Erosion in forestland

This section includes 3 studies published in peer review journals:

a) European Study: Assessment of cover changes and soil loss potential (Borrelli et al., 2016, Ecological Indicators): This study present the spatial patterns of forest cover changes in 36 countries and their impact in erosion potential.

b) Case Study in Italy (Borrelli et al, 2014, Applied Geography). This case study performs a risk assessment of human-induced accelerated soil erosion processes in the forestland.

c) Soil Loss in the Italian forest (Borrelli et al, 2016, Catena). High resolution erosion assessment in Italy using RUSLE2015

European Study: Assessment of cover changes and soil loss potential

Background information

The Member States of the European Union have committed to the maintenance and protection of forestlands. More precisely, the Member States aim to ensure the sustainable development and management of the EU’s forests. For 2013, Eurostat’s statistics about primary and secondary wood products in the European forest land (65% thereof privately owned) estimate a roundwood production of 435 million m3 in total. Harmonised information, i.e., spatially and temporarily differentiated, on forestry and wood harvesting activities in the European forests are missing however. This lack of information impedes the scientific assessment of the impacts that forest management practices have on the soil-related forest ecosystems (e.g., accelerated water soil erosion, delivery of inert sediments and pollutants within the drainage network, pauperization of aquatic ecosystems). It also prevents national and European institutions from taking measures aimed at an effective mitigation of the rapidly advancing land degradation.

This study provides a first pan-European analysis that delineates the spatial patterns of forest cover changes in 36 countries. The first dynamic assessment of the soil loss potential in the EU-28 forests is reported. The recently published High-resolution Global Forest Cover Loss map (2000–2012) was reprocessed and validated. Results show that the map is a powerful tool to spatiotemporally indicate the forest sectors that are exposed to cover change risks. The accuracy assessment performed by using a confusion matrix based on 2300 reference forest disturbances distributed across Europe shows values of 55.1% (producer accuracy) for the algorithm-derived forest cover change areas with a Kappa Index of Agreement (KIA) of 0.672.

New insights into the distribution of the forest disturbance in Europe and the resulting soil loss potential were obtained. The presented maps provide spatially explicit indicators to assess the human-induced impacts of land cover changes and soil losses on the European soil-related forest ecosystems. These insights are relevant (i) to support policy making and land management decisions to ensure a sustainable forest management strategy and (ii) to provide a solid basis for further spatiotemporal investigations of the forestry practices’ impacts on the European forest ecosystems.

Data

To get access to the data, please compile the online form; instructions will then follow how to download the data. The data download page will provide you access to the following datasets:

  1. European Forest Cover Change;
  2. Soil Loss Potential;
  3. Forest Harvest Layers (annual) for the Italian case study (below)

 

References

Borrelli, P., Panagos, P., Langhammer, J., Apostol, B., Schütt, B. 2016. Assessment of the cover changes and the soil loss potential in European forestland: First approach to derive indicators to capture the ecological impacts on soil-related forest ecosystems. Ecological Indicators, 60, 1208–1220

More Information - Contact

Pasquale Borrelli, European Commission, Joint Research Centre
Email: pasquale.borrelli@jrc.ec.europa.eu , Tel: 0039 0332-783021

Maps

Fig.1: Forest Cover Change (ha) and Forest Fires (ha)

Fig. 2: Soil Loss Potential


Case Study: Italy

Background

Climate change, globalization and the growing demand for raw materials result in an increasing demand for forest resources at a worldwide scale. In Europe, resources exploitation in terms of forest timber harvesting is the most widespread management practice (Eurostat, 2009). It is estimated that about 420 million m3 of roundwood forests were harvested in the European Union (EU-27) in 2010 to meet the domestic timber demand (Eurostat, 2011). In recent years, an increasing number of studies based on forest science have addressed the ecological sustainability of wood harvesting in the European forests (Reference). Locally, the European forest is cleared, degraded and fragmented by timber harvesting, man-made fires and land-use conversion (Cochrane, 2003; Richards & Tucker, 1988; Williams, 2000). The side effects of tree harvesting activities are major environmental issues.

