Spoon-leaved moss (Bryoandersonia illecebra) recovery strategy: chapter 8

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Recovery

Recovery Feasibility

All Canadian specimens of Spoon-leaved Moss are female, and no sporophytes have ever been documented.  However, the Canadian population cannot be surveyed in its entirety for male plants because sex determination in bryophytes requires destructive sampling, and the absence of sporophytes in collections does not definitively confirm the inability of Canadian populations to produce them.  With respect to asexual reproduction, extant colonies are presumably capable of expansion within their respective sites, and plant fragments are probably capable of dispersal over short distances, particularly with the assistance of water or other local vectors.   The extent to which vegetative propagation might be able to improve growth rate or abundance depends on factors such as natural rates and patterns of senescence, extent of available suitable habitat, and current trend in population size, which have yet to be documented.  Minimum viable population is not known for Spoon-leaved Moss, or for most bryophytes (if any), and modification of commonly-used methods (e.g. Menges 1990, 1991) would be required before it could be defined.

Without temporal demographic data for Spoon-leaved Moss or data pinpointing reasons for the species’ limitation and its potential decline, it is not clear that protecting current populations will be sufficient to ensure long-term persistence.  Spoon-leaved Moss has been known from one or two sites since the early 1980’s, which suggests that persistence is possible without intervention.  Intervention-based attempts to recover rare bryophyte populations, such as transplanting colonies, plants, fragments, or spores to manipulate gender ratios or augment populations, are not known in North America (but note that peatland restoration involves re-introducing moss diaspores (e.g. Rochefort & Bastien 1998, Rochefort et al. 2003)).  In Europe, however, ex-situ conservation and re-introduction have been applied to several rare bryophytes (e.g. Kooijman & Beltman 1994, UK Biodiversity Action Plan 2005).  Their potential for success in the current context cannot be predicted, but this recovery strategy provides an important opportunity for research that may serve future attempts to recover rare bryophyte species.  A wide body of literature exists describing bryophyte plant and diaspore propagation for experimental purposes (e.g. references cited in Kallio & Saarnio 1986, Wiklund & Rydin 2004, Cleavitt 2005), and can provide important background information to help increase the chances of success.

Additional considerations for recovery feasibility include the existence of sufficient habitat to support the species, and the ability to reduce threats to the species or its habitat.  These criteria appear to be met for Spoon-leaved Moss, as shown by the species’ persistence in the region despite dense human activity, the protective designations placed on all sites where it occurs, and observations that direct human disturbance of the sites is unlikely (R. Gould, personal communication). 

In brief, recovery of Spoon-leaved Moss is currently considered to be feasible.  This conclusion will be reviewed in the context of future research findings.

Recovery Goal, objectives and corresponding approaches

Recovery Goal

The goal of this recovery strategy is to conserve existing populations of Spoon-leaved Moss in the long term and, if possible, to restore the species’ long-term stability and self-sustainability in Ontario by increasing the size of existing populations and/or increasing the number of known occurrences.  Target population number and size are therefore set at the minimum of current levels for each of the three sites of occurrence in 2005, pending research to determine the feasibility of increased targets.

Recovery Objectives

Without specific demographic information with which to confirm the trends in the Canadian population or to define the minimum viable population, and without a firm understanding of key factors limiting Spoon-leaved Moss, setting realistic, relevant recovery objectives and performance measures is an uncertain process reflecting the best interpretation of available data (Menges 1991, Schemske et al. 1994, Nantel & Gagnon 1999).  However, this does not preclude the development of recovery targets or commencement of activities.  It is also important to recognize the distinction between rarity, which may be normal for Spoon-leaved Moss as a peripheral species in Canada, and endangerment (e.g. Morse 1996), which the recovery process is designed to reverse.  Threat management can only increase the species’ status within the bounds of its naturally limited capacity.

With this in mind, the following objectives are to be addressed within the next five years in support of the recovery goal.

1. Monitor habitat to detect potential threats at all three sites of occurrence annually (or more frequently) and address causal agents.
2. Maintain or increase current population size (measured as area occupied by moss and number of colonies) at each site of occurrence by protecting plants and critical habitat.
3. Identify broad-scale conservation initiatives in the Carolinean life zone relevant to the Spoon-leaved Moss and identify activities on which to collaborate. 
4. Increase the knowledge base with respect to species demography, biology, distribution, abundance, habitat requirements, critical habitat, threats, transplant/introduction techniques, and/or feasibility of recovery to the extent that long-term sustainability is confirmed or that:

Broad strategy to be taken to address threats

Threats of habitat degradation and population decline must be addressed through the broad strategies of monitoring, management and research (Table 3).  All activities (Table 3) involve careful on-going planning, re-evaluation and communication throughout the recovery process.  They take into consideration the three-step approach advocated by Schemske et al. (1994) for developing efficient recovery strategies:  1) determine the biological status (increasing, decreasing, or stable) of the species through demographic research, 2) identify the life history stages with the greatest effect on biological status, 3) explore the biological reasons for variation in those life history stages.  These steps serve to prioritize research and, subsequently, recovery activities according to factors that are of greatest relevance to the species’ persistence.

There is no detailed demographic information on Spoon-leaved Moss, and collecting these data is given first priority (along with threat monitoring) among research and recovery activities.  It seems doubtful, however, that sufficient data can be gained from Canadian populations, given their limited number and extent and their long-lived perennial life strategy, to apply population modeling.  Monitoring of core (US) populations (Nantel & Gagnon 1999), which are more numerous and thus more conducive to demographic modeling, may help to identify vulnerable life history stages in the species, and the degree to which populations north of the international border are characteristic of the species in general.  In the meantime, however, casual observation suggests that important demographic components of the species (male plants, reproducing individuals) are absent or rare in Canada.  At least one population has persisted for over twenty years, but overall population decline is inferred.  In the absence of hard demographic evidence, it seems most likely that barriers to reproduction (and therefore dispersal) may be greater than those to growth and survivorship, and the proposed research reflects this priority.  Investigating these barriers (e.g. through transplant trials, controlled growth experiments) will reveal the human activities likely to affect reproductive ability, and the feasibility and methods of reducing their limiting effect. 

