3 Biodiversity Indicators And Monitoring For Ecological Management

Toby Gardner

3.1 Introduction

The fate of much of the world’s terrestrial biodiversity depends upon our ability to improve the management of ecosystems that have already been, or are currently being, modified by humans (Gardner et al., 2009; Wright, 2010; Pereira et al., 2012; Malhi et al., 2014). Monitoring, as a means of detecting the changing state of an ecosystem, and identifying ways in which existing management approaches can be made more sustainable, is a central part of any strategy to safeguard biodiversity in the long-term.

This chapter presents a broad overview of some of the key features of any process to monitor and evaluate biodiversity. Selection of appropriate indicators are a central part of this, yet as is the case for the assessment of any indicator, good biodiversity indicators represent only a necessary, yet not sufficient condition for a monitoring process to provide the kind of support necessary to foster improvements in sustainability.

The chapter briefly identifies ways in which biodiversity monitoring can be most effective in facilitating and guiding any management process – whether it is the management of a protected area, a multiple-use reserve, managed forest or wetland or urban park. A lot of existing texts on biodiversity indicators and monitoring focus primarily on the technical details of how to survey biodiversity in the field. Here I take a few steps back and focus on the importance of first thinking about the why and what of monitoring, as well as the ways in which monitoring activities fit within a wider framework of the management system itself – whatever that management system may be. Following this, I present an overview of different types of indicators that can be used to support a biodiversity monitoring program, including different ways to assess the status and trends of biodiversity.

The chapter is based heavily on the work of Gardner (2010a), which provides a more comprehensive overview of the status of biodiversity monitoring (with a focus on forest ecosystems) and presents a detailed operational framework of ways in which the process of collecting biodiversity data and indicators can make a more effective and meaningful contribution to the way in which we manage and conserve our natural heritage for future generations.

3.2 The Context And Purpose Of Biodiversity Monitoring

3.2.1 Why Should We Be Worried About Biodiversity Monitoring In The First Place?

The straightforward answer to this question is that monitoring is generally done badly yet remains the only way by which we can assess the state of our ecosystem and improve on our ability to conserve biodiversity into the long-term.

Despite its theoretical importance, monitoring is often trivialised as being a simple “tick the box” exercise, necessary to satisfy auditing requirements. The focus is often only on which indicators to choose and how they should be sampled and recorded. Yet poorly conceived monitoring programs can often do more harm than good – resulting in a waste of precious resources, and an undermining of the credibility and value of monitoring in the eyes of management authorities and decision makers (Sheil et al., 2004; Lindenmayer and Likens, 2010).

A large number, if not the majority, of existing biodiversity monitoring programs are centred on providing a “surveillance style” record of how biodiversity (e.g. the population size of a particular species or the area of a specific vegetation type) changes over time. Such information is often used as a form of early-warning system. For example, information on population or species declines can be used to kick start conservation action, both in the form of a regulatory mechanism (e.g. as is done commonly in the management of fish stocks) and as a way of raising public and political awareness about environmental issues. Long-term monitoring of biodiversity across a network of sites can also help in developing an improved understanding of background levels of variability in natural systems, as well as capture information on hitherto unperceived threats (e.g. the impacts of climate change and disease on amphibians; Pounds et al., 2006). Surveillance style monitoring can also be an effective way to engage non-scientists in conservation. Good examples of this are the long-term, nation-wide bird surveys ran in Britain and North America that involve thousands of volunteers while also feeding information into national indicators of biodiversity loss (e.g. as developed by the British Trust for Ornithology on behalf of the UK government http://www.bto.org/research/indicators/index.htm).

Nevertheless, there are serious limits to a surveillance approach as a practical aid to ecosystem management. The main shortcoming is that it is disconnected from the management process. By this I mean that the design of the monitoring program has an isolated focus on the biodiversity of interest (e.g. are there more or less individuals of an endangered species in the management area?) and not on assessing the impact of the ongoing management activities themselves (e.g. importance of variability in logging cycles, road building or the design of nature corridors for effectively conserving the biodiversity of interest). Surveillance type approaches presume that a clear and workable plan of action is already available and that this can be launched into place once the warning bells start ringing. Unfortunately this is rarely the case.

