Wood energy – outdated source of energy or rehabilitation for degraded soils and landscapes?
Introduction
Wood is the first source of energy humankind discovered. Until today, it remains an important source of renewable energy for more than two billion people. Developing countries are main consumers of wood energy products due to the affordability, accessibility and easy handling.
As the world’s population is increasing and the transformation of energy supply systems is rather slow, wood energy will most likely remain an important source of energy for many developing countries. Especially in Sub Sahara Africa and Asia, estimates project an increase in demand for wood energy with an annual rate of 1.9% up to 2030.[1] In Sub Sahara Africa, currently 90% of the population relies on firewood and charcoal as primary source of energy for cooking and heating.[2]
Deforestation, forest fragmentation, and ensuing degradation of landscapes and soils are threatening not only the forest resource, but also the productivity of landscapes. Next to the expansion of agricultural lands, the extraction of energy wood is one of the major causes for the degradation of landscapes. Further reasons for the loss of forest cover are fires, land-use changes, illegal logging and low legal control.[3] Therefore, a modern and sustainable wood energy management is called for to:
- prevent shortages in energy supplies,
- at the same time combat landscape and soil degradation,
- and to meet an increasing demand for wood energy.
Reforestation as a way toward sustainable wood energy production
Reforestation can be a powerful tool to meet the increasing demand for wood energy, and reduce land and soil degradation. Reestablishing tree stands and forests also may have positive effects on biodiversity, carbon storage in landscapes, improved nutrient cycles and mitigation of climate change. There are many ways to plan and design Energy Wood plantations even for multiple outputs and impacts. They may therefore be easily adopted to the needs of the local population, regional development plans and the environmental conditions of the specific region.
Short rotation forestry is a fast way to produce comparably large quantities of wood energy. Fast growing species such as eucalyptus, southern beech, populous, pine, ash, and sycamore with a harvesting cycle of eight to twenty years are often used to provide wood within a short period of time.[4] Allochthonous species can be used to rehabilitate degraded lands, reestablish soil fertility and preparing sites for bringing back the autochthonous species. Further disturbance of ecosystems needs to be prevented. Therefore a constant monitoring and managing concept e.g. for possible invasive species or any negative effect on the ecosystem must be in place. In general, monoculture plantations of fast-growing species can accumulate biomass faster than native mixed-species plantings but often have less biodiversity value and are more susceptible to pests and negative effects of climate change. In areas with low precipitation, native species may often be equally productive, and less vulnerable to drought and climate change, than the most widely known tree species that are cultivated in monocultures.[5] The International Tropical Timber Organization (ITTO) recommends the use of indigenous tree species and a natural transfer from monocultures to mixed forests as fast as possible.[6]
Integrated systems can be adapted more specifically to the local conditions and needs. Mixed tree cropping is a method that can be considered as a more holistic approach, because it includes wood energy production but also additional sources of income for products such as nuts, fruits, honey, herbs and fungi.[6] Agroforestry systems typically combine tree planting with pastoral land or cropland either in time or in space to improve productivity and produce income from different sources. With a diversity of production methods , (location, size, species mix and tree density) a locally adapted and suitable wood energy supply can be designed depending on preferred production targets and environmental outcomes. Taking impacts from climate change into consideration, appropriate species should be selected for the current and expected future environmental conditions. The private sector, Government Agencies, Forestry and Energy experts as well as the local population should be included in the planning and the management of wood energy supply systems.
Land tenure, forest rights and the role of policy
Security of land tenure plays an important role in the development of a sustainable modern Forestry Sector and therefore also in sustainable Wood Energy development. Long-term planning, policy development, regulation, monitoring and market development are further key factors to ensure economic efficiency and maintenance of ecosystem services.
Unregulated access to forest resources and unchecked exploitation have led to serious negative impacts, such as deforestation and ensuing soil degradation.[1] Experience from community forestry approaches from Latin America, Asia and Africa confirm that the devolution of usufruct and or ownership rights are one of the necessary preconditions for a well-functioning forest management. Investments in wood production by the local population for multiple products highly depends on the security of rights to use and/or own forestlands.[7]
Forest tenure arrangements differ strongly between world regions and from country to country and depend on the particular political and legal system, including also the social system and its historical evolution.[1] States tend to hold full property rights on forests. However, devolving (limited) access and management rights to communities can reduce over-exploitation. Forest ownership, levels of enforcement of law and regulations and the degree of overlap between usage by formal owners and other resource users are the three main aspects to determine the forest incomes of rural households. The production of wood energy may extend beyond forestlands, may involve areas under agriculture or around homesteads and possible links to the food production sector need careful analysis and consideration.
Hence, wood energy programs/projects need to consider land tenure systems. They need to understand and innovate on how land and resource rights as well as custodian duties are distributed among individuals and groups within a given community.[1] In any case, secure and long-term forest rights given to communities are a key element to sustainable wood energy management.
