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The Challenge of Monitoring Biodiversity

By Claire Asher, on 4 August 2015

a guest blog by Charlie Outhwaite, written for the 2015 Write About Research Competition.

Biological diversity, or biodiversity, is a complex term encompassing the variety of life found on Earth. It incorporates not only differences between species but within species themselves and of the environments and ecosystems where they are found. We as humans benefit a great deal from the biodiversity on Earth in a range of ways; from the clean air we breathe to food, materials and medicines that are produced as a result. These products or services are known as ecosystem services and these services depend on biodiversity. Monitoring the status of biodiversity is therefore an important area of research, but offers its own challenges. New methods offer the chance to utilise data that has been underused in the past due to its associated biases and we are now able to explore and monitor the responses of biodiversity over time for many more species than has previously been possible. This has opened the door not only to more knowledge on a greater range of species but also allows us to look into what aspects are influencing these changes, such as the impact of climate change.

In April 1992, an agreement was signed by a number of government parties to the Convention on Biological Diversity (CBD) agreeing to the global target “to achieve by 2010 a significant reduction of the current rate of biodiversity loss”. Unfortunately, this target was never achieved and so, in 2010 an updated plan was established at the tenth meeting of the Convention in Nagoya, Japan. This revised plan includes 20 main targets, known as the Aichi Biodiversity targets, under 5 strategic goals each encompassing one aspect to benefit biodiversity.

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In order to measure progress towards these targets, at both a national and a global scale, a number of indicators of change have been developed, these are often simple graphs showing increases or decreases in the variable being monitored. For the UK, these are published annually by DEFRA (the Department for Environment, Food and Rural Affairs) in the Biodiversity Indicators in your Pocket report (BIYP). Indicators are composite measures of change and are a simple and easy way to communicate change over time. The most recent BIYP report includes a suite of indicators aimed to report on UK progress towards the Aichi targets. These range from indicators of change in volunteer time spent in conservation organisations to assess progress towards strategic goal A (Address the underlying causes of biodiversity loss by mainstreaming biodiversity across government and society) to indicators of the status of UK priority species for Strategic Goal C (To improve the status of biodiversity by safeguarding ecosystems, species and genetic diversity).

However, the monitoring of aspects of the goals is not simple and biodiversity itself provides a great challenge. Take target 12 for example; “By 2020 the extinction of known threatened species has been prevented and their conservation status, particularly of those most in decline, has been improved and sustained”. In order to assess whether the decline and extinction of threatened species has been prevented we need to be able to measure how many there are in the first place, and how that changes over time. Ideally, we would like to go out and count exactly how many there are of each species, but of course this is not possible. It would be difficult enough going out and counting every species in your own garden, let alone across the whole country. So, we have to use the next best alternative. In some cases, standardised monitoring schemes such as the Breeding Bird Survey are set up and species numbers are monitored using standardised techniques across specific sites. This data can then be used to accurately estimate the abundance of those species observed. However, this kind of data is costly to collect and requires a lot of time and effort and so, is not available for the majority of species.

An alternative form of data is biological records. Biological records are a data type that is high in quantity but has a number problems associated with it. Often collected by volunteers through citizen science projects, this type of data can be highly variable in its level of accuracy and completeness. However, with interest and participation in citizen science increasing, the amount of biological records data available is rising. With so much data on hand, and often for those groups of species that are less well studied (such as insects) and for which monitoring scheme data is unavailable, it is important that these data are put to good use. However, because of the problems associated with this data type, it is underused and underappreciated. The main problem is that it is collected in an unstandardized way, which introduces bias into the data. Records will often be collected by an individual at a location of their choosing and they may not report every species they see.

A number of robust statistical methods have been developed that are able to account for these associated biases. Bayesian occupancy models are a complex statistical technique which has been shown by Isaac et al (2015) to most effectively account for the biases of this type of data and produce reliable indicators of change. It is now being used to monitor changes in the biodiversity of less well studied groups of species using biological records from various recording schemes. For these species groups, this kind of data is all that is available and so employing these new methods for analysing biological records is enabling greater research into areas where little is currently known.