3.2.2 A Simple Framework For Biodiversity Monitoring As A Practical Aid To Ecosystem Management

In an ideal world we would have a perfect understanding of how different human activities and management interventions impact biodiversity, and we could use this understanding to dictate a clear code of practice (e.g. legal or certification standards) that guarantees responsible and more sustainable use. Assessments of management compliance could be made simply by monitoring the implementation of previously agreed management activities. This is often termed implementation monitoring (Noss and Cooperrider, 1994; Gardner, 2010a). However, this is clearly not the case. The biodiversity consequences of human activities are unpredictable, many threatening processes remain poorly understood, and in the vast majority of cases we have a poor understanding of how generic guidelines can be most effectively adapted to fit the context of particular site. To overcome this problem biodiversity monitoring is needed to satisfy two interrelated purposes that are central to any management process (Fig. 1):

• –   To ensure that recommended management practices do indeed translate into minimum levels of performance and biodiversity conservation on the ground. This is often termed effectiveness monitoring. Effectiveness monitoring should represent an integral part of any auditing or compliance process, e.g. for a certification standard or environmental regulatory framework.
• –   To evaluate the extent to which existing management standards are adequate and how they can be further refined to ensure continued progress towards long-term conservation goals. This is often termed validation monitoring. This is essentially the same as applied research and provides a valuable mechanism for learning about how to improve opportunities for biodiversity conservation within any management process

Done well, monitoring should provide a linchpin between ultimate management goals and the ongoing management process - the guiding hand by which conservation objectives can be translated into improved on-the-ground management. To achieve this broad purpose monitoring serves two specific and inter-related functions.

First, it is an assessment tool that is used to assess the status or condition of biodiversity in a managed system (wherever conservation management strategies may already exist). In so doing it can provide an assessment of management performance and compliance against pre-determined standards. Without reliable information on the status and trends of the ecosystem it is impossible to expect that managers can ensure the conservation of viable populations of native species and the maintenance of key ecological processes (Noss, 1999).

Second, it is an evaluation tool that is used to compare the effectiveness of alternative management actions, whether existing or potential - thereby providing a means to both validate the adequacy of existing management approaches and identify directions for future progress towards more sustainable systems of use. In essence this is the philosophy of adaptive management, which although much discussed (and required – at least on paper - by many management authorities) has rarely been implemented effectively on the ground. Key to successfully integrating biodiversity monitoring within the wider ecosystem management process is recognition of the complementary role played by these different types of monitoring approaches and their associated indicators (Fig. 1).

Once the purpose of a monitoring activity has been established (e.g. effectiveness or validation monitoring or both) there is a logical series of steps in developing the rest of the program (Fig. 2; Green et al,. 2005; Gardner, 2010b). If the only purpose is to provide an audit function then the task is relatively straightforward – indicators and minimum standards are determined by the relevant authority and monitoring data are collected to ensure that standards have been met (Fig. 3). By contrast, validation monitoring is a much more involved process that requires measuring changes across different levels of cause and effect, from changes in management practices (ultimate drivers), through changes in ecosystem structure and function (proximate drivers), to changes in biodiversity - with the end goal of generating recommendations for how to improve management (Fig. 4).

Biodiversity conservation goals provide a reflection of societal values and political or institutional intent in management, and create the entire context and sense of purpose of biodiversity monitoring, as well as the basis for selecting individual monitoring objectives and indicators. Conservation goals can be focussed on safeguarding individual species of conservation concern (e.g. threatened species or species of particular functional importance in ecosystems such as key seed dispersers and pollinators), or may adopt a broader, ecosystem-wide perspective to ensuring the protection (or restoration) of ecological integrity across whole management areas or landscapes (as determined by deviations from an appropriate reference condition such as a neighbouring reserve or set-aside area). Both goals are complementary (Lindenmayer et al., 2007; Gardner, 2010a) yet the maintenance and restoration of ecological integrity invokes a much broader conservation challenge than that which is focussed on preserving a particular set of species. Assessments of ecological condition or integrity are very well developed for aquatic systems (see Linke et al., 2007), yet despite offering much promise have received comparatively little attention in the terrestrial world.

Clear objectives are essential to ensuring that the time, money and expertise are not wasted in any monitoring program. Because no monitoring program has sufficient resources to address all possible objectives it is necessary to prioritise investment so as to deliver the greatest benefits with respect to long-term conservation goals. This includes identifying which areas of management have the greatest impact on the biodiversity of concern, where the greatest areas of scientific uncertainty lie, and what is possible with the funds and human resources available.

