Payments for ecosystem services (PES) are a relatively new economic policy instrument, and the factors that drive and explain their environmental performance are poorly understood. Here a meta-analysis of causal relationships between the institutional design and environmental performance of 47 payments for watershed services (PWS) schemes worldwide showed a significant effect on environmental achievement of the terms and conditions of scheme participation, including the selection of service providers, community participation, the existence and monitoring of quantifiable objectives, and the number of intermediaries between service providers and buyers. Direct payments by downstream hydropower companies to upstream land owners for reduced sediment loads were identified as a successful PWS example. No other significant explanatory factors, such as specific type of watershed service, age or scale of implementation of the PWS scheme were detected. The results are highly dependent on the reliability of the input variables, in particular the measurement of the environmental performance variable. Despite efforts to find quantitative information on the environmental performance of existing PWS schemes, such empirical evidence is lacking in many of the schemes studied. International monitoring guidelines are needed to facilitate comparisons, identify success factors and support the future design of cost-effective PWS schemes.

Concerns about anthropogenic climate change have resulted in promotion of renewable energy sources, especially wind energy. A concern raised against widespread windfarm development is that it may negatively impact bird populations as a result of bird collision with turbines, habitat loss and disturbance. Using systematic review methodology bird abundance data were synthesized from 19 globally-distributed windfarms using meta-analysis. The effects of bird taxon, turbine number, power, location, latitude, habitat type, size of area, time since operation, migratory status of the species and quality of evidence were analysed using meta-regression. Although the synthesized data suggest a significant negative impact of windfarms on bird abundance, there is considerable variation in the impact of individual windfarm sites on individual bird species, and it is unclear if the negative impact is a decline in population abundance or a decline in use owing to avoidance. Anseriformes experienced greater declines in abundance than other taxa, followed by Charadriiformes, Falconiformes and Accipitriformes, and Passeriformes. Time since windfarms commenced operation also had a significant impact on bird abundance, with longer operating times resulting in greater declines in abundance than short operating times. Other variables, including turbine number and turbine power either had very weak but statistically significant effects or did not have a significant effect on bird abundance. Windfarms may have significant biological impacts, especially over longer time scales, but the evidence-base is poor, with many studies being methodologically weak, and more long-term impact assessments are required. There is clear evidence that Anseriformes (wildfowl) and Charadriiformes (waders) experience declines in abundance, suggesting that a precautionary approach should be adopted to windfarm development near aggregations of these taxa in offshore and coastal locations. The impact of windfarm developments on bird populations must also be viewed in the context of the possible impact of climate change in the absence of windfarms.

Adaptive management (AM) emerged in the literature in the mid-1970s in response both to a realization of the extent of uncertainty involved in management, and a frustration with attempts to use modelling to integrate knowledge and make predictions. The term has since become increasingly widely used in scientific articles, policy documents and management plans, but both understanding and application of the concept is mixed. This paper reviews recent literature from conservation and natural resource management journals to assess diversity in how the term is used, highlight ambiguities and consider how the concept might be further assessed. AM is currently being used to describe many different management contexts, scales and locations. Few authors define the term explicitly or describe how it offers a means to improve management outcomes in their specific management context. Many do not adhere to the idea as it was originally conceived, despite citing seminal work. Significant confusion exists over the distinction between active and passive approaches. Over half of the studies reporting to implement AM claimed to have done so successfully, yet none quantified specific benefits, or costs, in relation to possible alternatives. Similarly those studies reporting to assess the approach did so only in relation to specific models and their parameterizations; none assessed the benefits or costs of AM in the field. AM is regarded by some as an effective and well-established framework to support the management of natural resources, yet by others as a concept difficult to realize and fraught with implementation challenges; neither of these observations is wholly accurate. From a scientific and technical perspective many practical questions remain; in particular real-world assessments of the value of experimentation within a management framework, as well as of identified challenges and pathologies, are needed. Further discussion and systematic assessment of the approach is required, together with greater attention to its definition and description, enabling the assessment of new approaches to managing uncertainty, and AM itself.

