Bark beetle impacts on ecosystems and society

In this post Jesse Morris discusses his research, published today in Journal of Applied Ecology ‘Managing bark beetle impacts on ecosystems and society: priority questions to motivate future research

Forests provide many goods and services that have ecological, economic, and social value. Management agencies and scientists often refer to these benefits as ecosystem services. Some examples of ecosystem services include purifying air, controlling water runoff and soil erosion, providing wood and other forest products, and regulating climate through carbon storage.

In recent decades, many mountain forests in Western North America and Central Europe have been devastated by native bark beetles, such as mountain pine beetle and spruce bark beetle. Millions of acres of trees have died and in the hardest hit areas, such as British Columbia, over 90% of the mature trees have died from bark beetle attacks. In British Columbia, mountain pine beetles have killed an estimated 710 cubic megameters of lodgepole pine, roughly the volumetric equivalent of concrete used to construct New York City.

Social and ecological scientists have used the recent and widespread outbreaks in British Columbia, Colorado, and the Czech Republic as a research opportunity.  The effects of bark beetle outbreaks on ecosystems are often measured in terms of area affected, host tree mortality rates, and alterations to forest structure and composition. Impacts to human systems tend to focus on changes in property valuation, infrastructure damage from falling trees, landscape aesthetics, and the quality and quantity of timber and water resources.


In April 2015, we assembled an international group of scientists and land managers in Santa Fe, NM, motivated by the proliferation of recent studies to integrate the findings of recent social and ecological studies because few efforts have attempted to synthesize these bodied of work. Our goal was to identify where key knowledge gaps exist in our current understanding of how bark beetle disturbances impact coupled social-ecological systems. After spirited discussion we came away with a list of 25 questions that address a mix of applied and theoretical research topics that connect directly with management needs, such as bark beetle population monitoring and models to predict where future outbreaks might occur. In general, the research priorities we highlighted emphasize the need to improve outbreak monitoring and detection, educate the public on the ecological role of bark beetles, and develop integrated marketplace metrics that facilitate comparison of ecosystem services across sites.

The article published in Journal of Applied Ecology is a product of the Mountain Social Ecological Observatory Network (MtnSEON) Research Coordination Network and IGPG: Past Global Changes. The workshop was organized around the Western Forest Insect Work Conference, which is an annual international conference attended by forest managers and academic scientists.

A new method for assessing the age of old-growth forests

In this post, Associate Editor Nathalie Butt discusses a recent paper ‘Tree-ring based metrics for assessing the functional naturalness of forests by Alfredo Di Filippo, Franco Biondi, Gianluca Piovesan and Emanuele Ziaco.

Valuable ecosystems

Primeval forest, or ancient woodland in the UK, is an integral part of many epic stories and myths throughout human history, especially in Europe:  just think of all those old tales with bears and wolves! Old-growth forest provides the setting and narrative for societal development. Our interaction with these complex and diverse ecosystems has shaped landscapes across huge scales, spatial and temporal; half of Europe’s primary forest was cleared before the Middle Ages (up to 600 years ago). We consider primary or virgin forests to be old and largely undisturbed climax systems, with long periods of stability, which means that species-rich communities of fauna and flora are often found in these habitats. In many cases, species unable to compete in more disturbed forests act as indicator species for this type of forest, for example, bluebell as an ancient woodland indicator in the UK.


Bluebell woods. (Photo credit: Wikimedia Commons).

In addition to supporting rare species, old growth forests are important for a range of ecosystem services such as carbon storage (both in the trees themselves and in the soils), provisioning of clean water, air purification and soil maintenance, and climate moderation and control at different scales. Over recent decades, scientific interest in, and understanding of, forest dynamics has highlighted the need to manage and conserve old-growth forest, only 20% of which remain globally. One previously unresolved issue has been how to accurately define and quantify ‘old growth’ itself.

Forest naturalness and old-growth status

Until now, old-growth forest studies have defined ‘old growth’ based on structural and age conditions using proxy indicators of long-term ecological processes (functional dynamics) and forest naturalness (which increases with forest age), such as tree size and stem density of living and dead trees. However, trends (in mean stem diameter or density in forest stands) may be non-linear, and if the selected attributes don’t increase linearly with stand development, the transition from mature stand to primary old-growth status may not be captured, and long-term changes in late successional multi-aged forests may not be tracked. Some kind of naturalness score could be very useful for understanding long-term ecological processes, as it would measure the ecological distance between managed, early and mature old-growth forests. More exact knowledge of the age, naturalness, ecological processes and forest structure is vital for forest monitoring and conservation efforts focussing on these immensely important and valuable ecosystems.


