Invasion Biology needs assessment of current policies and measures

In this post Associate Editor Céline Bellard discusses the recent paper ‘Managing the risk of wildlife disease introduction: pathway-level biosecurity for preventing the introduction of alien ranaviruses‘, by Pablo García-Díaz, Joshua Ross, Andrew Woolnough and Phillip Cassey.

Invasive alien species are one of the major drivers of global biodiversity loss. Among the most notorious invasive species, emerging wildlife diseases like the chytrid fungi are a globally widespread threat to native amphibian species. Emerging wildlife diseases have been responsible for putting hundreds of species at risk of population extinction, with no sign of slowing down. Rapid declines in amphibian populations have occurred around the world.

In order to combat this threat, it is now widely recognized that early detection and rapid response is one of the critical defences against the establishment of invasive species. In particular, one of the most efficient ways to reduce the risk of new invasions is to implement stringent biosecurity measures. For instance, border and post-border surveillance are particularly recommended to prevent new introductions of emerging diseases.

To address this risk, Australia has a number of screening, surveillance and quarantine measures in place to manage the risk of unintentional transport of infected alien amphibians. Yet the capacity of such measures to limit new introductions has seldom been evaluated. This is symptomatic of invasion biology generally, but it is critical that evidence-based research is adopted to inform managers, and incorporate the assessment of optimal surveillance and biosecurity strategies.

García-Díaz et al. assessed the capacity of Australian border and post-border biosecurity activities to prevent the introduction of alien ranaviruses. They collected information on 287 detections of alien amphibian individuals detected on both airplanes and ships arriving in Australia. By developing a hierarchical model to describe transport pathways into Australia and the biosecurity measures that are implemented, they assessed the capacity of existing biosecurity activities to act as an effective barrier against ranaviruses.

Their conclusion is unequivocal: border and post-border biosecurity programs in Australia reduced the risk of introduction of alien ranaviruses.  García-Díaz et al. provide a clear illustration of the effectiveness of the Australian biosecurity system to detect potential introduction of alien ranaviruses via the unintentional transport of alien amphibians. Their work draws attention to the fact that such programs are efficient and should be implemented in other countries to continue prevention of emerging diseases.  This study highlights again that an international response to fight emerging diseases is highly recommended, entirely necessary, and could be efficient to prevent future invasions. Moreover, their work encourages further research to assess other early detection measures against invasive species and identify their gaps to improve further our capacity to combat invasive species.

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A common midwife toad (Alytes obstetricans) that died during a ranavirus outbreak, Galicia, North-western Spain. Ranavirus outbreaks have produced die-offs in amphibian populations all over the world, and the research by García-Díaz et al. demonstrates that implementing biosecurity activities reduce the risk of introduction of alien ranaviruses. Photo credit Marius Von Essen.

If you want , you can follow the Invasion Ecology Group on Twitter for updates on their research: @InvasionEcology

Old villages are hot-spots of farmland bird diversity

In this post Zuzanna Rosin discusses her paper ‘Villages and their old farmsteads are hot-spots of bird diversity in agricultural landscapes‘, published today.

The decline of farmland biodiversity is one of the major ecological and conservation problems in Europe. To date many efforts have been made to slow down the rate of this process, however, recent studies confirm ongoing negative trends. To counteract this decline, it is crucial to recognize farmland habitats benefiting biodiversity. Scientists and practitioners focused on the land-use and agricultural practices in crops while villages, being an economic and socio-cultural centre of farmland, have received much less attention in that context. Whereas today western European countryside is usually dominated by a high proportion of modern settlements mainly used only for living, central-eastern Europe still has a large number of old traditional villages and single old farmsteads conducting small-scale farming. However, due to large scale social and economic processes that started after the fall of communism in 1989, old farmsteads (linked to agricultural production) and homesteads (used mainly for living) are being replaced by modern homesteads that greatly differ in structure from the former ones.

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This is how some Polish villages still look. Photo credit: Darek Świtała.

