Lessons in Ecosystem Management from Management of Threatened and Pest Loranthaceous Mistletoes in New Zealand and Australia

Loranthaceous mistletoes are interesting because of their complex dependence on suitable host trees and avian dispersers and because of their patchy distribution at the landscape level. Although their over- and under-abundance in Australia and New Zealand have been widely documented, little attention has been given to the need for an ecosystem approach to their management. Although the current status of mistletoes is very different in Australia and New Zealand, some of the causal factors and the long-term effects of changes in mistletoe abundance are similar in the two countries. We suggest that mistletoe abundance in pre-European landscapes was dependent on a series of evolutionary and environmental filters relating to host specificity, pollination, dispersal, infection, environmental habitat quality, predation, and disturbance. European settlement modified these filters in a number of ways, resulting in either increases or decreases in mistletoe abundance. The three broad groups of changes that have occurred with European settlement involve fragmentation, predation, and altered disturbance regimes. Although managers have usually addressed mistletoe over- or under-abundance with short-term solutions (e.g., pruning infected trees), we suggest that management must address the underlying causes of the problems involving mistletoes. This requires an ecosystem approach to management that addresses both the direct and indirect causes of the current status of mistletoes.     

Stormflow hydrochemistry of a river draining an abandoned metal mine: the Afon Twymyn, central Wales

Contaminated drainage from metal mines is a serious water-quality problem facing nations that exploit metal mineral resources. Measurements of river hydrochemistry during baseflow are common at mine sites, whilst detailed hydrochemical information regarding stormflow is limited and often confined to a single event. This study investigates the seasonal evolution of stormflow hydrochemistry at an abandoned metal mine in central Wales, UK, and the possible sources and mechanisms of metal release. Significant flushing of metals was observed during stormflow events, resulting in concentrations that severely exceeded water-quality guidelines. The relationship between metal concentrations and river discharge suggests dissolution of efflorescent metal sulphates on the surface of the mine spoil as the principal source of the contamination. High fluxes of Pb during stormflows are linked to extended periods of dry weather prior to storm events that produced water table drawdown and encouraged oxidation of Pb sulphide in the mine spoil. However, some Pb flushing also occurred following wet antecedent conditions. It is suggested that Fe oxide reduction in mine spoil and translatory flows involving metal-rich pore waters results in flushing during wetter periods. Detailed measurements of stormflow hydrochemistry at mine sites are essential for accurate forecasting of long-term trends in metals flux to understand metal sources and mechanisms of release, to assess potential risks to water quality and instream ecology, and to gauge the potential effectiveness of remediation. In order to protect riverine and riparian ecosystems, it is suggested that routine monitoring of stormflows becomes part of catchment management in mining-impacted regions.     

Effects of interactions between anthropogenic stressors and recurring perturbations on ecosystem resilience and collapse

Insights into declines in ecosystem resilience and their causes and effects can inform preemptive action to avoid ecosystem collapse and loss of biodiversity, ecosystem services, and human well-being. Empirical studies of ecosystem collapse are rare and hampered by ecosystem complexity, nonlinear and lagged responses, and interactions across scales. We investigated how an anthropogenic stressor could diminish ecosystem resilience to a recurring perturbation by altering a critical ecosystem driver. We studied groundwater-dependent, peat-accumulating, fire-prone wetlands known as upland swamps in southeastern Australia. We hypothesized that underground mining (stressor) reduces resilience of these wetlands to landscape fires (perturbation) by diminishing groundwater, a key ecosystem driver. We monitored soil moisture as an indicator of ecosystem resilience during and after underground mining. After landscape fire, we compared responses of multiple state variables representing ecosystem structure, composition, and function in swamps within the mining footprint with unmined reference swamps. Soil moisture declined without recovery in swamps with mine subsidence (i.e., undermined), but was maintained in reference swamps over 8 years (effect size 1.8). Relative to burned reference swamps, burned undermined swamps showed greater loss of peat via substrate combustion; reduced cover, height, and biomass of regenerating vegetation; reduced postfire plant species richness and abundance; altered plant species composition; increased mortality rates of woody plants; reduced postfire seedling recruitment; and extirpation of a hydrophilic animal. Undermined swamps therefore showed strong symptoms of postfire ecosystem collapse, whereas reference swamps regenerated vigorously. We found that an anthropogenic stressor diminished the resilience of an ecosystem to recurring perturbations, predisposing it to collapse. Avoidance of ecosystem collapse hinges on early diagnosis of mechanisms and preventative risk reduction. It may be possible to delay or ameliorate symptoms of collapse or to restore resilience, but the latter appears unlikely in our study system due to fundamental alteration of a critical ecosystem driver. Efectos de las interacciones entre los estresantes antropogénicos y las perturbaciones recurrentes sobre la resiliencia y el colapso de los ecosistemas     

Climate forecasts in disaster management: Red Cross flood operations in West Africa, 2008

In 2008, the International Federation of Red Cross and Red Crescent Societies (IFRC) used a seasonal forecast for West Africa for the first time to implement an Early Warning, Early Action strategy for enhanced flood preparedness and response. Interviews with disaster managers suggest that this approach improved their capacity and response. Relief supplies reached flood victims within days, as opposed to weeks in previous years, thereby preventing further loss of life, illness, and setbacks to livelihoods, as well as augmenting the efficiency of resource use. This case demonstrates the potential benefits to be realised from the use of medium‐to‐long‐range forecasts in disaster management, especially in the context of potential increases in extreme weather and climate‐related events due to climate variability and change. However, harnessing the full potential of these forecasts will require continued effort and collaboration among disaster managers, climate service providers, and major humanitarian donors.     