What can we learn from tree-ring dating?

Di Filippo et al. devised a novel method of more accurately estimating forest age and naturalness by using tree-ring data to give information on canopy age, disturbance and growth trajectories.  This allowed them to describe the intensity and temporal distribution of biological and ecological processes, and the development of old-growth status.


Tree rings (Photo credit: Wikimedia Commons).

They used a network of old-growth European beech Fagus sylvatica forests across Italy and Austria containing the oldest (500-600 years) broadleaf trees in the Northern Hemisphere. The beech forests ranged across several bioclimatic zones: from warm Mediterranean to cool Alpine. Age and functional history indicators vary with local environment, and biogeoclimatic conditions constrain the onset and development rate of old-growth attributes. This means that there is no universal size- or age-related threshold indicator of old-growth status (with the exception of some age structures that clearly indicate a forest is not in an old-growth state, such as tree stumps clearly marking historical management). However, it is possible to develop a framework of benchmark indicators within each bioclimate zone: the indicator of forest naturalness Di Filippo et al. developed varied consistently with forest structural complexity, and thus more accurately describes forest development than current methods.


Distribution map of European beech. (Photo credit: Wikimedia Commons).

Managing and conserving our ancient forests

Ideally, perturbations should be managed to maintain natural habitat and landscape conditions, thus protecting ecosystem function, in order to support the full range of seral stages and their associated biodiversity. Old-growth beech forests are characterised by distinctive slow growth processes that underpin extraordinary tree longevity, adding further value to these unique ecosystems. The new approach of Di Filippo et al. provides an improved method for describing and quantifying the legacies of forest management, and is a valuable contribution to our understanding of forest naturalness. This work could inform the identification and protection of old-growth forests, provide a point of reference for the impact of silvicultural practices, and help define conservation targets and and evaluate the effectiveness of restoration projects.


European beech forest. (Photo credit: Wikimedia Commons).

Gone with the wind: canopies of next generation tropical forests will function differently based on today’s understory recruitment

In this post Jarrah Wills discusses his recent paper ‘Next-generation tropical forests: reforestation type affects recruitment of species and functional diversity in a human-dominated landscape

Diverse understory development within forest plantations can provide conservation value in highly modified tropical landscapes, but how many species should be used to establish a framework to encourage recruitment: one species, two species, more? And how does the quality of the understory environment and functional traits of the species matter when it comes to kick-starting understory recruitment? To find answers to these questions we compared species and functional diversity of understories beneath small-scale community-based mixed-species plantations, known as ‘Rainforestation Farming’ that uses mostly native species and aims to provide biodiversity and socio-economic benefits, and exotic monoculture (Swietenia macrophylla) plantations to more natural regenerating selectively logged forest understories across the island of Leyte, Philippines.

In tropical countries the goals and reforestation techniques of smallholder tree-farmers often differ from those of an industrial owner. Smallholders may not prioritize production and timber uniformity over a great diversity of forest products. Consequently, management techniques such as thinning and weed control are not as high priorities, as maximising basal area, and minimising growing deformities is not the goal. In smallholder plantations trees are often selectively harvested with just a few cut down depending on local need. Under these management practices, understories can develop, which may increase the value of these plantations for conservation, by providing habitat and ecosystem services such as nutrient cycling and hydrological flow. Extending plantation rotation times may also provide additional non-timber forest products that extend the socio-economic value of plantations beyond timber alone.


Unique harvesting technique often used in small-scale community-based plantations (Photo credit: Jack Baynes).

We found that exotic mahogany monocultures recruit some understory diversity (averaging 11 species, compared to 19 for mixed-species plantations and 24 for regenerating selectively logged forests) highlighting that re-establishing any tree cover in a highly fragmented landscape can provide conservation value. The family Moraceae maintained similar levels of diversity across forest types, emphasizing their strong dispersal abilities, likely via habitat generalist bird species. Fruit size classes, indicated the strong association these plantations have with local people, with monoculture understories containing the highest number of large fruited domesticated species (e.g. Mangifera indica and Theobroma cacao) and potentially increasing their socio-economic value within the next generation. The functional group that was largely missing in the exotic monocultures was wind-dispersed native tree species, which showed threefold less abundance in monoculture plantations relative to naturally-regenerating selectively logged forest.

