                  FOR PUBLICATION
  UNITED STATES COURT OF APPEALS
       FOR THE NINTH CIRCUIT

LEAGUE OF WILDERNESS DEFENDERS-         
BLUE MOUNTAINS BIODIVERSITY
PROJECT, an Oregon non-profit
corporation,
                 Plaintiff-Appellant,
                 v.                           No. 11-35451
UNITED STATES FOREST SERVICE;                   D.C. No.
                                            6:10-cv-06302-HO
JOHN ALLEN, in his official
capacity as Forest Supervisor,                  OPINION
Deschutes National Forest; BOV
EAV, in his official capacity as
Director of the Pacific Northwest
Research Station,
              Defendants-Appellees.
                                        
        Appeal from the United States District Court
                 for the District of Oregon
        Michael R. Hogan, District Judge, Presiding

                  Argued and Submitted
             March 7, 2012—Portland, Oregon

                     Filed July 30, 2012

    Before: William A. Fletcher, Raymond C. Fisher, and
               Jay S. Bybee, Circuit Judges.

           Opinion by Judge William A. Fletcher




                             8501
8504      LEAGUE OF WILDERNESS DEFENDERS v. USFS




                         COUNSEL

Sean Malone, Eugene, Oregon, Ralph Owen Bloemers, CAS-
CADE RESOURCES ADVOCACY GROUP, Portland, Ore-
gon, Rachel Fazio, Cedar Ridge, California, for the appellant.

John David Gunter, II, U.S. DEPARTMENT OF JUSTICE,
Washington, D.C., OFFICE OF THE U.S. ATTORNEY,
Portland, Oregon, for the appellees.

Scott W. Horngren, AMERICAN FOREST RESOURCE
COUNCIL, Portland, Oregon, for Amicus Curiae Interfor
Pacific, Inc.
          LEAGUE OF WILDERNESS DEFENDERS v. USFS         8505
                           OPINION

W. FLETCHER, Circuit Judge:

  This case involves an Experimental Forest Thinning, Fuels
Reduction, and Research Project (“the Project”) in the Des-
chutes National Forest in the eastern Cascades of central Ore-
gon. The Project allows logging and controlled burning on
roughly 2,500 acres of the Pringle Falls Experimental Forest.
The purpose of the Project is two-fold: to reduce the risk of
wildfire and beetle infestation, and to conduct research on
ponderosa pine forest management.

   The League of Wilderness Defenders–Blue Mountains Bio-
diversity Project (“the League”) filed suit against the U.S.
Forest Service (“the Service”) and Service officials, alleging
that the agency’s environmental impact statement (“EIS”) for
the Project fails to comply with the National Environmental
Policy Act (“NEPA”). The district court granted summary
judgment to the Service, relying in part on the fact that the
Project involves research in an experimental forest. We
affirm.

                      I.   Background

 A.   Experimental Forests and the Lookout Mountain Unit

   In 1931, the Forest Service established the Pringle Falls
Experimental Forest within the Deschutes National Forest as
“a center for silviculture, forest management, and insect and
disease research in ponderosa pine forests.” The Experimental
Forest is located in the eastern Cascades, about twenty-five
miles southwest of Bend, Oregon. It is administered by the
Service’s Pacific Northwest (“PNW”) Research Station and is
one of about eighty experimental forests that the Service man-
ages in the United States and its territories. See generally
Ariel E. Lugo et al., Long-Term Research at the USDA Forest
Service’s Experimental Forests and Ranges, 56 BioScience
8506       LEAGUE OF WILDERNESS DEFENDERS v. USFS
39 (2006) (discussing scientific contributions from long-term
research projects in experimental forests).

   The Service manages its experimental forests under the
Forest and Rangeland Renewable Resources Research Act of
1978 (“Research Act”), 16 U.S.C. §§ 1641-1650. The
Research Act recognizes that the federal government “has an
important and substantial role in ensuring the continued
health, productivity, and sustainability of the forests and
rangeland of the United States.” Id. § 1641(a)(1). It gives the
Secretary of Agriculture broad authority to designate experi-
mental forests and to conduct any research within them that
he “deems necessary to obtain, analyze, develop, demonstrate,
and disseminate scientific information about protecting, man-
aging, and utilizing forest . . . resources.” Id. §§ 1642(a),
1643(a); see also 7 C.F.R. § 2.60(a) (delegating the Secre-
tary’s authority to the Service). One of the five major areas of
research identified in the Act is “protecting vegetation and
other forest and rangeland resources . . . from fires, insects,
[and] diseases.” 16 U.S.C. § 1642(a)(3).

   The Research Act supplements, rather than limits or
repeals, other laws that impose obligations on the Service. Id.
§ 1645(e). These include NEPA, which requires that agencies
prepare an EIS for any major federal action “significantly
affecting the quality of the human environment,” 42 U.S.C.
§ 4332(2)(C), as well as the National Forest Management Act,
which requires that site-specific actions approved by the Ser-
vice comply with forest resource management plans, 16
U.S.C. § 1604(i). The relevant management plan here is the
1990 Deschutes Forest Plan, which provides that the goal of
the Pringle Falls Experimental Forest is “field research activi-
ties.”

   The Lookout Mountain Unit (“the Unit”) is located within
the Pringle Falls Experimental Forest. When the Service
added the roughly 3,500-acre Unit to the Experimental Forest
in the 1930s, it noted that the Unit was “especially well-suited
          LEAGUE OF WILDERNESS DEFENDERS v. USFS          8507
for experiments in thinning and pruning and for studies of
growth and site factors.” The Unit contains a large block of
closed-canopy forest that “may represent some of the most
productive ponderosa pine sites in central Oregon.” The Unit
has experienced only minor disturbances since 1845, when a
wildfire burned most of the trees. The disturbances include
thinning in the 1970s and 80s, as well as several completed
and ongoing research projects. Aside from these disturbances,
trees in the Unit have “grown exceptionally well.”

