F. Gerard

Land cover change in Europe between 1950 and 2000 determined employing aerial photography.

BIOPRESS (‘Linking Pan-European Land Cover Change to Pressures on Biodiversity’), a European Commission funded ‘Global Monitoring for Environment and Security’ project, produced land cover change information (1950—2000) for Europe from aerial photographs and tested the suitability of this for monitoring habitats and biodiversity. The methods and results related to the land cover change work are summarized. Changes in land cover were established through 73 window and 59 transect samples distributed across Europe. Although the sample size was too small and biased to fully represent the spatial variability observed in Europe, the work highlighted the importance of method consistency, the choice of nomenclature and spatial scale. The results suggest different processes are taking place in different parts of Europe: the Boreal and Alpine regions are dominated by forest management; abandonment and intensification are mainly encountered in the Mediterranean; urbanization and drainage are more characteristic of the Continental and Atlantic regions.

Measuring Woody Encroachment along a Forest-Savanna Boundary in Central Africa

Abstract Changes in net area of tropical forest are the sum of several processes: deforestation, regeneration of previously deforested areas, and the changing spatial location of the forest–savanna boundary. The authors conducted a long-term (1986–2006) quantification of vegetation change in a 5400 km2 forest–savanna boundary area in central Cameroon. A cross-calibrated normalized difference vegetation index (NDVI) change detection method was used to compare three high-resolution images from 1986, 2000, and 2006. The canopy dimensions and locations of over 1000 trees in the study area were measured, and a very strong relationship between canopy area index (CAI) and NDVI was found. Across 5400 km2 12.6% of the area showed significant positive change in canopy cover from 1986 to 2000 (0.9% yr−1) and 7.8% from 2000 to 2006 (1.29% yr−1), whereas <0.4% of the image showed a significant decrease in either period. The largest changes were in the lower canopy cover classes: the area with <0.2 m2 m−2 CAI decreased...

Comment on ‘A first map of tropical Africa’s above-ground biomass derived from satellite imagery’

We present a critical evaluation of the above-ground biomass (AGB) map of Africa published in this journal by Baccini et al (2008 Environ. Res. Lett. 3 045011). We first test their map against an independent dataset of 1154 scientific inventory plots from 16 African countries, and find only weak correspondence between our field plots and the AGB value given for the surrounding 1 km pixel by Baccini et al. Separating our field data using a continental landcover classification suggests that the Baccini et al map underestimates the AGB of forests and woodlands, while overestimating the AGB of savannas and grasslands. Secondly, we compare their map to 216 000 × 0.25 ha spaceborne LiDAR footprints. A comparison between Lorey’s height (basal-area-weighted average height) derived from the LiDAR data for 1 km pixels containing at least five LiDAR footprints again does not support the hypothesis that the Baccini et al map is accurate, and suggests that it significantly underestimates the AGB of higher AGB areas. We conclude that this is due to the unsuitability of some of the field data used by Baccini et al to create their map, and overfitting in their model, resulting in low accuracies outside the small areas from which their field data are drawn.

The use of digital aerial photography and CORINE-derived methodology for monitoring recent and historic changes in land cover near UK Natura 2000 sites for the BIOPRESS project

BIOPRESS – Linking pan‐European land cover change to pressures on biodiversity – is a European Community Framework 5 project, which aims to develop a standardised product that will link quantified historical (1950–2000) land cover change to pressures on biodiversity. It exploits archived historic and recent aerial photographs (a data source that has remained consistent over the last 60 years) to assess land cover change around Natura 2000 sites within 30×30 km windows and 15×2 km transects. The CORINE (Coordination of Information on the Environment) land cover mapping methodology has been adapted for use with aerial photographs. Sample sites are mapped to CORINE Land Cover (CLC) classes, and then backdated to assess change. Results from eight UK transects (and associated windows) are presented. Changes in land cover classes are interpreted as pressures: urbanisation, intensification, abandonment, afforestation, deforestation and drainage. Urbanisation was the major pressure in all but two transects (both in the uplands), and intensification was of similar importance in most transects. Afforestation was a significant pressure in two transects. In six out of the eight transects, annual change was greater in the 1990–2000 period than in the 1950–1990 period. The methodology has been demonstrated to provide quantitative results of long‐term land cover change in the UK rural landscape at a spatial scale that is relevant to management decisions. The methods are transferable and applicable to a wide range of landscape studies.

