4DForM-at

Starting point / motivation

Global and climate change lead to a modified political and economic framework, requiring an adapted management of forests as one of the key natural resources. Economical competitive pressure, related to globalization, and increasing environmental risks, related to climate change, lead to an increased demand for detailed information on the forest resource, which can support target-oriented forest management and risk and cost reduction.

The traditional forest inventory can give this information only on a punctual basis. Moisture information for example, is only available for a small number of sites (10 - 15) over whole Austria, which cannot address forest managers with an area-wide scope.

However, forest soil moisture is one key parameter for the understanding of forest health and the exposure of forests to draught or landslide risks. A second key parameter is the species composition of forests, defining tolerance spectra of trees and the risk for the dispersal of plant diseases.

Contents and goals

The aim of the project 4DForM-at is to develop an area-wide applicable mapping product for forest soil moisture conditions considering species compositions.

Methods

The mapping products will combine microwave remote sensing data (Sentinel-1) with multispectral data (Sentinel-2) and will additionally integrate high resolution digital surface models from airborne laser scanning and photogrammetry in order to define homogeneous forest topographic units for multi-temporal analysis.

The latter will allow an innovative object based analysis on homogeneous forest units addressing the forest structure and topography in relation to moisture and species composition. The units will be derived by a segmentation approach considering forest structural (tree heights, crown coverage, crown diameters) and topographic metrics (slope, aspect, topographic openness) and will be used for both soil moisture mapping and species mapping.

The innovation in moisture mapping will be the aggregation of Sentinel-1 based soil moisture mapping in forest-topographic units, allowing the investigation of the relationships between microwave transmissivity of the forest canopy and the strength of the recorded moisture signal.

Expected results

The innovation in species mapping will be the use of multitemporal signatures derived for forest-topographic units and signal-unmixing experiments using Radiative Transfer Modelling (RTM). An innovative 3D reconstruction of selected forest plots and a monitoring of canopy densities (by Hemispherical Photographs) and leaf reflectance (by field spectrometer) through the year will be conducted and used for detailed signal unmixing experiments by RTM.

Besides the management of Sentinel-1 and 2 data, the project is based on a network of in-situ reference sites (Austrian Forest Inventory), were forest structural parameters and soil moisture information is known.

Coordinator

Austrian Academy of Sciences

Project partner

• Austrian Research Centre for Forestes
• TU Vienna, Department of Geodesy and Geoinformation

Austrian Academy of Sciences
Dr. Martin Rutzinger
Technikerstr. 21a
Otto Hittmair-Platz 1, ICT
A-6020 Innsbruck