Author: Journal of Applied Ecology

This blog post is also available in German here.

Dominik Poniatowski and colleagues describe how they evaluated the environmental drivers of species richness and biomass of grasshoppers in grasslands, comparing this between nature reserves and intensively-used agriculture landscape.

Grassland exhibiting low land-use intensity is considered a hotspot of biodiversity in Central Europe. However, particularly since the mid-20th century, grassland land use has often been intensified, or they have been converted to arable land or afforested. As a result, many grassland species have disappeared regionally. One way of preserving the remaining species-rich grasslands is to designate nature reserves. However, the efficiency of such areas is still the subject of controversial debate.

What did we do?

With this large-scale study, covering an area of almost 2,000 km² in Central Europe, we wanted to find out whether the species richness and biomass of grasshoppers in grasslands inside of and outside of nature reserves differ. At the same time, we collected numerous environmental data to analyse the causes of possible differences. Previous studies have not adequately considered this aspect. As a result, we can now clearly identify which measures should be taken to promote species-rich insect communities in grassland.

What did we find out?

Through our study, we can show that significantly fewer grasshopper species occur in intensively used agriculture landscape grasslands (hereinafter termed ‘wider countryside’), and that there is also less grasshopper biomass than in grasslands within nature reserves. There are several reasons for the observed differences.

In the wider countryside, for example, the high land-use intensity has a negative impact on grasshoppers. Almost all sites there are heavily drained, allowing for frequent mowing. Only a few grasshopper species can cope with this. In addition, grasshopper species that require high soil moisture for egg development are usually absent or only occur sporadically in the wider countryside.

Another important factor that influences species numbers is habitat diversity. This is significantly higher in nature reserves than in the wider countryside. In nature reserves, various habitats such as mesic, wet grassland, reed beds, swamps and shrubs can be found in a small area. Nature reserves, therefore, provide a home for numerous species. 

What measures would be useful?

Wider countryside

In the intensively-used agricultural landscape, the production of animal feed and food is the top priority. Measures to promote biodiversity can therefore only be implemented here if they are adequately remunerated. Simple, yet very effective measures in mown grassland, include reducing the frequency of mowing and applying less fertilizer. At a regional level, there are already some examples of how the promotion of biodiversity can work in combination with conventional land use. However, such projects have not yet had a widespread effect, as only limited financial resources are available.

Another nature conservation measure to promote species diversity in the normal landscape would be to increase habitat diversity. This can be achieved, for example, by creating or restoring fallows, field margins, fringes and hedges. This would benefit not only grasshoppers, but numerous groups of insects.

Nature reserves

The designation of nature reserves is intended to preserve the flora and fauna found there, and regulations for nature reserves often set priorities. In the study area, for example, the focus is on the protection of meadow birds. Accordingly, farmers are only allowed to mow the grassland after June 15, as the meadow birds have usually finished breeding by this time.

From our point of view, however, the insect fauna could also be promoted with a simple measure. In other parts of Central Europe, for example, the maintenance of unmown strips has proven to be a successful nature conservation measure. Many animals find refuge here after mowing and can recolonize the entire area from there after some time. A small proportion of unmown grassland per site (around 10%) and each mowing event is enough to achieve a noticeable effect for nature conservation. This would also not contradict the aims of meadow bird conservation. On the contrary, insects are an important source of food for many animal species, such as meadow birds.

We also recommend stabilising the water balance by dismantling or blocking drainage systems. However, this is significantly more expensive and more complex to implement than the maintenance of uncut refuges. Against the background of increasingly summer droughts, however, such measures should also be considered.

If we do not succeed in keeping the water in the areas, we will gradually lose the typical species of wet grassland. The scarcity of the Marsh Grasshopper (Pseudochorthippus montanus) and the high frequency of some typical dry grassland species such as the Bow-winged Grasshopper (Chorthippus biguttulus) and the Heath Grasshopper (Chorthippus mollis) make it clear that some sites in the study area are already too dry and that there is an urgent need for action.  