Because of its high heterogeneity, the village environment is attractive to many bird species. Old buildings have complex structures and a multitude of sites (e.g. old roof tiles, chimneys and beams) that are used for nesting by several species. Moreover, surroundings of old houses are highly heterogeneous, being composed of old deciduous and fruit trees (rich in cavities), shrubs (suitable for several open nesting species), garden plots and ruderal vegetation (foraging sites). Furthermore, ponds, farm animals and farm residues (e.g. grain, manure) associated with farmsteads provide a wide range of food and foraging microhabitats. All these favourable (micro)habitats are disappearing from the agricultural landscapes of central-eastern Europe due to several simultaneously progressing socio-economic processes: expansion of cities, trends of urban people moving to rural areas, farm modernisation and village abandonment. These changes may be one of the key factors contributing to the loss of farmland biodiversity in Europe, since new homesteads are structurally simplified, having the environs of the house homogeneous, poor in potential nesting and foraging sites, usually dominated by lawns with single shrubs or trees.

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Typical new homestead with simplified surroundings of the house. Photo credit: Piotr Skórka.

In our paper we evaluated the importance of villages for breeding bird communities at three spatial scales (single rural property, village and landscape) in farmland of Poland. We found that at the single property scale, half of the recorded 33 bird species preferred old farmsteads, while only one species preferred new homesteads. Old properties had higher species richness and abundance than new ones, and farmsteads hosted a higher number of species than homesteads. Species declining in Europe were positively associated to old farmsteads (e.g. house martin Delichon urbica, house sparrow Passer domesticus), old homesteads (e.g. yellowhammer Emberiza citrinella, icterine warbler Hippolais icterina) and some to new farmsteads (yellow wagtail Motacilla flava). At the village scale, bird species richness and abundance strongly decreased with increasing proportion of new homesteads. At the landscape scale, the village showed clearly a distinct bird community composition with several species observed exclusively in this habitat (e.g. barn owl Tyto alba) and shared the highest average bird abundance compared to other environments (open fields, forest-field ecotones, forests and towns).

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Tree sparrow (Passer montanus) and many other bird species prefer old rural properties over the new ones. Photo credit: Darek Świtała.

Our study discovers villages and their old farmsteads as an exceptionally important environment that may play a significant role in the conservation of farmland birds in central-eastern Europe. Having in mind that the number of new homesteads still increase at the expense of old rural properties, we may expect further decline of farmland biodiversity. Fortunately, there are some measures that can be applied in order to scale down the decrease of (micro)habitats associated to old villages. We propose following recommendations that may be relevant for conservation and policy: (1) in rural districts, there should be implemented educational programs developing the awareness of people that some simple practices, such as providing artificial nesting sites, planting native trees, maintaining orchards, etc., can benefit biodiversity, (2) villages and farmsteads should be included as part of EU conservation policies (promotion of bird-friendly architecture and surroundings of the house through the use of subsidies) and (3) changes in the structure of rural villages should be compensated by increasing the number of similar alternative habitats (e.g. mid-field trees, shrubs, ponds) in the surrounding landscape.

High Intensity Fires – do they reverse bush encroachment or speed up the loss of tall trees?

In this post Izak Smit discusses his recent paper ‘An examination of the efficacy of high-intensity fires for reversing woody encroachment in savannas‘.

Woody densification in savannas

Many studies have documented how grasslands and open savannas are being invaded by woody plants. This phenomenon is predicted to increase as atmospheric CO2 levels increase, favouring woody plants at the expense of grasses. Woody encroachment can have many negative effects, including loss of agricultural production (↑cover ≈ ↓livestock), changed herbivore assemblages (↑cover ≈ ↓grazers) and reduced eco-tourism opportunities (↑cover ≈ ↓game viewing opportunities ≈↓tourism). Herbicides or mechanical clearing can reverse woody densification, but are expensive and impractical over large scales, and often have unintended and negative ecological consequences. Frequent fire can also be used to combat woody densification, but few studies have explored whether high intensity fire can be used as a large, infrequent disturbance to reverse densification. In our study we examined the effectiveness of high intensity fires for reducing woody cover in the Kruger National Park (South Africa) (Fig. 1).

