Matthias Dees

Airborne laser data for stand delineation and information extraction

A literature review of new publications in the field of 3D data for forest applications shows that the application of airborne laser scanner data (ALS) is in the focus of research today due to its great potential for practical applications. While there is a lot of research carried out to derive forest management parameters based on laser metrics deduced from a single tree assessment or a statistical area based assessment, the delineation of stand or sub‐stand units derived from laser metrics itself is a rather new approach. In order to describe stand characteristics statistical grid cell approaches or single tree approaches have been developed. The LIDAR based segmentation of stand or sub‐stand units is rarely documented. This article provides information on enhanced processes to delineate stand or sub‐stand units and to extract different forest information based on airborne laser derived parameters. For the stand delineation an automatic process was developed which provides a stand or sub‐stand unit delineation which is according to the first results sufficiently uniform within stands and sufficiently different in species, age class, height class, structure and composition between stands in order to be distinguishable from adjacent areas. With a combined method the stand boundaries as they are established by the mapping units today, as well as sub‐stand units which have in common physical characteristics indicating the same management disposition, were assessed. Finally a first validation of the forest stand unit delineation is provided, indicating the high potential of ALS data for separating stand units.

Spatial assessment of forest cover and land-use changes in the Hindu-Kush mountain ranges of northern Pakistan

Anthropogenic activities and natural processes are continuously altering the mountainous environment through deforestation, forest degradation and other land-use changes. It is highly important to assess, monitor and forecast forest cover and other land-use changes for the protection and conservation of mountainous environment. The present study deals with the assessment of forest cover and other land-use changes in the mountain ranges of Dir Kohistan in northern Pakistan, using high resolution multi-temporal SPOT-5 satellite images. The SPOT-5 satellite images of years 2004, 2007, 2010 and 2013 were acquired and classified into land-cover units. In addition, forest cover and land-use change detection map was developed using the classified maps of 2004 and 2013. The classified maps were verified through random field samples and Google Earth imagery (Quick birds and SPOT-5). The results showed that during the period 2004 to 2013 the area of forest land decreased by 6.4%, however, area of range land and agriculture land have increased by 22.1% and 2.9%, respectively. Similarly, barren land increased by 1.1%, whereas, area of snow cover/glacier is significantly decreased by 21.3%. The findings from the study will be useful for forestry and landscape planning and can be utilized by the local, provincial and national forest departments; and REDD+ policy makers in Pakistan.

Rapid assessment of linear transport infrastructure in relation to the impact on landscape continuity for large ranging mammals

Many Eastern European countries still host landscapes with high value due to their habitat quality and size. Some of these countries are new member states of the European Union, and EU-accession is accompanied by huge investments in the development of traffic infrastructure. Environmental assessments mandatory for road constructions in the EU do not necessarily require explicit measures for the mitigation of fragmentation, and technical constructions associated with road building are frequently assumed to provide sufficient possibilities for wildlife crossings. We evaluated those technical structures at two motorway sections separating relevant subpopulations of the brown bear (Ursus arctos) in Bulgaria. Our assessment revealed that the permeability of the two motorways has been considerably overestimated. A total of just 13 out of the 77 potential crossing possibilities of the two roads together meet the requirements we defined for suitable wildlife crossings. We found that the potential for improvement of the crossing functionality of already existing technical facilities along the motorways is very limited. Given the dependence on a small number of habitat paths connecting suitable crossings with habitat on both sides of the road, connectivity between subpopulations is vulnerable to fragmentation impacts.

Methods for Mapping Forest Disturbance and Degradation from Optical Earth Observation Data: a Review

Purpose of ReviewThis paper presents a review of the current state of the art in remote sensing-based monitoring of forest disturbances and forest degradation from optical Earth Observation data. Part one comprises an overview and tabular description of currently available optical remote sensing sensors, which can be used for forest disturbance and degradation mapping. Part two reviews the two main categories of existing mapping approaches: first, classical image-to-image change detection and second, time series analysis.Recent FindingsWith the launch of the Sentinel-2a satellite and available Landsat imagery, time series analysis has become the most promising but also most demanding category of degradation mapping approaches. Four time series classification methods are distinguished. The methods are explained and their benefits and drawbacks are discussed. A separate chapter presents a number of recent forest degradation mapping studies for two different ecosystems: temperate forests with a geographical focus on Europe and tropical forests with a geographical focus on Africa.SummaryThe review revealed that a wide variety of methods for the detection of forest degradation is already available. Today, the main challenge is to transfer these approaches to high-resolution time series data from multiple sensors. Future research should also focus on the classification of disturbance types and the development of robust up-scalable methods to enable near real-time disturbance mapping in support of operational reactive measures.