3.3 Indicators For Biodiversity Monitoring

In discussing environmental indicators in general Hammond (1995, pp:1) define an indicator as “something that provides a clue to a matter of larger significance or makes perceptible a trend or phenomenon that is not immediately detectable. [. . .] Thus an indicator’s significance extends beyond what is actually measured to a larger phenomena of interest’’. Indicators provide the practical tool by which changes in management practices, system attributes and ecological processes can be measured, and minimum performance standards or thresholds evaluated. Consequently the choice of indicator is fundamental in defining the approach to both monitoring and management (Lindenmayer and Burgmann, 2005). It is important to clearly distinguish the concept of an indicator from that of an attribute: attributes are all encompassing and relate to any quantifiable element of concern, whereas indicators only represent the subset of attributes or attribute features that are used as surrogates of other valued attributes (see Chapter 8 for examples related to forest restoration).

To assist in relieving the significant confusion that surrounds the indicator concept, Table 1 provides a typology of indicator types that helps reveal problems of synonymity and identifies the role of different indicators within a simple hierarchical pressure-state-response framework. In general terms – whether for biodiversity or any other kind of sustainability indicator - it is useful to consider two main types of indicator; those whose function is prescriptive, and those whose function is evaluative (Kneeshaw et al., 2000; Rempel et al., 2004 - although these concepts can be confounded depending on the perspective of the observer, see Table 1). Management policy and process indicators are both prescriptive in that they are used to measure or verify the existence or implementation of certain policies and management strategies. Management practice indicators are termed such because they are used to measure the implementation of management practices. In a similar sense they are also referred to as “driver” or “pressure” indicators (e.g. Hagan and Whitman, 2006), as well as indicators of management response to some earlier observation or warning sign. In contrast, performance indicators are evaluative in the literal sense that they are used to evaluate changes in management performance. I distinguish the concepts of indirect versus direct performance indicators, and recognise that both are commonly used to measure management performance (e.g. for certification standards, FSC, 2002; and see Newton and Kapos, 2002). Because of the difficulties in reliably linking management impacts to changes in the distribution and abundance of actual species, direct species-based performance indicators are often more useful as evaluators of performance standards rather than direct measures of compliance.

3.3.1 Management Practice Indicators

Management practice indicators directly measure management practices, including local and landscape level interventions. Together they detail which aspects of a given ecosystem are managed (i.e. as distinguished from un-managed activities and external threats). The assessment of management practice indicators forms the basis of an implementation monitoring program that is used to evaluate compliance against an agreed management standard.

3.3.2 Management Performance Indicators

When the consequences of management are uncertain (a condition that is almost always true) performance-based indicators provide a more transparent and comparable assessment of management accountability than is possible with process-based indicators.

Ecosystem managers very rarely have the capacity or expertise necessary to directly manage populations and species. Instead they manipulate structural and functional aspects of the ecosystem, which in turn have a variety of consequences for biodiversity (Lindenmayer and Franklin, 2002; Lindenmayer and Fischer, 2006; Gardner et al., 2009). To accommodate this fact ecosystem managers address the problem of biodiversity conservation through a combination of coarse and fine filter management approaches (Hunter, 1990).

Coarse filter management is focused on creating or maintaining the ecosystem structures and ecological processes required for the persistence of a wide range of species. By contrast, species specific or fine-filter management addresses the direct resource or habitat needs for particular target species that are not addressed through coarse filter approaches. The extent to which coarse filter approaches ensure adequate resource provision for a large number of species is poorly understood for much of the world, and requires testing through validation monitoring (Table 1). Coarse and fine-filter management approaches can be evaluated through monitoring programs using a combination of what I term here indirect and direct performance indicators.

Indirect performance indicators provide the foundation for a performance-based standard and are intended to represent the proximate drivers of any observed changes in biodiversity (Table 1). For example in a managed forest system indirect performance indicators are commonly made up of stand and landscape-level indicators of forest structure (sensu Lindenmayer et al., 2000) which provide a readily accessible and quantifiable indication of ecologically relevant forest management impacts. Some indicators of ecological processes such as major disturbance regimes (e.g. fire, flood, pest-outbreaks), and changes in soil or water contaminant loads, can also represent valuable indirect indicators of performance (although at the same time they also provide direct measures of performance if the management goal is concerned with soil contamination, and not biodiversity). The key requirement of any indirect performance indicator, whether structural or process-based, is that any changes in biodiversity can be clearly linked to actual management impacts through a logical chain of cause and effect.

Direct performance indicators differ from indirect performance indicators because they directly measure changes in the valued attributes rather than their perceived ecological requirements (e.g. native species rather than habitat availability). For biodiversity monitoring programs, direct performance indicators can be considered as synonymous with biological indicators (and their myriad forms) and target species (Table 1 and see below). A comprehensive ecological monitoring program may also encompass indicators of ecological processes that play important roles in the maintenance of biodiversity (e.g. leaf litter decomposition, Ghazoul and Hellier, 2000; or soil properties, Curran et al., 2005), yet whose links to management activities are poorly understood.

