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Appendix D
The Nature Conservancy:
Aquisition Priorities
and Preserve Selection and Design
ACQUISITION PRIORITIES
In 1917, the Ecological Society of America (ESA) formed the Com-
mittee for the Preservation of Natural Conditions for Ecological Study,
chaired by Victor Shelford. For 26 years, that committee tried to locate
and preserve natural areas for scientific research, and it actively support-
ed conservation organizations. Some of the membership objected to
ESA's active support policy, and in 1946, Shelford formed a private
independent organization, The Ecologists' Union, which eventually
published an inventory of 691 nature sanctuaries. In 1950, The Ecolo-
gists' Union was renamed The Nature Conservancy (TNC). McIntosh
(1985) stated "it has proven markedly successful in securing natural
areas using a revolving fund and arranging for their protection, either by
transferring responsibility to a stable institution in state or federal gov-
ernment or by managing it themselves."
Goals
TNC states Hat its primary objective is to conserve biological and
ecological diversity. To this end, TNC lists, classifies, characterizes,
and inventories "the enormous diversity and complexity of our biota,
ecosystems, and landscapes." The Nations Heritage Program Operation
Manual (NHPOM) states, "many earlier conservation inventories suf
247
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248 SETTING PRIORITIES FOR LAND CONSERVA TION
fared from objectives that were unclear or overly general. By lumping
together information on biology, scenery, recreation values, exploitable
resource potential, property ownership, etc. the results were muddled."
To accomplish TNC's objective, natural heritage inventory programs
were established. Those programs are defined as
a permanent and dynamic atlas and data bank on the existence, identity,
characteristics, numbers, condition, status, location and distribution of the
elements of natural biological and ecological diversity, of the individual occur-
rences of these elements in the landscape, of existing preserves, of outstanding
sites of potential preserves, of associate land ownerships, and of sources of
additional information and documentation.
The programs (which are updated continually) collect, manage, and
use biological, ecological, and related information in cooperation with
various state agencies. With the formation of the first state natural
heritage program in South Carolina in 1974, a systematic and workable
approach was developed by incorporating element occurrences (EO) and
ranking as a core to classify natural areas. Heritage programs (also
known as conservation data centers) have been established in all 50
states, 13 Latin American countries, 4 Canadian provinces, the Caribbe-
an, and the Soup Pacific. During the past 40 years, TNC has acquired
5.5 million acres in the United States and Canada and 15 million acres
in Latin America (Sawhill, l991b).
Priorities
Because it is impossible to inventory all biological diversity, heritage
programs tend to focus on He rarest, most endangered, and most vuIner-
able species (including intraspecific tax e) and communities with a special
emphasis on vertebrates and vascular plants. However, micro-organ-
isms, nonvascular plants, and invertebrates do receive attention if spe-
cialists Wink Hey are imperiled. TNC selects "the last of the least, and
He best of He rest." Attention is devoted to a comprehensive inventory
iAn element occurrence is any type of biological or ecological entity, e.g.,
species or community, in a geographic area.
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APPENDIX D
249
of communities and ecosystems within each state "at a practical level of
discrimination . ~
Priority ordinal ranking is based upon Tenements of natural diversity,"
which NHPOM defines as "~e basic units of the classification system
and the targets of the heritage inventory. These units are natural entities
which . . . represent the full array of natural diversity for the state or
region covered." Sites are ranked for the rarity of the elements and the
quality of the element occurrence as well as other values, uses, or bene-
Bts a site might have in addition to its potential contribution to biological
diversity conservation. Those values include ecological service func-
tions, such as aquifer recharge and erosion prevention, and other bene-
f~ts, such as recreation, aesthetic enjoyment, and historic and archeologi-
cal significance. This helps to identify potential partnerships and in-
crease the feasibility of implementation (R. Jenkins, pers. comm., TNC,
1991~. The goal is for all species to receive a "global" conservation
ranic. All North American vertebrates and 90% of the North American
vascular plants have been assigned ranks, as have many other taxa.
Operations
Heritage programs are established within states when a state agency
or other Institution expresses a desire to cooperate and agrees to take
over full support after start up. In the absence of expressed cooperation,
TNC can begin operations entirely on private funding. The staff is hired
by TNC in consultation with the cooperating agency and typically con-
sists of a botanist, a zoologist, a community ecologist, and an informa-
tion manager.