However, with human induced drivers being the biggest threat to biodiversity loss, it is not enough to simply monitor changes in species trends. There is a growing need to understand what is causing these trends and how a species’ traits can increase its susceptibility towards these drivers. Through a more thorough understanding of the effects drivers such as climate change have on a group of species, and which species within that group will be most affected, it would be possible to design conservation interventions to target those species most at risk, preventing future declines. This process could act as a form of triage, in determining those species that will be most affected so that conservation and policy action can be targeted to those areas in the first instance. This is becoming increasingly urgent as a mid-term report on progress towards meeting the CBD 2020 targets by Tittensor et al indicates that progress is not positive.

References

  • Defra (2014) UK Biodiversity Indicators 2014: Measuring progress towards halting biodiversity loss. Retrieved from http://jncc.defra.gov.uk/page-4229
  • Isaac, N. J. B., van Strien, A. J., August, T. A., de Zeeuw, M. P., & Roy, D. B. (2014). Statistics for citizen science: extracting signals of change from noisy ecological data. Methods in Ecology and Evolution, doi:10.1111/2041-210X.12254
  • Tittensor, D. P., Walpole, M., Hill, S. L. L., Boyce, D. G., Britten, G. L., Burgess, N. D., … Parks, B. C. (2014). A mid-term analysis of progress toward international biodiversity targets, (October), 1–8.

CharlieOuthwaiteCharlie is a first year PhD Student based at the Centre for Ecology and Hydrology, Wallingford and working within the Biological Records Centre. Charlie’s PhD is linked with CBER UCL and the RSPB through a CASE partnership. Her research is looking into biodiversity status, drivers and indicators from biological records. Charlie’s interest in measuring and reporting changes in biodiversity has grown since working as an intern and research assistant within the Indicators and Assessments Unit at the Institute of Zoology. Within these roles she worked on the Living Planet Index and on developing a Canadian biodiversity indicator. Going from the reporting and development side of indicators she now hopes to reveal the role of drivers of change and how these interact with species traits to affect changes in biodiversity.

PREDICTS Project: Global Analysis Reveals Massive Biodiversity Losses

By Claire Asher, on 21 May 2015

The changing climate is only one of a myriad of pressures faced by global biodiversity – we are also changing habitats and altering land-use on an unprecedented scale. The first global analysis published from the PREDICTS project reveals the striking global effect of land-use change on local biodiversity patterns, and highlights the importance of future climate-mitigation strategies in shaping the future of biodiversity and the vital ecosystem services it provides.

Human activities are causing widespread change to and degradation of habitats, which has been linked to serious biodiversity declines globally. Land-use change comes in many forms, from deforestation and agriculture to urban development and road-building, and previous work by the PREDICTS project has shown how different types of land-use influence different types of species differently. We are interested in biodiversity loss at a global scale, and many metrics aim to quantify this, but viewing global patterns can obscure local-scale changes that are likely to be more important for the resilience of ecosystem services. Ecosystem services include clean air and water, food, medicine and nutrient cycling, among others, and are vital both for biodiversity and for human survival and well-being. The PREDICTS project considers local-scale changes to biodiversity in response to land-use change, to produce a powerful model that can be used to project the impact of future land-use and climate change. In their latest paper, published in Nature last month, the PREDICTS team reveal their most comprehensive analysis to date, showing massive reductions in local biodiversity since 1500, and projecting further widespread losses under several future climate and land-use scenarios. There is still hope, however, and strategies to mitigate greenhouse gas emissions without major land-use change could offer the opportunity for global biodiversity to recover.

