APPENDIX 1. Additional methodological
information
Definition of the Environmental Benefits Index
The term Environmental Benefits Index (EBI) was inspired by the USDA Conservation
Reserve Program as a programmatic rule for ranking the cost-effectiveness
of land units bidding for program participation. The scoring procedure
uses an arbitrary but plausible and simple-to-implement point system.
The highest points are assigned to mature forest and to wetlands. Secondary
forest and shade cocoa/cabruca are assigned moderate point values if located
in the same land unit as mature forest, because they then offer good prospects
for forest regeneration. Otherwise secondary forest and shade cocoa/cabruca
receive a lower score.
EBI was defined as follows:
EBI = [1000/(per-hectare land value)]*
[5 * P_mature +
5 * P_wetland +
3 * P_cabruca * D(P_mature) +
3 * P_secondary * D(P_mature) +
1 * P_cabruca * (1 - D(P_mature)) +
1 * P_secondary * (1 - D(P_mature))]
where D(x) = 0 if x = 0
D(x) = 1 if x > 0
P_mature = proportion of planning unit in mature forest
P_cabruca = proportion of planning unit in cabruca and
other tree shaded cocoa
P_secondary = proportion of planning unit in secondary
forest
where land value and land cover proportions are
calculated for the part of a land unit that is not urban, water-covered, or in a
protected area.
Land cover transition rules
Lacking a quantitative, behavioral model for land use change in Bahia, the
authors employed a simple deterministic model of change, assuming continuation
of current trends over a notional period of two decades. A transition matrix
specified future land cover under two different states for the land unit:
business-as-usual, and protected status (i.e. under conservation easement).
Selection into protection places all vegetation into ‘regenerating
forest’ status. Regeneration is costless (due to assumed seed sources)
except for pasture/agriculture pixels that are not in the same land unit as
mature or secondary forest; for these areas a reforestation cost is
incurred.
In the business-as-usual scenario we assume that, despite legal regulations
against clear-cutting or degradation of forest, mature forest will be degraded
gradually into secondary forest through timber and firewood extraction and
agricultural encroachment. Secondary forest will be permanently converted
to pasture or agriculture except in areas where it is near mature forest;
in such situations, it will remain secondary forest. In the business-as-usual
state, the fate of cabruca and other tree shaded cocoa culture depends
on local agronomic conditions. Cabruca will be partly replaced by other
forms of agriculture except in areas where previously established on soils
with the highest agricultural production capacity (prime farmland), on steep
terrain (larger than 70% slope) or on floodplains. For convenience of processing,
surviving cabruca and other tree shaded cocoa was reclassified to secondary
forest, because we assume that it has the same properties buffering edges
and facilitating gap crossing. Pasture and agriculture will remain unchanged,
because we assume no spontaneous abandonment and regeneration of farmland.
Bare land is assumed to be a temporary state of agricultural land that is
reclassified as agriculture/pasture for the future. Urban land uses and
other habitat types (e.g., mangrove, wetlands, water bodies) cannot be converted
into forest and are assumed to remain in their present condition. Similarly,
we did not anticipate changes for restinga and caatinga. For a summary of
all rules see the table below.
|
|
| Land Cover
Class |
Business As Usual Scenario |
Restoration Scenario |
|
| Mature forest
|
Secondary forest |
Mature forest |
| Secondary forest |
Secondary forest if near mature forest; otherwise pasture/agriculture |
Restored forest |
Cabruca and other
tree shaded cocoa
|
Secondary forest on fertile soils, in steep terrain or on flood plains;
otherwise pasture/agriculture (see text for details) |
Restored forest |
| Eucalyptus plantation |
No change |
No change |
| Pasture/agriculture
|
No change |
Restored forest |
Bare soil
|
Pasture/ agriculture |
Restored forest |
| Restinga |
No change |
No change |
| Caatinga |
No change |
No change |
| Mangrove |
No change |
No change |
| Wetlands |
No change |
No change |
| Water |
No change
|
No change |
| Urban |
No change
|
No change |
| No data |
No change
|
No change |
|
|