   In 2005, the Service observed that trees in the Unit had
grown to such an extent that their density put them at risk of
beetle infestation and wildfire. The Service had previously
calculated an upper management zone (“UMZ”) with a pre-
scribed stand density index (“SDI”). A stand is a group of
trees of similar size, species, and structure growing together.
SDI measures density based on mean tree size and the number
of trees within a stand. An SDI higher than the UMZ level
means that trees are at imminent risk of beetle infestation. In
2007, the Service determined that stands within the Unit had
an SDI between 132 and 224 percent of UMZ. This density
resulted in a reduced tree vigor, measured by the percentage
of a tree’s canopy occupied by green branches, and a slowed
growth rate. The Service expressed concern that widespread
infestation or wildfire would destroy some of the older trees
in the Unit and compromise ongoing and future research proj-
ects.

                       B.   Study Plan

   In December 2007, Service officials at the PNW Research
Station began to design a research project that would reduce
the fire and insect risk in the Unit while simultaneously
addressing scientific objectives. They prepared a Study Plan
entitled “Forest Dynamics After Thinning and Fuel Reduction
in Dry Forests.” The Plan identified six specific research
questions:
8508      LEAGUE OF WILDERNESS DEFENDERS v. USFS
    1.   What set of fuel reduction treatments best accel-
         erates the development of large trees while over
         the long-term reintroduce[s] natural disturbance
         processes that provide greater ecosystem resil-
         iency?

    2.   What is the long-term influence of climate
         change interacting with a set of fuel reduction
         treatments on vegetation dynamics and forest
         structure?

    3.   Can single cohort stands be readily converted to
         multi-cohort stands?

    4.   Do multi-cohort stands share the same risks of
         multiple, interacting stresses as single-cohort
         stands?

    5.   How does the dominant shrub, giant chinquapin
         (Chrysolepis chrysophylla), respond in the near-
         term to a set of fuel reduction treatments?

    6.   How does the residual stand structure resulting
         from a set of fuel reduction treatments interact
         locally and in the near-term with wind to cause
         additional structural changes?

A cohort is a group of trees that grew after a single distur-
bance and thus are roughly the same age. A multi-cohort
stand is a group of trees with two or more age classes.

   The Study Plan divided the study area into four blocks. It
designated five areas within each block for specified levels of
logging and controlled burning. It would leave one area undis-
turbed as a control group and would thin other areas to vari-
ous SDIs. The Service would then compare the growth of
trees in each area. The Study Plan’s working hypothesis for
the first research question, put simply, is that “removing more
           LEAGUE OF WILDERNESS DEFENDERS v. USFS           8509
small trees should allow the residual trees to grow to larger
diameters.” The Plan would answer some of the research
questions within a few years, while others would take several
decades.

  The Study Plan underwent two rounds of peer review in
2008: first, by six individuals internally; and second, by seven
double-blind external reviewers. The Director of the PNW
Research Station approved the Study Plan in March 2009.

                      C.   NEPA Process

   The Service began an environmental review of the Project
under NEPA while it was still developing the Study Plan. In
April 2008, the Service sent a scoping letter to interested par-
ties describing the proposed action. The Service also pub-
lished in the Federal Register a notice of intent to prepare an
EIS for the Project. See 73 Fed. Reg. 19,805 (Apr. 11, 2008).
In April 2009, the Service sent another letter to interested par-
ties describing the Project and the alternatives that were being
considered for analysis. The Service hosted two field trips to
the Unit to discuss the proposed Project with interested
groups, the first in August 2008 and the second in July 2009.
The League participated in the first field trip.

   In September 2009, the Service circulated a draft EIS for
the Project and received public comments. The Service also
consulted with other federal environmental agencies. In
November 2009, the Environmental Protection Agency wrote
that it was “supportive of the proposed project, both as a
means to address the risk of severe insect epidemic or cata-
strophic fire, and as an opportunity to study forest dynamics
after thinning and fuels reduction in dry forests.” In January
2010, the U.S. Fish and Wildlife Service issued a biological
opinion pursuant to the Endangered Species Act concluding
that the Project would not likely jeopardize the continued
existence of the threatened northern spotted owl.
8510       LEAGUE OF WILDERNESS DEFENDERS v. USFS
   In March 2010, the Service issued the final EIS for the
Project. The EIS examines in detail three alternatives — a no-
action alternative and two action alternatives. The two action
alternatives are variations of the experiment proposed in the
Study Plan. Alternative 2, the preferred alternative, would
result in logging approximately 27 to 29 million board feet of
timber on 2,554 acres — or about 70 percent of the trees
larger than 6 inches in diameter at breast height. It would
“thin from below” by cutting the smallest trees in an area until
the target SDI for a particular area is reached, thereby retain-
ing the largest trees in that area. In order to reach the desired
SDIs, Alternative 2 would remove a total of about one-third
of all trees greater than 21 inches in diameter within the
logged areas, or an average of about nine such trees per acre.
It would also construct about one mile of temporary road and
perform maintenance over thirty-five miles of existing roads.
Alternative 2 would amend the Deschutes Forest Plan to
exempt part of the Project area from geographic Eastside
Screens restrictions that, inter alia, prohibit logging old
growth trees greater than 21 inches in diameter east of the
Cascade Mountains. In the EIS, the Service describes the For-
est Plan amendments as non-significant because they would
affect only a small fraction of the Eastside Screens.

