Table
of Contents
Application
of TAMARIN
Optimization
Model
Conclusions
References
Credits
Chomitz
et al. (1999)
recommended a framework to guide the application of incentive-based policies
for encouraging the provision of environmental services – including biodiversity
conservation – by landholders. This framework, they propose, would
enable the simulation of alternative schemes that would “encourage clarity
in the definition of goals and permit the development of simple, implementable
strategies to reach those goals” (Chomitz
et al. 1999,
p. 168). Because land use, opportunity costs, and biodiversity value
vary spatially, the framework was envisioned as a means to exploit that
variation to craft simple, implementable policy options.
In this report
we describe an implementation of an analytical framework based upon the
suggestions in Chomitz
et al. (1999).
Specifically, we outline the framework and its basis in current conservation
science and economic theory, which are used to define the desired landscape
configuration for the conservation objectives. We then present a
case study in the “Mata Atlântica,” or Atlantic Forest, region of
south Bahia state in Brazil to illustrate an application of the framework,
named TAMARIN (Toolbox for Analysis of Mata Atlântica Restoration
Incentives). We demonstrate
TAMARIN by comparing a series
of scenarios, including the present situation and the likely future trend.
The results indicate the tradeoff between the suitability of sites for
conservation with their value for other purposes.
TAMARIN
performs two sets of GIS-based procedures, using a representation of the
study area divided into 98.01 ha planning units (990 x 990 m). First,
it assists planning teams to design scenarios and second to evaluate their
economic and ecological consequences. Scenarios can be created by
drawing on an electronic map, by defining rules for selection based on
conservation and/or economic criteria, or by an external optimization model
developed for the project. Scenarios can be constrained by a maximum
budget limit or can be unconstrained with the total costs being calculated
as a consequence of the plan. The framework can then calculate the
effects of the scenario and create a series of GIS themes, tables, graphics,
and reports that summarize the salient features for comparison with the
present situation and other scenarios.
In addition
to TAMARIN, the
project developed an external optimizing land allocation model (Optimal
Habitat Patch Selection or OHPAS) that selects the most cost efficient
set of areas for conservation action that satisfies the desired future
landscape configuration, if feasible within the budget constraint.
The optimal solution is then evaluated in terms of the same socioeconomic
and environmental factors as other scenarios inside TAMARIN.
The optimal scenarios therefore set benchmarks against which scenarios
for various policy instruments can be compared.
Top
of the Document
Central Atlantic Forest Corridor
The Atlantic
Forest, Mata Atlântica, is by far the most threatened major ecosystem
in Brazil, with less than 8% of its original area remaining. Conservation
International places it third on its list of the 19 highest-priority habitats
for conservation on the planet (based on the combination of threat and
uniqueness). Within the Mata Atlântica, the area in southern
Bahia is considered one of the highest priorities. In response to
this global importance, the Programa Estadual para a Conservação
da Biodiversidade (PROBIO) has funded a major biodiversity assessment and
planning project for south Bahia. The project area is named the Central
Atlantic Forest Corridor (hereafter referred to as the “Corridor”) (see
location map below). The dimensions of the Corridor are approximately
580 km (north-south) by 150-250 km (east-west).
Location map of Central
Atlantic Forest Corridor.
Bioregions in Central Atlantic
Forest Corridor.
Within a
tropical area this large, there is naturally a significant variability
of landscapes and land uses. Nine distinct bioregions are recognized
in the Corridor. Along the immediate coast lies a narrow band of
coastal, wetland, and riverine ecosystems. From east to west, the
wetter bioregions support a tropical wet forest that grades into moist
or semi-deciduous forest in the interior. Field surveys conducted
by the PROBIO project have revealed a remarkable species replacement in
both flora and fauna across the north-south gradient of the corridor.
In particular, the Rio de Contas and Rio Jequitinhonhia form biogeographic
barriers that foster speciation. Consequently, the vegetation types
and rivers divide the Corridor into nine bioregions.