Operations are detailed in NHPOM, which ensures that ~! heritage
programs have standard data collections and information storage. The
manual is a technical one; specific information to collect usually is left
to the discretion of He staff in each state and is, in part, dependent on
He information base already accrued in each state.
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250 SETTING By_
Why Heritage Programs Work
NHPOM lists the following principles as accounting for the success of
heritage programs.
Focused goal: The clearly stated goal is to conserve natural diversity
and to collect information on selected subsets of "all the possible land-
scape attributes." That restricted focus and standardized data manage-
ment have facilitated He accumulation of a valuable and highly usable
data base.
Common units of comparison: The heritage program developed the
concept of elements of diversity that are defined as species, community
types, or other special features. The standard nomencIamre is "element,
element occurrence, site (land unit of preserve design), tract (land own-
ership parcel), managed area (for a preserve or semiprotected area), and
source of information (publication, person, agency, file, etc.~.
Balanced information system: The information system consists of
computerized and manual files. Computer records are used for sorting,
report generation, and to answer specific questions. The result is a
permanent but continually growing data bank.
Factual information: The data base does not contain interpretations,
conclusions, or weighting values. The system contains "what the actual
elements are, what their characteristics are, exactly where on the land-
scape their occurrences can be found, how their locations and geograph-
ic extent relate to ownership tracts and existing preserves, etc." Thus,
an accumulative and factual data base develops that can be used by a
wide range of users for a variety of purposes.
Multi-institutional cooperation: State agencies typically conduct the
heritage inventories. TNC provides a standard methodology, initially
trains He staff, offers technical support, and coordinates data exchange
and multistate collaboration. In addition, TNC often provides private
funds for initial operations. As a result, heritage programs become
permanent within state governments but are open for cooperation with
other agencies and organizations. And the standard methodology pro-
vides a uniform and highly integrated data base.
Operational continuity: The heritage date base is a permanent in-
ventory that grows and evolves with time. Of importance is the estab-
lishment of an institutional memory that "becomes increasingly accurate,
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APPENDIX D
251
complete, and useful." The inventory includes information on what
works and what doesn't work.
Practical geographic scale: The location of heritage programs within
states has achieved a geographic scale that is manageable and compre-
hensive.
Successive approximation: The heritage program and its data base
change over time as methods become refined and new data accumulate.
Data ranking: A system of element priority ranlcs was designed to
focus data gathering on the rarer elements; inventories are not bogged
down with limitless information.
Standardization: The heritage program "exhibits an unprecedentedly
high degree of standardization throughout. Absolute uniformity is main-
tained, 'which is crucial for data exchange, efficient research, system
evolution, and data retrieval for users."
Central support, data bases, and networking: The science division
trains new staff, develops new procedures, compiles suggestions from
field offices, raises funds, maintains operating manuals, monitors indi-
vidual programs, facilitates interaction among programs, encourages
cooperation with over agencies and institutions, and maintains a central
data base.
Cooperation of the local TNC office: TNC's state field offices are
required to support the heritage programs in a variety of ways that are
beneficial for all parties.
Utility: Heritage data systems originally were designed to foster
biological conservation but have proven to be useful in other areas, such
as research, education, management, environmental impact review, and
development planning
Objective neutrality: The heritage program tries to maintain a stance
of objectivity to protect He integrity and credibility of the data base.
The Classification System
Faced with He enormous task of inventorying and preserving biologi-
cal diversity, TNC has set up a system of filters. The coarse filter is
designed to include most of the species present without dealing with
individual species. This is accomplished by classifying community
types. wig the preservation of most community types in a region, TNC
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252 SETTING PR70RITIES FOR LAND CONSERVATION
estimates that 85-90% of the biological diversity of a state will be pre-
served. However, some rarer species might be found only in a few
communities. Thus, a fine filter is imposed that lists individual species
and where they occur. NHPOM discusses how to decide which species
should be fine filtered, and instructions also discuss potential problems
wig subspecies and hybrids.
Once listed, pertinent information on a species' status is entered into
the data base for tracking. Manual files, including maps, are created.
