Assessing forestland area based on canopy cover in a semi-arid region: a case study

Quantifying and reporting the extent of forest resources is one of the primary objectives of forest resource assessments across geopolitical scales (e.g. local, regional, national and international). While there has been a substantial increase in the amount of environmental data, estimates for national and international assessments are often compiled from surveys conducted at fi ner geopolitical scales; therefore, defi nitional and methodological consistency are important ( Mather, 2005 ). Inconsistency can result in poor baselines and unreliable trend information ( Grainger, 2008 ). For example, anecdotal evidence suggests that the global forestland base has been shrinking. However, according to United Nations Food and Agriculture Organization (FAO) estimates, the forestland base increased from 3442 billion ha in 1990 to 3869 billion ha in 2000 ( FAO, 1995 , 2001 ). This point is further illustrated by forest area estimates for Australia which were 40 million ha and 155 million ha in 1990 and 2000, respectively ( Mather, 2005 ). The large increase of forest area in Australia was attributed to a defi nitional change used in the 2000 assessment. After accounting for changed defi nitions, improved data and revised national classifi cations, the 1990 worldwide forest area estimate was revised from 3442 billion ha to 3963 billion ha. Consistency Assessing forestland area based on canopy cover in a semi-arid region: a case study