The large freshwater lakes of the world are an extremely valuable resource, not only because 68% of the global liquid surface fresh water is contained in them, but because of their importance to the economies, social structure, and viability of the riparian countries. This review provides decision makers with the knowledge of large lakes (≥ 500 km2) essential to establishing policies and implementing strategies compatible with sustainable development. This is achieved by considering the present state of the lakes, the extent of changes and factors causing them, long-term consequences of these changes, major threats and possible states of the lakes into the year 2025. Case studies of lakes are presented, namely the St Lawrence Great Lakes of North America as representatives of glacial scour lakes of North America, northern Europe and Asia, and the African Great Lakes as representatives of tropical tectonic lakes. Lake Baikal is also included because it is unique for its species, great age, and largest single volume of liquid surface fresh water. The Aral Sea is further included because of the ecological disaster following diversion of water away from its basin. The major impacts on large lakes are diversions, eutrophication, invasive species, land-use change, overexploitation of resources, and pollution. These impacts can or do affect all the representative lakes, but to varying degree. The St Lawrence Great Lakes have been severely impacted by eutrophication, land-use change, overfishing, invasive species and pollution. Eutrophication has been reversed for these lakes and constraints are now in place on land use change, such as shoreline alteration and destruction of wetlands. With the demise of most commercial fishing, overfishing is no longer as important. Invasive species have become a major problem as increasingly non-indigenous species gain access to the lakes. Pollution continues as a major impact. These problems are likely to continue and seriously impact use of the resources as well as bring about changes in the biota. Among the African Great Lakes, invasive species are a major problem in Lake Victoria, and eutrophication associated with land-use change and overexploitation of resources is a growing problem. Many endemic species have been lost and many are threatened, so that species associations will have changed by 2025. The Aral Sea continues to disappear and in the future, the remaining largest part of it will continue to become increasingly saline and eventually disappear. A small body of water will remain as a freshwater lake with a productive, although small, fishery. Lake Baikal shows evidence of pollution in the southern basin and is likely to be impacted by land-use changes, primarily logging. Some non-indigenous species are present, but so far, they are not a major problem. Overexploitation of resources in the watershed could lead to adverse impacts on inshore waters. Overfishing has been recognized and appears under control. The major threat to Baikal is continued and growing pollution. Climate change and pollution are global problems that will affect all lakes, large and small. At present, while some warming has occurred, climate change appears not to have impacted large lakes. Present studies on the Laurentian Great Lakes predict possible major impacts. Pollution, especially from persistent toxic substances such as PCBs, is a global problem. Diversion of water out or away from large lakes will become more of a threat as global human population growth continues and water supplies from rivers and ground water become depleted.

Legally recognized Indian reserves of Brazilian Amazonia span over 100 million ha of largely intact forest and are potentially valuable for biodiversity conservation. An important example is provided by the Kayapó territories which span more than 13 million ha in Pará and Mato Grosso, Brazil, and protect a unique and vulnerable Amazonian forest type that is poorly represented in existing nature reserves. The Kayapó of southern Pará have stopped invasion of their lands by the most perverse threats to Amazonian forests, but they have become involved extensively in the sale of illegal logging concessions for the high-value timber species mahogany (Swietenia macrophylla). In 1992, the non-governmental organization Conservation International do Brasil (CI-Brasil) began a conservation and development project with the Kayapó community of A’Ukre with the objective of providing economic alternatives to logging and protecting a population of mahogany trees. This paper demonstrates the conservation benefits that can be achieved by supporting sustainable development of indigenous peoples in the Amazon. Specifically, we: (1) evaluate the ecological importance of the Kayapó reserves from a biodiversity conservation viewpoint, (2) evaluate the conservation success of the CI-Brasil project and test whether the implementation of the conservation alliance between A’Ukre and CI-Brasil satisfies common pool resource principles, and (3) propose a model for expanding the small-scale conservation results achieved by the CI-Brasil project to all Kayapó territories. Several mammals (Tayassu pecari, Pteronura brasiliensis, Priodontes maximus, Panthera onca) and at least one bird species (Anodorhynchus hyacinthinus) listed as endangered were regularly encountered within 15 km of A’Ukre. Taxa encountered at relatively high densities in the project area included large cracids, lowland tapir, and white-lipped peccary, indicating an ecosystem that is not severely impacted by hunting. Harvest offtakes of mahogany averaged 0.44 stems ha−1 within groves and 0.13 stems ha−1 at the landscape level. We estimate that 85% of the fruiting population of Swietenia macrophylla has been removed in harvested Kayapó territories in Pará. We found Kayapó social organization in A’Ukre to meet criteria of successful common pool resource institutions. The CI-Brasil project resulted in protection of an intact mahogany population in 8000 ha of forest maintained by the community for ecological research purposes and mahogany preservation. Our analysis attributes the success of the conservation alliance with A’Ukre to: (1) direct benefits accruing to all members of the community, (2) fulfilment of criteria for development of common pool resource institutions, and (3) long-term commitment of an external agency. We propose that by implementing these three elements elsewhere, the modest conservation result achieved at A’Ukre could be expanded to include the entire Kayapó nation and thereby contribute to conservation of more than 13 000 000 ha of forest and cerrado in the south-eastern Amazon.