   Alternative 3 uses the same research design and has the
same target numbers as Alternative 2 for SDIs in the various
areas of the Project. However, Alternative 3 would leave
undisturbed 372 acres of spotted owl habitat that would be
thinned under Alternative 2. This would reduce the total
logged area in the Project by about 15 percent. The EIS also
briefly describes six additional alternatives that it does not
consider in detail because they would not meet the Project’s
two purposes of risk reduction and research.

  The same day it issued the EIS, the Service published a
Record of Decision (“ROD”) selecting Alternative 2 and
approving the Project. The ROD explains that Alternative 3
would provide less risk reduction and would render the
           LEAGUE OF WILDERNESS DEFENDERS v. USFS            8511
research design incomplete without any significant corre-
sponding benefit to the spotted owl. The ROD concludes that
Alternative 2 “does the best job of meeting the statutory mis-
sion of the Experimental Forest by reducing the risk of losing
a large portion of it to fire or insects, and incorporating impor-
tant research into the design of risk-reduction activities.”

                 D.      Procedural Background

   In September 2010, the League filed suit against the Ser-
vice and Service officials, alleging that the EIS does not com-
ply with NEPA. The League sought declaratory and
injunctive relief.

   In May 2011, the district court granted summary judgment
to the Service. The court relied heavily on the fact that the
Project involves research within an experimental forest. It
wrote that “it would be short sighted for the courts to inter-
vene and dictate that the Forest Service consider alternatives
that hamper or eliminate research objectives . . . . While the
requirements of NEPA still apply, the necessary range of
alternatives and hard look are strongly informed by the
research objectives of the Forest itself.” The court concluded
that the EIS is adequately supported by scientific data and
takes a hard look at the significant impacts of the Project.

   The League timely appealed. In June 2011, the League
filed an emergency motion in this court for an injunction
pending appeal to prevent logging pursuant to the first timber
sale under the Project. Interfor Pacific, Inc., which had been
awarded the timber sale, joined the Service as amicus in
opposing the motion. A divided motions panel denied the
emergency injunction. Logging under the Project commenced
that month and will continue through 2013.

                   II.    Standard of Review

  We review de novo a district court’s decision on summary
judgment that an agency complied with NEPA. Or. Natural
8512        LEAGUE OF WILDERNESS DEFENDERS v. USFS
Desert Ass’n v. Bureau of Land Mgmt., 625 F.3d 1092, 1109
(9th Cir. 2010). We review an agency’s compliance with
NEPA under the Administrative Procedure Act. Id. We may
not set aside an agency action unless it is “arbitrary, capri-
cious, an abuse of discretion, or otherwise not in accordance
with law.” 5 U.S.C. § 706(2)(A). A decision is arbitrary and
capricious if the Service

    relied on factors Congress did not intend it to con-
    sider, entirely failed to consider an important aspect
    of the problem, or offered an explanation that runs
    counter to the evidence before the agency or is so
    implausible that it could not be ascribed to a differ-
    ence in view or the product of agency expertise.

Lands Council v. McNair, 537 F.3d 981, 987 (9th Cir. 2008)
(en banc) (internal quotation marks omitted), overruled on
other grounds by Winter v. Natural Res. Def. Council, 555
U.S. 7 (2008).

                       III.   Discussion

   The League argues that the EIS is deficient in three ways.
First, the EIS improperly cabins its analysis by specifying a
limited purpose and need for the Project, and by considering
only Project alternatives that fit predetermined specifications
contained in the Study Plan. Second, it lacks scientific integ-
rity because it overstates the risk of wildfire and beetle infes-
tation. Third, it fails to take a hard look at the Project’s
impacts on tree mortality and on wildlife species that depend
on standing dead trees for nesting habitat. We take each argu-
ment in turn.

       A.    Project Purpose and Alternatives Analysis

  [1] Congress created NEPA “to protect the environment by
requiring that federal agencies carefully weigh environmental
considerations and consider potential alternatives to the pro-
           LEAGUE OF WILDERNESS DEFENDERS v. USFS          8513
posed action before the government launches any major fed-
eral action.” Barnes v. U.S. Dep’t of Transp., 655 F.3d 1124,
1131 (9th Cir. 2011) (internal quotation marks omitted). Spe-
cifically, an EIS under NEPA must “inform decisionmakers
and the public of the reasonable alternatives which would
avoid or minimize adverse impacts or enhance the quality of
the human environment.” 40 C.F.R. § 1502.1; see also 42
U.S.C. § 4332(2)(C)(iii) (an EIS shall include “a detailed
statement [on] alternatives to the proposed action”). NEPA
regulations describe the alternatives analysis as “the heart of
the environmental impact statement.” 40 C.F.R. § 1502.14.
The analysis “present[s] the environmental impacts of the pro-
posal and the alternatives in comparative form, thus sharply
defining the issues and providing a clear basis for choice
among options by the decisionmaker and the public.” Id.

   [2] The scope of an alternatives analysis depends on the
underlying “purpose and need” specified by the agency for
the proposed action. City of Carmel-By-The-Sea v. U.S. Dep’t
of Transp., 123 F.3d 1142, 1155 (9th Cir. 1997); 40 C.F.R.
§ 1502.13 (“The [EIS] shall briefly specify the underlying
purpose and need to which the agency is responding in pro-
posing the alternatives including the proposed action.”
(emphasis added)). The agency need only evaluate alterna-
tives that are “reasonably related to the purposes of the proj-
ect.” Westlands Water Dist. v. U.S. Dep’t of Interior, 376 F.3d
853, 868 (9th Cir. 2004) (internal quotation marks omitted).