3.3.3 Biological Indicators

Chosen carefully, biological indicators can make an invaluable contribution to monitoring because they are the only method of synthesising the overwhelming complexity of ecological systems, and are therefore the most effective tool for linking conservation science to policy (UNEP, 2000). They also provide the highest level of information quality because biological indicators are valued attributes in their own right. Financial and logistical constraints mean that it is impossible to measure all elements of biodiversity (Lawton et al., 1998; Gardner et al., 2008), and biological indicators that can operate as surrogates for changes in ecosystem health or condition or the distribution and status of other species provide a practical solution to an otherwise intractable problem (Margules et al., 2002, Niemi and McDonald, 2004).

As surrogates of change in the condition and/or diversity of ecosystems, biological indicators can be used in a regulatory sense to provide an early warning signal of impending environmental change, as well as in a diagnostic sense, as an aid to interpreting the ecological consequences of alternative management strategies (Dale and Beyeler, 2001; Niemi and McDonald, 2004). The two fundamental requirements for all biological indicators are; (i) that they reflect something that cannot be measured directly, while also providing more information than that which relates only to the indicators themselves, and (ii) their measurement is logistically and financially feasible. Beyond this, the concept of an indicator species or species group can adopt a myriad of different meanings (Caro and O’Doherty, 1999; Lindenmayer et al., 2000). Although the semantics of biological indicators has a highly confused history in the ecological literature (Caro and O’Doherty, 1999; Caro 2010), I follow McGeoch (1998, 2007) in recognising three broad and overlapping categories of biological indicator that each correspond to conceptually different applications, namely; environmental indicators, biodiversity indicators and ecological indicators.

3.3.3.1 Environmental Indicators

Environmental indicators are species, or groups of species that provide a predictable and quantifiable measure of an environmental state or impact on some abiotic or physical parameter of interest that may be difficult or expensive to measure directly. They have most commonly been applied to indicate levels of pollutants and toxins in water, but also other measures such as soil fertility (McGeoch, 1998, 2007). Related terms include bioassays, accumulator species and biomarkers.

3.3.3.2 Biodiversity Indicators

Biodiversity indicators operate, as the name suggests, as surrogates of biodiversity, and are described as species or groups of species whose distribution or level of diversity reflects some measure of diversity of other taxa (i.e. their distribution is highly congruent with the distribution of other, unrelated species) (Noss, 1990; McGeoch, 1998, 2007). Despite often having weak theoretical and empirical support (Lindenmayer et al., 2000, 2002) this concept has dominated much of the discussion surrounding biological indicators. The term biodiversity indicator is commonly employed in reference to large-scale conservation planning assessments where understanding spatial patterns of species congruency is central to developing an effective network of protected areas. However, the concept also encompasses what I term here “cross-taxon disturbance response indicators” (and see Caro, 2010), which are applicable to monitoring systems and relate to those individual species or species groups that are used to capture the impacts of disturbance on other species or species groups (e.g. Barlow et al., 2007; Gardner et al., 2008).

3.3.3.3 Ecological Indicators

Ecological indicators are species that demonstrate the effect of environmental change and degradation on biota or biotic systems (Kremen, 1992; McGeoch, 1998, 2007; Howe et al., 2007). As some researchers have employed a more general usage for ecological indicators (e.g. Noss, 1999; Niemi and McDonald, 2004), I use the more specific term of “ecological disturbance indicators” with respect to their application for evaluating the ecological consequences of human disturbance in modified systems (see also Caro, 2010).

Ecological indicators may or may not capture the specific responses of other species to disturbance, but their primary utility is in providing a species-based gauge of the otherwise difficult to quantify holistic concepts of ecological condition and integrity, where measurements are made as some form of deviation from a reference or minimally disturbed state. The implication of a loss of integrity as signalled by a decline in ecological disturbance indicators is derived from what we know about what such species do. Indicator species groups that are both sensitive to environmental change, and are known to perform important ecological functions make excellent ecological disturbance indicators as they provide the most reliable inferences about the ecological and functional implications of disturbance.