Heritage staff are advised to concentrate initially on managed land in
compiling element lists. Managed land usually is in public or institu-
tional ownership with a professional manager or managing agency. This
information is important to heritage programs because: I) a large pro-
portion of He biological diversity of a state often occurs on managed
land, so conservation efforts will not be wasted on an element already
protected to some degree, 2) it is often easier to increase protection on
managed lands than on unprotected lands, and 3) managed areas often
have rich data bases that may be used by the heritage program.
Priorities for Acquisition
After a preliminary inventory information base is established within
a state, elements are ranked based upon data collected on the frequency
of occurrence of an element. The ranking is done at a global (G), na-
tional (N), and state (S) level. At each of these levels, an element is
ranked from I-5, with ~ being most critical and 5 being least critical;
e.g., a G! ranking means "critically imperiled globally because of ex-
treme rarity (5 or fewer occurrences or very few remaining individuals
or acres) or because of some factors making it especially vulnerable to
extinction." Subspecies may be ranked by attached a T and I-5 to the
global ranking.
When the ranking has been decided for an element, measures are rec-
ommended that should be taken to conserve the element, including in-
ventory, research, and stewardship.
Noss (1987) criticized TNC's system for not considering He relation-
ships of community types within real landscapes. Noss recommended
Hat TNC's coarse filter be expanded so that I) disturbance and regener-
ation patterns are included in the evaluation, 2) landscape mosaics are
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APPENDIX D
253
addressed, and 3) surrounding habitat and corridors are examined in
conjunction with Me EO. TNC has recognized this problem and is
following these recommendations.
TNC recently started a biological reserve initiative called the "Last
Great Places": 12 sites (S in the U.S. and 12 in Canada) ranging in she
from 12,000 to 1,000,000 acres have been targeted for preservation.
Each area has been judged as an ecologically salvageable landscape and
a Functioning, but endangered, ecosystem that contains rare species
(Sawhill, 1991a). All 12 sites have a core natural zone of critical habitat
and a surrounding buffer zone in which land-use practices could affect
the core. According to the TNC president, the initiative fully recognizes
We rights of residents in these areas and will attempt to design steward-
ship practices that are compatible wig conservation and human interests
(Sawhill, 1991a). This initiative will be science driven, with the twofold
objective of conservation and sustained yield. This requires emphasis on
the integration of humans into Me conservation equation through sustain-
able development schemes and cooperative management strategies for
multiuse landscapes. In Me future, project selection process probably
will favor sites that are or can be included in landscape complexes over
isolated sites of dubious long-term viability (R. Jenkins, pars. comm.,
TNC, 1991).
PRESERVE SELECTION AND DESIGN
Objective
The Preserve Selection and Design Manual (PS&D) CTNC, 1987) is
to help select the highest priority sites for protection of EOs based upon
information supplied by Me heritage program data base. This manual
deals primarily with the administrative procedures of designing reserves
and Aloes not deal at length with the scientific aspects of preserve de-
sign."
The protection activities rely on three information sources provided
by heritage programs:
I) The Natural Diversity Scorecard lists elements in order of their
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254 SETTING PRIORITIES FOR LAND CONSERVATION
global and state ranking and scores how well they are doing in terms of
protective status: well-protected, underprotected, or not protected.
2) The Site Tracing Record lists alphabetically the most important
sites to be protected, the EOs at these sites, the ownership, and protec-
tion status by ownership tract.
3) The Pr7onty Site Lists is produced by analyzing the site tracking
record and listing sites in order of significance that will contribute the
most to natural diversity preservation. These sites become the priorities
within states for preserve design.
The Administrative Process
The preserve design process has five phases:
I) Initiation of preserve design (site selection, budgeting, hiring
designer);
2) Preparation of a preserve design package by
a. identifying and mapping boundaries adequate to achieve He
conservation objective,
b. identifying potential threats to the site,
c. discussing stewardship requirements?
d. assessing ownership;
3) Analysis of package by state and regional director;
4) Assignment of protection levels
a. voluntary by owner/manager,
b. bequest,
c. legally binding protection agreement,
d. landowner-conveyed interest to conservation entity,
e. public agency agreement to conservation designation,
f. less-clan-fee acquisition,
g. dedication or trust investiture to conservation trust or estab
lished nature preserve system;
~_ .