   The League challenges the EIS’s statement of purpose and
need, as well as the range of alternatives that the Service con-
sidered. We review the purpose and need, along with the
choice of alternatives, under a “reasonableness standard” or
“rule of reason.” Id. at 866, 868. We first determine whether
the statement of purpose and need was reasonable, and then
whether the range of alternatives considered was reasonable
in light of that purpose and need. See id. at 865, 868.
8514       LEAGUE OF WILDERNESS DEFENDERS v. USFS
             1.   Statement of Purpose and Need

   [3] “[T]his court has afforded agencies considerable dis-
cretion to define the purpose and need of a project.” Friends
of Southeast’s Future v. Morrison, 153 F.3d 1059, 1066 (9th
Cir. 1998). “However, this discretion is not unlimited.” West-
lands, 376 F.3d at 866. Because they determine the range of
reasonable alternatives, an agency cannot define the purpose
and need of a project in unreasonably narrow terms. See Nat’l
Parks & Conservation Ass’n v. Bureau of Land Mgmt., 606
F.3d 1058, 1070 (9th Cir. 2010). “ ‘[A]n agency may not
define the objectives of its action in terms so unreasonably
narrow that only one alternative from among the environmen-
tally benign ones in the agency’s power would accomplish the
goals of the agency’s action, and the EIS would become a
foreordained formality.’ ” Friends of Southeast, 153 F.3d at
1066 (quoting Citizens Against Burlington, Inc. v. Busey, 938
F.2d 190, 196 (D.C. Cir. 1991)).

  The statement of purpose in the Project’s EIS provides:

    The primary purpose of the proposed project is to
    reduce risk to the site by reducing stand densities,
    and lowering susceptibility to catastrophic loss to
    insects, disease, and fire. By integrating the need to
    reduce risk to the site with the research goals of the
    PNW Research Station, treatments would be imple-
    mented in such a way that pertinent research ques-
    tions regarding long-term sustainability of ponderosa
    pine and mixed conifer forests in a changing climate
    can be answered.

The EIS identifies two needs for the Project. First, “[t]here is
a need to address the risk of a severe insect epidemic or cata-
strophic fire.” Second, “[t]here is a need to provide opera-
tional scale research opportunities through a series of thinning
and fuel reduction treatments applied across the landscape.”
The EIS explains that this second need “comes generally from
           LEAGUE OF WILDERNESS DEFENDERS v. USFS           8515
the establishment record for the Experimental Forest, and spe-
cifically from the study plan.” The EIS then lists the six
research questions from the Study Plan that the Project is
designed to address.

   [4] In assessing the reasonableness of a purpose and need
specified in an EIS, we must consider the statutory context of
the federal action. See Westlands, 376 F.3d at 866 (“Where an
action is taken pursuant to a specific statute, the statutory
objectives of the project serve as a guide by which to deter-
mine the reasonableness of objectives outlined in an EIS.”).
Here, two statutes inform the Project’s purpose and need. The
Organic Act gives the Service authority to “make provisions
for the protection against destruction by fire.” 16 U.S.C.
§ 551. The Research Act gives the Service authority to carry
out in experimental forests any research experiments that it
“deems necessary.” Id. § 1642(a). One of the five major areas
of research identified in the Research Act is “protecting vege-
tation and other forest and rangeland resources . . . from fires,
insects, [and] diseases.” Id. § 1642(a)(3). The EIS’s dual pur-
pose and need of risk reduction and research opportunities
comes directly from these statutory authorities.

   The League argues that the EIS states “an unreasonably
narrow purpose and need” and incorporates “rigid implemen-
tation” of the Study Plan. The League contends that, as a
result of the narrowness of the stated purpose and need, only
a single alternative — the Study Plan — could satisfy them.
However, the statement does not incorporate the specifics of
the Plan’s proposed experiment. Rather, the statement refers
to the Plan because it contains an extensive discussion of the
research objectives and working hypotheses behind the six
study questions. See Muckleshoot Indian Tribe v. U.S. Forest
Serv., 177 F.3d 800, 812-13 (9th Cir. 1999) (per curiam)
(statement of purpose and need “appear[ed] too narrow” when
read in isolation, but was ultimately reasonable because it
“expressly incorporate[d]” broader objectives).
8516       LEAGUE OF WILDERNESS DEFENDERS v. USFS
   As in Muckleshoot, some language in the EIS, when read
in isolation, suggests that the statement of purpose and need
contemplates implementation of the Study Plan. For example,
the EIS asserts that it compares the alternatives “for their abil-
ity to implement the study plan.” The EIS also rejects a pro-
posed alternative on the ground that it “would not meet the
purpose and need of implementing the study plan.” When
read in context, however, these and similar statements were
directed to the six research questions and objectives described
in the Plan, rather than to any rigid implementation of the spe-
cifics of the Plan. Thus, the first sentence excerpted above
reads in full that the EIS compares the alternatives “for their
ability to implement the study plan and answer the specific
research questions.” (Emphasis added.) Moreover, the stated
purpose and need could not have required “rigid implementa-
tion” of the Study Plan, as the League maintains, because
Alternative 2, the preferred alternative that the Service ulti-
mately selected, removed forty-nine acres of logging from the
Plan’s proposed design in response to conservation groups’
concerns about a sensitive cinder butte in the northeast section
of the Project area. Alternative 3 deviated even further from
the Plan by removing an additional 372 acres in order to
reduce the potential impact on spotted owl habitat.