Understanding the Past and Present

The PREDICTS team have assembled a database of over 1,130,000 records of species abundance and nearly 330,000 records of species richness across more than 11,000 sites worldwide. The database includes results from 284 scientific publications, and represents over 25,000 species. Using this incredible resource, the team compared species richness and abundance between sites with different land-use types and produced a statistical model to quantify local biodiversity responses to land-use change. This enabled them to infer changes in species assemblages since the year 1500.They found that species richness and total abundance were both strongly influenced by land-use type and intensity, with reductions in biodiversity outside of primary vegetation and the worst losses seen in intensively used areas. Local biodiversity was also negatively impacted by human population density and accessibility (measured by the distance to the nearest main road). In the worst-affected habitats, changing land-use away from primary vegetation reduced species richness and abundance by an average of about 40%, and globally, land-use change was responsible for an average reduction in species richness and abundance of around 9%. The value of secondary vegetation (forest recovering from past damage) for biodiversity depended strongly on how mature the habitat was, with species diversity increasing over time, and mature secondary vegetation most closely resembling primary habitats. Restoration projects do, therefore, have the power to return biodiversity to damaged habitats, but (unsurprisingly!) it will take time.

Previous estimates have suggested that local losses of species richness and diversity greater than 20% are likely to substantially impair ecosystem services contributed to by biodiversity and reduce overall ecosystem function. Some scientists believe biodiversity loses at this scale may push populations towards ‘tipping points’ where ecosystem function declines lead to further species loss. Thus, in the worst-affected habitats considered by the PREDICTS team, which experienced on average a 31% loss of local species richness, ecosystem function is likely to be substantially impaired.

Changes in species richness and abundance may underestimate the real impact of land-use change because the measure fails to capture the composition of a community. The team therefore compared the species composition between sites and found that communities tended to be similar under similar land-use. Communities living in primary and secondary vegetation were most alike, while more disturbed habitats such as plantation forest, pasture and cropland tended to support a different cluster of more human-tolerant species. Human-dominated landscapes lost far more natural local diversity than more pristine sites where natural vegetation remains.

Reconstructing past biodiversity loss indicated that the greatest reductions in species richness occurred in (unsurprisingly) the 19th and 20th centuries, and that by 2005 local species richness worldwide had reduced by 13.6% due to land-use change and related anthropogenic pressures. How will this trend continue into the future?

Projecting the Future

The PREDICTS team then went on to combine their analysis of current species’ responses to land-use change with four climate scenarios produced by the Intergovernmental Panel on Climate Change, to project future changes in biodiversity under different socioeconomic scenarios of land-use change. Projecting as far as 2095, the PREDICTS model projects rapid biodiversity losses under a ‘business-as-usual’ land-use scenario, with species richness projected to drop a further 3.5%. These loses are not likely to be uniformly distributed, however, with the largest loses predicted to occur in economically poor but highly biodiverse regions, such as Southeast Asia and Sub-Saharan Africa. Buisness-as-usual results in rapid human population growth and agricultural expansion, and most closely matches recent trends, and yields the most severe losses in biodiversity of any scenario considered by the PREDICTS team. Continuing on as we have been does not bode well for biodiversity or the vital ecosystem services it provides us.

Projected net change in local richness from 1500 to 2095. Source: http://www.nature.com/nature/journal/v520/n7545/abs/nature14324.html.

Projected net change in local richness from 1500 to 2095. Source: http://www.nature.com/nature/journal/v520/n7545/abs/nature14324.html.

Perhaps surprisingly, the second-worst scenario for biodiversity is in fact the scenario with the least climate change (IMAGE2.6). This is because this scenario achieved reduced emmisions and climatic change by rapidly converting the world’s forests (primary vegetation) to crops and biofuel. In contrast, the IPCC scenario MiniCAM 4.5, which mitigates climate change through the use of carbon markets, crop improvements and diet shifts, however, is projected to increase average species richness. Not all our possible solutions to curb greenhouse gas emissions and reduce climate change will necessarily spell good news for biodiversity.

It isn’t all bad news, though. The right strategies can promote biodiversity globally, even producing increases in species richness by 2095 of up to 2%, and the PREDICTS team say widespread biodiversity loss is not inevitable. Concerted efforts and the right socioeconomic choices can make long-term global sustainability of biodiversity an achievable goal.

Original Article:

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This research was made possible by funding from the Natural Environment Research Councik (NERC) and the Biotechnology and Biological Sciences Research Council (BBSRC).