The absence of wind-dispersed tree species, such as those from the Dipterocarpaceae family, is significant because they are ecologically dominant and economically important throughout Asia, making up the key framework of the forests in the emergent layers of the canopy. These species are typically highly valued as a timber resource, consequently being subjected to high rates of logging, resulting in a low prevalence and low genetic diversity. Being wind-dispersed they also have relatively shorter dispersal distance especially in highly modified and fragmented landscapes and seed production is often irregular being dependent on unpredictable and sometimes rare mass fruiting events.

Wind-dispersed emergent tree species provide the structural framework in tropical forest ecosystems, but a considerable amount of research and focus has been on animal-dispersed species in tropical forests. Our results show that in addition to other limited functional groups such as large-seeded animal-dispersed species, native wind-dispersed tree species should also be considered in the restoration of tropical forest.

Avian pest control in vineyards

In this post Michelle Harrison and Cristina Banks-Leite discuss a recent paper by Luc Barbaro and colleagues ‘Avian pest control in vineyards is driven by interactions between bird functional diversity and landscape heterogeneity‘.

The global wine industry currently contributes roughly US$303 billion to the world’s economy (Plant and Food Research, 2013). Wine is a key export for many European countries such as Italy, France and Spain and is a growing industry in countries like China and in the Middle East. As such it provides hundreds of thousands of jobs and services a global demand for wine that continues to grow with each passing decade. Thus it is important to understand the mechanisms that influence grape production and yield.

Vineyard establishment has major implications for local ecosystems, with the vast majority of native vegetation being removed. Soil is unearthed for plowing and often sterilised with chemicals and vines are treated with fertilisers and fungicide (Turner et al., 2010; Couloma et al., 2006). As monocultures, the vineyards provide little habitat value for native mammals, birds and reptiles, attracting higher numbers of non-native species (Hilty et al., 2006; Hilty and Merenlender, 2004).  It is well documented that birds provide important ecosystem services for agricultural systems (Wenny et al., 2011; Maas et al., 2015), particularly with regards to pest management. However, the relationship between the functional composition of bird communities and the degree of top-down control on arthropod populations is not as well understood.

This recent study by Luc Barbaro and colleagues determined the effect of habitat complexity on bird functional diversity and its associated control of arthropod populations. In southern France, Barbaro sampled the bird communities of 20 vineyards and measured the level of insectivorous activity by quantifying predation marks left on plasticine ‘caterpillars’. The vineyards varied at the local scale in terms of sward heterogeneity and the surrounding landscape matrix composition.


One of the vineyards and the surrounding habitat.

Surprisingly, the researchers found that bird functional diversity (a proxy for the number of ecosystem functions birds may perform in the ecosystem) decreased as the complexity of surrounding landscape increased. However, when focusing on avian insectivores the opposite trend was found, with abundance increasing with the percentage of semi natural habitat in the surrounding matrix. On a local scale, sward heterogeneity was associated with an increase in bird functional diversity. These trends were reflected in the level of avian predation on the plasticine models. Avian functional evenness was the metric with the greatest power in determining levels of insectivorous activity in more heterogeneous environments.


An unattacked plasticine ‘caterpillar’

Top-down control of folivorous arthropods by bird predators has been documented in agro-forests such as cocoa and coffee plantations. In such agricultural systems, where heterogeneous forest structure and high plant diversity promote and maintain a diverse insectivorous bird population, ecosystem services can be preserved (Van Bael et al., 2008). Even in these plantations, connectivity to surrounding native forest habitat was important in sustaining bird diversity (Raman, 2006). Similarly, avian communities have been shown to be important in controlling arthropod numbers in monocultures such as palm oil (Koh, 2008). Across all climatic zones, from tropical to boreal regions, plants generally perform better in the presence of birds (Mäntylä et al., 2011), due to pest control.

What are the implications of this study for vineyard management and agro-ecology in general? Agriculture, by its nature, promotes the dominance of monocultures and the homogenization of habitats often to the point where ecosystem services are no longer provided by local animal communities. Without these natural ecosystem functions, farmers increasingly rely on chemical control of pests, which is both detrimental to the environment and has cumulative effects up the food chain. Clearly, it is important to the industry to maintain a viable population of insectivorous species in situ. This study suggests that local matrix composition is key in achieving this and should be included in any management plans and policy decisions going forward. Surrounding grasslands and woodlands provide vital habitat for birds that enter vineyards to forage for insects. The effect of local sward heterogeneity within the vineyards also needs to be taken into account to provide sufficient cover for insectivorous species. Proper management could decrease plant damage, increase yield and reduce the need for frequent pesticide application.

Caring for and sharing data created by volunteers

In this post Quentin Groom discusses his recent Commentary paper ‘Is citizen science an open science in the case of biodiversity observations?