Although the results of genetic studies are difficult to relate directly to population viability or demographic ‘fitness’ of a plant population (Ellstrand & Elam 1993, Schemske et al. 1994), they are proposed here as a means of researching dispersal distances and paths, as well as gender, within the Canadian population and between Canadian and US populations. Despite the rationale presented above, reproductive limitation may not be the key limiting factor for Spoon-leaved Moss in Canada.  Thus, although studies of factors limiting establishment and growth are not given first priority at this time, all research of ecological requirements (see section 2.3 – data gaps) is encouraged for its potential value in determining current limiting factors (Schemske et al. 1994), or in facilitating re-introduction if it becomes necessary.  Although full scientific certainty may never be achieved, measures should be set in place immediately with the understanding that the broad strategy is dynamic and that the results of monitoring, management and research will continually supply information for ongoing development of the recovery strategy.   

Effects on other species

No immediate negative impacts on non-target species, natural communities or ecological processes are anticipated to result from the proposed recovery activities.  Generally speaking, the protection of Carolinian habitat from degradation will benefit all species at affected sites. 

Research and monitoring activities that take place at Spoon-leaved Moss sites should be structured in such a way that neither site access nor the activities themselves significantly modify or damage the site or its resident biota (including Spoon-leaved Moss), and the effects of recovery activities should themselves be monitored to ensure that this is the case.  The need to collect Spoon-leaved Moss, for genetic studies for example, will be carefully evaluated and regulated so as to minimize impact on the populations.

Evaluation

Performance measures for evaluating success in meeting the stated recovery objectives will include the extent to which each objective has been met, using the broad strategies identified above.

Performance measures of biological effect of recovery activities:

·     Status and condition of known populations

• Population number, colony number, and area occupied at minimum of 2005 level
• National status maintained or upgraded at next assessment (2013)
• Stable or increasing provincial and local populations in terms of number of localities and local abundance

Performance measures of recovery activity process:

·     Establishment and ongoing implementation of threat monitoring

• Annual monitoring and documentation complete
• Management and research plans reflect results of threat monitoring

·     Establishment and ongoing implementation of population monitoring

• Temporal trend or fluctuation (or lack thereof) in local population size (colony number, area occupied) has been described
• Annual monitoring and documentation complete
• Management and research plans reflect results of population monitoring

·     Establishment and ongoing implementation of research

• Critical habitat identification has progressed beyond 2005 level
• Recovery feasibility is established with respect to at least one additional criterion
• Additional populations found are mapped and incorporated into the recovery program and areas searched are fully documented
• Identification of limiting factors has progressed beyond 2005 level
• Species biology and ecology can be described in greater detail than in 2005
• Research results are incorporated into updated research schedule
• The necessity of and approaches to re-introduction has been evaluated in preparation for incorporation into management plans
• Published research articles reflect research results

·     Establishment and ongoing implementation of communication strategy

• Spoon-leaved Moss management activities incorporated into all relevant management/planning documents
• All land use compatible with recovery activities

·     Establishment and ongoing implementation of management plans

• Management plans and activities reflect most recent available data from within and outside the recovery program

Knowledge Gaps

As stated above, although recovery activities should commence immediately based on the available information, the recovery objectives and activities are designed in this recovery strategy to undergo regular revision based on new information arising from research and monitoring.  Four main knowledge gaps have been suggested throughout this document (Table 4) and are addressed in the preceding research schedules.

Recommended Approach for Recovery

It has already been emphasized that recovery goals and activities for Spoon-leaved Moss should be incorporated into the management plans of the organizations (Ontario Ministry of Natural Resources, Niagara Peninsula Conservation Authority, Ontario Parks) that own and manage the land on which the species resides.  No recovery strategies for individual species currently overlap with that of Spoon-leaved Moss, but there may be other opportunities for integrating species-specific recovery into other recovery or conservation efforts.  For example, the plight of Carolinian species in southern Ontario is the object of considerable, well-publicized concern, and research and recovery activities have been initiated on many scales.  The accessibility of the recovery goal for Spoon-leaved Moss, as for all rare Carolinian species, will be affected by the success of management activities directed to preserving other Carolinian species and to restoring ecological integrity to the landscape of southern Ontario (e.g. Ambrose & Kirk 2004).  Consultation with the Carolinian Woodland Plant Recovery Team, which isattempting to address the ecosystem approach to recovery of Carolinian woodland habitat, and the associateddraft recovery strategy (in preparation) would also be productive.

Some of the research recommended in this strategy involves monitoring or measuring populations in the United States.  Cross-border initiatives such the Canada-US Framework for Co-operation in identifying and recovering shared species at risk (Environment Canada 2001) highlight the potential for data exchange and resource sharing with respect to rare plants.  While Spoon-leaved Moss is not rare in the United States, opportunities for the Framework or other programs to facilitate co-operation should be explored.  For example, the genetic or adaptive features of Canada’s peripheral populations may be of conservation significance in the global context.

Statement of When One or More Action Plans in Relation to the Recovery Strategy Will Be Completed

In the absence of a recovery team for Spoon-leaved Moss, a Recovery Implementation Group will need to be formed to develop an Action Plan and implement the recovery activities.  It is suggested that an Action Plan to implement the broad strategies identified in this recovery strategy be developed by 2008.