Read the full article “Grassland nature reserves safeguard a high species richness and biomass of grasshoppers” in Journal of Applied Ecology.

Callie Cho and Robin Naidoo talk us through how, using observed animal movements rather than conventional resistance surface models, a connectivity conservation blueprint for African elephants in the Kavango-Zambezi transfrontier conservation area (KAZA) in southern Africa was produced. This is explored further in the new research article.

A key aspect of effective conservation management is understanding landscape connectivity—how easily animals can move between vital resource areas. While policy makers and researchers have increasingly begun to examine landscape connectivity, the conventional resistance modelling approach to assessing landscape connectivity has significant limitations, mostly due to small sample sizes and overextrapolation. 

Conventional models, often based on limited data from a small part of the overall study area, account for connectivity using a single, broad-scale model for the entire landscape. This type of resistance modelling may miss important smaller areas that are crucial for daily or seasonal animal movements. On the other hand, assessing functional connectivity by observing animal movements can provide a more accurate picture of landscape connectivity, but the sample size of collared animals needed to do this is typically prohibitive. 

So, how do we best measure landscape connectivity in instances where we do have a large amount of animal movement data? We aimed to answer this question by examining elephant movements in the world’s largest terrestrial trans frontier conservation area.   

The test case: Elephant movement in KAZA  

Spanning 520,000 km² across five countries, the Kavango-Zambezi trans frontier conservation area (KAZA) in southern Africa exemplifies the complex interplay between human needs and wildlife conservation.

Its diverse ecosystems, from savannahs to forests to wetlands, host about half – 227,000 – of Africa’s remaining savannah elephants (Loxodonta africana) and around 3 million people. This global conservation priority aims to balance protected areas, game reserves, and human settlements in a trans frontier landscape, presenting a unique challenge in managing human-wildlife coexistence. 

Our study 

Our goal with this research was to provide a robust picture of landscape connectivity for elephants in KAZA by using data on actual, observed animal movements. To do so, we assembled a database of around 4 million GPS observations from almost 300 collared elephants between 2009 and 2023; the single-largest elephant GPS tracking database ever assembled. Then, we assessed the way in which elephants use this landscape at 3 different scales:  

• Micro-corridors: small-scale movement corridors. 

• Inter-PA (protected area) pathways: important areas in KAZA that connect core protected areas. 

• Macro-corridors: areas important for connectivity across the entire set of GPS-collared elephant movement trajectories. 

We identified micro-corridors by examining elephant grid cell use, speed, and directionality thresholds in a set of well-studied micro-corridors in the Okavango panhandle region of Botswana. Applying these thresholds to elephant movement parameters in all 100-m grid cells in KAZA allowed us to map similar micro-corridors across the entire landscape.

Then, we mapped all elephant movement pathways that connected relevant pairs of protected areas. Lastly, to identify macro-corridors, we calculated betweenness centrality for each grid cell per elephant. This metric quantifies a cell’s importance as a movement conduit by measuring how often it lies on the shortest paths between other locations. Finally, we aggregated these scores across all pixels in KAZA to create a comprehensive map highlighting key areas of connectivity throughout the transfrontier landscape. 

Our results   

We found that anthropogenic factors influence elephant movement at both micro and inter-PA levels. Elephants utilize micro-corridors to access water, navigating through areas of human activity and altered landscapes such as fences, agricultural fields, and urban areas.

While inter-PA pathways varied extensively, human settlements also channeled these movements into specific corridors in certain parts of the landscape.  For macro-corridors, there were important priorities identified both within and outside of protected areas, underscoring the crucial role that both protected and unprotected lands play in facilitating transboundary wildlife movement. 

Perhaps most importantly, we found minimal overlap between connectivity priorities at different scales, underscoring the necessity of multi-scale movement analyses to inform comprehensive conservation strategies. 

Takeaways 

Our study utilized the largest database of elephant GPS data gathered to date and provided a movement-based conservation blueprint for elephant connectivity in KAZA. The KAZA governance structure provided a platform for data sharing and collaboration among disparate groups of researchers and highlights how collaborative research can amplify our power to conduct rigorous applied connectivity science.

