Forests are crucial for biodiversity and ecosystem service delivery. They provide natural habitats for plant and animal life, protection against soil erosion and flooding, carbon sequestration, climate regulation and have great recreational and cultural value. Forest is the predominant natural vegetation in Europe, but the remaining forests in Europe are far from undisturbed D. Most are heavily exploited.
Exploited forests typically lack higher amounts of deadwood and older trees as habitats for species, and they often show a high portion of non-native tree species for example, Douglas fir. The largest areas of old-growth forests in the EU are found in Bulgaria and Romania Loss of old-growth forest, in combination with increased fragmentation of the remaining stands, partially explains the continuing poor conservation status of many forest species of European concern.
Source: EEA. On the plus side, current total wood harvest remains well below the annual re-growth and total forest area increases. This is supported by socio-economic trends and national policy initiatives to improve forest management, coordinated in the framework of Forest Europe, a cooperation platform at ministerial level of 46 countries, including those of the EU Forest management is not only aimed at safeguarding wood harvest, but takes a wide range of forest functions into account, and thus serves as a framework for biodiversity conservation and the maintenance of ecosystem services in forests.
Nevertheless, many issues remain to be addressed. A recent EU Green Paper 31 focuses on the possible implications of climate change for forest management and protection in Europe and on enhancing monitoring, reporting and knowledge-sharing. There are also concerns regarding the future balance between wood supply and demand in the EU given the planned increases in bioenergy production The concept of ecosystem services is probably most obvious for agriculture. The prime objective is food provision, but farmland delivers many other ecosystem services.
Farmland soils play a key role in nutrient and water cycling. European agriculture is characterised by a dual trend: large-scale intensification in some regions, and land abandonment in others. Intensification is aimed at yield increases and requires investment in machinery, drainage, fertilisers and pesticides.
It is also often associated with simplified crop rotations. Where socio-economic and biophysical circumstances do not allow this, agriculture remains extensive or is given up. These developments have been driven by a combination of factors including technological innovation, policy support and international market developments, as well as climate change, demographic trends and lifestyle changes.
The concentration and optimisation of agricultural production has had major consequences for biodiversity, as has become apparent in the decline of farmland birds and butterflies. Although its natural and cultural value is recognised in European environment and agriculture policies, the current measures being taken within the framework of the CAP are not sufficient to prevent further decline. Sixty-one of the habitat types of Community interest of the EU Habitats Directive are related to agricultural management, mainly grazing and mowing The assessment reports provided by EU member states under the Habitats Directive 35 indicate that the conservation status of these agricultural habitats is worse than the others.
The vast majority of CAP support still benefits the most intensive productive areas and farming systems Decoupling subsidies from production F and obligatory cross-compliance with environmental legislation can ease agricultural pressures on the environment to some extent, but this is not enough to ensure the continuing management that is needed for effective HNV farmland conservation.
Intensification of agriculture poses threats not only to biodiversity on farmland, but also to biodiversity in farmland soil. The total weight of microorganisms in the soil below a hectare of temperate grassland can exceed 5 tonnes — as much as a medium-sized elephant — and often exceeds the above-ground biomass.
These biota are involved in most of the key soil functions. Soil conservation is therefore a major environmental concern as soil degradation processes are widespread in the EU Chapter6.
The conversion of land to certain types of biofuel crop production leads to intensification in terms of fertiliser and pesticide use, increased pollution load and further biodiversity loss. Much depends on where the conversion takes place, and the extent to which European production contributes to reaching the biofuel target. The available information suggests that the trend towards concentration of agriculture in the most productive areas, as well as to further intensity and productivity increases, is likely to continue Map 3.
Note: Estimate based on land-cover data Corine, and additional biodiversity datasets with varying base years roughly — Resolution: 1 km2 for the land-cover data, down to 0. The figures in the map green shades correspond to estimated coverage of HNV farmland within 1 km2 grid-cells. Because of the error margins in the interpretation of the land-cover data, these figures are best treated as probabilities of occurrence rather than land-cover estimates. Occurrence of HNV farmland in the pink, purple and orange areas is most certain, since these delineations are based on actual habitat and species data.
Apart from the direct effects of land conversion and exploitation, human activities such as agriculture, industry, waste production and transport cause indirect and cumulative effects on biodiversity — notably through air, soil and water pollution. A wide range of pollutants — including excess nutrients, pesticides, microbes, industrial chemicals, metals and pharmaceutical products — end up in the soil, or in ground- and surface water. Atmospheric deposition of eutrophying and acidifying substances, including nitrogen oxide NOX , ammonium plus ammonia NHX and sulphur dioxide SO2 , adds to the cocktail of pollutants.