The temporary absence of a vegetation cover directly exposes the forest soils to the impacts of rainfall events (Morgan, 2005). This alters the natural water balance of the forestlands increasing the magnitude of down-slope soil mobilization (water soil erosion). The occurrence of accelerated soil erosion processes associated with forest harvesting were found in several European locations including England, Italy among others (Stott et al., 2001). Facing the fact that the forestland and forest soils are among the most valuable and strategically most multifunctional natural assets, the European Union and the United Nations strongly encourage policies targeting the forest resources conservation . The challenge for the immediate future is to assure that the forests meet the various humans needs and, at the same time, to minimize the negative effects of the human interference on the forests (safeguarding forest and soil biodiversity, recreational needs, and ecosystem services). Such ambitious undertaking, however, requires in-depth knowledge about the current status of European forests as an important precondition. An adequate knowledge about forest harvesting districts that are involved in the wood supply chain and related soil erosion processes needs to be archived.

Key Problem and Research Aim

Up-to-date the erosion processes deriving from forestry activities and wildfires were not considered in our modeling (Van der Knijff et al., 2000, Grimm et al., 2001, Grimm et al., 2003, Jones et al., 2003, Bosco et al., 2014). As result, the forests have been considered immutable environments where soil erosion processes have not been adequately represented. The current state of the art in erosion research lacks knowledge about where and how water soil erosion occurs in the Europe forests poses a threat to forest ecosystems (including water bodies receiving pollutants). In addition, the lack of research in spatial and temporal patterns of soil erosion in forestlands, particularly at the landscape to regional scales, prevents national and European institutions from taking actions aimed at an effective mitigating of land degradation.

The overall aim of the study is to perform a risk assessment of human-induced accelerated soil erosion processes in the forestland sectors of a test area of the European Union. The selected physiographic unit is Italy, which falls in a Mediterranean region particularly prone to erosion. In Italy, forestland is the second most common type of land use covering about 87,592 km² (29% of the land surface), out of which 42% is currently managed as coppice forest (INFC, 2007). As a result, a vast area of the country, mostly located in mountainous areas characterized by heavy bursts of intensive and erosive rainfalls that hit the steep slopes (van der Knijff et al., 1999), is subject to operations of wood extraction. For some of these forest landscapes this practice of land resource exploitation may result in irremediable damages. To achieve this aim, the spatio-temporal pattern and dynamic changes of the specific soil erosion risks of the Italian forests will be investigated by means of a spatially distributed modeling approach. To enable the modeling phase of soil erosion, initially, the vegetation changes that are the direct cause of the instability in the natural balance and thus responsible for the accelerated erosion process need be carefully mapped.

Conceptual schema

From a technical point of view, the proposed research project targets the following three general objectives which, chronologically, correspond to distinct stages of the project advancement:

  • A1 – To create an updated quantification of the Italian forest sectors that, from 2002 to 2011, were subject to tree harvesting activities or wildfires
  • A2 – To provide maps and statistics of accelerated soil erosion processes in disturbed and undisturbed Italian forestland by means of modeling operations within a GIS environment.
  • A3 – To provide a scenario of potential future dynamics of soil erosion by water in the Italian forest environment induced by a change of influence factors such as, human pressure or climate.

Results

This study presents a thorough approach, based on the application of multi-spectral remote sensing Landsat imagery, to determine human-induced forest cover change in Italy during the decade 2002–2011. A total of 785.6 ×1 04 ha of forestland was mapped using the main forest classes described within the CORINE land cover 2006 database (3.11 – broad-leaved forest; 3.12 – coniferous forest; 3.13 – mixed forest). The approach employs multi-temporal Landsat imagery to determine large-scale spatiotemporal variations in forest cover with a high degree of precision. The semi-automated procedure is based on Normalized Difference Vegetation Index (NDVI) pixel-oriented image differencing technique. The results were validated and rectified as a result of on-screen visual interpretation, whereby all the false-positive forest changes that were incorrectly mapped during the automatic procedure were identified and removed. The derived high-resolution data of forest cover change show that 317,535 ha (4.04% of the total forest area in Italy) were harvested during the period under review. The 125,272 individual clear-cut areas identified are mainly located within protected areas of the European Natura 2000 network. The outcome of this study is a publicly accessible database that can encourage further studies in the framework of international biodiversity and soil protection conventions.

