The Use of Remote Sensing Data to Estimate Land Area with Forest Vegetation Cover in the Context of Selected Forest Definitions

Tomasz Hycza,Agnieszka Kamińska,Krzysztof Stereńczak

doi:10.3390/f12111489

Abstract

(1) Background: Like many other countries, Poland is obliged to report forest area to the Climate Convention (UNFCCC Kyoto Protocol) and the Food and Agriculture Organization of the United Nations (FAO/UN). Differences between national and international forest definitions lead to differences between actual and reported forest area. Remote sensing is a useful tool for estimating forest area for reporting purposes. One of the most important parts of the estimation is the choice of a basal area to calculate the percentage of vegetation cover. (2) Methods: Height, crown projection area, and minimum complex area were used to classify the area with forest vegetation. Percentage canopy cover was determined using three different methods based on segmentation polygons, triangular grid and canopy height model pixels. The accuracy of the above methods was verified by manual vectorization performed on a selected set of test plots in the Milicz study area according to the international definitions. The differences were examined using three statistical metrics. (3) Conclusions: This paper compares for the first time methods for determining the area for which canopy cover is calculated (using data from (ALS) and discusses the differences between them in the context of accuracy (the correspondence between the results and the reference data) and the complexity of the process (time and effort required to perform the analysis). This is important in the context of reporting, estimating carbon stocks and biodiversity to mitigate the effects of climate change. Method 2 proved to be the most accurate method, Method 1 was found to be the worst option. Accuracy was better in the case of the Kyoto Protocol definition.

Highlights

Throughout the world there are a number of forest definitions
We focus on the use of airborne laser scanning data and the estimation of three variables that determine the presence of forest vegetation in the international forest definitions: Elevation, Crown Projection Area and Forest Complex Area, which have not been fully considered in previous works, i.e., [32,33,34]
The accuracy of the above methods was verified by manual vectorization performed on a selected set of 270 test plots (10 × 10 m2 ) and 30 test plots (30 × 30 m2 ) in the Milicz study area according to the definition formulated by FAO/UN and the Kyoto Protocol

Summary

Introduction

Throughout the world there are a number of forest definitions. Some of these are formulated in national law and apply only to the forests of that state, while others are international. The differences in forest definitions arise from the different characteristics of forest vegetation around the world and the different forms of forest management [1]. The differences in forest area under different definitions are influenced by the geometric characteristics of trees [2,3,4,5,6]. There are some economic and political reasons why different countries consider certain areas to be forests [7]. One consequence of using different definitions is the discrepancy in area statistics between individual countries or continents.

Objectives

Methods

Results

Discussion

Conclusion