New Global Mapping Tool Reports Major Global Watershed Tree Loss

According to Global Forest Watch (GFW) Water, a new global mapping tool and database, the world’s major watersheds lost 6% of their tree cover on average from 2000 to 2014.

GFW Water examines how forest loss, fires, unsustainable land use and other threats to natural infrastructure affect water security throughout the world. GFW Water provides data sets, statistics and risk scores for all of the world’s 230 watersheds.

Findings from GFW Water reveal some of the watersheds most threatened by forest loss, fires and erosions.

The watershed of Sumatra, Indonesia, experienced the most forest loss from 2000 to 2014, losing more than 22% of its forest cover (8 million hectares, or an area about the size of South Carolina). Research shows that the major drivers include: agricultural expansion, logging, and infrastructure extension as a result of expanding global markets for pulp, timber and oil palm. Forest clearing in the region has intensified floods, landslides, fires and water pollution.

Natural infrastructure approaches—like establishing conservation zones, engaging in agroforestry and other sustainable forestry practices, and regulating road development—can mitigate and prevent further damage in watersheds like Sumatra.

According to GFW Water, watersheds lost more than half of their forests prior to 2000. The watershed of Krishna, India, was once covered by forests, but fewer than 3% of these trees remain today as a result of urbanization and cropland expansion. Communities in the area suffer from frequent droughts and floods, as well as high levels of water pollution from agricultural runoff. Sedimentation also is a recurring challenge to reservoirs and dams. Planting new seedlings in deforested areas, enhancing natural forest generation, and integrating trees with crops and ranchlands could help watersheds like Krishna.

The Philippines watershed faces some of the highest erosion rates as a result of highly erodible soil, a long and intense rainy season, mountainous landscapes, and expansive agriculture. The region frequently suffers from landslides. In 2006, following days of heavy rain, a massive mudslide occurred in the province of Southern Leyte, causing widespread damage and loss of life.

Planting or maintaining vegetation along roads and waterways to capture sediments and pollutants; creating barriers on steep slopes to slow soil movement; and reducing the amount of pesticides, fertilizers, animal waste and other agricultural products entering waterways can help watersheds threatened with erosion.

In the watershed of Angola, NASA satellites detected more than 130,000 fire occurrences annually for the past 10 years. Over one day (Aug. 29, 2016), there were 267 fire alerts. This is a common occurrence in western Africa, as farmers often use fire to fertilize soil and clear the field of unwanted vegetation.

In areas like western Africa where fires are deliberately set to manage land, alternative solutions such as growing crops in between woody plants can help prevent unwanted vegetation while bringing other benefits like improved crop production and erosion control. In regions like California where dense forests fuel catastrophic wildfire, mechanical forest thinning and controlled burns can reduce wildfire severity and related sediment and ash pollution.

To learn more about the methodology behind GFW Water, refer to the Global Forest Watch Water Metadata Document.

Source: Global Forest Watch