Our results can be used to inform conservation policy and management and can be adapted to include more species in the future. Crucially, we found that connectivity priorities vary with scale, necessitating tailored assessments and conservation approaches at the different levels. As human-wildlife interactions intensify due to population growth and climate change, understanding the connectivity of shared landscapes like KAZA is vital for conflict mitigation and enhanced conservation. 

Read the full article “Landscape connectivity for African elephants in the world’s largest transfrontier conservation area: a collaborative, multi-scalar assessment” in Journal of Applied Ecology. 

Author Cheryl Schultz talks us through a new study which highlights the importance of active management interventions in helping to buffer effects of climate change, and helping to improve population trends for at-risk butterflies.

Where did the idea come from?

With extensive coverage in academic and popular publications, the widespread decline of butterflies is well-known. Butterflies face a triumvirate of threats: the cumulative effects of habitat loss, climate change and pesticides are severely impacting butterflies – and other wildlife – around the globe.

In recent years, scientists have spent a lot of time documenting this biodiversity crisis, which is important but fundamentally a depressing direction of research. 

At the local level, natural area managers make daily decisions about how to address the onslaught of threats. In some cases, the managers benefit from close partnerships with researchers actively engaged in trying to identify the best possible management actions to reduce threats while, at the same time, not impacting at-risk species. In many other cases, the managers must rely solely on their knowledge of the local systems and actions they can take given the constraints of available funding. The collective long-term effects of these actions are often unknown, and have received much less attention than large-scale patterns of biodiversity loss and population declines.

Phenological change – or the change in the seasonal timing of activity – is one of the most documented fingerprints of climate change. For many butterfly species, the timing of their adult activity period has shifted weeks earlier in association with climate-driven warming. Many ecologists and conservation biologists are concerned that phenological changes will further reduce populations of at-risk species, many of which have already been impacted by substantial habitat loss.

We decided to evaluate relationships among changes in phenology, local land management actions, and population viability (trends toward increase vs. decline) through time. We focused on at-risk species, partly because there are more resources for local management of at-risk species in the U.S., and partly because these species are often not included in broad-scale analyses because working with sparse datasets for rare species is often challenging. 

So, our study differs from most work on the status of butterfly populations in two ways: we evaluated the effects of local site management, and we focused on the at-risk species that are often the targets of management actions.

What did we do?

To understand the combined effects of changes in phenology and management interventions, we sought out long-term datasets for at-risk butterflies across the United States. These included species listed under the U.S. Endangered Species Act and butterfly species considered ‘Species of Greatest Conservation Need’ (SGCN) within individual states at the time we started the study. After making calls to dozens of species experts over the course of about two years, we were able to gather datasets with enough information to understand phenology and abundance for 114 populations of 31 at-risk butterfly species or subspecies in 10 U.S. states. 

For each of the populations, we then sought to document management interventions that were carried out to enhance butterfly habitat over the time period for which butterfly data were available. Through a combination of agency reports, emails and phone interviews, which involved contacting dozens more people – including contacting local site managers as well as species experts – over another 1-2 years, we documented annual management interventions for 90 of these populations.

What did we find?

The strongest signal in our analysis was that, overall, populations with frequent management interventions were doing better than those which lacked management actions. Sites used various forms of management, including controlled burning, planting, mowing and other actions to enhance the habitats depending on the needs and budget constraints of individual sites.

Because multiple actions often occurred together we did not separate the effects of different kinds of management on population growth rates. For example, land managers used a combination of fire, mowing, and grass-specific herbicides to reduce non-native grasses and restore historic disturbance regimes for Fender’s blue butterfly at USFWS Baskett Slough National Wildlife Refuge.  

On average, butterfly populations in our data set were declining, which is not surprising given that we were specifically targeting at-risk species. Nearly all populations at sites that received no habitat management were declining. Populations tended to be stable or growing at sites with regular management actions (some form of active attention taken every 1-1.5 years), although this average reflects a range of population trends, from declining to rapidly recovering populations in sites with regular management.