Volunteers are the single largest source of biodiversity observations. Without their work we could not monitor the declines of native species nor the spread of invasive species. Their work provides data on the diversity of life, its geography, the migration of animals and numerous other aspects of life. In recent years online citizen science projects have blossomed with the general public getting involved with the cataloguing of collections, transcription of notebooks and the collection of specimens. Yet, apart from a few notable exceptions, it is hard to find out where these data are stored, who has access to these data and, if they are shared, under which licence. If you contribute to such a project, try it for yourself. You might find a general statement about data sharing, but in the majority of cases you will not find specific details.


Part of a citizen science team on Sauk Mountain. Photo by Park Ranger (Cascades Butterfly Project Team) (CC BY 2.0 (, via Wikimedia Commons.

Coordinators of citizen science projects are well intentioned and will probably not waste the effort of volunteers. So does their data sharing policy matter? Well I think it does, for a number of reasons. Volunteers are donating their free time and skill to these projects in the expectation that the data will be used and valued. These data are in high demand to provide the evidence to policy makers that we need to do something about biodiversity loss and the global extinction crisis. Furthermore, not all data holders are aware of data standards and the importance of interoperability. I recently collaborated on a paper investigating the licensing of biodiversity observation data. This paper showed that citizen science data are often shared with more restrictive licences than other data providers. Data licensing is just one aspect of data sharing, but an important one. We need standard licensing so that researchers know which data they can use and under which conditions.


Recording mountain goat survey results for the high country citizen science project, Siyeh Pass. Photo by GlacierNPS (CC BY 2.0 (, via Wikimedia Commons

As a biodiversity informatician I look forward to the day when we have automated workflows that can harvest data from all over the world and can output information, such as maps and biodiversity indicators. Such systems could alert us to developing problems, such as catastrophic population declines; the emergence of invasive species and outbreaks of wildlife disease. Too often we only become aware of these issues after the window of opportunity has passed, spotting these trends early will only become possible if barriers to interoperability are removed and heterogeneous licensing is one of these barriers.

If, like me, you contribute to volunteer recording and citizen science projects, ask yourself how these data are shared. If you don’t like what you find, do not stop volunteering, but make the organization aware of your opinion. I suspect many of them have not considered these issues and just need your encouragement to change. If you are running a citizen science project, write a data management plan, including details of licensing, data sharing, data embargoes and archiving. Then make this plan public to show how seriously you take good data management. Nothing values a volunteer’s contribution more than making it useful for evermore and for everyone.

Getting people working on ecosystem functions connected

There’s news for people working on ecosystem functions and their monitoring: the Ecosystem Function Working Group has been recently launched by the Group on Earth Observations Biodiversity Observation Network (GEO BON), and the group is looking for its members.

You may wonder what GEO BON is: GEO BON is an international networking platform part of GEO, the Group on Earth Observations. Within the GEO family, GEO BON represents biodiversity, which is one of GEO’s nine Societal-Benefit-Areas. GEO BON’s mission is to improve the acquisition, coordination and delivery of biodiversity observations and related services to users including decision makers and the scientific community. Its secretariat is hosted by iDiv in Leipzig and supported by the German Science Foundation.

The new working group within GEO BON hopes to research, identify and derive Essential Biodiversity Variables (EBVs) related to ecosystem functions; the group will also work towards highlighting those ecosystem function EBVs relevant to the generation of global biodiversity indicators.

But what are EBVs? The concept of EBVs was originally developed at the request of the Convention on Biological Diversity, following a workshop in 2011. Following multiple discussions across varied groups of stakeholders, EBVs were originally defined as measurements required for studying, reporting and managing biodiversity change. Six classes of EBVs were distinguished: genetic composition, species populations, species traits, community composition, ecosystem structure and ecosystem functions.


EBVs are expected to possess a set of characteristics, which include (1) sensitivity to change over time; (2) a focus on ‘state’ variables (as per the ‘Pressure State Response’ framework routinely used by the Convention on Biological Diversity); and (3) generally falling between low-level (primary) observations and high-level indicators of biodiversity change. Other important characteristics included scalability, technical and economic feasibility for global implementation and usefulness for informing progress toward the Convention on Biological Diversity targets.

The most recently agreed definition of EBV reads as follow: “An EBV is a variable or a group of linked variables that allows quantification of the rate and direction of change in one aspect of the state of biodiversity over time and across space. An EBV is critical for understanding and predicting changes in the most integrated and established global indicators of biodiversity. The following requirements should be fulfilled: EBVs are sensitive to changes; observing or deriving EBVs on a global scale is technically feasible using standardised, proven methods; generating and archiving EBV data is also affordable, mainly relying on coordinated observing systems using proven technologies, taking advantage, where possible, of historical datasets.”

