Mapping Mountain Peatlands and Wet Meadows Using Multi-Date, Multi-Sensor Remote Sensing in the Cordillera Blanca, Peru

Abstract

Wetlands (called bofedales in the Andes of Peru) are abundant and important components of many mountain ecosystems across the globe. They provide many benefits including water storage, high quality habitat, pasture, nutrient sinks and transformations, and carbon storage. The remote and rugged setting of mountain wetlands creates challenges for mapping, typically leading to misclassification and underestimates of wetland extent. We used multi-date, multi-sensor radar and optical imagery (Landsat TM/ PALSAR/RADARSAT-1/SRTM DEM-TPI) combined with ground truthing for mapping wetlands in Huascarán National Park, Peru. We mapped bofedales into major wetland types: 1) cushion plant peatlands, 2) cushion plant wet meadows, and 3) graminoid wet meadows with an overall accuracy of 92%. A fourth wetland type was found (graminoid peatlands) but was too rare to map accurately, thus it was combined with cushion peatland to form a single peatland class. Total wetland area mapped in the National Park is 38,444 ha, which is 11% of the park area. Peatlands were the most abundant wetland type occupying 6.3% of the park, followed by graminoid wet meadows (3.5%) and cushion wet meadows (1.3%). These maps will serve as the foundation for improved management, including restoration, and estimates of landscape carbon stocks.

What do we know about Peruvian peatlands?

“…Over three quarters of the Amazon peatlands are found in the North, in the department of Loreto (Gumbricht et al 2017). In the Andes, most of the peatlands are located at over 3,800 m (Chimner et al 2019).…”

“…In the mountains, peatlands are characterized by the dominance of vascular cushion plants like Distichia spp., graminoids like Cortadeira spp. (Chimner et al 2019), and sedges and mosses like Sphagnum spp. (Cooper et al 2010;Benavides and Vitt 2014).…”

“…It is estimated that, in Peru, 60% of Amazon peatlands are minerotrophic (Lähteenoja and Page 2011); Andean peatland data are insufficient to provide an estimation. The vast majority of peatlands studied in the puna and jalca highland marshes are minerotrophic (Cooper et al 2010;Chimner et al 2019); and although bofedal peatlands are commonly called ombrotrophic bogs, their hydrological characteristics suggest that they too are minerotrophic (Cooper et al 2010;Chimner et al 2019).…”

“…In the Andes, mining activity and highways and dams construction alter the hydrology and/or pollute soils and water with sediment and toxic substances (Maldonado Fonkén 2014 (Planas et al 2020). The absence of peatlands demarcation and zoning in bofedales hampers efforts to improve their management and redirect grazing towards areas without peat (Chimner et al 2019). On the other hand, the extraction of peat for its use in agro-export crops and horticulture, carried out by people outside the communities, has increased alarmingly in recent years (Machuca 2018;Ziegler 2020), affecting the livestock production system and contributing to the rapid depletion and irreparable loss of the resource.…”

“…A relevant first step is for Peru to generate a national map and inventory of its peatlands, to clarify their exact location and quantify both their size and their C stocks, which are currently being estimated by specific studies. Research gaps on Peruvian peatlands remain important despite significant progress in recent years (Draper et al 2014;Hergoualc´h et al 2017;Falen and Honorio 2018;Bhomia et al 2019;Chimner et al 2019;Freitas et al 2019;Schulz et al 2019;van Lent et al 2019;Griffis et al 2020). Table 3 presents the areas of research that are needed to improve knowledge essential for the protection and sustainable management of Peru's peatlands.…”