Butterfly populations were also changing in phenology, but the impacts of these changes were relatively subtle. As expected, most populations were shifting their phenology to be earlier in the year, but some populations did not shift much, and a few shifted to be later. There were no associations between common metrics of phenology (such as change in the start of the flight period) and trends in abundance. However, butterfly populations which had little shift in phenology over time (i.e., phenological constancy) were associated with a higher frequency of habitat management and were more likely to have positive population trends.

What does this mean?

Our results imply that, at a broad level, habitat management works to reverse population declines. While this may seem like common sense, it is a strong contrast to the predominant current scientific literature on climate change, which is largely focused on how climate change is impacting species across the globe and is agnostic to local management efforts to alter population trends. In contrast, we believe that the effects of global stressors like climate change and pesticides are not independent of habitat management: a species in higher quality habitat can often tolerate a less favorable climate.  

The association between changes in abundance and phenological constancy and habitat management provide one hypothesis for how management can mitigate climate change. Management interventions might create spatial heterogeneity which, in turn, allows butterfly activity to track optimal conditions by moving within a site rather than shifting phenology. There is a budding literature on approaches that might allow species to persist-in-place rather than need to shift-in-space. We do not dispute the large-scale influence of global climate change, but our findings suggest that local-scale management can mediate some of the effects of climate change and other threats of global change, at least over the short-term.

In closing, we applaud the actions of the local land managers who contributed to this study.  In the academic literature, these actions are often perceived as too “local” and “specific” to be included in analyses of global biodiversity trends. Indeed, obtaining these data was one of the most labor-intensive parts of our study. 

Although there is no “silver bullet” to reverse the impacts of global stressors, we see this as a positive message for the prognosis for our butterfly populations. Although individuals and local organizations can only indirectly affect stressors like climate change, we can also take on-the-ground steps to improve habitat quantity and quality and directly increase resilience at-risk butterfly populations.

This research received funding from the U.S. Strategic Environmental Research and Development Program, the U.S. Fish and Wildlife Service Center for Pollinator Conservation and the U.S. Geological Survey John Wesley Powell Center for Analysis and Synthesis.

Read the full article “Phenological constancy and management interventions predict population trends in at-risk butterflies in the United States” in Journal of Applied Ecology.

Are you looking to learn more about the peer review process through hands-on experience? Are you less than five years post-PhD and live in/are from the Global South? Why not consider applying for Journal of Applied Ecology’s 2025 mentoring scheme!

What is the mentoring scheme?

Since 2015, Journal of Applied Ecology has welcomed a small group of mentees with minimum editorial experience each year. This voluntary two-year position aims to develop mentees’ understandings of the peer review process and to boost confidence. Each successful candidate can expect to:

• Be appointed to one of five Senior Editors who can help guide them through the peer review process, acting as on-going support throughout the two years.
• Receive continous support for any queries from the Editorial Office.
• Gain experience in the peer review process by assessing manuscripts via selecting reviewers and submitting recommendations to Senior Editors.
• Have opportunities to help shape the future of Journal of Applied Ecology through submitting ideas and getting involved in journal initiatives.

Eligibility

Please note that applicants must:

• Be less than five years post-PhD (we will also consider people who have had career breaks).
• Be based in the Global South (as defined here), or have a temporary research position in the Global North. This decision aims to help mentees develop their research agenda by engaging with international networks.

Feedback from a past mentee

Gudryan Baronio, mentee 2022-2024

‘As a Brazilian ecologist, I have been fascinated by articles focusing on applied ecology since the beginning of my academic journey. In 2022, I was accepted into the editorial mentoring program for Journal of Applied Ecology, a role I held until 2024. This experience was incredibly enriching, expanding my previous editorial experience from a lower-impact scientific journal to an international platform.