   The League bases its challenge in part on an argument that
the Service created the Study Plan “prior to initiating the
NEPA process.” NEPA regulations require that an agency
“integrate the NEPA process with other planning at the earli-
est possible time.” 40 C.F.R. § 1501.2. Here, the Service
began the NEPA process nearly a year before the Plan was
finally approved. As described above, in April 2008 the Ser-
vice sent a scoping letter to interested parties and published
a notice of intent to prepare an EIS in the Federal Register.
A few months later, the Service hosted a field trip in the Unit
to discuss the proposed Project with interested parties and
then modified its proposal as a result of these discussions. In
reviewing an EIS’s statement of purpose and need, the
“ ‘touchstone for our inquiry’ ” is whether the resulting alter-
          LEAGUE OF WILDERNESS DEFENDERS v. USFS         8517
natives analysis “ ‘fosters informed decision-making and
informed public participation.’ ” Westlands, 376 F.3d at 868
(quoting California v. Block, 690 F.2d 753, 767 (9th Cir.
1982)). Based on the record before us, we conclude that the
purpose and need in the challenged EIS adequately informed
decisions by the Service and participation by the public.

   [5] In sum, given the purpose of the Research Act, the
Project’s location in an experimental forest, and the “consid-
erable discretion” we afford agencies in this area, Friends of
Southeast, 153 F.3d at 1066, we agree with the district court
that the EIS’s statement of purpose and need is reasonable.

                 2.   Range of Alternatives

   [6] NEPA regulations require that an EIS “[r]igorously
explore and objectively evaluate all reasonable alternatives”
to the proposed action, including alternatives “not within the
jurisdiction of the lead agency.” 40 C.F.R. § 1502.14(a), (c).
“The existence of a viable but unexamined alternative renders
an environmental impact statement inadequate.” Natural Res.
Def. Council v. U.S. Forest Serv., 421 F.3d 797, 813 (9th Cir.
2005) (internal quotation marks omitted). However, “the EIS
need not consider an infinite range of alternatives, only rea-
sonable or feasible ones.” Westlands, 376 F.3d at 868 (inter-
nal quotation marks omitted). An agency need not consider
alternatives that “extend beyond those reasonably related to
the purposes of the project.” Id. (internal quotation marks
omitted). The agency must also “briefly discuss” the reasons
why it eliminated any alternatives from detailed study. 40
C.F.R. § 1502.14(a).

  The EIS considers in detail a no-action alternative and two
action alternatives: Alternative 1 contemplates no action;
Alternative 2 would log 27 to 29 million board feet of timber
on 2,554 acres; and Alternative 3 would log 23 to 25 million
board feet on 2,182 acres. Both action alternatives would
divide the Project into approximately 20 units, each of which
8518       LEAGUE OF WILDERNESS DEFENDERS v. USFS
would be treated to one of five levels of thinning: (1) no thin-
ning (the control units); (2) thinning to UMZ; (3) thinning to
75 percent of UMZ; (4) thinning to 75 percent of UMZ with
creation of small openings; and (5) thinning to 50 percent of
UMZ. The EIS also briefly describes six additional alterna-
tives that it excludes from detailed consideration because they
would not meet the Project’s dual purpose and need.

   [7] In another context, an EIS analyzing in detail two
action alternatives that differed only in proposed acreage
would likely be inadequate. See, e.g., Muckleshoot, 177 F.3d
at 812-13 (“[T]he Forest Service failed to consider an ade-
quate range of alternatives [where t]he EIS considered only a
no action alternative along with two virtually identical alter-
natives.”). But we agree with the district court that the special
circumstances of a research project in an experimental forest
“necessarily narrowed consideration of alternatives.” As the
district court observed:

    The Pringle Falls Experimental [F]orest is, by
    design, intended to facilitate management, insect,
    and disease research in ponderosa pine forests east of
    the Cascades. While the requirements of NEPA still
    apply, the necessary range of alternatives and hard
    look are strongly informed by the research objectives
    of the Forest itself. The Forest Service simply cannot
    entertain every alternative without regard for ele-
    ments that are unique to the research forest that
    accounts for protecting against a major disturbance
    event that would destroy the ability to carry out on-
    going long-term research in the area, or preclude
    important future research opportunities.

   The League argues that the Service failed to consider in
detail a reasonable alternative that would have retained, either
throughout the Project area or within the Eastside Screens, all
trees greater than 21 inches in diameter. The League argues
that such an alternative would be consistent with the need to
           LEAGUE OF WILDERNESS DEFENDERS v. USFS              8519
reduce the risk of wildfire and beetle infestation, as well as
with the need to provide operational scale research that
addresses the Service’s scientific objectives regarding the
effects of removing small trees. The EIS explains that the Ser-
vice briefly considered the League’s proffered alternative, but
eliminated it from detailed study because modeling indicated
that retaining all trees greater than 21 inches in diameter
would not achieve the targeted stand densities and thus not
fulfill the Project objectives.

   [8] In its briefing to us, the Service justifies its rejection of
the League’s proffered alternative on two grounds. First, the
Service contends that the proposed 21-inch-diameter-limit
would not achieve the Project’s risk-reduction purpose. The
EIS’s risk-reduction purpose refers to “thinning to the UMZ
or below.” The EIS notes that retaining all trees greater than
21 inches in diameter would result in densities “above the rec-
ommended UMZ.” Under our prior case law, agencies need
not consider in detail proposed alternatives that fail to meet
specifically identified targets or densities. See, e.g., Carmel,
123 F.3d at 1155-57 (upholding a statement of purpose and
need for a highway project that included a specific level of
desired traffic service).

