improve our understanding of the determinants and processes responsible for the hydro-sedimentary behaviour at the medium catchment scale (~0.1-10 km2), and the variability of aquatic bacteria along the stream reaches of riparian buffers and bacteria detached from the soil surface and transported in overland flow waters. In addition, TecItEasy will endeavour to establish a typology of aquatic bacterial assemblages to be used as a proxy of the “health” of agro-ecosystems, so as to define practical guidelines for the sustainable management and integrated development of montane landscapes (i.e. choice of crops and practices, and functionally optimized landscape mosaics). These guidelines will aim specifically at limiting soil erosion and nutrient losses along agricultural hillslopes, conserving the filtering functions of riparian zones hence mitigating the contamination of stream water and production systems, and maintaining the functional diversity of aquatic bacterial communities along stream paths.
Monsieur Olivier Ribolzi (Géosciences environnement Toulouse - IRD)
The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.
IRD-UMR 234 GET Géosciences environnement Toulouse - IRD
IRD- UMR 211 BIOEMCO Biogéochimie et écologie des milieux continentaux - IRD
UMR 5557 LEM - CNRS DR7 Laboratoire d'Ecologie Microbienne
Help of the ANR 298,505 euros
Beginning and duration of the scientific project: February 2014 - 36 Months