Integrating LiDAR and high-resolution imagery for object-based mapping of forest habitats in a heterogeneous temperate forest landscape

ABSTRACT Land-cover mapping (LCM) at a fine scale would be useful for forest management across heterogeneous natural landscapes. However, the heterogeneity of land covers at such scales results in complex spectral and textural properties that hinder the applicability of LCM. Besides, the method suffers from, e.g. inconsistent representation of different land-cover types, lack of sufficient and balanced training samples, and instability of classifiers trained by a high number of predictor variables. Even well-known object-based classification approaches are challenged with an objective evaluation of segmentation outputs. Here we classified partially ambiguous land-cover types across heterogeneous forest landscapes in the Bavarian Forest National Park (Germany) by combining metrics from airborne light detection and ranging (LiDAR) and colour infrared (CIR) imagery data and a random forest classifier implemented in an object-based paradigm. We evaluated the segmentation results by creating a global quality score based on inter- and intra-measurements of variance and the number of segments. Selected segmentation outputs were combined with balanced training samples to run the classification algorithm based on representative blocks within the national park. The entire processing chain was implemented in an open-source domain. The final segmentation consisted of LiDAR-based height, image-based Normalized Difference Vegetation Index (NDVI) and red band, with 20 cluster seeds and a minimum segment size of 40 pixels. In the classification, the most important variables included the height of the top layer, NDVI, Enhanced Vegetation Index (EVI) and Green–Red Vegetation Index (GRVI). The average values of 500 random forest runs indicated an overall accuracy of 86.6% and an estimated Cohen’s kappa coefficient of 85.2%, with different probabilities of correct classification for land-cover classes. Mature deciduous, standing deadwood, fallen deadwood, meadow, and bare soil classes were classified most accurately, whereas classification of young coniferous, intermediate-age coniferous, mature coniferous, young deciduous, and intermediate-age deciduous were associated with the highest uncertainties. Our methodology is sufficiently robust to be applied to other similarly structured sites across temperate forested landscapes. The versatility of the method is partially guaranteed by the proposed segmentation quality score, which satisfactorily corrects under- and over-segmentation.

Chapter 1 – Biomass Supply Assessments in Europe: Research Context and Methodologies

Abstract Since early 2000, several biomass assessment studies were delivered at European and global level mostly driven by the increasing demand for the development of bioenergy and biofuels, and the need to secure sustainable, continuous supply for the emerging plants. Ongoing research and development and industrial development plus increased drivers to use renewable raw materials in industrial sectors beyond energy have seen the focus of the biomass markets widen to include value chains for bio-based chemicals, pharmaceuticals, and other materials. Consequently, research is now exploring increasingly varied configurations of value chains with the aims of understanding which types and quantifying how much biomass can be extracted sustainably, generate financial returns, and help the industry achieving high-quality products for consumers. This chapter sets the scene for research on biomass supply assessments in Europe and reviews 40 studies delivered during the last 14 years. It analyzes context, key components in terms of terminology, framework conditions and assumptions, models used, and evidence provided so far for policy, research, and industry. It further discusses the main challenges, identifies gaps, and provides recommendations.

Assessing Lignocellulosic Biomass Potentials From Forests and Industry

Lignocellulosic biomass from forests and forest industries represents a crucial resource for the bioeconomy. Many assessments have been carried out over the last decade to quantify biomass potentials from forests and forest industries. The results from these assessments are quite diverse because of varying definitions and assumptions. Here we report on a recent comprehensive assessment carried out in the frame of the S2Biom project for 37 countries in Europe. We present the methodology to estimate biomass from forests and the forest industries, with a specific effort to estimate forest biomass supply costs. A set of biomass potentials is presented, that offers flexibility to users to select biomass potentials according to specific requirements, information demands, and policy contexts. Results are presented at the regional level for different types of potentials and with associated costs to allow better insight into the composition of the potential. The associated S2Biom toolset and database allows users to select results based on own preferences and needs, thereby offering the most comprehensive assessment of forest biomass potentials currently available in Europe.