The effects on ecosystems include damage to forests and lakes from acidification; habitat deterioration due to nutrient enrichment; algal blooms caused by nutrient enrichment; and neural and endocrine disruption in species by pesticides, steroidal estrogens and industrial chemicals like PCBs. Most European data regarding the effects of pollutants on biodiversity and ecosystems concern acidification and eutrophication G. The area subject to acidification has decreased further since With sulphur emissions declining, nitrogen emitted by agriculture is now the principal acidifying component in our air Agriculture is also a major source of eutrophication through emissions of excess nitrogen and phosphorous, both used as nutrients.
From an aesthetic point of view, every one of the millions of species is unique, a natural work of art that cannot be recreated once lost. Mind-bogglingly diverse. The simplest aspect to consider is species. About 1. The heartland of biodiversity is the tropics, which teems with species. In 15 hectares 37 acres of Borneo forest, for example, there are species of tree — the same number as the whole of North America.
Recent work considering diversity at a genetic level has suggested that creatures thought to be a single species could in some cases actually be dozens.
Then add in bacteria and viruses, and the number of distinct organisms may well be in the billions. The concern is that many species are being lost before we are even aware of them, or the role they play in the circle of life. The best studied creatures are the ones like us — large mammals. In many places, bigger animals have already been wiped out by humans — think dodos or woolly mammoths.
The extinction rate of species is now thought to be about 1, times higher than before humans dominated the planet, which may be even faster than the losses after a giant meteorite wiped out the dinosaurs 65m years ago. The sixth mass extinction in geological history has already begun , according to some scientists.
Species extinction provides a clear but narrow window on the destruction of biodiversity — it is the disappearance of the last member of a group that is by definition rare. The results are scary. Billions of individual populations have been lost all over the planet, with the number of animals living on Earth having plunged by half since Humans may lack gills but that has not protected marine life. The situation is no better — and perhaps even less understood — in the two-thirds of the planet covered by oceans.
Seafood is the critical source of protein for more than 2. Altogether, there are at least a million species of insect and another , spiders, molluscs and crustaceans.
Resilience is a somewhat different aspect of stability indicating the ability of an ecosystem to return to its original state following a disturbance or other perturbation. Species diversity has two primary components: species richness the number of species in a local community and species composition the identity of the species present in a community.
While most research on the relationship between ecosystem diversity and stability has focused on species richness, it is variation in species composition that provides the mechanistic basis to explain the relationship between species richness and ecosystem functioning. Species differ from one another in their resource use, environmental tolerances, and interactions with other species, such that species composition has a major influence on ecosystem functioning and stability. The traits that characterize the ecological function of a species are termed functional traits, and species that share similar suites of traits are often categorized together into functional groups.
When species from different functional groups occur together, they can exhibit complementary resource-use, meaning that they use different resources or use the same resources at different times. For example, two animal predators may consume different prey items, so they are less likely to compete with one another, allowing higher total biomass of predators in the system. In the case of plants, all species may utilize the same suite of resources space, light, water, soil nutrients, etc.
Increasing species diversity can influence ecosystem functions — such as productivity — by increasing the likelihood that species will use complementary resources and can also increase the likelihood that a particularly productive or efficient species is present in the community. While primary production is the ecosystem function most referred to in this article, other ecosystem functions, such as decomposition and nutrient turnover, are also influenced by species diversity and particular species traits.
Stability can be defined at the ecosystem level — for example, a rancher might be interested in the ability of a grassland ecosystem to maintain primary production for cattle forage across several years that may vary in their average temperature and precipitation. Figure 1 shows how having multiple species present in a plant community can stabilize ecosystem processes if species vary in their responses to environmental fluctuations such that an increased abundance of one species can compensate for the decreased abundance of another.
Biologically diverse communities are also more likely to contain species that confer resilience to that ecosystem because as a community accumulates species, there is a higher chance of any one of them having traits that enable them to adapt to a changing environment. Such species could buffer the system against the loss of other species.
In this situation, species identity — and particular species traits — are the driving force stabilizing the system rather than species richness per se see Figure 2.
Figure 1: Conceptual diagram showing how increasing diversity can stabilize ecosystem functioning Each rectangle represents a plant community containing individuals of either blue or green species and the total number of individuals corresponds to the productivity of the ecosystem. Green species increase in abundance in warm years, whereas blue species increase in abundance in cold years such that a community containing only blue or green species will fluctuate in biomass when there is interannual climate variability.
