To focus the assessment using VECs, e.g. for species:
- Charismatic and emblematic species
- Economic importance
- Protected status
- Rarity
- Endangerment/conservation status
- Susceptibility and/or responsiveness to defined impacts (indicators)
- Umbrella species
- Important ecological role (e.g. position in food chain, keystone species)
- Availability of consistent survey methods
- Expediency/tractability for survey
Key functional attributes and processes:
- Nutrient cycles (can effect system productivity and species composition)
- Energy flow (affects ability of systems to 'support' component species)
- Productivity (affects ecosystem function and species composition)
- Eutrophication (a form of increased productivity with implications for species composition)
- Succession (knowledge of patterns of succession is important for predicting community change over time)
- Colonization (can be a key in maintaining populations)
- Dispersal (can be key in maintaining populations and is also important with respect to ability to recover following impact)
- Competition (altered competition has implications for species composition and patterns of succession)
- Assimilative capacity (can affect ability of a system to absorb or recover from pollution)
- Population processes (breeding, migration)
The baseline
At some point it is necessary to define the 'baseline' against which future impacts can be assessed
The baseline study should anticipate the future state of the environment assuming the project is not undertaken - the 'no action alternative'
Baseline studies should be undertaken for each alternative (site) so that the implications of each alternative can be assessed
New field based data are necessary (e.g. biodiversity survey) if information is not available, or is old and not relevant to the assessment
Although many EIAs fail to consider alternatives, alternatives are really at the 'heart' of the EIA. Many EIA professionals consider them as essential 'raw material' of good EIA.
- Project characteristics
- Location and size
- Schedule of construction and operation
- Activities, emissions, disturbance
- Extent, magnitude and duration of
- Alternatives for site and design
- Past, current and future proposals
- Associated developments
- Characteristics of ecosystems
- Distributions and ranges
- Species composition
- Structural organisation,
- Population sizes, stability
- Rarity, endemism
- Endangerment
- Extinction risk
- Genetic diversity
Impact evaluation
(Prediction of outcomes relative to baseline taking into account the the range and magnitude of the impacts) and the resilience, fragility, stability, conservation significance, threat status, uniqueness of biodiversity affected
Biophysical changes
- Habitat loss or destruction (e.g. vegetation clearing)
- Altered abiotic/site factors (e.g. soil removal and compaction)
- Mortality of individuals (e.g. through collision)
- Loss of individuals through emigration (e.g. following destruction of habitat)
- Habitat fragmentation (e.g. barrier effect of road and pipeline)
- Disturbance (physiological and behavioural)
Ecological changes
- Mortality of individuals due to better access
- Reduced population (due to reduced habitat, size and quality)
- Altered population dynamics (due to altered resource availability)
- Increased competition (due to shrinking resources)
- Altered species composition and habitat changes (due to fragmentation)
- Reduced gene flow (due to restricted migration)
- Habitat isolation causing reduced breeding success
- Altered prey-predator relationships
Cumulative impacts (time- and space-crowded effects)
- Habitat 'nibbling' (progressive loss and fragmentation throughout an area)
- Reduced habitat diversity, e.g. at the landscape level (associated with reduced biological diversity at other levels in organizational hierarchy)
- Habitat fragmentation over time, resulting in progressive isolation and reduced gene flow
- Reduced genetic diversity can result in loss of resilience to environmental change and increased risk of extinction
- Irreversible loss of biological diversity (e.g. through destruction of unique population units)
Impact Assessment: involves evaluation of magnitude, extent and significance of environmental impacst
Significance can be determined through professional judgement, reference to regulations and criteria evolved
The conclusions of the impact assessment can ultimately be used by decision-makers when determining the fate of the project application
Impacts can vary in nature, magnitude, extent, timing, duration and reversibility
Questions to ask when evaluating impact significance
- What impact will the project have on the genetic composition of each species?
- Do major systemic or population changes appear to be taking place?
- How will the proposal affect ecosystem processes? Is this proposal likely to make the ecosystem more vulnerable or susceptible to change?
- Does the proposal set a precedent for conversion to a more intensive level of use of the area?
- Is the biological resource in question at the limit of its range?
- Does the species demonstrate adaptability.
- What level of confidence or uncertainty can be assigned to interpretations of the effects?
Direct and indirect drivers of change
Example
Impacts of roads
- Habitat fragmentation and modification: e.g. introduction of barriers
- Restriction of animal movements
- Injury and mortality of wildlife
- Soil erosion and hydrological alterations
- Environmental contamination / pollution
- Human colonisation-induced disturbances
Examples of potential impacts of roads on wildlife
| Project characteristics/ activity | Direct impacts | Indirect impacts | Cumulative/ syergistic impacts |
|---|---|---|---|
| Clearing of vegetation | Loss or degradation of habitat | Reduction in habitat use | Decline in wildlife population and diversity |
| Increase in traffic volume | Increased road kills | Decline in populations | Change to trophic dynamics and species composition |
| Road alignment through wildlife habitat | Increased access to pristine wildlife habitat areas | Unplanned development | Decline in habitat quality |
| Poaching | Species decline | ||
| Land acquisition for road | Displacement of people | Colonization pressure in unsettled areas | Deterioration of previously undisturbed natural areas |
Animal mortality on roads in protected areas of India and Nepal (1997-1998)
| Number of individuals killed per year | Wildlife habitats and the nature of roads on which mortality is reported | |||||
|---|---|---|---|---|---|---|
| Tadoba Tiger Reserve | Sariska Tiger Reserve | Gir National Park and Sanctuary | Corbett Tiger Reserve | Pench Tiger Reserve | Royal Bardia National Park Nepal | |
| FR | SH | SH | SH | NH | NH | |
| Chital | 2 | 1 | 3 | |||
| Sambar | 3 | 1 | ||||
| Nilgai | 2 | 1 | ||||
| Wild boar | ||||||
| Lion | 2 | |||||
| Leopard | 1 | 4 | ||||
| Tiger | 2 | 5 | 2 | |||
| Langur | 17 | 37 | 1 | |||
| Civet | 3 | 1 | ||||
| Porcupine | 1 | |||||
| Barking deer | 2 | |||||
| Mongoose | 4 | 1 | ||||
| Hyaena | 2 | 1 | ||||
| Jungle cat | 1 | 1 | ||||
| Total road kills | 29 | 8 | 6 | 46 | 6 | 6 |
| Source | Dubey, 1997 pers. comm. | Johnsingh et al. 1998 | Singh & Kamboj 1996 | Uttar-anchal Forest Dept. | Areendran & Pasha 1999 pers. comm. | Karki & Shreshtha 1998 pers. comm. |