Dehesas, rangelands occupied by scattered oak trees and characterized by silvopastoral uses, cover about 3.1 million ha in south-western Spain. There is considerable debate about the long-term persistence of holm oak (Quercus ilex) populations in dehesas, since most stands are overaged and seedlings and saplings are sparse. The forest cycle has been disrupted in most dehesas. Regeneration has been inhibited since stands were opened for agriculture and grazing. Oak diameters from three land-use groups (young dehesa [YD], middle-aged dehesa [MD], and old dehesa [OD]) in Cáceres Province, Spain, were compared. These groups differed in the age of the land-use system, i.e. time since the original Mediterranean forest was cleared. The dehesa systems were established about 80 (YD), 150 (MD) and 500 (OD) years ago. An analysis of 66 holm oak cross sections revealed a close correlation (r2 = 91.2%) between tree rings and diameters, so that diameter seems to be a reliable indicator of tree age. Nested analysis of variance showed significant variation in diameters between the land-use groups. There is generally a positive relationship between tree age and the age of agrosilvopastoral use of the dehesas. Sparse holm oaks in the dehesas are primarily remnants from the first forest cycle. Local differences in growth conditions (for example soil quality and tree density) contribute further significant diameter variation on a between-plot level. Diameter structure of abandoned dehesas showed two peaks and a high proportion of trees in the smallest size class. This indicates that the forest degradation process is reversible. An effective regeneration policy should promote a rotating 20- to 30-year set-aside of dehesa parcels.

Utilization of animal wildlife and their by-products by farmers in Nigeria, as confirmed by this survey, is for cultural and religious ceremonies and traditional medicine. The pattern of consumption of wild animals depends on what species are available in different ecological zones. In traditional medicine, some wildlife by-products are acceptable nation-wide, while in religion, farmers are very selective — especially the Muslims. Culturally, utilization is largely by tribal and ethnic background. In the installation of traditional rulers and in performing traditional rites, some specific wild animals and their byproducts must be sacrificed.

Wild animals are so vital to the rural people that adequate consideration must be given to maintaining wildlife habitats when rural development projects are planned. This is especially important when these projects involve major land-use changes or modification of traditional agricultural practices. Much of the small mammal, bird, and reptile, habitat is comprised of small wild patches, marshes, or narrow riparian strips, which can easily be destroyed by short-sighted activities. This wildlife is a valuable renewable resource which can continue to produce benefits only if adequate habitats and protection are available.

Protected areas (PAs) have long struggled to successfully enforce compliance with their regulations. Even some of the best-funded PAs in the world face shortcomings in using enforcement as an effective deterrent to PA opposition. This suggests that traditional enforcement on its own may be insufficient for effective resource protection. Research was undertaken to understand why some would-be offenders refrain from harmful actions toward neighbouring national parks while others do not. Perceptions of the trustworthiness of PA managers were the most consistent predictors of exercised restraint on behalf of those living within the immediate vicinities of the Great Smoky Mountains National Park, Virgin Islands National Park and Podocarpus National Park. These trust assessments were most commonly based upon respondents' perceptions of positive personal interactions between PA managers and the public, of PA managers' receptiveness to local input, of the benefits and disadvantages associated with PA presence, and of PA officials' effective performance of their duties and equitable treatment of different groups. The study reveals trust and legitimacy as key factors related to voluntary compliance in situations where general agreement with PA regulations does not necessarily exist and provides insight into how trust and legitimacy can be developed or eroded.