Besides the
biological differences between bioregions, there are related differences
in land use and land tenure. The northern and central lowland forest
bioregions are dominated by cabruca, a form of shade plantation
for cocoa. Cabruca provides better habitat for forest canopy species
than most other forms of agriculture but is not as suitable for understory
birds as primary forest. Unfortunately, global market forces, government
policies, and invasion of a devastating crop disease, are inducing farmers
to convert cabruca to pasture. Farm size tends to be smallest and
population density is greatest in this part of the Corridor. The
southern tabuleiro forest bioregion retains some of the largest forest
fragments in the corridor region. Farm size tends to be larger, and
as a result, population density tends to be lower than in the northern
bioregions. The interior semi-deciduous forest bioregions have been
largely converted from forest to pasture, with only clusters of very small
forest fragments remaining. Of the 74, 219 km² in the Corridor,
only 8.8% remains as primary forest.
Top
of the Document
Principles
TAMARIN
is based on conservation principles of representation, resilience, and
redundancy. These are translated into the following specific criteria
used in designing TAMARIN: 1) entire environmental/species gradients
should be represented, 2) at the biogeographical scale, representation
should only be counted if a forest fragment is larger than the area needed
to maintain viable populations of focal species, 3) edge habitat is less
suitable for interior forest species and should not count toward the representation
goals, 4) several such forest fragments are necessary in each region as
backups in case of catastrophic loss of any single fragment, and 5) restoration
is most likely to be successful in close proximity to primary forest fragments.
From theoretical
and empirical economics studies, we incorporated the following economic
principles into TAMARIN: 1) opportunity costs vary spatially in
response to relatively predictable biophysical and socioeconomic factors;
2) recognition of the variability may lead to more cost efficient conservation
strategies; 3) economic incentives will more likely elicit the desired
behavior from private landholders than command-and-control strategies;
and 4) policy instruments derived from these principles must be based on
a relatively simple set of rules that address the conservation objectives,
yet are understandable and equitable to all stakeholders. Part of
the challenge is that policies are directed towards changing land uses
with the hope that those changes will produce the desired outcomes in landscape
structure/function/composition.
Top
of the Document
Assumptions
We designed
TAMARIN
to be extremely flexible in allowing users to change many of the assumptions
underlying it. Based on discussions with local experts, we made a
number of basic baseline assumptions about future land use trends, the
ability of the land to be restored to forest, the role of reserves, the
minimum size forest patch needed to maintain viable populations for focal
species, and other landscape ecological factors. We assumed that
recent land use trends will continue over the next one or two decades if
conservation interventions are not applied:
·Primary
forest will no longer be converted to other uses because it primarily remains
on marginal lands and has legal protection, but it will be degraded into
secondary forest. Secondary forest will be permanently converted
to pasture or agriculture except where adjacent to primary forest.
Cabruca will be entirely replaced by other forms of agriculture.
Pasture and agricultural lands and eucalyptus plantations will persist.
·Agricultural
land and pasture that is abandoned will be recolonized by forest within
a relatively short period (circa two decades). Cabruca, because it
retains most of the native canopy trees, will recover more quickly.
·Primary
forest in existing reserves will be protected from serious degradation,
and disturbed sites in reserves will gradually recover.
·
A
conservation program for the corridor can either purchase land or purchase
easements on the land. Purchase of the land will cost the market
value of the property. We assume that to purchase a conservation
easement, an owner must be paid an incentive at least equal to the foregone
opportunity cost of the land in addition to the management costs.
·We
defined the desired forest landscape configuration in terms of representation,
redundancy, and resilience parameters. It was decided to require
representation of at least two forest habitat units in all seven forest
bioregions. A contiguous area of forest (primary and, if necessary,
restored forest) had to be at least 10,000 ha, based on unpublished analysis
of extinction probabilities for the Cebus xanthosternos, the
yellow-breasted capuchin. A contiguous habitat unit of this size
is expected to give 95% probability of survival for 100 years. Because
C.xanthosternos
can traverse nonforest habitats to reach other forest fragments, we relaxed
the contiguity requirement by allowing fragments within 1000 m to be considered
part of the same functional habitat unit. (Photo by Russell Mittermeier).
·Edge
effects will degrade small forest fragments over time, rendering them of
low biodiversity value. We assume a depth-of-edge-influence extending
300 meters from edges into forest fragments (Gascon et al. 2000).
Core forest was defined for this study as primary or restored forest greater
than 300 m from an edge of agriculture/pasture or urban area.
Top
of the Document
Application of TAMARIN
We used TAMARIN
to design and evaluate five basic scenarios, including three stylized approaches
that conservationists in the corridor had previously suggested. This
provided an opportunity to demonstrate TAMARIN to a workshop in
Salvador, Bahia, in June 2001, illustrating the tradeoffs inherent in corridor
planning and the value of a formal framework for doing it. We also
include one of the optimal scenarios here as a benchmark for comparison
with other designs.
