Recent forest expansion in Thailand: a methodological artifact?

Abstract

Several Asian developing countries recently reported a net increase in forest cover. In Thailand, such reports have been vehemently rejected by forest officials, researchers, politicians, and international organizations alike. According to the dominant interpretation, the apparent forest regrowth derives from a methodological artifact. While the determination of the true evolution of forest cover has important implications, this interpretation has never been subject to scrutiny. This article presents a broad range of data and analyses suggesting important flaws in this interpretation. Based notably on (1) a critical review of available forest statistics and the methodology used to produce these statistics, (2) case study material from northern Phetchabun Province, and (3) an analysis of recent sub-national remote-sensing surveys, we reject the dominant interpretation of official statistics and suggest that reforestation has increased in Thailand and plausibly became the overall trend in the late 1990s.

When is a forest a forest? Forest concepts and definitions in the era of forest and landscape restoration

“…Rubber plantations have replaced nearly all of the natural forest in Xishuangbanna, China (Li et al 2007 ). Similar trends in replacement of native old-growth and second-growth forest by exotic tree plantations have been documented in southern Chile (Zamorano-Elgueta et al 2015 ), Thailand (Leblond and Pham 2014 ), and India (Puyravaud et al 2010 ). Across SE Asia, nearly 2500 km 2 of land previously classified as natural vegetation with tree cover was converted to rubber plantations between 2005 and 2010 (Ahrends et al 2015 ).…”

Factors affecting forest area change in Southeast Asia during 1980-2010

“…This implies that forest scarcity per se may have led to FT in the three countries. Although the pattern and processes of FT in the three countries have been well studied[ 6 ][ 14 ] [ 34 ][ 35 ][ 36 ], clarifying why the three particular countries, but not the other five countries, have already exhausted their forest resources and experienced FT would lead to a better understanding of the entering point of the forest scarcity pathway.…”

Variability in mangrove change estimates and implications for the assessment of ecosystem service provision

“…This is also an issue with estimates for terrestrial forests (e.g. Leblond & Pham, 2013), although this is surprising, because large-scale mapping technologies have been in operation for decades, and metadata and error estimates are regularly created alongside remote sensing estimates. Without publishing such information, users cannot independently ascertain the validity of census estimates and statements (Olander et al, 2008), so in the absence of other independent sources, they must trust and propagate such authoritative sources during their analyses (Grainger, 1996;Friess & Webb, 2011).…”

“…The impact of differing forest definitions on estimates of area is often discussed for terrestrial forests, and may hold lessons for mangroves. In Thailand, authorities only offered an official definition of forest cover in the mid-late 1990s, and it has been modified several times since, most recently to include younger secondary forests; changing definitions have complicated the discussions of whether Thailand's terrestrial forest resource is increasing or decreasing in area (Leblond & Pham, 2013).…”

“…Our results strongly suggest that historical estimates of mangrove change (along with other forest types; Grainger, 2008) may not yet satisfy the UNFCCC criteria. Indeed, a government's interpretation of forest surveys may have significant financial implications under a REDD+ scenario (Leblond & Pham, 2013), and uncertainty regarding emissions estimates is one of the main reasons for the delay in implementing REDD+ (Baker et al, 2010).…”