More Information – Links (Citations)

Forest Harvest

Figure 1: Forest change from July 2002 to July 2011. Note that the forest changes (brown) may be enhanced in size because of the small scale of the map. 
Figure 2: Forest change area at province level (EU NUTS-3 units)


Soil erosion in the Italian forest. First comprehensive monitoring and modelling approach

Background

As a member of the European Union, Italy has committed to the maintenance and protection of its forests based on sustainable forest development and management practices. According to Eurostat, Italy has the seventh largest forest surface available for wood supply in the EU-28, which is equal to 8.086 million hectares. For 2012, the Italian National Institute of Statistics estimated the total roundwood production of Italy to be 7.7 million m3, from a harvested forest surface of 61,038 hectares. Large parts of the country’s forests, mainly located in vulnerable mountainous landscapes that are highly sensitive to environmental changes, are subject to anthropogenic disturbance driven by wood supply interests. Despite the extensive logging activities and the well-known impacts that such management practices have on the soil-related forest ecosystems, there is a lack of spatially and temporally explicit information about the removal of trees. Hence, this study aims to: i) assess the soil loss by water erosion in Italian forest areas, ii) map forest harvests and iii) evaluate the effects of logging activities in terms of soil loss by means of comprehensive remote sensing and GIS modelling techniques.

Approach Overview

The spatio-temporal pattern of rill and inter-rill soil erosion processes in Italian forest lands is based on a spatially distributed modelling approach (Figure 1). Prior to the soil erosion modelling phase, the status of the vegetation and the logged areas were outlined by remote sensing and GIS operations. As a first step, the impact of a 30-year period of forest logging was established based on forest change detection techniques (2002-2011) and a rules-based approach that randomly generated clear-cut areas (1982-2001). As the second step, the long-term soil loss rates (Mg ha-1 y-1) were predicted by means of a revised version of the Universal Soil Loss Equation (USLE).

Study Area

The study area covers about 785.6·104 ha, which corresponds to the main forest units described within the CORINE land cover 2006 database (EEA, 2014), i.e. broad-leaved forests (547.9·104 ha, 70%), coniferous forests (128.6·104 ha, 17%) and mixed forests (109.1·104 ha, 13%).

Results

The derived high-resolution data regarding forest cover change shows that 317,535 ha (4.04% of the total forest area in Italy) were harvested during the period under review (Figure 2). The predicted long-term annual average soil loss rate was 0.54 Mg ha-1 yr-1 (equal to 67.946 x 103 Mg yr-1) (Figure 3). The average rate of soil loss in forests that remained undisturbed during the modelled period is equal to 0.33 Mg ha-1 yr-1. Notably, about half of the soil loss (45.3%) was predicted for the logged areas, even though these cover only about 10.6% of the Italian forests. The identified erosion hotspots may represent a serious threat for the soil-related forest ecosystems, and are in contrast to the EC Thematic Strategy for Soil Protection and Water Framework Directive.

Figure 1: Workflow — Assessment of vegetation cover, tree harvesting and soil loss potential for the Italian forestland.

 

Figure 2: Forest harvesting averaged by 2.5 × 2.5 km grid.

 

Figure 3: Left) Average long-term soil loss potential modelled assuming the absence (L1) and presence (L2) of forest harvesting activities. Right) Post-harvest vegetation development. (a) Landsat false-colour time-series (bands 4/3/2) for the period from Summer 2004 (i) to Summer 2009 (iv) (Path 192 Row 30 — Tuscany). (b) Average Landsat NDVI time-series for 250 clear-cut areas spread across the country. (c) Average MODIS EVI 16-day time-series extracted by the JRC Phenolo model for 510 clear-cut areas spread across the country (the continuous line indicates the moving average). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

 

More Information – Links (Citations)

Borrelli, P., Panagos, P., Märker, M., Modugno, S., Schütt, B. 2016. Assessment of the impacts of clear-cutting on soil loss by water erosion in Italian forests: First comprehensive monitoring and modelling approach. CATENA, doi:10.1016/j.catena.2016.02.017

 

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Title: Soil erosion in forestland in Europe (using RUSLE2015)
Resource Type: Datasets, Soil Threats Data
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Year: 2015
Publisher: European Commission - DG JRC
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