The cessation or reduction of fishing in marine protected areas (MPAs) should promote an increase in abundance and mean size and age of previously exploited populations. Thus density-dependent changes in life-history characteristics should occur when populations are allowed to recover in MPAs. In this review, we synthesize the existing information on resource limitation in marine ecosystems, density-dependent changes in life-history traits of exploited populations and evidence for biomass export from MPAs. Most evidence for compensatory changes in biological variables has been derived from observations on populations depleted by high fishing mortality or on strong year classes, but these changes are more evident in juveniles than in adults and in freshwater rather than in marine systems. It is unclear if adults of exploited marine populations are resource limited. This may suggest that exploited populations are controlled mainly by density-independent processes, which could be a consequence of the depleted state of most exploited populations. MPAs could be a useful tool for testing these hypotheses. If we assume that resources become limiting inside MPAs, it is plausible that, if suitable habitats exist, mobile species will search for resources outside of the MPAs, leading to export of biomass to areas which are fished. However, it is not possible to establish from the available data whether this export will be a response to resource limitation inside the MPAs, the result of random movements across MPA boundaries or both. We discuss the implications of this process for the use of MPAs as fisheries management tools.

The distributions of forest and deforestation throughout the tropics are poorly known despite their importance to regional biodiversity and global climate and biodiversity. Deforestation estimates based on surveys or sampling have large errors, and high-resolution, wall-to-wall mapping of tropical forests is necessary to assess the impacts of fragmentation. Landsat satellite images from the mid-1980s and early 1990s were thus used to map closed-canopy tropical forest extent and anthropogenic deforestation in an approximately 700 000 km2 area of Amazonian Bolivia with precipitation >1000 mm yr−1. Total potential forest cover extent, including tropical deciduous forest, was 448 700 km2, while the area of natural non-forest formations was 245 100 km2. The area deforested was 15 500 km2 in the mid-1980s and 24 700 km2 by the early 1990s. The rate of tropical deforestation in the forest zone of Bolivia with >1000 mm yr−1 precipitation below 1500 m elevation and north of 19° S, was 1529 km2 yr−1 from 1985–1986 to 1992–1994. Our estimates of deforestation are significantly lower than those reported by the Food and Agriculture Organization of the United Nations (FAO). We document a spatially-concentrated ‘deforestation zone’ in Santa Cruz where >60% of the Bolivian deforestation has occurred. These results indicate that the rate of deforestation in Bolivia has been rapid despite a relatively small human population, and, as in Brazil, clearance has concentrated in the more deciduous forests.

As global fishing effort increasingly expands into deeper water, concerns exist over the ability of deep-sea fishes to sustain fisheries. There is however little quantitative evidence to support these concerns for the deep-sea cartilaginous fishes (Chondrichthyes: sharks, rays and chimaeras). This paper compiled available life history data for this group to analyse their ability to rebound from population declines relative to continental shelf and pelagic species. Deep-sea cartilaginous fishes have rates of population increase that are on average less than half those of shelf and pelagic species, and include the lowest levels observed to date. Population doubling times indicate that once a stock has been depleted, it will take decades, and potentially centuries, before it will recover. Furthermore, population recovery rates decrease with increasing depth, suggesting species that occur deepest are those most vulnerable to fishing. These results provide the first assessment of the productivity of deep-sea chondrichthyans, highlighting that precautionary management of developing deep-sea fisheries is essential if stocks and biodiversity are to be maintained.

Wild animals often destroy standing crops and prey on livestock, causing economic losses to farmers. Crop and wildlife damage are becoming serious for many Indian protected areas, and this study aimed to characterize the problem in villages in and around the Sariska Tiger Reserve (STR), Rajasthan, India. Data were collected using a semi-structured questionnaire in 37 villages followed by a semi-structured questionnaire administered to 180 households, quadrat sampling and focus group discussions. Crop and livestock depredation evidently affected nearly half of the households in villages adjacent to the STR, but damage varied considerably amongst villages and with distance from the Reserve border. Wild animal distribution and protection measures which people adopted also influenced the damage. Nilgai (Boselaphus tragocamelus() and wild boar ((Sus scrofa() were reported to be responsible for at least half of the total damage to the major crops caused by wild animals. Tigers and leopards were the main livestock predators; the former preyed mostly on larger livestock and the latter on smaller animals such as goats and sheep. More than two-thirds of the villagers spent considerable time and money guarding crops and protecting livestock. Guarding was the most popular means followed by physical fences around fields. In spite of damage to crops and livestock, the local people still had a positive attitude towards the STR, because of tangible benefits derived from the Reserve in terms of fodder and fuelwood, and cultural/religious attitudes towards wild animals. Settlement of rights to collect fuelwood and fodder within the Reserve appears to be one acceptable measure to compensate for losses besides an immediate review of hunting policy. Suggestions given by local people to minimize losses have implications for the long term sustainability of the STR as a protected area.

