Mapping the paramo land-cover in the Northern Andes

2021

Article référencé dans le Web of Science WOS:000697598000001

Peyre G., Osorio D., Francois R., Anthelme Fabien

International Journal of Remote Sensing, 2021, 42 (20), p. 7777-7797 ISSN 0143-1161

The Andean paramo is a biodiverse and vulnerable tropical high-mountain region, whose spatio-ecological patterns remain understudied. The lack of general characterization of its overall extent, land-cover classes, and treeline spatial features hinders our capacity to understand its responses to human impacts and predict future land-system changes. To address this knowledge gap, we classified the land-cover of the paramo in the Northern Andes. Moreover, we estimated (1) the paramo's total extent and its distribution among the Andean countries, (2) the relative extent of 12 of its main land-cover classes, categorized into natural vegetation, natural abiotic and anthropogenic groups, and (3) the preliminary position and anthropogenic influence of its bordering treeline. Relying on Landsat 8 imagery, we performed hybrid manual-automated classifications using the Maximum Likelihood and Random Forest algorithms. The two resulting final classifications were manually checked for errors compared to Google Earth and VegParamo data, and used to produce the expert classification. Finally, we delimited the treeline based on regional forest connectivity, and applied it to the expert classification to evaluate paramo elevations, surface areas and land-cover classes above the Andean treeline. The paramo extent was estimated at 24,301 km(2), distributed between Ecuador (47%), Colombia (43%), Venezuela (8%) and Peru (2%). Natural vegetation, especially shrublands, rosette plant communities and grasslands were dominant (altogether, 65%), whereas classes reflecting intense land-use covered 12% overall. The average treeline reached 3546 m and was bordered uphill at 16% with anthropogenic land-cover classes. The paramo's extent is smaller than previously suggested. It remains a (semi-) natural region, yet the expansion of crops and pastures towards high elevations is a critical concern for long-term sustainability. Future research can build on our findings to predict land-system changes and assess priority areas for conservation. We recommend for future research to focus on remnant forest patches and treeline connectivity in priority.

Etudes, transformation, conservation du milieu naturel [082] ; Télédétection [126]

EQUATEUR ; COLOMBIE ; VENEZUELA ; PEROU ; ANDES

Fonds IRD [F B010083139]

fdi:010083139