The scenarios
were:
·Current—an
evaluation of the present situation according to the landcover map, which
was derived from 1997 satellite imagery. This defines a benchmark
of how the landscape is currently configured.
·Business-as-usual—our
assumption about the likely future if no conservation interventions were
applied except for existing reserves.
·Cabruca—a
restoration of cabruca (i.e., select all cells with greater than 50 ha
of cabruca).
·Link
reserves—linking the existing reserves with a series of connecting swaths
of habitat of 1-2 km wide. The highest cumulative path of habitat
suitability, analogous to a least cost path, determined linkages.
·Viable
islands—manually selecting blocks of planning units to meet the conservation
objectives in high suitability/low cost areas. This scenario was
an attempt to manually emulate an optimization approach to show, to a first
approximation, how efficiently the objectives might be met.
·Optimal
benchmark—a least cost scenario (based on OHPAS) that ensures that
at least two habitat blocks are protected per bioregion, and that the blocks
are at least the minimum size and contain at least 1,000 ha of primary
forest.
Scenarios
were evaluated according to ecological and socioeconomic criteria.
The ecological goals of representation, resilience, and redundancy were
deemed met if each of seven distinct bioregions encompassed at least two
protected ‘viable habitat units’ of 10,000 connected hectares each.
Habitat in the viable habitat units could consist of primary forest or
abandoned land (secondary forest, cabruca, or agriculture/pasture) assumed
to regenerate into forest. Additional ecological criteria included
area of primary forest placed under protection, the number of habitat units
with at least 1,000 ha or primary forest as a source of propagules, and
proportion of total forest exposed to edge effects. Socioeconomic
criteria included affected population and opportunity cost of conservation.
We considered two alternative assumptions about the opportunity cost of
conservation. The high assumption used the full market value of the
land; the low assumption assumed that landholders derived some benefits
from the land even if agricultural uses were restricted, and hence that
a conservation easement could be purchased for less than the full market
value.
The following
table summarizes key results for the six scenarios. There are several
striking results worth noting in the table. First, in the current
scenario the conservation objectives are met in six of the seven bioregions,
but the majority of remaining forest consists of small patches (mostly
edge forest) within the gap crossing distance. That is, very few
of the fragments are large, relatively round blocks of core habitat.
As a consequence of our business-as-usual assumptions, the percentage of
primary forest significantly declines in the other four scenarios (from
8.8% to less than 2% in most cases). Much of this decline is in the
loss of small, scattered fragments consisting of mostly edge forest (note
that ¾ of remaining forest is in the edge zone in the Current scenario).
This lack of remaining large fragments required the restoration of nearly
half of the planning units selected in both the Viable islands and the
optimal benchmark scenarios. In addition, the habitat-friendly cabruca
land use disappears by assumption in all future scenarios, thus lowering
the habitat quality of the matrix (the nonforest agricultural lands surrounding
natural habitat). Maintaining cabruca as a strategy (while failing
to conserve primary forest) entails very high loss of primary forest and
extremely high financial cost, while still not achieving the conservation
objectives in two bioregions where cabruca is not found. By focusing
directly on the stated conservation objectives, a corridor can apparently
be designed at a remarkably low financial cost, as low as $6 million US
(R$12 Brazilian) for easements or environmental compensation, by our initial
estimates for the optimal benchmark scenario. However, the optimal
benchmark was unable to find a second planning patch or block in the Northern
Semi-deciduous bioregion that was of minimum size and also contained enough
primary forest.