Fig 1

Fig. 1: Large-scale fire experiment in Kruger National Park, South Africa, used to test the effectiveness of high intensity fires for reducing the cover of woody shrubs. Photo credit: Izak Smit

Fire intensity effects on woody cover

We compared woody vegetation structure (cover and height) in areas exposed to repeated high intensity and low intensity fires, as well as protection from fire. We collected pre- and post-fire 3D information on woody vegetation using a LiDAR sensor mounted on an aeroplane (Fig. 2). We found that two successive high intensity fires opened up the landscape and reduced woody cover, as intended. In comparison the areas burnt by two successive low intensity fires became even denser over the 4 year study period (Fig. 3). The high intensity fire was successful, at least in the short term, in reducing woody cover, but we were surprised at the number of tall trees (>10m tall,  with a canopy radius of >3m) that collapsed following high intensity fires (Fig. 4). Tall trees are normally considered to be unaffected by fires because their canopies are beyond the flame zone, but more than a third of tall trees collapsed after two successive high intensity fires. This was much higher than the rate of collapse following low intensity fires (6%), or protection from fire (3%). Trees are apparently vulnerable to high-intensity fires because they have been compromised by having their bark removed by elephants (often also leading to wood borer infestation, Fig. 5).

Fig 2

Fig. 2: Pre- and post-fire LiDAR of the same area, showing how 3D vegetation structure was affected by high intensity fire (black depicts ground cover, and grey-to-white scale indicates increasing height of woody vegetation; blue lines show examples of large-canopied trees observable both before and after fire treatments, whereas the red circle highlight an area where fire reduced cover of small shrubs). Images derived from Carnegie Airborne Observatory (CAO) imagery collected during the study.

 

Fig 3

Fig 3: LiDAR derived woody cover in 2010 (before first fire application) and 2014 (after fire applications in 2010 and 2013) for four fire intensity treatments [no fire (control), two successive low intensity fires, two successive high intensity fires, and a high intensity fire followed by a moderate intensity fire]. Fires were two years apart. Woody cover was reduced after high intensity fires, but increased under the no-burn and low intensity fire treatments. Image credit: Izak Smit.

High intensity fires as management tool

We were hoping our results would indicate that high intensity fires could be used to reduce cover of encroaching shrubs. Although we confirmed this, at least in the short term, the accompanying damage to tall trees creates a management conundrum. High-intensity fires can be used to reduce bush encroachment, but only at considerable cost to the tall tree component. Considering that top-killed small shrubs can potentially recover rapidly after fires  (Fig. 6), and that recovery of tall trees will be slow (Fig. 4), it is clear that a regime of infrequent, high-intensity fires can simultaneously produce a positive and a negative outcome. Trees are important in the landscape, inter alia for nutrient cycling, shade for large mammals, habitat for small fauna and nesting sites for raptors. Therefore, managers will need to make trade-offs when contemplating the manipulation  of fire intensity to achieve specific goals. One solution may be to repeatedly apply high-intensity treatments to some areas, and not to others. This could generate a heterogeneous landscape where grasses become dominant and tall trees become scarce in some places, but in others tall trees persist (or at least decline at slower rates), and shorter woody shrubs increase in dominance. Whether this would be acceptable, or practical, remains to be tested. We predict that in areas without elephants or with lower elephant densities, high intensity fires may have less of an impact on tall trees.

Fig 4

Fig. 4: Collapse of tall mature trees following high intensity fire, probably exacerbated by pre-fire damage (e.g. bark removal by elephants). Recovery of the tree layer would take a long time. Photo credit: Izak Smit.

Fig 5

Fig. 5: Elephant damage to mature tall trees – elephants remove bark within the “flame-zone” height (a), allowing wood to dry and become vulnerable to wood borer infestation (b). These exposed scars create “weak” points, enabling high intensity fires to set the main stem alight, leading to eventual toppling of the tree (c). Photo credit: Brian van Wilgen (a) & Izak Smit (b & c).

Fig 6

Fig. 6: Basal resprouting from the roots (a-b) or coppicing from aerial parts (c) allows small shrubs to recover previous dimensions much faster after fires, as opposed to tall mature trees (see Figs. 4-5). These photos were taken within weeks of fire. Photo credit: Izak Smit (a) & Navashni Govender (b & c).

Evolution of plant materials for ecological restoration: insights from the applied and basic literature

In this post Erin Espeland discusses the recent paper ‘Evolution of plant materials for ecological restoration: insights from the applied and basic literature‘ by herself and co-authors Nancy Emery, Kristin Mercer, Scott Woolbright, Karin Kettenring, Paul Gepts and Julie Etterson.

