Adaptive management in practice: Conservation of a threatened plant population

Abstract

We applied an adaptive management approach to reduce extinction risks faced by a disjunct and ecologically significant population of Black Cypress Pine (Callitris endlicheri), listed as an endangered population on the New South Wales Threatened Species Conservation Act 1995. In summer 2001-2002, an unplanned fire burnt the population, resulting in mortality of most standing plants. Concerns were raised about the potential impact of herbivores, particularly feral Rusa Deer (Cervus timorensis), on the recruitment of post-fire seedlings that might replace the loss of fire-killed standing plants. We applied an adaptive management approach to detect trends in the population following the fire, and to evaluate and trial in situ management options for mitigating threats to the remaining plants. Post-fire monitoring detected continuing declines in both the remaining adult population and the post-fire cohort of seedlings, and identified browsing by Deer as a serious and ongoing threat to the population. We designed a controlled experiment, with the aid of natural and artificial 'nurse plants' to assess the effects of herbivore exclusion on seedling growth and survival, and to test for differences in those effects under alternative management strategies. The experiment was designed and implemented with little cost other than field time and with logistic constraints on replication. By protecting exposed seedlings from browsing using woody debris, we were able to significantly increase seedling growth and survival, and to quickly arrest the population decline. Our results suggest that excluding Deer from the population by more permanent means will have a significant positive effect on its long-term persistence. Our case study demonstrates the utility of adaptive management approaches in threatened species conservation, their feasibility even under severe budgetary and logistical constraints, and how ongoing monitoring and experimentation are crucial for successful management of biodiversity.

Adaptive management: where are we now?

“…Of those reporting success, this was either in terms of enhanced stakeholder involvement (Bryan et al 2009), progress towards achieving management objectives (Bryan et al 2009;Eberhard et al 2009;Mackenzie & Keith 2009), or informative assessment and monitoring (Ascoli et al 2009;Blackstock 2009;Bryan et al 2009;Castley et al 2009;Densmore & Karle 2009;Melzer et al 2009;Newlin & Johnson 2009). Five studies had more than one objective in management, and five focused on management at a landscape scale.…”

The tortoise and the hare? Post-fire regeneration in mixed Eucalyptus - Callitris forest

“…By contrast, Mackenzie and Keith (2009) found that the density of protected (ungrazed) C. endlicheri seedlings declined by 19% within a 12-month period, from 2 to 3 years after fire. Initial seedling densities may have been underestimated in our study, as sampling began in April 2004, 15 months after the fire.…”

“…In contrast, Mackenzie and Keith (2009) recorded high mortality of C. endlicheri seedlings in an area grazed by feral Cervus timorensis (Rusa Deer) in coastal New South Wales. Over 12 months, 98% of unprotected seedlings were browsed at least once, leading to a 59% decline in seedling density (Mackenzie and Keith 2009). Seedlings of the related species, C. glaucophylla, are known to be sensitive to repeated browsing by rabbits and sheep (Lacey 1972).…”

Habitat Assessment and Conservation Status of Endangered Northeastern Bulrush

“…In a review of recovery plan implementation, only about half included monitoring the results of management activities (Boersma et al 2001). Yet continued monitoring of populations and threats is necessary for effective conservation and adaptive management in plants (MacKenzie and Keith 2009). Those recovery plans that incorporate "explicit and dynamic science" are more likely to be successful (Boersma et al 2001), pointing towards the need for continual basic research of endangered species and re-visitation of recovery plan goals.…”