Ideas and Options for a National Forest Inventory in Turkey

A national forest policy requires a solid information base on forests for three reasons. First, to fulfils international standards for the monitoring of forests, especially for carbon storage and biodiversity (Helsinki criteria, Kyoto protocol); second, to identify areas that require political action, including monitoring of the success of measures taken; and third, to provide a sound and reliable information base for private decision-makers about the expected wood supply. Presently, the Turkish national forest service is launching an initiative towards a national forest inventory (NFI) initiated by Prof. Asan, University of Istanbul. During an exchange programme, some initial considerations for an NFI system an NFI were worked up and will be presented in this paper. These initial considerations focus on sampling design, the use of remote sensing and the use of the available information on Turkish forests. First, an overview on the present inventory methods on the forest management level will be given in order to analyse (i) our present knowledge and deficiencies of the information on Turkish forests and (ii) what use could be made of this information in the framework of a National Forest Inventory concept. Furthermore, natural conditions and the possibility of using remote sensing will be analysed. Initial concepts to use the regional forest maps (generalised maps in the scale 1:100,000, based on maps from forest management inventories) and remote sensing will be presented. The regional forest maps and mapping based on remote sensing using optical high-reso.lution satellite data (TM/SPOT/IRS1/ASTER) are to be used with the statistical pre-stratification method to enable different sampling densities and identify non-forest sampling plots. A forest map based on remote sensing is included in the concept to supplement the statistical information. The use of very high-resolution satellite data (e.g. IKONOS) will be discussed. Finally, open questions for preparatory studies will be identified.

Sustainability impacts of increased forest biomass feedstock supply – a comparative assessment of technological solutions

ABSTRACT Sustainably managed forests provide renewable raw material that can be used for primary/secondary conversion products and as biomass for energy generation. The potentially available amounts of timber, which are still lower than annual increments, have been published earlier. Access to this timber can be challenging for small-dimensioned assortments; however, technologically improved value chains can make them accessible while fulfilling economic and environment criteria. This paper evaluates the economic, environmental and social sustainability impacts of making the potentially available timber available with current and technologically improved value chains. This paper focuses on increasing the biomass feedstock supply for energy generation. Quantified impact assessments show which improvements – in terms of costs, employment, fuel and energy use, and reduced greenhouse gas emissions – can be expected if better mechanized machines are provided. Using three different methods – Sustainability Impacts Assessment (SIA), Life Cycle Assessment (LCA), and Emission Saving Criteria (ESC) – we calculated current and innovative machine solutions in terms of fuel use, energy use, and greenhouse gas emissions, to quantify the impact of the technology choice and also the effect of the choice of assessment method. Absolute stand-alone values can be misleading in analyses, and the use of different impact calculation approaches in parallel is clarifying the limits of using LCA-based approaches. The ESC has been discussed for the recast of the Renewable Energy Directive. Potential EU-wide results are presented.

An Efficient Approach to Combine Remote Sensing and Sample Based Inventory for Forest Enterprises in Transition to Near-Natural Forest Management

This paper is based on results of a study in a state forest enterprise in Nordrhein-Westfalen, Germany. This study was motivated from both introducing new technological options, and the necessity to adapt and change the inventory and monitoring system within forest management due to developments and changes in the silvicultural concepts and changing management objectives (ecology, bio-diversity, stability, effective cost management, organisational changes). The paper focuses on the aspect of silvicultural concepts. The developed and evaluated system, can be used both in age class forest, in forests in transition and in near-natural forests. The system was tested together with some options with respect to remote sensing data and analysis methods. The finally proposed concept consists of five information levels, that are useful for long-term-planning and ongoing management: (i) an ortho-image-map based on colour infrared photos, (ii) mapping of single objects of high interest, (iii) stand mapping and description, (v) reliable overall and structural data for groups of stands (iv) reliable overall and structural data for the whole enterprise with (iv) and (v) based on a sample based continuos forest inventory. For the estimating procedure within the sample based continuos forest inventory a stratification estimation technique, that reduces the estimation errors compared to simple estimation, is developed. It is demonstrated, that the system is highly cost efficient and of high information quality at the same time.