Native plant materials can evolve during seed collection, increase, and planting. We survey the evolutionary and agricultural literature and apply it to the problem of restoration, supporting the contention that intentional and unintentional selection could ultimately reduce the persistence and contribution to ecosystem function of ecological restorations.

During seed collection, increase, and planting, restoration populations are subject to genetic sampling as well as natural and artificial selection, potentially resulting in successful adaptation to the propagation or early restoration environment but maladaptation to natural or established restoration environments.

The existing literature is specific regarding traits susceptible to maladaptation and how their evolution could impact population function in the wild. They include seed dormancy, seed dispersal, competitive ability, phenology, pathogen susceptibility, and resource allocation. Not only do we expect shifts in trait means as a result of restoration and propagation practice, but we also expect reductions in variance, which in turn reduces the opportunity for selection and adaptive capacity of restored populations.

We show how to use neutral genetic markers and field observations (together or separately) to test for evolution as a result of propagation and/or restoration practices. The paper concludes with six tools for “evolutionarily enlightened management” of restoration: 1) conduct multiple collections from source and production populations, 2) use sources from several native populations that are in close proximity, 3) maintain large effective population size on the production farm, 4) track seed sources through propagation and restoration, 5) intentionally promote gene flow, and 6) reduce selection.

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Measuring the success of reforestation for restoring biodiversity and ecosystem functioning

This blog post discusses a recent paper by Mia Derhé, ‘Measuring the success of reforestation for restoring biodiversity and ecosystem functioning‘.

Restoring rainforests: Recovering both biodiversity and ecosystem functioning

Rapid anthropogenic forest change means that many countries are now running out of large areas of primary forest and so the future of tropical forest biodiversity depends more than ever on the effective management and restoration of human modified landscapes. Ecological restoration is therefore becoming increasingly applied in tropical forests to mitigate biodiversity losses and recover ecosystem functions.

Photo credit TREAT

A restored riparian corridor connecting two remnant rainforest patches in Far North Queensland. Photo credit: TREAT (Trees for the Evelyn and Atherton Tableland).

What are we trying to recover and how do we measure it?

Ecological restoration can have a variety of intended outcomes, from increasing the abundance of certain threatened species, to improving soil stability or protecting watersheds. In order to determine the success of such projects, clear goals need to be set, and progress towards these pre-determined goals needs to be effectively assessed.

Two of the main goals of ecological restoration are the recovery of biodiversity and the recovery of ecosystem functioning, yet most researchers assume that increasing species diversity equates with an intrinsic recovery of ecosystem function, but this is very rarely tested and is not always the case. We need to understand the mechanistic link between biodiversity and ecosystem functioning in order to focus on restoring this relationship so that we can create healthy, stable ecosystems.

In a new paper published yesterday in the Journal of Applied Ecology, researchers from Lancaster University, CSIRO and the Queensland Museum show how diversity and ecosystem processes simultaneously respond to tropical forest restoration, and examine the mechanistic link between faunal diversity and ecological functions.

Simultaneous assessment of diversity and functioning

The researchers used pitfall traps to sample 3,317 dung beetles from 12 different restoration sites of varying ages (2 – 17 years) and compared them with 4 reference rainforest sites and 4 degraded pasture sites within the Wet Tropics of Australia. Species diversity metrics, community structure and functional diversity metrics of dung beetles were examined, along with important ecosystem functions that they mediate (secondary seed dispersal, dung removal and soil excavation).

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A rainforest dung beetle community comprised of rolling and tunnelling species in Far North Queensland. Photo credit: Mia Derhé

The findings reveal that replanting of native tree species to previously deforested areas can recover faunal communities and ecosystem functions in a relatively short period of time (< 20 years). Most strikingly, however, the study demonstrated that the traditional species-based view of diversity is insufficient when exploring the relationship between diversity and functioning and predicting the response of ecosystem functions to restoration. The findings show that functional diversity measures, which define the diversity and abundance distribution of traits within a community, are more accurate predictors of functional recovery than species-based metrics.

