361framework. Recent advances in seasonal forecasting technology may reduce
uncertainty in the prediction of restoration activities and increase the effi ciency
of programs that may have low probability of success in average or below-
average precipitation years.- Long-term restoration success in arid and semiarid ecosystems is challenging
given environmental constraints and uncertainties regarding future system
dynamics, which can present a big challenge for adaptive management (Beever
et al. 2014 ). Consequently, restoration strategies must be applied strategically
and effectively to maximize conservation values. For example, integrating adap-
tive management into planning and implementing restoration projects that meet
sage-grouse habitat needs and promote resistance to annual grass invasion and
resilience to disturbance is essential. Relatively low success rates may require
redefi ning goals and accepting less ambitious outcomes. - Furthermore, variability in arid and semiarid ecosystems and low probability of favor-
able weather in any given year may require acknowledging multiple acceptable restora-
tion outcomes, relatively long-term management objectives, and an expectation of
multiyear management treatments (Hardegree et al. 2012 ; Herrick et al. 2012 ).
Maintenance of a positive trajectory toward a set of alternative desirable states based on
biodiversity, functional, or sustainability goals will undoubtedly be a more feasible
objective than the traditional goal of achieving a static and largely hypothetical, late-
successional, historical plant community (Whisenant 1999 ; Hardegree et al. 2011 ).
12.7 Research Needs
Our general review of the exotic annual Bromus species impacting arid and semiarid
ecosystems combined with our summary analysis for B. tectorum suggests a num-
ber of promising research directions. In particular, based on our assessment of com-
mon characteristics responsible for annual grass persistence (e.g., transient, yet
typically large, seed banks, altered soil resources and litter production, displace-
ment of native species, and frequent disturbance from fi re), we suggest a few salient
research needs to improve our understanding of specifi c ecological processes
(Sheley et al. 2010 ; James et al. 2013b ):
- Large seed banks are a highly effective reserve for Bromus that can perpetuate
populations and compromise control efforts (Young et al. 1969 ; Diamond et al.
2012 ). This aspect of annual grass management suggests that much more research
is needed to improve our understanding of how control methods impact mortality,
germination and establishment, and plant reproduction (Davies and Johnson 2011 ).
Consequently, integrated, and long-term control efforts are needed in conjunction
with revegetation of desirable perennial species to further explore how restoration
outcomes can be enhanced when seedling emergence, seed production, and seed
dispersal of Bromus are minimized (Chambers et al. 2007 ; Brisbin et al. 2013 ). - Soil surface characteristics such as plant litter, bare ground, and biological soil
crusts strongly infl uence seed germination of annual grasses (Boudell et al. 2002 ;
12 Assessing Restoration and Management Needs for Ecosystems...