In contrast, in the community containing both green and blue individuals, the decrease in one species is compensated for by an increase in the other species, thus creating stability in ecosystem productivity between years. Note also that, on average, the diverse community exhibits higher productivity than either single-species community. This pattern could occur if blue or green species are active at slightly different times, such that competition between the two species is reduced.
This difference in when species are active leads to complimentary resource utilization and can increase total productivity of the ecosystem. In contrast, if stability is defined at the species level, then more diverse assemblages can actually have lower species-level stability. This is because there is a limit to the number of individuals that can be packed into a particular community, such that as the number of species in the community goes up, the average population sizes of the species in the community goes down.
For example, in Figure 2, each of the simple communities can only contain three individuals, so as the number of species in the community goes up, the probability of having a large number of individuals of any given species goes down. The smaller the population size of a particular species, the more likely it is to go extinct locally, due to random — stochastic — fluctuations, so at higher species richness levels there should be a greater risk of local extinctions. Thus, if stability is defined in terms of maintaining specific populations or species in a community, then increasing diversity in randomly assembled communities should confer a greater chance of destabilizing the system.
Figure 2: Conceptual model illustrating the insurance hypothesis Simple communities are represented by a box; in this case, these communities are so small that they can only contain 3 individuals. For example, this could be the case for a small pocket of soil on a rocky hillslope.
Looking at all possible combinations of communities containing 1, 2 or 3 species, we see that, as the number of species goes up, the probability of containing the blue species also goes up.
Thus, if hillslopes in this region were to experience a prolonged drought, the more diverse communities would be more likely to maintain primary productivity, because of the increased probability of having the blue species present. A wealth of research into the relationships among diversity, stability, and ecosystem functioning has been conducted in recent years reviewed by Balvanera et al. The first experiments to measure the relationship between diversity and stability manipulated diversity in aquatic microcosms — miniature experimental ecosystems — containing four or more trophic levels, including primary producers, primary and secondary consumers, and decomposers McGrady-Steed et al.
These experiments found that species diversity conferred spatial and temporal stability on several ecosystem functions. Stability was conferred by species richness, both within and among functional groups Wardle et al. When there is more than one species with a similar ecological role in a system, they are sometimes considered "functionally redundant.
More recently, scientists have examined the importance of plant diversity for ecosystem stability in terrestrial ecosystems, especially grasslands where the dominant vegetation lies low to the ground and is easy to manipulate experimentally.
In , David Tilman and colleagues established experimental plots in the Cedar Creek Ecosystem Science Reserve, each 9 x 9 m in size Figure 3A , and seeded them with 1, 2, 4, 8 or 16 species drawn randomly from a pool of 18 possible perennial plant species Tilman et al.
Plots were weeded to prevent new species invasion and ecosystem stability was measured as the stability of primary production over time. Over the ten years that data were collected, there was significant interannual variation in climate, and the researchers found that more diverse plots had more stable production over time Figure 3B. In contrast, population stability declined in more diverse plots Figure 3C.
These experimental findings are consistent with the theory described in the prior section, predicting that increasing species diversity would be positively correlated with increasing stability at the ecosystem-level and negatively correlated with species-level stability due to declining population sizes of individual species. Figure 3: A biodiversity experiment at the Cedar Creek Ecosystem Science Reserve a demonstrates the relationship between the number of planted species and ecosystem stability b or species stability c.
All rights reserved. Thus conserving or restoring the composition of biological communities , rather than simply maximizing species numbers, is critical to maintaining ecosystem services C Local or functional extinction, or the reduction of populations to the point that they no longer contribute to ecosystem functioning, can have dramatic impacts on ecosystem services. Local extinctions the loss of a species from a local area and functional extinctions the reduction of a species such that it no longer plays a significant role in ecosystem function have received little attention compared with global extinctions loss of all individuals of a species from its entire range.
Loss of ecosystem functions, and the services derived from them, however, occurs long before global extinction. Often, when the functioning of a local ecosystem has been pushed beyond a certain limit by direct or indirect biodiversity alterations, the ecosystem-service losses may persist for a very long time C Changes in biotic interactions among species—predation, parasitism, competition, and facilitation—can lead to disproportionately large, irreversible, and often negative alterations of ecosystem processes.