As a member of the editorial team, I engaged with a wide range of topics related to applied ecology, including some cutting-edge developments. My mentor, Romina Rader, a senior editor, guided me through the process, assigning manuscripts for which I served as the handling editor. I also received manuscripts from other senior editors, including Jos Barlow, Martin Nuñez, and Cate Macinnis-Ng. My primary responsibility was to review manuscripts related to ecological interactions in agroecological systems, with a particular focus on predation, pollination, and seed dispersal. However, this process has always been helped by Lydia, Journal of Applied Ecology’s careful and kind assistant editor.

This experience gave me a deeper understanding of the time-consuming nature of the review process and the significant effort required to thoroughly evaluate scientific discussions between authors and reviewers. It also greatly improved my abilities as a scientific author. By gaining insight into the editorial process and exposure to a variety of subjects, I learned how to better present ideas to reviewers, facilitating more effective communication during the publication process.

In December 2023, I attended the BES Annual Meeting in Belfast, an opportunity made possible by the BES’s recognition of the dedication of its editors, which included complimentary registration for the event. Participating in this event as an editor was a unique experience, allowing me to connect with other editors and gain a deeper understanding of the editorial process and the ideas shaping our field.

 Since July 2024, I have been serving as an associate editor for Journal of Applied Ecology, a role I intend to continue as long as possible. As an ecologist from the Global South, I am deeply aware of the potential for ecology and its applications to improve quality of life while preserving the natural environment. Moreover, the role of editor not only keeps me constantly updated but also challenges me to engage with and discuss the latest knowledge being submitted and published.’

You can hear more from our current mentees here.

How can you apply?

If you’re interested in the scheme, please fill out this form. You’ll need to include the following when applying:

• What you know about publishing and the peer review process currently, as well as what you’d like to learn more about and gain from the scheme.
• A brief overview of your areas of expertise and research interests.
• Which Senior Editor you feel would be best suited as your mentor based on your research areas. You can find out more about them here.
• A copy of your CV.

If you have any questions about the scheme or the application process, please email Lydia via [email protected].

Deadline for applications: 1st October 2024, 5pm GMT.

Angus Retallack explains how, using remote sensing data over a 22-year observation period, vegetation recovery after the removal of livestock and the introduction of conservation-focused management can be assessed.

Arid and semi-arid rangelands cover close to 50% of the Earth’s land surface and are relied upon by a diverse range of stakeholders including Indigenous people, pastoralists and environmental conservationists. Sustainable use and conservation of these regions requires effective monitoring to understand the impacts of management, and to adapt practices into the future.

Achieving this monitoring is where difficulties arise. Extreme fluctuations in vegetation driven by highly variable climatic conditions, and the vast scales of these regions, makes measuring change in condition difficult.

Challenges in monitoring rangeland condition

Traditional on-ground monitoring techniques at small sample sites are insufficient for inferring conditions across extensive rangeland regions. But remote sensing methods provide an ideal solution: frequent images from satellite platforms allow measurements at broad scales while capturing the inherent variability in space and time of such ecosystems.

However, an effective method for separating management-driven change from climate variations and trends is required, with past approaches dependent on reference areas that are in good condition as well as reliable climate data, both of which are unavailable for much of the world’s rangelands. Our study presents a new method that uses satellite image time series to assess the effects of differing land management and is simple to understand and implement.

Conservation and sheep grazing management compared: Bon Bon Station Reserve

Bon Bon Station Reserve is a formerly operational sheep station in the southern Australian rangelands that has been destocked and managed for conservation by Bush Heritage Australia over the past 15 years. We use this ~2160 km² property to test our method for assessing relative change in land condition over time.

We used fractional ground cover data from satellites, which shows the relative proportions of bare ground, living photosynthetic vegetation and woody or non-living non-photosynthetic vegetation. This fractional cover data was acquired in monthly time steps over 22 years, with a spatial resolution of 250 metres.

We compared Bon Bon to immediately surrounding pastoral stations that have been consistently stocked with sheep over the study period (2001 – 2022). This design means we can assume that variations in climate are experienced across all properties, and that any relative changes in fractional cover between stocked (surrounding) and destocked (Bon Bon) areas must be the result of management differences, and not due to changes in climatic conditions.