Conservation implications

“Functional diversity captures differences in species’ morphology, life-history traits and ecological niches, which affect community reassembly processes and subsequent changes to ecosystem function. Traditional taxonomic indices do not capture these complexities and so could potentially misjudge the true response of biodiversity and functioning to land-use change, disturbance and ecological restoration” said lead author Mia Derhé of Lancaster University Environment Centre.

“We provide clear evidence that species-based measures of diversity are insufficient predictors of ecosystem functioning in the context of forest restoration. We therefore recommend that scientists and practitioners incorporate functional trait information and measures of ecological functions when evaluating the efficacy of restoration practices. This is particularly important, since effective assessment of ecological restoration projects is critical in justifying the use of restoration in natural resource management as well as improving best practice.”

restoration in action

Restoration practitioners planting native tree seedlings on the Atherton Tablelands, Far North Queensland. Photo credit: Mia Derhé

seed emerging at treat

Castanospermum austral seedling germinating in a revegetation nursery on the Atherton Tablelands. Photo credit: Mia Derhé

Using reef fish movement to inform marine reserve design

In this post Rebecca Weeks discusses her recent paper ‘Using reef fish movement to inform marine reserve design‘.

The majority of marine protected areas in Pohnpei (Federated States of Micronesia) are too small to protect the species that people care about most. But when livelihoods depend on fishing, establishing large no-take areas is a big challenge.

Overfishing and unsustainable fishing practices are amongst the greatest threats to coral reefs in Micronesia. So from a conservation perspective, it’s easy to say that “bigger is better” when it comes to establishing no-take marine protected areas (MPAs).

But at the same time, fishing underpins the livelihoods, food security, and cultural identity of many Micronesians. Many fishers understand the need for marine management, as they see fish populations, and their catch, declining. But they are understandably reluctant to see large no-take areas established, unless they can see a clear benefit of doing so.

Previous conservation planning processes in Pohnpei produced impressive designs on paper, but have fallen short during implementation.

Pohnpei’s protected area network achieves the Micronesia Challenge goal to protect 30% of marine and 20% of terrestrial habitats – a feat not matched by many larger, more developed countries. But focusing on achieving international targets for biodiversity conservation has not created local support for protected areas. This support, and subsequent compliance with regulations, is essential if MPAs are to benefit either conservation or fisheries management.

Well designed and effectively managed no-take MPAs can increase fish size and density within their boundaries, and even, in time, boost populations in surrounding areas. However, of the 18 existing MPAs on the reefs surrounding Pohnpei and nearby Ant Atoll, few are working effectively.

Many of the existing MPAs are far too small (5% of MPAs are smaller than 1 km2, 70% are smaller than 5 km2) to protect mobile fish species. Guidelines recommend that to be effective, no-take MPAs must be at least twice the size of the “home range” of species they aim to protect.  A home range describes the area in which a fish spends most of it’s time, day to day (eating, sleeping etc.). Provided their entire home range is within an MPA, fish will remain protected. If the MPA is too small, there’s a good chance they will swim out of the safe zone and be caught.

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Ant Atoll, lying off the west coast of Pohnpei and one of the protected areas used in this study. Image credit: Rebecca Weeks

 

A team of conservation scientists and practitioners from The Nature Conservancy, the Conservation Society of Pohnpei and the Australian Research Council Centre of Excellence for Coral Reef Studies decided that it was time to rethink the design of Pohnpei’s MPAs, to try and improve their adequacy and management effectiveness. This time around, the planning process prioritised local management objectives – i.e. for the fish species that people want to see in the lagoon and on their plates!

We first asked a group of community members, traditional leaders, conservation officers, and representatives from the government, to tell us which fish species mattered most to them. They listed species important for local fisheries (groupers, rabbitfish, parrotfish, surgeonfish, snapper and trevally) and some with cultural and conservation importance (humphead wrasse and bumphead parrotfish).

We then armed them with information on the size of their MPAs, and how far their chosen fish move on a daily basis. Many in the group were experienced fishermen, and were excited to be able to use their own knowledge to help improve the design of their MPAs. All reported back that at present, Pohnpei’s MPAs were too small to protect the species they care about most. Naturally, this led to serious discussion about how the marine protected area network could be improved.