Visions of nature are the subject of much philosophical and policy debate. The present paper focuses, however, on the visions of nature held by people not professionally involved in the issue, namely those of the general public. These visions constitute the democratic basis of environmental conservation and the frame for effective two-way communication between professionals and communities on nature protection and management. It appears that the general public in Europe and the USA has developed a strong general ‘biophilia’ (nature-friendliness). One indicator of this is that in quantitative research, 70–90% of the population recognize the right of nature to exist even if not useful to humans in any way. In qualitative research settings, lay people reveal a remarkable richness and depth of views and experiences of nature. A quantitative survey on images and values of nature, and a qualitative study consisting of in-depth interviews on the relationship between childhood experiences in nature and adult visions of nature were conducted in the Netherlands. A factor analysis revealed a classification of types of nature, which included ‘wild nature’, ‘arcadian nature’, ‘penetrative nature’ and other such images that, with wild nature in the lead, were ascribed a smoothly decreasing degree of naturalness. Asked to rank the values and functions of nature, the top three were formed by the value for human health, the intrinsic value and the value for future generations. In the qualitative interviews, indications were found that more intense childhood experiences with nature could be associated with later ascription of a high degree of naturalness to wild nature, and less intense experiences with later ascription of a high degree of naturalness to arcadian nature. Many significant experiences took place beyond the reach of parental supervision. Findings such as these are of obvious relevance for environmental education and the design of ‘experiential nature’ in and around protected areas. Social science research concerning nature protection is often triggered by frictions between local people and protected area authorities. Such situations tend to be dominated by the airing of grievances, demands for economic compensation and so on, and these then also tend to dominate the research findings. Taking place away from these specific hot spots of conflict, social science research of the types discussed in this paper shows that many non-conflictual lines of communication are open for nature protection agencies.

Fish populations are classical examples of commonproperty resources and tend to decline over time. According to the conventional wisdom, they decline through a process popularly known as ‘the tragedy of the commons’, whereby selfish users are locked into a deterministic mechanism in which they are both the villains and the victims. However, the commons paradigm is not the model of reality for all fisheries. There are many sustainable fisheries, and detailed studies of some of them indicate that they do not fit the commons paradigm because there are factors which violate some of the hidden assumptions of the commons paradigm.

In many community-based and small-scale fisheries, there are unwritten regulations or customary laws that prevent individuals from maximizing their private gains at the expense of community interests. Far from being owned by no one and freely open to any user, many of the fish stocks of the world are under claims of ownership by communities of fishermen who exercise use-rights and who control access to the resource. As seen in examples from Oceania and North America's west coast, open-access and common property conditions were created, and the ‘tragedy’ started only after the destruction of such traditional marine tenure systems.

Extinctions have altered island ecosystems throughout the late Quaternary. Here, we review the main historic drivers of extinctions on islands, patterns in extinction chronologies between islands, and the potential for restoring ecosystems through reintroducing extirpated species. While some extinctions have been caused by climatic and environmental change, most have been caused by anthropogenic impacts. We propose a general model to describe patterns in these anthropogenic island extinctions. Hunting, habitat loss and the introduction of invasive predators accompanied prehistoric settlement and caused declines of endemic island species. Later settlement by European colonists brought further land development, a different suite of predators and new drivers, leading to more extinctions. Extinctions alter ecological networks, causing ripple effects for islands through the loss of ecosystem processes, functions and interactions between species. Reintroduction of extirpated species can help restore ecosystem function and processes, and can be guided by palaeoecology. However, reintroduction projects must also consider the cultural, social and economic needs of humans now inhabiting the islands and ensure resilience against future environmental and climate change.