|
|
|
Baseline
Scenarios
|
|
|
|
|
Present
|
|
Business-as-usual
|
|
Restore
cabruca
|
|
Link
reserves
|
|
Viable
islands
|
|
Optimal
benchmark
|
|
|
#
planning units selected
|
|
N/A
|
|
N/A
|
|
7,801
|
|
5,203
|
|
1,670
|
|
1,339
|
|
|
#
regions with 2 habitat units > 10,000 ha
|
|
6
|
|
1
|
|
5
|
|
6
|
|
7
|
|
6
|
|
|
#
viable habitat units with > 1000 ha of primary forest
|
|
12
of 12
|
|
4
of 4
|
|
5
of 19
|
|
10
of 12
|
|
13
of 15
|
|
13
of 13
|
|
|
%
of corridor in forest
|
|
8.8
|
|
1.1
|
|
11.3
|
|
6.9
|
|
3.1
|
|
2.7
|
|
|
%
of forest in depth-of-edge-influence zone
|
|
74
|
|
14
|
|
33
|
|
12
|
|
12
|
|
12
|
|
|
Total
easement value of selected units (million reais)
|
|
N/A
|
|
N/A
|
|
140
|
|
96
|
|
14
|
|
12
|
|
Top
of the Document
Optimization Model
TAMARIN
assists users to craft conservation strategies and evaluate them but does
not enforce the desired landscape configuration objectives. As such
the process is essentially rule-based, where the rules are the criteria
a planner thinks might create a plausible policy option. We also
wanted to have a tool that would select planning units for conservation
that did ensure that the landscape objectives were achieved and do so at
least cost. Such optimal solutions may not always be feasible to
implement for other reasons, but they provide a benchmark to measure how
much more it will cost to select a suboptimal solution. The optimization
reserve design process involves the following three steps:
1.Determine
for each planning unit the environmental compensation costs and suitability
in terms of amount of primary (and potentially restorable) forest.
This was easily done through queries of TAMARIN’s database.
2.The
size of the basic planning unit is small in regard to what would be minimally
acceptable as a viable conservation area. A Planning Patch is defined
as a set of connected planning units, which in concert meet the conditions
of resilience. In this second step, we generate a large number of
planning patches, from which to design a reserve system. This patch
growing process (PGP) is based upon a computer algorithm that systematically
generates possible patches for consideration that contain a minimum of
10,000 ha of primary and/or restored forest. Further,
each Planning Patch must contain at least 1,000 ha of primary forest.
3.The
third step involves a large-scale optimization model (OHPAS) that
selects a set of Planning Patches that together optimize a set of objectives
and constraints. The idea is that the set of possible planning patches
spans the set of representative design alternatives. The selection
of the optimal set involves minimizing cost as well as meeting all of the
desired constraints. The selection of Planning Patches is also subject
to the need to represent different bioregions. Regional distribution
constraints maintain that at least a minimal set of Planning Patches is
selected in each region.
Top
of the Document
Conclusions
TAMARIN
was developed to facilitate the design and evaluation of alternative scenarios
for application of economic incentives to identify priority sites within
a large region for rainforest conservation or restoration. In particular,
our goal was to integrate current principles in conservation biology with
economic theory in a GIS framework that makes explicit the costs and benefits
of each incentive option. Compensation of the opportunity costs of
conservation is employed here as an incentive to modify behavior as an
alternative to outright acquisition or command and control strategies such
as agroecological zoning. Although we made many assumptions for our
example scenario concerning the desired landscape configuration, opportunity
costs, and trends in land use change, the framework is very flexible in
allowing stakeholders and planners to substitute competing assumptions
and objectives. These substitutions can be made as new GIS themes
or simply as parameters to be entered when defining a scenario. We
also discovered that users of the TAMARIN framework invented a mode
of flexibility we had not foreseen. At a workshop held in Salvador,
Brazil, in June, 2001, planning groups spontaneously began applying different
economic incentives in different locations as they allocated a hypothetical
budget.
The
suite of models for optimization of the conservation and economic objectives
constitute another significant contribution of the project. The patch
growing process, PGP, used GIS data from TAMARIN to generate
a set of sample planning patches that were guaranteed to satisfy the landscape
criteria for minimum patch size and minimum amount of primary forest.
Thus any patches selected automatically achieved the conservation objectives.
The
OHPAS optimization model then did the actual selection of the
desired number of patches, controlled the amount of overlap allowed among
them, and minimized the cost. This report presents only the initial
application of this set of models for the corridor. We have only
begun research on the implications of varying assumptions and objectives.
The real
value of TAMARIN is not in assisting with making better decisions
per se but in facilitating the planning process by interpreting spatial
information to understand the tradeoffs between conservation and other
social goals. Stakeholders and planners are forced to be explicit
and quantitative in defining the desired future landscape configuration,
to think not just about the current landscape but how it is likely to change,
and to be creative in formulating equitable and affordable economic policies
that can achieve the desired landscape with minimal disruption to the social
fabric. The details of designing an incentive program, including
the identification of exactly which parcels are eligible, would still need
to be developed at a finer scale with more stakeholder involvement.