In addition to direct interactions, such as predation, parasitism, or facilitation, the maintenance of ecosystem processes depends on indirect interactions as well, such as a predator preying on a dominant competitor such that the dominant is suppressed, which permits subordinate species to coexist. Interactions with important consequences for ecosystem services include pollination; links between plants and soil communities , including mycorrhizal fungi and nitrogen-fixing microorganisms; links between plants and herbivores and seed dispersers; interactions involving organisms that modify habitat conditions beavers that build ponds, for instance, or tussock grasses that increase fire frequency ; and indirect interactions involving more than two species such as top predators, parasites, or pathogens that control herbivores and thus avoid overgrazing of plants or algal communities C Many changes in ecosystem services are brought about by the removal or introduction of organisms in ecosystems that disrupt biotic interactions or ecosystem processes.
Because the network of interactions among species and the network of linkages among ecosystem processes are complex, the impacts of either the removal of existing species or the introduction of new species are difficult to anticipate C See Table 1. Table 1. As in terrestrial and aquatic communities , the loss of individual species involved in key interactions in marine ecosystems can also influence ecosystem processes and the provisioning of ecological services. For example, coral reefs and the ecosystem services they provide are directly dependent on the maintenance of some key interactions between animals and algae.
As one of the most species-rich communities on Earth, coral reefs are responsible for maintaining a vast storehouse of genetic and biological diversity. Substantial ecosystem services are provided by coral reefs—such as habitat construction, nurseries, and spawning grounds for fish; nutrient cycling and carbon and nitrogen fixing in nutrient - poor environments; and wave buffering and sediment stabilization.
The total economic value of reefs and associated services is estimated as hundreds of millions of dollars. Yet all coral reefs are dependent on a single key biotic interaction: symbiosis with algae.
Biodiversity affects key ecosystem processes in terrestrial ecosystems such as biomass production , nutrient and water cycling, and soil formation and retention—all of which govern and ensure supporting services high certainty. The relationship between biodiversity and supporting ecosystem services depends on composition, relative abundance, functional diversity , and, to a lesser extent, taxonomic diversity. If multiple dimensions of biodiversity are driven to very low levels, especially trophic or functional diversity within an ecosystem, both the level and stability for instance, biological insurance of supportive services may decrease CF2 , C Region-to-region differences in ecosystem processes are driven mostly by climate, resource availability, disturbance, and other extrinsic factors and not by differences in species richness high certainty.
In natural ecosystems , the effects of abiotic and land use drivers on ecosystem services are usually more important than changes in species richness. Plant productivity , nutrient retention, and resistance to invasions and diseases sometimes grow with increasing species numbers in experimental ecosystems that have been reduced to low levels of biodiversity.
In natural ecosystems, however, these direct effects of increasing species richness are usually overridden by the effects of climate, resource availability, or disturbance regime C Even if losses of biodiversity have small short-term impacts on ecosystem function, such losses may reduce the capacity of ecosystems for adjustment to changing environments that is, ecosystem stability or resilience, resistance, and biological insurance high certainty.
The loss of multiple components of biodiversity, especially functional and ecosystem diversity at the landscape level, will lead to lowered ecosystem stability high certainty. Although the stability of an ecosystem depends to a large extent on the characteristics of the dominant species such as life span, growth rate, or regeneration strategy , less abundant species also contribute to the long-term preservation of ecosystem functioning.
As tragically illustrated by social conflict and humanitarian crisis over droughts, floods, and other ecosystem collapses, stability of ecosystems underpins most components of human well-being , including health , security, satisfactory social relations, and freedom of choice and action C6 ; see also Key Question 2. The preservation of the number, types, and relative abundance of resident species can enhance invasion resistance in a wide range of natural and semi-natural ecosystems medium certainty.
Although areas of high species richness such as biodiversity hot spots are more susceptible to invasion than species- poor areas, within a given habitat the preservation of its natural species pool appears to increase its resistance to invasions by non-native species. This is also supported by evidence from several marine ecosystems, where decreases in the richness of native taxa were correlated with increased survival and percent cover of invading species C Pollination is essential for the provision of plant-derived ecosystem services , yet there have been worldwide declines in pollinator diversity medium certainty.
Many fruits and vegetables require pollinators, thus pollination services are critical to the production of a considerable portion of the vitamins and minerals in the human diet. Although there is no assessment at the continental level, documented declines in more-restricted geographical areas include mammals lemurs and bats, for example and birds hummingbirds and sunbirds, for instance , bumblebees in Britain and Germany, honeybees in the United States and some European countries, and butterflies in Europe.
The causes of these declines are multiple, but habitat destruction and the use of pesticide are especially important.
Estimates of the global annual monetary value of pollination vary widely, but they are in the order of hundreds of billions of dollars C Biodiversity influences climate at local, regional, and global scales, thus changes in land use and land cover that affect biodiversity can affect climate.
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