The figure below shows changes in each of the three fractional cover components from the first 5 years to the last 5 years of the study period, with clear increases in persistent non-photosynthetic cover, and decreases in persistent bare cover concentrated within Bon Bon, and coinciding clearly with the western boundary.

Over the 22 year study period, persistent non-photosynthetic cover increased by 1.1% at Bon Bon relative to surrounding properties, persistent photosynthetic cover increased by 0.5% and persistent bare ground decreased by 2.1%. These changes became noticeable around the time of stock removal from Bon Bon in 2008.

Implications for rangeland managers

Previously, measuring changes in vegetation in highly variable rangeland ecosystems has been a difficult task, requiring complex statistical methods and large amounts of often unattainable or poor quality climatic data. Focusing on accessibility and ease of implementation, this method provides an opportunity for land managers of vast rangeland areas to assess relative changes in vegetation cover.

By understanding how vegetation changes relative to surrounding areas, it is possible to understand how changes in management practice may have influenced vegetation condition, allowing management strategies to be adapted and improved for better outcomes into the future.

Read the full article “Remote sensing for rangeland conservation monitoring: Impacts of livestock removal after 15 years” in Journal of Applied Ecology.

Laura Sutcliffe discusses her latest study where, alongside colleagues, she investigated the spatial distribution of vascular plant species richness and their contribution to the food web via biomass and flower units in conventional and agri-environment cereal fields.

The study: Arable plants

Arable plants are usually simply referred to as weeds, reflecting their low status in society and also in biodiversity research. Whilst there is a wealth of literature dedicated to how to get rid of them, the biodiversity value of the several hundred species of arable-adapted plants in Europe is a relatively niche subject. Through agricultural intensification a large proportion of arable plant species are now threatened or extinct, and those that remain are mostly limited to the outermost metre or so of a field. This is a group that is both metaphorically and literally close to the edge.

But arable plants are also the base of the agricultural food web, and closely linked to declines in e.g. insects and birds. We looked at the spatial distribution of wild plants in cereal fields in Germany, and how this varies with different agri-environment schemes. In this way we wanted to demonstrate what these measures are capable of providing in terms of diversity and food-web resources (flower units and plant biomass) at the field level. We also wanted to contribute further evidence to the discussion on whether landscape configuration (i.e. field size) or management is more effective to promote biodiversity.

Findings

In contrast to conventional cereals, “extensive” management (lower sowing density, no synthetic pesticides or fertilizers) maintains arable weed populations into the field interior. This means a much higher resource provision at the field level: extrapolating to a 1ha field results in 127,000 flower units in extensive management compared to 1900 flower units in conventional management. The concentration of wild plants at the field edge means that smaller field sizes in conventional agriculture do increase in-field arable plant populations at a landscape scale.

But, it may be more practical for the farmer and better for the yield to instead incorporate extensive buffer strips around the outside of larger conventional fields. This may also help to reduce spray-drift and fertilizer run-off, and has long been recommended as a measure in nature conservation practice. An important consideration in this recommendation is that we are focusing on arable plants, and not on species that mainly use the habitats between the fields like hedgerows or ditches. As always in conservation, the best intervention depends very much on the specific landscape and the organism group you want to promote.

Why is this important?

This study is part of a wider project looking at the real-world effects of conservation measures in conventional farmland. Whilst organic farming is most often recommended as the best way to promote biodiversity, the reality is that the vast majority of farmland (around 90% in the EU) is conventional. Much of this area has very low levels of even generalist species in the landscape, reducing resilience to pests and fragmenting populations.

Within the FR.A.N.Z. project, ten farmers from across Germany agreed to test out different conservation measures over ten years, providing access for ecological and economic research and demonstrating the results to colleagues. In this way, they hope to inspire other farmers to integrate more nature conservation into their farming practice and give a boost to biodiversity in the landscape.

Read the full article “Close to the edge: Spatial variation in plant diversity, biomass and floral resources in conventional and agri-environment cereal fields” in Journal of Applied Ecology.