Comparison of a New Percent Tree Cover Dataset with Existing One and Categorical Land Cover Datasets in Eurasia

Toshiyuki Kobayashi,Ryutaro Tateishi

doi:10.4236/ars.2013.24037

Abstract

The global tree cover percentage is an important parameter used to understand the global environment. However, the available percent tree cover products on global or continental-scale are few, and efforts to quantitatively validate these maps have been limited. We produced a new percent tree cover dataset at 500 m resolution in 2008 for Eurasia using reference data interpreted from Google Earth. It is a part of percent tree cover (PTC) data in Global Mapping project. In this study, the dataset was compared with existing global percent tree cover dataset, MODIS Vegetation Continuous Fields, MOD44B. We assessed the agreement of these datasets with two existing global categorical land cover datasets and statistic data in Eurasia. The result showed that estimates of tree cover in our new map and MOD44B were relatively similar at randomly sampled sites. Our map and MOD44B agreed with either or both of land cover maps at 93% of sites and 91% of sites, respectively, for pixel blocks. However, we found that MOD44B disagreed with our map and categorical land cover datasets at about half of the sampled sites where the difference of tree cover percentage between our map and MOD44B was large, especially in the areas with significant differences (more than 50%). Disagreed areas were concentrated in forests of Russia and Indonesia, and in herbaceous dominated vegetation of UK and Ireland. We also found that both our map and MOD44B were somewhat different from the data reported by FRA 2010.

Highlights

Forests, by playing an important role in regulating the climate and water resources, and by providing habitats for many species, are of great importance for life on earth
For blocks of multi pixels, our map disagreed with land cover maps by more than 20% at 39 sites (GlobCover) and 7 sites (MODIS V51), and MOD44B disagreed with land cover maps by more than 20% at 33 sites (GlobCover) and 9 sites (MODIS V51)
For MOD44B, 42.1% and 98.7% of sites with higher tree cover percentage agreed with GlobCover and MODIS V51, respectively, and 85.5% and 49.4% of sites with lower tree cover percentage agreed with GlobCover and MODIS V51, respectively

Summary

Introduction

By playing an important role in regulating the climate and water resources, and by providing habitats for many species, are of great importance for life on earth They have recently been converted to unsustainable forms of land use because of urbanization and deforestation by expanding human populations. Maps showing the tree cover percentage are useful in many fields [14,15] They were used as one independent variable to model the global forest canopy height for mapping ecosystem vertical structures [16]. They are useful for making environmental policies and elucidating the present environmental situation for education. There are studies showing that existing maps’ accuracy of estimating global tree cover is not high, in sparsely forested areas of the circumpolar taiga-tundra transition zone and special areas and eco-

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