An environmental assessment of land cover and land use change in Central Siberia using quantified conceptual overlaps to reconcile inconsistent data sets

Environmental monitoring and assessment frequently require remote sensing techniques to be deployed. The production of higher level spatial data sets from remote sensing has often been driven by short-term funding constraints and specific information requirements by the funding agencies. As a result, a wide variety of historic data sets exist that were generated using different atmospheric correction methods, classification algorithms, class labelling systems, training sites, map projections, input data and spatial resolutions. Because technology, science and policy objectives are continuously changing, repeated natural resource inventories rarely employ the same methods as in previous surveys and often use class definitions that are inconsistent with earlier data sets (Comber, Fisher and Wadsworth 2003). Since it is generally not economically feasible to recreate these historic land cover/land use data sets, often inconsistent data sets have to be compared. An environmental assessment of land cover and land use change in Central Siberia is presented. It utilises several different digital land cover maps generated from satellite data acquired in different years. The specific characteristics of different land cover maps create difficulties in interpreting change maps as either land cover/land use change or a pure data inconsistency. Many studies do not explicitly deal with these inconsistencies. It is argued that a rigorous treatment of multi-temporal data sets must include an explicit map of consistency between the multi-temporal land cover maps. A method utilising aspects of quantified conceptual overlaps (Ahlqvist 2004) and semantic-statistical approaches (Comber, Fisher and Wadsworth 2004a,b) is presented. The method is applied to reconcile three independent land cover maps of Siberia, which differ in the number and types of classes, spatial resolution, acquisition date, sensor used and purpose. A map of inconsistency scores is presented that identifies areas of most likely land cover change based on the maximum inconsistency between the maps. The method of quantified conceptual overlaps was used to identify regions where further investigations on the causes of the observed inconsistencies seem warranted. The method highlights the value of assessing change between inconsistent spatial data sets, provided that the inconsistency is adequately considered.

Studying the change in fAPAR after forest fires in Siberia using MODIS

Disturbance events such as fire have major effects on forest dynamics, succession and the carbon cycle in the boreal biome. This paper focuses on establishing whether characteristic spatio‐temporal patterns of the fraction of Absorbed Photosynthetically Active Radiation (fAPAR) occur in the initial two years after a fire event in Siberian boreal forests. Time‐series of MODIS fAPAR were used to study post‐fire dynamics during the year of the fire and the following two years. Three forest types (evergreen needle‐leaf, deciduous needle‐leaf and deciduous broadleaf) grouped into three latitudinal regions, ranging from 51° N to 65° N, were studied by analysing a sample of 14 burned areas. For each of the burned areas an adjacent unburned control plot was selected with the aim of separating inter‐annual variations caused by climate from changes in fAPAR behaviour due to a burn. The results suggest that (i) the forest types exhibit characteristic fAPAR change trajectories shortly after the fire, (ii) the differences in the fAPAR trajectories are related to the forest type, (iii) fAPAR changes are not significantly different among the latitudinal regions, and (iv) the limited temporal variability observed among the 3 years of observations indicates that fAPAR varies very little in the initial years after a fire event.

Fire/Climate Interactions in Siberia

This paper presents an intercomparison of two burned area datasets, the L3JRC daily global burned area dataset derived from SPOT-VEGETATION and the FFID burned area dataset from MODIS. Burned area dynamics are presented and the influence of climate on the fire regime is discussed. Feedbacks of the fire dynamics to the climate system are evaluated. The Russian fire danger index is presented and compared to satellite observations of fires.

Exploring the Biophysical Drivers of Amazon Phenology: Preparing Data Sets to Improve Dynamic Global Vegetation Models

We explore the relative influence of biophysical drivers on phenology to assist validation and parameterization of Dynamic Global Vegetation Models. Using 6.8 years of MODIS data we created a vegetation index time series to map the spatial variability of vegetation phenology in the Amazon. TRMM and CERES data were used as a measure of two biophysical variables, precipitation and net radiation respectively. Using a Fourier transform and cross spectral analysis two aspects were considered from these data, the coincidence of: (A) spatial patterns, presence and strength in the annual cycle, and (B) the coherency and phase differences between the phenology and the biophysical variables. Using the Amazon as a study area we find that the coincidence between phenology and the drivers in annual power strength was not linear and in an area of high coherency we found radiation and phenology was almost in phase, whilst precipitation was not. The correspondence of slightly subdued annual phenology with strong annual radiation indicated that other drivers also influence the strength of the phenology.

Chapter 19 – Emerging and Potential Future Applications of Satellite-Based Soil Moisture Products

This chapter describes the emerging applications for satellite-based soil moisture (SM) data and proposes possible future uses, backed up by some preliminary research which has helped to identify this need. Applications across the ecological and hydrological sciences, in a wide range of discipline areas, are considered. The more established application areas of numerical weather prediction and climate modelling are not considered in this chapter. The chapter starts with applications of global relevance, and then goes on to focussing on the potential applications in Africa, where the needs for accurate information on water resources are particularly urgent in order to address issues of food and water security. Finally, the current limitations and future developments influencing the application of satellite SM data are discussed.

Emerging and Potential Future Applications of Satellite-Based Soil Moisture Products

This chapter describes the emerging applications for satellite-based soil moisture (SM) data and proposes possible future uses, backed up by some preliminary research which has helped to identify this need. Applications across the ecological and hydrological sciences, in a wide range of discipline areas, are considered. The more established application areas of numerical weather prediction and climate modelling are not considered in this chapter. The chapter starts with applications of global relevance, and then goes on to focussing on the potential applications in Africa, where the needs for accurate information on water resources are particularly urgent in order to address issues of food and water security. Finally, the current limitations and future developments influencing the application of satellite SM data are discussed.