Although
TAMARIN was tailored to the planning issues and data sources
of south Bahia, the ecological and economic underpinnings make it adaptable
to many other locations.
There
are many potential enhancements to TAMARIN that would
increase its utility for regional conservation planning. Several
that have immediate value include:
·Allow
users to identify a nucleus of a forest block and have an option where
the software would automatically expand each nucleus to a viable fragment,
much like the planning patch program does.
·Developing
a formal land use change model was beyond the scope of
this project, but could be a valuable addition to TAMARIN.
·Add
an option to design feasible alternative policy instruments for a range
of environmental services (carbon sequestration and watershed services)
and natural capital (biodiversity) and explore the tradeoffs between them.
This project
focused on tool development rather than analysis. Thus there are
many opportunities for additional analysis of alternative assumptions,
trade-offs, and weights in both the TAMARIN framework and the optimization
tools. We have not yet begun to formally study the implications of
alternative policy options for economic incentives. The incorporation
of other conservation benefits, such as carbon sequestration and watershed
services, would make a richer research and planning environment for determining
the relationship between biodiversity conservation and incentives for other
conservation issues.
In the near
future,
TAMARIN will be made publicly accessible along with the
GIS data from our project collaborators for use in conservation planning
in south Bahia. Check our web site at http://www.biogeog.ucsb.edu/projects/wb/wb.html
for updates on its status and applications.
Presentations
of the results of this project have been made at two scientific conferences:
TAMARIN: A landscape
framework for evaluating economic incentives to foster rainforest restoration.
David Stoms. Presented at the 17th Annual Symposium of
the International Association for Landscape Ecology, US Regional Association,
Lincoln, Nebraska, April 2002.
Solving a large
scale reserve design problem in Bahia, Brazil. Richard Church, Ross
Gerrard, and David Stoms. To be presented at the INFORMS Annual Meeting,
San Jose, California, November 2002.
Top
of the Document
References
Chomitz, K. M.,
E. Brenes and L. Constantino. 1999. Financing environmental
services: The Costa Rican experience and its implications. Science
of the Total Environment 240: 157-169.
Credits
Although
staff of the University of California developed the TAMARIN software,
Santa Barbara, many people and institutions contributed to its development
and realization. The original concept is due to Kenneth Chomitz,
who contributed to the design of the economic aspects of the framework.
Gustavo Fonseca and Keith Alger (Conservation International (CI) /Center
for Applied Biodiversity Science (CABS)) also made important contributions
to the framework design and to its application to south Bahia. Crucial
data components included: the land cover characterization undertaken by
Charlotte Landau (Universidade
Federal de Minas Gerais); the vegetation classification by Andre
Carvalho (Centro
de Pesquisas do Cacau) and Wayt Thomas (New York Botanical Garden);
the land value survey data gathered by IESB under the supervision of Heloisa
Orlando and interpolated by Timothy Thomas; the RADAMBRASIL land characteristics
maps provided by the Instituto Brasileiro de Geografia e Estatística
(IBGE). This project benefited greatly from additional contributions
of data, expertise, and local knowledge of the ecological and cultural
environments of south Bahia provided by participants in a sister project
funded by Programa Estadual para a Conservação da Biodiversidade
(PROBIO) and administered by IESB and CABS. We are grateful also
to participants in three workshops (two in Ilheus and one in Salvador)
who provided in-depth feedback on TAMARIN during its development.
We regret any inadvertent omissions from this list of contributors.
This project
was funded through a contract between The World Bank (Contract Manager
Kenneth Chomitz, Development Research Group, World Bank) and the University
of California at Santa Barbara (Principal Investigator, Frank Davis; Co-PI,
David Stoms). Funding was provided by World Bank Research Support
Board grant no. 683-42 and by the Rain Forest Trust. In-kind contributions
were made by the PROBIO project. We also thank Kathy Scheidemen,
John Sanchez and other staff at UCSB’s Institute for Computational Earth
System Science for contract accounting and administration. Mike Colee provided
computing support at the UCSB Biogeography Lab. Doug Fischer of the
UCSB Geography Department helped with some of the programming for the optimization-modeling
component of the project. Thanks also to Peter Choi for help in testing
the TAMARIN software and reviewing the users manual.
Top of the Document
Return
to project home page
Final
Report to The World Bank, Washington, DC