Because a primary goal of biodiversity conservation is to improve our understanding of the consequences of anthropogenic-induced stressors on native biota, ecological disturbance indicators as defined here represent arguably the most critical objective in the field of biological indicators (McGeoch, 1998, 2007; Pearce and Venier, 2005). An important way in which ecological disturbance indicators are quite distinct from environmental indicators is that they assess the effects or ecological consequences of environmental change (the indicator itself is of intrinsic interest), whereas environmental indicators are used more simply as a gauge of change in a particular abiotic environmental parameter (McGeoch, 1998). Because ecological disturbance indicators indicate functional changes to an ecological system (as measured by a deviation from a reference condition), they reveal insights into the consequences of ecosystem management that cannot be gained from direct measurement.

3.3.3.4 Focal Species

In addition to the indicator concepts as described above, there are additional types of indicator that operate as partial surrogates for biodiversity yet have been defined to have a more specific usage and fall under the general category of “focal” species (e.g. Lambeck, 1997; Caro and O’Doherty, 1999). Focal species have been developed largely in response to criticisms of the biodiversity indicator concept as based on patterns of species congruency, and are characterised as species that have particular ecological requirements, the protection of which can help ensure the conservation of other species, encompassing the concepts of umbrella species, keystone species, and resource or process-limited species (Mills et al., 1993; Lambeck, 1997; Noss, 1999). Under a framework developed by Lambeck (1997, see also Noss, 1999) focal species are used to identify specific threats, and the species most sensitive to each threat are then used to define the minimum acceptable level at which that threat can occur. Consequently, they encompass elements of both the biodiversity and ecological indicator species concept, yet as noted by Niemi and McDonald (2004), focal species tend to differ from ecological disturbance indicator species because they do not necessarily serve to measure ecological condition, nor do they convey a clear stress-response relationship.

3.3.3.5 Target Species Of Particular Conservation And Management Concern

There are a number of individual species which, for a variety of reasons, may deserve to be monitored for their intrinsic interest, and not because they necessarily indicate patterns of any other species or ecological processes, or condition. Here I term all such species “target species”. Many legal and voluntary ecosystem management guidelines give particular emphasis to the role of target species of conservation concern (i.e. endemic, threatened and endangered species) as a focus for biodiversity monitoring and evaluation programs. Identification of threatened and endangered species may be made on the basis of regional, national and global listings, each of which involves a distinct set of selection criteria. However, the globally accepted standard for classifying extinction risk and identifying threatened species is the IUCN Red List (Mace et al., 2008). In addition, other species that are deserving of particular management attention include invasive and pest species that may have significant impacts on local biodiversity, as well as species that are of particular economic or cultural importance for local people (e.g. non-timber forest products such as palms, nuts and game meat, Godoy and Bawa, 1993) or “flagship species” that are used to motivate conservation action, Caro and O’Doherty, 1999).

3.4 Putting Biodiversity Monitoring Into Practice

Ultimately theoretical arguments concerning the purpose, design and implementation of monitoring programs can only go so far towards ensuring success. Many biodiversity monitoring programs either fail or fall short of their original intentions because insufficient attention is given to the factors that determine viability in the real world -in particular the role of people in monitoring.

Deciding on the appropriate blend of people to be responsible for designing and running a biodiversity monitoring program depends on both the desired level of detail as well as who the data are intended to benefit. In many ecosystems an integrated approach to monitoring that combines expert guidance and management from professional scientists with a close involvement of local people (whether they be local management authorities or representatives of local communities) is likely to provide the most attractive solution. The contribution of professionals ensures scientific rigour in program design and data analysis, while the involvement of local people facilitates the process of implementing any management recommendations - providing a cost-effective and sustainable means of data collection as well as a potentially rich source of local knowledge to aid interpretation of results. In addition to efforts to improve cost-effectiveness, the viability of biodiversity monitoring can be further enhanced by increasing the relevance and utility of monitoring products to as wide an audience as possible, including relevant management authorities responsible for standard development, government agencies responsible for national biodiversity assessments, the scientific community and environmental educators. Biodiversity monitoring and management should be viewed not as strictly scientific activities, but instead as inherently social processes that are influenced and guided by science. Without clear recognition of the broader societal context within which the monitoring process and the collection of information about the changing status of biodiversity and the environment, is situated, as well as the underlying conservation values that define the ultimate purpose of monitoring, even the most technically robust monitoring programs will be committed to failure. The challenge of putting biodiversity monitoring to work will ultimately depend, more than anything else, on human behaviour and our capacity to change. As John Meynard Keynes so astutely put it “The difficulty lies not so much in developing new ideas as in escaping from old ones”.

Acknowledgements

The content of this chapter is based on the work of Gardner (2010a, 2010b). I am grateful to Agnieszka Latawiec for inviting me to write this chapter on biodiversity indicators and monitoring and for coordinating the organization of the entire book project.

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