Working groups (such as the newly launched Ecosystem Function Working Group) are expected to deliver on four fronts over the coming three years: specifically, this new working group is expected to (1) identify research opportunities (relevant in this case to ecosystem functions) supporting the identification/implementation of EBVs; (2) derive/identify potential datasets; (3) articulate the links between these EBVs and global indicators; and (4) provide guidance to national biodiversity networks in terms of in situ monitoring of these EBVs (through, for example, the production of reports/guidelines).

Admittedly, the creation of the working group doesn’t come with funding to support the work that needs to be done. However, group members can obtain GEO BON support letters for funding applications directly related to the working group aims. Ultimately, the working group represents a networking platform, and so the main benefits to members are knowledge transfer, the potential access to new collaborations, and access to a clear pathway for the generated science to inform global policy and conservation.

So, are you working on ecosystem functions and interested to join? Have some questions? Then just drop me an email (! And please do feel free to pass on this information to anyone you think might be interested.

Nathalie Pettorelli

Choosing the appropriate analytical resolution for protected area planning

Blog post by Moreno Di Marco, Centre for Biodiversity and Conservation Science, The University of Queensland, Brisbane, Australia.

Based on: Di Marco, M., Watson, J.E.M., Possingham, H.P. & Venter, O. (2016). Limitations and trade-offs in the use of species distribution maps for protected area planning. J. Appl. Ecol. doi 10.1111/1365-2664.12771.

From local-scale management to global scale policy, conservation decisions are influenced by the knowledge of where species are distributed. Maps of the geographic range of species (or simply ‘range maps’) are typically used to determine the overlap between threatened species and protected areas, and to find new places in need of protection.

The Red List of the International Union for Conservation of Nature is  the most comprehensive source of species range maps globally, often used for analyses of protected area coverage and planning. At the same time, it is widely recognised that IUCN range maps suffer from commission errors, where species are supposed to be present in locations where they are actually absent, and omission errors, which is the opposite case.

Commission errors are particularly worrisome in conservation applications for two reasons: first, they can lead to a false perception of species protection, hence to an overestimation of the actual protection level; second, they can drive conservation investment toward areas of little conservation value, where species are not present.


The effect of commission errors can be reduced by removing from a range map those habitats which are considered unsuitable for the species, using habitat models. However, habitat models are data demanding and their use is not always possible, especially for analyses focused on many species. Therefore the adoption of a coarse analytical resolution has been suggested as a valuable alternative. In this case, species’ distributions are represented using coarse grids (100-200 km), thus minimising the probability of including unoccupied grid cells.

However, aside from reducing the effect of commission errors, the adoption of a coarse resolution also affects the efficiency of a conservation plan, i.e. the ability to select a minimal additional area to be protected for achieving an adequate representation of all species. We demonstrated these contrasting effects by performing a set of protected area planning analyses for the world’s threatened terrestrial mammals at various resolutions. We compared species range maps with habitat models to show the difference between protected species ranges and protected habitats.

We found that planning for new protected areas using range maps results in a small overestimation of species protection, where the proportion of protected species range is higher than the proportion of protected suitable habitat. The adoption of a coarse analytical resolution can slightly mitigate this effect.

When employing a resolution of 10 km, a global protected area expansion of 3 million km2 (an area almost the size of India) would suffice to achieve adequate protection for all the 1,115 species in our analyses, if looking at their IUCN ranges. However, a shortfall of 28 species emerges if looking at the protected suitable habitat within those ranges. At a resolution of 200 km, the shortfall for an equal figure of protected area expansion would be just 7 species. At this coarse resolution it was also twice as likely (80% vs 40% at a 10 km resolution) that the priority grids for the protection of species ranges were also considered a priority for protecting species suitable habitats. However the adoption of a 200 km resolution lead to the selection of a total of 12 million km2 of protected area in order to achieve adequate coverage for all species, which is four times larger than the area selected under a 10 km resolution.

In conclusion, our findings demonstrate that adopting coarse resolutions in protected area planning results in unsustainable increases in costs, with limited reduction in the effect of commission errors in IUCN range maps. We recommend that, if some level of uncertainty is acceptable to managers, using range maps at resolutions of 20–30 km is the best compromise for reducing the effect of commission errors while maintaining cost-efficiency in protected area planning analyses.