Facultative pheromonal mimicry in snakes: “she-males” attract courtship only when it is useful

Males of many animal species mimic females, and thereby deceive rival males. Facultative shifts in posture, color, or movement allow a male using visually-based mimicry to adopt and terminate mimicry rapidly. Pheromonal mimicry is rare in vertebrates perhaps because it is difficult to redeploy pheromones rapidly enough to adjust male tactics to local conditions. In Manitoba garter snakes (Thamnophis sirtalis parietalis), female mimicry benefits males immediately after they have emerged from hibernation. While the snakes are cold and slow, courtship warms them and protects them against predatory crows. This benefit disappears as soon as the snakes are warm. We show that (unlike females) she-male garter snakes attract courting males only when they are cold. Low temperatures may suppress volatility of “less attractive” components of the pheromones (saturated methyl ketones) that she-males use to attract courtship, allowing male snakes to function as transvestites only when this tactic is beneficial.     

Neighborhood and habitat effects on vital rates: expansion of the Barred Owl in the Oregon coast ranges

In this paper, we modify dynamic occupancy models developed for detection-nondetection data to allow for the dependence of local vital rates on neighborhood occupancy, where neighborhood is defined very flexibly. Such dependence of occupancy dynamics on the status of a relevant neighborhood is pervasive, yet frequently ignored. Our framework permits joint inference about the importance of neighborhood effects and habitat covariates in determining colonization and extinction rates. Our specific motivation is the recent expansion of the Barred Owl (Strix varia) in western Oregon, USA, over the period 1990-2010. Because the focal period was one of dramatic range expansion and local population increase, the use of models that incorporate regional occupancy (sources of colonists) as determinants of dynamic rate parameters is especially appropriate. We began our analysis of 21 years of Barred Owl presence/nondetection data in the Tyee Density Study Area (TDSA) by testing a suite of six models that varied only in the covariates included in the modeling of detection probability. We then tested whether models that used regional occupancy as a covariate for colonization and extinction outperformed models with constant or year-specific colonization or extinction rates. Finally we tested whether habitat covariates improved the AIC of our models, focusing on which habitat covariates performed best, and whether the signs of habitat effects are consistent with a priori hypotheses. We conclude that all covariates used to model detection probability lead to improved AIC, that regional occupancy influences colonization and extinction rates, and that habitat plays an important role in determining extinction and colonization rates. As occupancy increases from low levels toward equilibrium, colonization increases and extinction decreases, presumably because there are more and more dispersing juveniles. While both rates are affected, colonization increases more than extinction decreases. Colonization is higher and extinction is lower in survey polygons with more riparian forest. The effects of riparian forest on extinction rates are greater than on colonization rates. Model results have implications for management of the invading Barred Owl, both through habitat alteration and removal.     

Reducing sediment and phosphorus in tributary waters with alum and polyacrylamide

The Salton Sea is the largest inland water body in California, covering an area of 980 km(2). Inflow to the Salton Sea (1.6 km(3) yr(-1)) is predominately nutrient-rich agricultural wastewater, which has led to eutrophication. Because internal phosphorus release from the bottom sediments is comparatively low and external phosphorus loading to the Salton Sea is high, reduction of tributary phosphorus is expected to reduce algal blooms, increase dissolved oxygen, and reduce odors. Removing both dissolved phosphorus and phosphorus-laden sediment from agricultural drainage water (ADW) should decrease eutrophication. Both alum and polyacrylamide (PAM) are commonly used in wastewater treatment to remove phosphorus and sediment and were tested for use in tributary waters. Laboratory jar tests determined PAM effectiveness (2 mg L(-1)) for turbidity reduction as cationic > anionic = nonionic. Although cationic PAM was the most effective at reducing turbidity at higher speeds, there was no observed difference between the neutral and anionic PAMs at velocity gradients of 18 to 45 s(-1). Alum (4 mg L(-1) Al) reduced turbidity in low energy systems (velocity gradients < 10 s(-1)) by 95% and was necessary to reduce soluble phosphorus, which comprises 47 to 100% of the total P concentration in the tributaries. When PAM was added with alum, the anionic PAM became ineffective in aiding flocculation. The nonionic PAM (2 mg L(-1)) + alum (4 mg L(-1) Al) is recommended to reduce suspended solids in higher energy systems and reduce soluble P by 93%.     

Transparency,accountability and empowerment in sustainability governance: a conceptual review

ABSTRACT

This paper offers a conceptual examination of the power-effects of transparency, as information disclosure, on those making accountability claims against actors deemed to be causing significant environmental harm. Informed by Lukes’s ([2005]. Power: A radical view (second edition). Basingstoke: Palgrave Macmillan.) multi-dimensional theory of power, I review recent scholarship to interrogate four hypotheses positing empowerment for accountability claimants arising from the disclosure of sustainability information. Across public and private governance forms, academic research suggests that information disclosure promotes the communication of the sustainability interests of affected parties, and in some cases enhances the capacity of these parties to evaluate justifications provided by relevant power-wielders. However, evidence is weaker that disclosure of sustainability information empowers accountability claimants to sanction or otherwise steer those responsible; and there is little support that transparency fosters wider political interrogation of the configurations of authority producing environmental harm. Differentiating between behavioural and non-behavioural understandings of power allows an evaluation of these research findings on the power-related effects of information disclosure.