   [9] Second, the Service contends that the 21-inch-
diameter-limit alternative would not fulfill the research pur-
pose of the Project. The Service maintains that the diameter-
limit alternative would not yield statistically valid compara-
tive data among the areas specified for different densities of
logging. The EIS explains that “leaving all, or more, of the
larger trees than is proposed in the study plan would provide
biased results that would be considered questionable.” Given
the research purpose of the Project and its location in an
experimental forest, the EIS does not have to consider in
detail an alternative that would not provide the research data
that the Service seeks to obtain.

  The League also argues that the EIS fails to consider in
detail an alternative that would retain all trees greater than 12
8520       LEAGUE OF WILDERNESS DEFENDERS v. USFS
inches in diameter. However, the EIS expressly rejects the 12-
inch-diameter-limit alternative because it would not achieve
the risk-reduction purpose of the Project. The EIS explains
that “[t]hinning only the smallest trees would not reduce stand
density enough to reduce the risk of insect and disease-caused
mortality.” Accordingly, the EIS does not have to consider
this alternative in detail.

   [10] In sum, the EIS only needs to consider in detail alter-
natives that would address both of the Project’s stated pur-
poses and needs by meaningfully reducing the risk of beetle
infestation and wildfire while attempting to answer the six
research questions. See Ariz. Past & Future Found., Inc. v.
Lewis, 722 F.2d 1423, 1428 (9th Cir. 1983) (“Alternatives
that do not accomplish [both] purposes of the project may
properly be rejected as imprudent.”). The League has failed to
identify a “viable but unexamined alternative” that would sat-
isfy both these goals. Natural Res. Def. Council, 421 F.3d at
813. Accordingly, we hold that the range of alternatives con-
sidered in the EIS is reasonable.

                   B.   Scientific Integrity

   [11] NEPA regulations require that an agency ensure the
“scientific integrity” of the discussions and analyses in an EIS
and explicitly refer to “the scientific and other sources relied
upon for conclusions in the [EIS].” 40 C.F.R. § 1502.24. As
a reviewing court, we are “most deferential when the agency
is making predictions[ ] within its area of special expertise.”
Lands Council, 537 F.3d at 993 (internal quotation marks
omitted). “At the same time, courts must independently
review the record in order to satisfy themselves that the
agency has made a reasoned decision based on its evaluation
of the evidence.” Earth Island Inst. v. U.S. Forest Serv., 442
F.3d 1147, 1160 (9th Cir. 2006) (internal quotation marks
omitted), overruled on other grounds by Winter, 555 U.S. 7.

   The League argues that the EIS overstates the risk of wild-
fire and beetle infestation in the Unit. In particular, the
           LEAGUE OF WILDERNESS DEFENDERS v. USFS                8521
League takes issue with the EIS’s use of the terms “immi-
nent,” “catastrophic,” and “stand-replacing.” For example, the
EIS states that trees in the Unit

    have structural characteristics that indicate they are
    at imminent risk of catastrophic loss to bark beetles
    and high risk of loss to wildfire. . . . [T]here is a high
    and increasing probability that ponderosa pine across
    the Lookout Mountain [U]nit will support a
    landscape-scale western pine or mountain pine beetle
    outbreak, or a large stand-replacing event.

The League makes three arguments under the heading of sci-
entific integrity: (1) the EIS overstates the risk of beetle infes-
tation, (2) it overstates the risk of wildfire, and (3) it fails to
acknowledge that greater tree mortality would occur under the
Project than under the no-action alternative.

   [12] First, the League argues that the EIS relies on three
scientific reports that do not support its assessment of the risk
of beetle infestation. The League’s focus on these reports is
misplaced. All three reports support the general proposition
that excessive density presents a risk of beetle infestation
leading to “serious” or “excessive” tree mortality, and that
controlled thinning can reduce that risk. The studies do not
use the terms “imminent” or “catastrophic,” but the EIS does
not cite these studies for the specific language that the League
challenges on appeal. Other documents cited in the EIS refer
to density levels where beetles caused “imminent mortality”
and “catastrophic losses” at “epidemic” or “landscape” levels.
A Deschutes National Forest report in 1996 established UMZ
density levels above which particular stands would be consid-
ered “imminently susceptible” to insect attack. The Study
Plan, which underwent both internal and external peer review,
also concluded that trees within the Unit “currently have
structural characteristics which place them at imminent risk of
catastrophic loss to bark beetles.” We therefore cannot say
that the EIS lacks “scientific integrity” or misrepresents the
8522       LEAGUE OF WILDERNESS DEFENDERS v. USFS
scientific literature when it asserts that trees within the Unit
face such a risk.

   The League contends that the Service’s UMZ levels lack
scientific integrity because, in its view, the density of trees in
the Unit has continued to increase well above the UMZ with
only “modest natural mortality every 10 years or so.” How-
ever, the UMZ levels have support in the scientific record and
are entitled to deference as a calculation that is within the
agency’s area of special expertise. See Lands Council, 537
F.3d at 993. Moreover, in challenging only the Service’s reli-
ance on density to determine susceptibility to infestation, the
League overlooks the agency’s reliance on additional mea-
surements of tree health within the Unit, such as declining
growth rate and low tree vigor. The League cites a district
court case involving a successful NEPA challenge to the Ser-
vice’s erroneous reliance on one of the same scientific reports
on tree density at issue here. See Earth Island Inst. v. Morse,
No. 2:08-cv-01897, 2009 WL 2423478, at *5-8 (E.D. Cal.
Aug. 5, 2009). However, in that case, the Service flatly mis-
stated the significance of a particular density target identified
in the report. Id. at *7. The League does not point to a similar
error here.