Development of protection strategy, including
stewardship needs,
b. required level of protection,
c. cost effectiveness for desired level of protection,
d. adequate information for TNC use.
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APPENDIX D
255
As a result of this process, a preserve design package is constructed
that is considered "the unit of proposal and approval" and should contain
all He relevant information necessary for TNC to make a decision about
preserving a tract.
The acquisition is approved and funded at the state level, but for
projects more Han $200,000 regional approval is required; for acquisi-
tions more Han $500,000, approval by the national board is necessary
(Ben Pierce, pers. comm., TNC, Wyoming Field Office, 19911.
The PS&D manual contains a memorandum describing He current
effort to computerize He design process. A standard form is available
to design planners that prescribes information to be included.
How To Design a Preserve
The PS&D describes how to design a preserve, but the discussion is
prefaced by a caveat:
None of these materials, however, will quite give you the answers you want
or tell you how to design a preserve for particular elements and there is nothing
in them that can be distilled into a set of generally recognized and incontrovert-
ible rules.... Some central questions are what the minimum viable size a re-
serve must be to retain the greater part of its biota over the long term and what
the minimum viable population a species must have to avoid a significant loss
of alleles and eventual extinction on a site.
Sites are categorized as megasiees (more than 64,000 acres), macro-
sites (more Han 3,200 acres), or standard sites (fewer than 3,200 acres).
Mega- and macrosites are categorued according to the following priori-
ties: I) unique sites wig large numbers of endemic and nearly endemic
species, 2) sites containing the range or most of He range of an endemic
species, 3) buffers and/or corridors to protect larger, far-ranging spe-
cies, and 43 representative sites of presettlement ecosystems.
Each proposed mega- and macrosite is ranked for I) quality/signifi-
cance/uniqueness/representativeness, 2) condition, 3) viability, and 4)
defensibility/manageability wig a letter grade from A (excellent) to D
(poor).
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256 SEWING PRIORITIES FOR LAND CONSERVA TION
Minimum Viable Size of Preserves
The PS&D states Hat preserves may lose species over time, particu-
larly if they are small, but the causes of species loss are not well under-
stood, and the probability of loss differs among tuna. Many plant spe-
cies (e.g., prairie flora) have existed for a long time on small plots.
Practicality is often the overriding issue: "big" may be best, but big is
also expensive and frequently nonexistent because of habitat loss and
fragmentation.
The PS&D uses the tea "minimum viable size of preserves," al-
though it is generally understood that minimal viable preserve size varies
with the EOs targeted for preservation. A hectare may be sufficient to
preserve a self-fertilizing, long-lived plant, but a half million hectares in
a fragmented landscape may be insufficient to preserve a population of
a large vertebrate predator. It might be possible, nonetheless, to cIassi-
fy different types of EOs and provide some general guidelines for opti-
mal to minimal reserve sizes.
Minimum Viable Population Size
TNC recognizes that small populations are more subject to extinction
than large populations for genetic and environmental reasons, but states
that minimal population sue cannot realistically be determined by ana-
lyzing any one factor. The PS&D concludes that each preserve is an
experiment in minimal population size, and reserve designers should try
to prescribe boundaries and management practices that minimize extinc-
tion. TNC tries to ensure that rare EOs are preserved in enough places
"that the likelihood of all going extinct at Be sane time is vanishingly
small."
The committee believes that more precise and relevant terminology
could be developed related to population and genetic factors. In addi-
tion, it might be possible to develop more general guidelines than those
mentioned above drawing upon knowledge of past extinctions, evolution-
ary trends, and the genetic structures of populations. Even if generaliza-
tions were not possible, a list of factors could be provided that could
guide more objectively Me preserve designer. Available information on
factors for EOs designated for preservation could be collected. Exam
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APPENDIX D
257
pies of factors would include genetic structure, population size, effective
breeding population size, breeding structure, longevity, net reproductive
rate, degree of niche specialization, stability/predictability of local cli-
mate (from long-term climate data), probability of natural catastrophes
(by looking at historical records), and landscape information. Much of
this information is not available for most species. But an ordinal rank-
ing scale could be developed as done for the EO.