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A planning workshop where local management objectives were prioritised. Photo credit: Rebecca Weeks

Fast forward 4 months to October 2015, and the designation of the Palikir Pass Marine Sanctuary. Better known as a world class surf break, underneath the waves Palikir Pass is an important site where reef fish aggregate to spawn. Pohnpei’s newest MPA is also the largest (12 km2) on the reefs surrounding the main island of Pohnpei. Though the initial proposal for the MPA covered less than half of this area, fishers saw how they could benefit from a larger no-take closure which would encompass the home ranges of the species they catch, and include more habitats that those species use during their lifetime.

Our article describes how using the ecology of locally important coral reef fish species to drive MPA design not only better engaged Micronesian stakeholders in conservation planning, but also influenced decision-makers towards establishing larger MPAs. MPAs which are designed to protect focal species are likely to also benefit many others. In the long term, this is likely to benefit both local fisheries and conservation!

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Communicating your research – press releases

Over the last few years it has become increasingly important to communicate and publicise your research, not only to help direct your work to the relevant readers but also to raise your profile as a researcher.

One of the many ways you can disseminate your Journal of Applied Ecology article is by sending out a press release through your organisation. Here, we’ve put together some guidance if you’ve been wondering why and how to do this.

Why should I send out a press release?

Engaging with the media is an important part of communicating your research to non-academic audiences, and in particular the general public. The impact of scientific research is becoming more and more important for funding bodies and government so being able to demonstrate that your research is of far-reaching and widespread interest to society is invaluable.

Decision-makers and policymakers consider public opinion so it is important to make sure your research and the evidence you have generated is represented in the media. You are an expert in your field and know your research better than anyone else, so are best-placed to make sure your topic of expertise is accurately portrayed.

Is a press release the best way to communicate my research?

When deciding whether to organise a press release for your article it is worth considering whether spending your time on this is the most effective way of disseminating your research. Will a journalist be likely to report on your article? – Do your results have a direct impact on society? What benefits are there to the public? Can your results be used by the public to change their behaviour? Is it particularly timely? Is there a human interest angle? Is it a topic which generally gets good press coverage? Is there anything else that makes an article newsworthy (great pictures, video or audio, charismatic species, controversial issues, novel methods)?

impact on society

Do your results have a direct impact on society? Photo credit: Scott Maxwell: http://www.lumaxart.com.

If you think a journalist is unlikely to report on your research, then don’t forget that it is still important to make it easy for researchers and practitioners working in related areas to read your work. You can engage with them by writing a lay summary or blog post (e.g. for The Applied Ecologist’s blog) of your work, make a podcast or short video, or directly contact policymakers, decision-makers and funding bodies with your article and a summary of the key messages. If you would like to discuss options for how to best promote your research contact us.

How do I organise a press release?

At this stage, if you’ve decided that sending out a press release is the most effective way to disseminate your research you will need to think about how to organise it and let us know you are planning a press release. The BES has a press officer who coordinates press releases for the society and the journals. You can find information on how we coordinate press releases with article publication on our website.

Get to know your organization’s press officer so that you can approach them when you have an exciting article that might be covered by news outlets.

You need to work with your press officer to ‘sell’ your story and persuade media organisations to cover it.

Get to know

Get to know your press officer. Photo credit: Scott Maxwell: http://www.lumaxart.com.

What tips can you give me for writing a press release?

  • Think about who the relevant audience is e.g. reach out to the media outlets local to where the study was carried out.
  • Consider the timing of your press release – can it tie in with a specific event?
  • Make the title clear, short and snappy.
  • Clearly present the message of your press release and explain why your results are important.
  • Make it understandable to non-scientists, write in simple terms and keep it jargon-free.
  • Keep it short (300–500 words), but make sure all the relevant details are included.
  • Include pictures, infographics, videos and animations that can help explain the key messages.
  • Include the Journal name, article title, author list and the article URL, which we will give to you.
Clearly present your message

Clearly present your message. Photo credit: Scott Maxwell: http://www.lumaxart.com.

You can also watch our Senior Editor, Nathalie Pettorelli give her top tips on engaging with the media here:

What if I have any other questions about press releases?

Get in touch with us. We will continue to update this blog as we receive more questions.