   The League also contends that the EIS’s use of “imminent”
and “catastrophic” is inconsistent with the plain meaning of
those terms. NEPA regulations require that an EIS “be written
in plain language . . . so . . . the public can readily understand
[it].” 40 C.F.R. § 1502.8; see also Pac. Rivers Council v. U.S.
Forest Serv., ___ F.3d ___, 2012 WL 2333558, at *5 n.8 (9th
Cir. June 20, 2012). The League asserts that the agency’s use
of the terms is hyperbolic and may have been designed to gain
unwarranted public support for the Project. Although under
the circumstances the EIS probably should have defined the
terms in its Glossary, it does disclose in its analysis of the no-
action alternative that imminent risk does not mean immediate
mortality. The EIS states:
           LEAGUE OF WILDERNESS DEFENDERS v. USFS              8523
    Because the [Unit] trees are at a relatively high sus-
    ceptibility to insects, there is an increasing probabil-
    ity that the level of pine beetle-caused mortality will
    become more prevalent even in the short term [less
    than 10 years]. In the long term, beyond 10 years,
    increased levels of beetle-caused mortality will
    occur, and can be expected to reach epidemic levels.

The Study Plan, attached as an appendix to the EIS, also
explains that “[w]hile wildfire and insect outbreaks are not a
100% certainty, there is a recognized risk from both fire and
insects and this risk increases with time.” Although it is a
somewhat close question, we conclude that the EIS’s use of
these terms is not arbitrary and capricious or an abuse of dis-
cretion.

   Second, the League argues that the EIS’s assertion that
trees within the Unit face a “high risk of loss to wildfire,”
including, possibly, “a large stand-replacing event,” is incor-
rect. The League points to the Service’s fire models which,
“under current fuel and stand conditions,” found a potential
for a passive crown fire over only about half of the Project
area. A passive crown fire is a surface fire with individual tree
torching, and generally represents moderate fire behavior with
flame lengths between four and eight feet; an active crown
fire consumes the tops of trees and represents high fire behav-
ior, with flame lengths greater than eight feet. However, the
League overlooks the EIS’s prediction that, without some log-
ging or prescribed burning over the next twenty years, half the
area will develop a potential for active crown fire, and the
other half will develop a potential for passive crown fire,
thereby leaving the entire Project area susceptible to “moder-
ate or high fire behavior.”

   The League argues that the EIS does not present scientific
evidence supporting its assertion that there is a “high and
increasing probability” that trees in the Unit will face a “large
stand-replacing event.” But in its own administrative appeal,
8524       LEAGUE OF WILDERNESS DEFENDERS v. USFS
the League quoted forest ecologist Dr. Edwin Royce, who
wrote that the experimental forest shows “many locations in
need of fuel reduction in order to minimize the probability of
the forest being consumed by a future crown fire.” The peer-
reviewed Study Plan also concludes that the Unit’s present
condition was “conducive to a landscape-scale wildfire.”
Given this, the lack of citation to specific scientific evidence
supporting the assertion does not warrant reversal. This is not
an instance, as in Earth Island, 442 F.3d at 1167, where the
Forest Service “misunderstood” or “misrepresented” its data
about projected tree mortality in an EIS.

   Third, the League argues that the EIS lacks scientific integ-
rity because it does not reconcile its goal of reducing the risk
of “catastrophic” tree mortality with its preferred alternative
that would allow logging of 70 percent of all trees greater
than 6 inches in diameter within the Project area. This argu-
ment mischaracterizes the Project’s risk-reduction goal and
overlooks the function of an experimental forest. The EIS’s
stated concern about the risk of catastrophic loss is not simply
that a large number of trees might be killed (whether by log-
ging, beetles, or wildfire), but rather that widespread mortality
caused by beetles or wildfire would “mean the loss of existing
high-value, long-term studies and eliminate most future
research opportunities.” In its statement of purpose and need,
the EIS explains that “[r]educing risk of loss will protect long-
term studies and keep large blocks of homogenous structure
to maintain options for future research opportunities.” The
EIS also warns of “indiscriminate mortality caused by pine
beetles” that would “negatively impact[ ]” the ability to con-
duct research in the Unit. The EIS’s discussion of fire risk
notes that even fires of relatively low intensity could be “dev-
astating” within the Experimental Forest, where ongoing
research projects depend on particular trees and plots. Thus,
the EIS clearly explains that its risk-reduction goal was not
solely to save trees in the Project area, but rather to protect
those trees for ongoing and future research. Even though the
proposed Project might result in more tree mortality than a
           LEAGUE OF WILDERNESS DEFENDERS v. USFS          8525
beetle infestation or wildfire, it would do so as part of a con-
trolled research study that would also protect ongoing and
future research opportunities.

                       C.   Hard Look

   [13] “Our role in reviewing an EIS is to ensure that the
agency has taken a ‘hard look’ at the potential environmental
consequences of the proposed action.” League of Wilderness
Defenders Blue Mountains Biodiversity Project v. Allen, 615
F.3d 1122, 1135 (9th Cir. 2010) (internal quotation marks
omitted). Taking a “hard look” includes “considering all fore-
seeable direct and indirect impacts. Furthermore, a ‘hard look’
should involve a discussion of adverse impacts that does not
improperly minimize negative side effects.” N. Alaska Envtl.
Ctr. v. Kempthorne, 457 F.3d 969, 975 (9th Cir. 2006) (inter-
nal quotation marks and citation omitted). “[G]eneral state-
ments about possible effects and some risk do not constitute
a hard look absent a justification regarding why more defini-
tive information could not be provided.” Or. Natural Res.
Council Fund v. Brong, 492 F.3d 1120, 1134 (9th Cir. 2007)
(internal quotation marks omitted).

