1 features in order to properly site solar energy facilities, which needs to be considered at the 2 project-specific scale. However, even with careful siting designs, the protection of water

3 resources will require monitoring and modeling to assess resulting impacts and to inform 4 adaptive management strategies.

5

6

7 5.10 ECOLOGICAL RESOURCES

8

9

10 5.10.1 Vegetation

11

12As discussed in Section 5.10.1 of the Draft Solar PEIS, impacts on vegetation that could

13result from utility-scale solar energy development include those associated with initial site

14characterization, facility construction, operations, and decommissioning. The potential impacts

15would be directly related to the amount of land disturbance, the duration and timing of

16construction and operation periods, and the habitats affected by development (i.e., the location of

17the project). Potential impacts on terrestrial and wetland plant communities and habitats from the

18development of utility-scale solar energy projects would include direct impacts from habitat

19removal as well as a wide variety of indirect impacts on or off the project site. Indirect effects,

20may be associated with invasive species, groundwater withdrawal, erosion, sedimentation,

21alteration of drainage patterns, habitat fragmentation, fugitive dust, spills, soil compaction,

22topsoil removal, vegetation maintenance, air emissions, or increased human access.

23

24Plant communities and habitats affected by direct or indirect impacts from project

25activities could incur shortor long-term changes in species composition, abundance, and

26distribution. Some impacts may also continue after the decommissioning of a solar energy

27project. Direct impacts would primarily include the destruction of habitat during initial land

28clearing on the solar energy project site, as well as habitat losses resulting from the construction

29of access roads, natural gas pipelines, and electric transmission lines. As identified in the recent

30ethnographic studies, Native American tribes are concerned about impacts on traditionally used

31plants (SWCA and University of Arizona 2011). Restoration of plant communities on

32temporarily disturbed land or following decommissioning may result in plant communities that

33are different from native communities in terms of species composition and representation of

34particular vegetation types, such as shrubs. The establishment of mature native plant

35communities may require decades, and some community types may never fully recover from

36disturbance. Restoration of plant communities in areas with arid climates would be especially

37difficult and may be unsuccessful in some areas. However, the BLM is committed to the

38oversight of restoration efforts and ensuring that the Vegetation Management Plan for the site is

39followed.

40

41Information provided in the Draft Solar PEIS remains valid; there are no updates for this

42section.

43

44

4result from utility-scale solar energy development include those associated with initial site

5characterization, facility construction, operations, and decommissioning. The potential impacts

6would be directly related to the amount of land disturbance, the duration and timing of

7 construction and operation periods, and the habitats affected by development (i.e., the location of 8 the project). Indirect effects, such as those resulting from the erosion of disturbed land surfaces

9and disturbance and harassment of animal species, are also possible, but their magnitude is

10considered proportional to the amount of land disturbance. Recent ethnographic studies indicated

11that Native American tribes have concerns about impacts on traditionally important wildlife

12species, such as bighorn sheep and horned toads (SWCA and University of Arizona 2011).

13

14The impacts on wildlife remain the same as presented in Section 5.10.2 of the Draft Solar

15PEIS. However, comments on the Draft Solar PEIS raised concerns that the impacts of noise on

16wildlife (particularly behavioral impacts) were not adequately addressed. Therefore, the

17following text replaces the text on page 5-78 and the first paragraph on page 5-79 of the Draft

18Solar PEIS:

21(e.g., exacerbating fragmentation impacts), increase stress levels, decrease

22immune response, reduce reproductive success, increase predation risk, degrade

23communication, and cause hearing damage (Habib et al. 2007; Manci et al. 1988;

24Pater et al. 2009). Generally, deleterious physiological responses to noise occur at

25exposure levels of 55 to 60 dB(A) or more (see Barber et al. 2010). Noise levels

26tend to be lower than this at distances greater than 500 ft (152 m) from the noise

27source. The response of wildlife to noise would vary by species; physiological or

28reproductive condition; distance; and the type, intensity, and duration of the

29disturbance. Brattstrom and Bondello (1983) reported that peak sound pressure

30levels reaching 95 dB resulted in a temporary shift in the hearing sensitivity of

31kangaroo rats (Dipodomys spp.), and that at least 3 weeks was required for the

32recovery of hearing thresholds. The authors postulated that such hearing shifts

33could affect the ability of the kangaroo rat to avoid approaching predators.

36wildlife and result in a long-term reduction in use by wildlife in those

37areas. Herrera–Montes and Aide (2011) noted that bird species richness and

38occurrence were significantly lower at sites near a highway, while anurans (frogs

39and toads) were not affected. This was due to birds calling during the day when

40high levels of traffic occur. Also, some anurans occur at high densities and form

41noisy choruses (e.g., >80 dB), which allows them to tolerate anthropogenic noise.

42However, Sun and Narins (2005) reported that man-made acoustic interference

43may affect anuran calling in some species by modulating their call rates or by

44suppressing calling behavior (in turn, this may stimulate calling in other species).

45Some species can overcome interference from intermittent anthropogenic noise by

46timing their calls to coincide with periods of silence (Egnor et al. 2007). Noise

1can exacerbate impacts on wildlife caused by habitat fragmentation and human

5likely to occur only with frequently repeated, predictable exposures, and

6acclimation can be lost if enough time passes between repeat exposures

7(Wright et al. 2007). Also, it could be the visual element of the event rather than,

8or in addition to, the auditory component that causes the observed reaction in

9wildlife (AMEC Americas Limited 2005). Acclimation to a noise stimulus does

10not prevent other effects such as hearing loss. The apparent tolerance to noise

11stress could be the result of the animal or population having to remain in the area

12because of the absence of alternative habitats, high energetic costs associated with

13avoidance, or even reduced hearing from the frequency of the noise stimulus

14(Wright et al. 2007). Also, acclimation could cause possible sensitization, such

15that the animal may demonstrate an enhanced stress response when exposed to a

16different new stressor (Wright et al. 2007).

19on birds. Responses of birds to disturbance often involve activities that are

20energetically costly (e.g., flying) or affect their behavior in a way that

21might reduce food intake (e.g., shift away from a preferred feeding site)

22(Hockin et al. 1992). A variety of adverse effects of noise on raptors has

23been demonstrated, but for some species, the effects were temporary,

24and the raptors became habituated to the noise (Brown et al. 1999;

25Delaney et al. 1999). A review of the literature by Hockin et al. (1992) showed

26that the effects of disturbance on bird breeding and breeding success include

27reduced nest attendance, nest failures, reduced nest building, increased predation

28on eggs and nestlings, nest abandonment, inhibition of laying, increased absence

29from the nest, reduced feeding and brooding, exposure of eggs and nestlings to

30heat or cold, retarded chick development, and lengthening of the incubation

31period. The most adverse impacts associated with noise could occur if critical life-

32cycle activities were disrupted (e.g., mating and nesting). For instance,

33disturbance of birds during the nesting season could result in nest or brood

34abandonment. The eggs and young of displaced birds would be more susceptible

35to cold or predators.

38chronic anthropogenic noise exposure on wildlife (Barber et al. 2010;

39Bayne et al. 2008). Noise exposure can cause physiological stress either directly

40(as described above) or indirectly through secondary stressors such as annoyance.

41These secondary stressors can increase the ambiguity in received signals or cause

42animals to leave a preferred resource area (Wright et al. 2007). Noise can inhibit

43(mask) the perception of sounds. Masking can affect the ability of wildlife to use

44sound for spatial orientation, for example, to detect potential mates, detect

45predators or prey, respond to begging calls from young, defend territories,

46maintain pair bonds, hear alarm calls, interfere with feeding, and reduce breeding