TNC might be reluctant to adopt such a system. If the ranking sug-
gests that a preserve may be too small to sustain an EO for a reasonable
length of time, the mission of TNC directs it to err on the conservative
side: that is, even if the best scientific information suggests a low
chance of success, TNC may attempt preservation, because extinction is
forever.
TNC acknowledges that "there are so many factors to consider in
doing preserve design that we cannot enumerate them all. In future
years . . . we would like to draw up a list of these factors, plus provide
a good bibliography on preserve design."
Preserve Configuration and.lustification
The PS&D states that preserve design theory suggests that preserves
should be as round as possible (to minimize edge) and connected by
corridors for facilitating migration. But in all practicality, TNC admits
Hat preserve shape and juxtaposition are difficult to control because of
ownership patterns and past habitat disturbance. If an EO does become
extinct on a preserve, TNC will consider reintroduction from elsewhere.
This criterion show Cat TNC works within the constraints of the real
world. Tracts available for preserves tend to be much smaller than
desirable, but accumulating many unconnected tracts containing rare
EOs might reduce the probability of extinction; if local extinctions oc-
cur, reintroductions are possible.
The concept of corridors is not well defined, according to a member
of TNC's board of directors (Sto~zenberg, 1991), and corridors are
considered an inadequate substitute for suitable habitat:
I'm a skeptic about corridors. What I'm not a skeptic about is large habitat
as a requirement for viable persistence of species. The most important thing is
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258 SETTING PRIORITIES FOR LAND CONSERVATION
always to identify the remaining habitat of the most endangered species and
ecosystem types. If you don't save those, the things that occupy them are
simply gone (Stolzenberg (1991) quoting TNC Director of Science, Robert
Jenkins.'
SimberIoff and Cox (1987) point out also Hat corridors can provide
access for parasites, predators, pests, fire, and poachers.
Noss and Harris (1986) are strong advocates of corridors, and Stol-
zenburg (1991) described three studies that demonstrate the efficacy of
corridors for maintaining populations: Harper in Brazil found that corri-
dors were essential for maintaining antbirds in patches of jungle, Bennett
In Australia discovered that corridors provide both transportation and a
conduit for gene exchange, and Merriam in Canada found that woodIots
connected by wooded fencerows demonstrated a continual process of
extinction and recolonization by small mammals and birds.
In practice, some TNC conservation efforts have integrally incorporat-
ed corridors. Merrill Lynch (TNC, Norm Carolina) designed "the
granddaddy of all corridors" in a 30,000 acre reserve in Pinhook Swamp
in northern Florida, which was a cooperative effort between TNC and
the Forest Service. Lynch is planning a multicorridored project,
436,000 acres of the Alligator River Wildlife Refuge (in collaboration
with the USFWS, TNC, and the Conservation Fund), targeted for black
bear and red wolf protection (Sto~zenburg, 1991~. And TNC's "The
Last Great Places" initiative is clearly directed at saving landscapes with
core habitat surrounded by buffer zones.
Element and Site Stewardship
The PS&D insists that proper stewardship requires highly specific
information about an element and the site it occurs on. It may take
several years to collect the needed natural history of an element and the
possible constraints on managing for its survival. The PS&D manual,
however, does not help the field staff set priorities based upon scientific
information on what information should be collected. The manual does
not provide a review of pertinent ecological or conservation literature
from either an empirical or theoretical perspective.
This criterion of TNC acquisition strategy shows an attentiveness to
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APPENDIX
259
practicality. PS&D briefly dismisses most theoretical issues concerning
preserve design and focuses on what site-specific information is needed
and what can be obtained. For example, for an endangered plant, what
are pollinators and seed dispersal agents? What is soil type and habitat
affinity? Are Here Greats from neighboring farmers through herbicide
use?
This type of detective work is absolutely necessary, and obviously
successful, based upon the history of TNC preservation efforts. Site-
specific data from field surveys is one key to TNC success. It is impor-
tant, Dough, Mat data gatherers be instructed in the empirical and theo-
retical literature that may cast light on how to monitor and measure the
ecological health of a particular site. The PS&D manual and its succes-
sor documents may be one way to accomplish this.
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Representative terms from entire chapter:
heritage programs