   “[W]e employ a rule of reason standard to determine
whether the EIS contains a reasonably thorough discussion of
the significant aspects of the probable environmental conse-
quences.” League of Wilderness Defenders, 615 F.3d at 1130
(internal quotation marks omitted). This standard “requires a
pragmatic judgment whether the EIS’s form, content[,] and
preparation foster both informed decision-making and
informed public participation.” Native Ecosystems Council v.
U.S. Forest Serv., 418 F.3d 953, 960 (9th Cir. 2005) (internal
quotation marks omitted).

  [14] The League argues that the EIS fails to take a hard
look at the Project’s impacts on overall tree mortality and on
wildlife species that depend on standing dead trees. The
League’s argument about tree mortality fails for the reasons
8526      LEAGUE OF WILDERNESS DEFENDERS v. USFS
discussed above. Most important, the League mischaracterizes
the purpose of the Project when it suggests that “reduction in
tree mortality is the primary goal.” The League also argues
that the EIS fails to quantify the predicted level of mortality
caused by wildfire or insects under the no-action alternative.
However, the EIS describes the expected mortality in qualita-
tive, rather than quantitative, terms, and explains its reasons
for doing so. For example, it states that “[t]he expected level
of this mortality [caused by beetle infestation under the no-
action alternative] is difficult to predict, given the unique
nature of this . . . area. A likely outcome from bark beetle
infestation would be larger-than-normal patches of tree mor-
tality and loss of some of the larger-diameter trees in the
stand.” We have previously suggested that qualitative analy-
ses are acceptable in an EIS where an agency explains “why
objective data cannot be provided.” Klamath-Siskiyou Wild-
lands Ctr. v. Bureau of Land Mgmt., 387 F.3d 989, 994 & n.1
(9th Cir. 2004). Here, the EIS discusses the expected tree
mortality under the no-action alternative and provides a rea-
sonable “justification regarding why more definitive informa-
tion could not be provided.” Brong, 492 F.3d at 1134 (internal
quotation marks omitted).

   Second, the League argues that the EIS fails to take a hard
look at the Project’s impacts on snag-dependent wildlife.
Snags are standing dead trees greater than 10 feet tall and 10
inches in diameter. Several important species of woodpecker,
as well as other birds and small mammals, rely on snags for
nesting and other habitat.

   The EIS analyzes the Project’s impacts on individual snag-
dependent species, as well as on snags more generally. Rely-
ing on an inventory of the Project area, the EIS estimates that
each acre currently contains about seven snags between 10
and 20 inches in diameter and one snag greater than 20 inches
in diameter. The EIS notes that this is more snags than in
other areas within the watershed, but is still below optimal
levels for some species. The EIS states, “The existing low
           LEAGUE OF WILDERNESS DEFENDERS v. USFS           8527
density of snags[,] coupled with the importance of large diam-
eter snags to many of the [relevant] species, emphasizes the
need to retain all existing snags as possible in the planning
area, as well as creating conditions that will favor the recruit-
ment of large snags.” The EIS acknowledges that the pro-
posed action would remove some snags for roads and worker
safety and might destroy others during prescribed burning.
However, it states that “[i]t is not the intention of any of the
proposed actions to remove snags.” The EIS assures that dur-
ing logging operations “[a]ll existing snags would remain
except where snags must be felled for roads, log landings, or
occupational safety.”

   The EIS compares the predicted future impacts on snag-
dependent species under the no-action and proposed action
alternatives. Under the no-action alternative, the EIS
acknowledges that beetle infestation would result in short-
term creation of larger snags and that wildfire would “create
pulses of dead wood,” after which “there would be [a] gap of
dead habitat until the residual stand matures and the snag cre-
ation process starts again.” By contrast, the EIS discloses that
the action alternatives initially would decrease the rate of snag
creation, but predicts that they eventually would result in the
creation of larger snags. The EIS has a basis in the record for
this qualitative prediction. When the Service tried to quantify
future snags under the different alternatives, however, it found
that “[t]he effort quickly proved questionable” because it
relied on too many variables and assumptions about how cer-
tain trees might interact with one another over time. The EIS
concludes that the issue “did not seem to warrant” the “con-
siderably larger effort” that a more detailed quantitative anal-
ysis would require. Instead, the EIS proposes ongoing
monitoring during the Project to assess the assumptions about
the effects of prescribed fire on snags.

   [15] The Service’s analysis of impacts on snag-dependent
species constitutes a hard look under our precedent. As with
tree mortality, its qualitative prediction about impacts on
8528      LEAGUE OF WILDERNESS DEFENDERS v. USFS
snag-dependent species suffices because it explains why pre-
cise quantification was unreliable. See Brong, 492 F.3d at
1134. In WildWest Institute v. Bull, 547 F.3d 1162, 1175 (9th
Cir. 2008), we held that a Service EIS took an adequate “hard
look” at a logging project’s impact on a snag-dependent
woodpecker where it discussed the woodpecker’s habitat
needs and acknowledged that some snags would be removed
or burned, but noted that the Project would generally retain
snags. The EIS in this case does that and more.

                         Conclusion

   [16] The Service proposes a forest management research
project in an experimental forest specifically set aside for
such study. The EIS considers in detail a reasonable range of
alternatives that would fulfill both of the Project’s goals by
reducing the risk of wildfire and beetle infestation, and by
addressing six specified research objectives. The EIS is ade-
quately supported by scientific data and takes a hard look at
the significant impacts of the Project.

  AFFIRMED.
