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close this bookBioenergy Primer: Modernised Biomass Energy for Sustainable Development (UNDP, 2000, 153 p.)
close this folderChapter 4. Environmental Issues
View the document(introduction...)
View the document4.1. Soil Quality and Fertility
View the document4.2. Biodiversity
View the document4.3. Energy Balances
View the document4.4. Carbon Emissions
View the document4.5. Hydrology
View the document4.6. Chemical Loading of Soil and Ground/Surface Water
View the document4.7. Restoring Degraded Land
View the document4.8. Environmental Indicators for Evaluating a Project
View the documentReferences for Chapters 3 and 4

4.8. Environmental Indicators for Evaluating a Project

To the extent that they can be measured, quantitative indicators are helpful in evaluating overall impacts. Table 4.5 offers some possible quantitative indicators. These indicators relate to many of the impacts that are discussed in the preceding sections. Most of them are relatively straightforward, and should be measured at intended project sites, estimated for prospective project designs, and then regularly measured for ongoing projects.

Table 4.4. Selected Species Tolerant to Specific Conditions

species

Acacia
aurinculiformis

A.
mearnsii

A.
saligna

A.
senegal

Albizia
lebbek

Azadirachta
indica

Casuarina
equisetifolia

Casuarina
sequisetifolia

Cupressus
arizonica

Eucalyptus
brockwayi

E.
camaldulensis

E.
globulus

E.
gomphocephala

E.
intertexta

E.
microtheca

E.
occidentalis

E.
salmonophloia

Gmelina
arborea

Leucaena
Leucocephala

Parkinsonis
aculeata

P.
articulata

Pinus
halepensis

Prosopis
juliflora

P.
tamarugo

Schinus
molle

Tamarix
articulata

Zizyphus
mauritiana

conditions




























arid lands



Ö

Ö





Ö

Ö

Ö



Ö

Ö

Ö

Ö



Ö








heavy soils

Ö

Ö

Ö

Ö

Ö

Ö





Ö

Ö



Ö

Ö


Ö

Ö









impeded drainage

Ö














Ö













alkaline soils

Ö


Ö




Ö




Ö


Ö


Ö

Ö



Ö

Ö








saline soils



Ö





Ö



Ö


Ö



Ö




Ö








Source: Ramsay, 1985

Table 4.5. Selected Indicators of Environmental Sustainability

Category

Impact

Quantitative indicators, based on assessment of:

Soil quality and fertility permeability

Nutrient depletion, acidification, organic content loss, soil texture.

Soil analyses. (Soil density, porosity, water-permeability, temperature; heat conductivity, heat capacity; nutrients: phosphorus, potassium, sulfur, nitrogen, magnesium, etc.)

Biodiversity
Energy balances

Conversion of genetically rich or poor habitat.
Increased use of sustainable, renewable resources.

Biodiversity under alternate/prior land uses.
Relative full fuel-cycle consumption of fossil resources.

Carbon balances

Reduction in carbon (and other greenhouse gas) emissions.

Relative fuel fuel-cycle emissions of carbon, including carbon sequestered above and below ground in biomass supply systems

Hydrology/water resources

Water consumption or replacement, quality.

Water table height, surface water availability, seasonality, quality.

Chemical inputs and runoff

Increased or decreased loadings of fertilizers, herbicides, pesticides, COD/BOD

Soil, surface water and ground water analyses.

Land quality

Restoring or degrading of land.

Land quality and productivity under alternate/ prior land uses. Diversity of products and uses provided.

Air quality

Avoided outdoor and indoor pollution from waste combustion, pollution from bioenergy cycle.

Analyses of outdoor and indoor air quality. Investigation of human respiratory health impacts.

Box 4-1. Restoring Degraded Land and Establishing Bioenergy Crops: Sample Strategies

Soil temperature: Supply mulch and use cover crops to provide shade. Plant during relatively cool periods (temperatures in excess of 30ºC can cook plant roots).

Soil fertility: Supply mulch and use cover crops that build soil organic matter and help to recycle nutrients. Use leguminous species, manure, or, if necessary, chemical fertilisers (phosphates are often necessary). In some cases, it will be possible to make existing nutrients available by adjusting the soil pH.

Retaining water: Supply mulch and use cover crops to retain soil moisture. Plant in depressions to retain accumulated water and aid water infiltration near the plants. Create contours, channels, and other physical structures to harvest water and direct it to areas of plant growth.

Draining water: Use plants with high water demands (such as many Eucalyptus species). Use physical measures to drain land.

Erosion: Reduce ground-level wind speeds and water flow rates using mulch and cover crops. Stabilise soils using crops with appropriately deep, extensive, and quickly growing roots (for example, Casuarina has been used to stabilise sand dunes). Create wind breaks and water barriers by using physical structures (contours, bunds, etc.) and crops (hedgerows, etc.).

Browsing: Remove or greatly reduce browsing pressure, using fences, predators, guards. Grow species that are unpalatable or otherwise resistant to grazing, while providing alternate sources of fodder if necessary. Otherwise grazing can easily devastate a young colony of plants.