Influence of reforestation on soil
Wood Energy production whether from reforestation or short term rotation plantations can help both degraded and agricultural soils to improve by developing a higher aggregate stability, lower bulk density, higher porosity, better aeration, improved water storage capacity and larger litter deposition. Especially on degraded land and on sloping land reforestation reduces runoff and soil erosion. In riparian areas, it can lower sediment entry into streams. Reforestation of mountainous and other elevated areas can lead to an improvement of water quality and a better regulation of water yields. Some species, such as eucalyptus, can lower saline water tables, but the associated increasing salinization of soil and ground water may reduce the long-term viability of such plantings.[5]
Globally, forests are estimated to sequester approximately double the amount of carbon (1 t/ha/year) compared to croplands. Species choice in tree plantings is important for carbon sequestration in soils. The largest increase of soil carbon is documented under broadleaved species (27%), only intermediate values under eucalypts (12%) and little change has been observed under conifers (2%).[5]
Reforestation can also lead to increased availability of certain macronutrients such as sodium, phosphorus, calcium, potassium and magnesium. For example, soil sodium increased by 71% up to 250% in some plantings of Eucalyptus and in soils under conifers, the mineralization and availability of phosphorus usually increases compared to agricultural sites.[5] Plantations of nitrogen-fixing tree species are able to increase productivity and to improve soil conditions of degraded land areas. Such plantations will lower soil inherent thresholds that prevent the natural regrowth from seed potential already on site.
Good practice examples
Participatory forest management - Senegal
In Senegal, around 84% of the households depend on wood energy. Over-exploitation of the forests and over-grazing has led to deforestation, soil erosion and desertification. Senegal’s forests are mainly public and regulated by the forest code (1993) and the decentralization process (1996). In 2008, the forest service decreed that charcoal production is only allowed in forest areas under sustainable management.
The GIZ supported Program addresses fuel wood issues within a wider context of community based multipurpose forest management and facilitates the process of transferring land use rights to rural communities. The communities established and implemented a detailed management plan with the goal to harmonize locally perceived needs and expectations with a sustainable wood energy management. Through the management plans, logging is now limited to 50% of the standing wood energy volume and rotation periods are fixed at eight or twelve year. Additionally, improvements of the charcoal production system were promoted and improved cook stoves were distributed. The participating regions have put 30 000 ha of forests under Community Management and reforest 5 250 ha of degraded land and 76 800 ha of mangrove forest.[1]
Village-based individual reforestation - Madagascar
Madagascar’s forest is one of the most important biodiversity hotspots of the world and contains an especially high rate of endemic species. Non-regulated forest access leads to severe deforestation (caused mainly by energy and exotic wood extraction, livestock grazing and land use transformation). Consequences are heavy soil erosion and frequent floods.
The GIZ-Project’s approach is based on voluntary participation of communities willing to rehabilitate degraded lands and addresses the entire value chain of wood energy. Communal decision makers were included in the process to clarify and transfer property rights to individual landowners. Overall, 2 900 households afforested 8 000 hectares of highly degraded wasteland around 68 villages, using mainly eucalyptus. This increases their income (about 40%) and strengthens their economic situation. Smallholder households involved in the afforestation project now manage 3 hectares of energy forest each, producing about 2.6 tons of charcoal per year for a projected period of at least 27 years without further investment.[1]
Conclusion
Wood Energy can have an economically stimulating positive impact in rural areas: create employment, income, and support rural development efforts.[8] In order to achieve reforestation and landscape rehabilitation for rural development on a long-term perspective risks and benefits need to be evaluated beforehand. Wood energy projects can only thrive, if accepted and supported by the local population and implemented by policy makers and land managers.[5] Wood energy development needs to be part and parcel of regional and local development plans and their sound implementation. A long-term perspective including secure forest tenure and rights is crucial for the sustainability of wood energy projects. Well-designed wood energy projects can contribute substantially to sustainable landscape utilization and rehabilitation of degraded land as well as to an overall positive development in rural areas. To achieve efficiency in wood energy supply the sustainability of the production and efficiency in transformation and use are necessities. The subsector then may then contribute significantly to the formal regional and local economy.
Autors: Karl Moosmann, Martina Alrutz
References
[1] Sepp, S., Sepp, C., Busacker, D. (2014): Towards sustainable modern wood energy development.Stocktaking paper on successful initiatives in developing countries in the field of wood energy development. Editor: GIZ and Global Bioenergy Partnership (GBEP).
[2] Garrity: Creating EverGreen Food-Energy Systems for Rural Electrification in Africa.
[5] Cunningham et al. (2015): Balancing the environmental benefits of reforestation in agricultural.
Regions. In: Perspectives in Plant Ecology, Evolution and Systematics 17, S. 301–317.
[6] Greenpeace New Zealand (1994): The Plantation Effect. An Eco forestry Review of the Environmental Effects of Exotic Monoculture Tree Plantations in Aotearoa/New Zealand.
[8] Moosmann (2016): Successful initiatives in developing countries in the field of wood energy development. Results from the stocktaking study „Towards sustainable modern wood energy development“, GIZ and GBEP, Presentation.
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