An effective protected area system is essential for the long-term conservation of Myanmar's biodiversity. This study examined the attitudes of 2915 residents in 97 communities around three protected areas (PAs) in upper Myanmar: Alaungdaw Kathapa National Park in the western mountains, Htamanthi Wildlife Sanctuary in the hills bordering the Chindwin and Uru rivers, and Chatthin Wildlife Sanctuary in the central dry zone. Logistic regression indicated a positive attitude toward the PAs was most highly correlated with a perception of conservation benefits and benefits resulting from management of the areas. Attitude was also significantly correlated with a perception of extraction benefits, conflicts with PA staff and crop damage by wildlife. Socioeconomic variables were less powerful than perceptions in predicting attitude and, unlike perceptions, their effects varied among the areas. The much greater effect of perceptions, especially positive ones, on people's attitudes indicates that understanding perceptions is important to improving the relationship between local residents and these PAs. This finding underscores the fact that a focus on conflicts to understand people's attitudes toward PAs may undervalue or miss critical positive perceptions that people hold. Understanding local residents' perceptions of PAs makes possible the creation of strategic, place-based management strategies that build on people's positive perceptions and mitigate their negative perceptions.

In some developing countries there is a call to open-up protected areas and even National Parks for low-intensity use by the local population to alleviate the pressure of the rapidly increasing human population, or because conservationists have been able to ‘take’ too much land according to others. This conflict in land-use has been noted by conservation authorities, and proposals have been formulated to give way to such pressure. Moreover, it has been suggested that there can be a harmonious coexistence between wildlife and livestock, so that opening-up of protected areas would not necessarily be to the detriment of wildlife, and also that the indigenous populations were able to manage wildlife and their habitats in the past (so why not again in the future). The last point in the concerted attack on the status of the protected areas is that ‘conservation is an alien concept in Third World countries’.

In this paper is reviewed the question as to whether there ever has been such a harmonious coexistence between wildlife and pastoral Man in East Africa, and aerial census data from a number of districts in Tanzania and Kenya have been used to demonstrate that livestock outcompetes wildlife. At present ‘prestige overstocking’ is not the case any more, due to the fact that the human population outgrows the livestock population. Apparently, a very high rate of population growth is at the root of the call for more land, and even if, for example, the whole of the Serengeti were to be handed over to the local Masai, this enormous, relatively undisturbed ecocomplex could absorb the growth of the Masai population for only some forty years.

Finding the key to increased development should not be sought in an opening-up of protected areas but in payment of in absentia benefits by the rich western countries. This money should be used for developing programmes aimed at population limitation, increased income for the rural poor, and increased sustainable human densities in areas outside the protected areas.

Introduction

In most countries, protected area managers are primarily interested in biology (McNeely & Miller 1984; Nelson & Serafin 1997). This perspective is not suitable for effective nature conservation because there is no real separation between geological and biological processes. Geology is important in all kinds of planning projects because geology is part of all natural systems. Understanding of climate, landforms and biodiversity depends on geological studies. Even human habitation and cultural heritage depend on geology. During the last 30 years, numerous studies have shown that biological conservation is essential to the welfare of all human beings. Nevertheless, the concept of geoconservation and preservation of the geological heritage has appeared only recently (Wilson 1994; Sharples 1998; Barettino et al. 1999, 2000; Osborne 2000).

I argue that real nature conservation can only be attained if geology is integrated into protected area management at the same level of importance as biology and all natural processes are considered together.

Wildlife is an essential component of all ecosystems. Most places in the globe do not have local, timely information on which species are present or how their populations are changing. With the arrival of new technologies, camera traps have become a popular way to collect wildlife data. However, data collection has increased at a much faster rate than the development of tools to manage, process and analyse these data. Without these tools, wildlife managers and other stakeholders have little information to effectively manage, understand and monitor wildlife populations. We identify four barriers that are hindering the widespread use of camera trap data for conservation. We propose specific solutions to remove these barriers integrated in a modern technology platform called Wildlife Insights. We present an architecture for this platform and describe its main components. We recognize and discuss the potential risks of publishing shared biodiversity data and a framework to mitigate those risks. Finally, we discuss a strategy to ensure platforms like Wildlife Insights are sustainable and have an enduring impact on the conservation of wildlife.

Since 1970 a large number of environmental problems have been identified as resulting from the long-term effects of human impacts. Consideration of human activity within the environment as three orders of impact, provides a basic framework for the appreciation and evaluation of long-term problems. Consequent upon dam construction, major changes of flood magnitude and frequency and of the quantity and calibre of sediment loads (first-order impacts), will induce the readjustment of channel morphology and ecology (second-order impacts). However, the macrophytic and macro-invertebrate population, for example, are also adjusted to channel morphology—particularly channel shape and substrate composition—so that further readjustments of the macrophyte and macro-invertebrate populations may be effected by changes of channel form (third-order impacts).