Bio- and landscape diversity Theme 7 Theme

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Bio- and landscape diversity: Theme # 7 Theme 7: Ecosystems diversity • What is ecosystem diversity • Factors of ecosystem diversity • Stability and diversity • Fragile ecosystems • Ecotones

Bio- and landscape diversity: Theme # 7 What is ecosystem An ecosystem is a biological community of interdependent organisms together with the environment that they inhabit and with which they interact. Central to the concept of ecosystem is the idea that living organisms (plants, animals, and microorganisms) interact with every other element in their local environment. The term “ecosystem” was first used by Roy Clapham in 1930 to mean the combined physical and biological components of an environment. However in a scientific publications the term ecosystem was first used by British ecologist Arthur Tansley in his landmark paper "The Use and Abuse of Vegetational Concepts and Terms“ (1935). Tansley defined an ecosystem as “the whole system, … including not only the organism-complex, but also the whole complex of physical factors forming what we call the environment“. The boundaries of ecosystems are usually not fixed in any objective way, although sometimes they seem obvious, as with the shoreline of a small pond. Usually the boundaries of an ecosystem are chosen for practical reasons having to do with the goals of the particular study. While studying the ecosystems not spatial (boundaries and area), but functional approach is most important. Sir Arthur George Tansley (1871 - 1955), an English botanist. He is recognized as the author of the term “ecosystem” (1935) and was one of the founders of the British Ecological Society. Tansley ranks among the twentieth century's most important ecologists.

Bio- and landscape diversity: Theme # 7 What is ecosystem Ecosystems made up of abiotic elements and biotic elements The elements of ecosystems are linked together by energy flows and the flows of matter. Energy in ecosystems could not be renewed and is coming mostly from the sun. The flows of matter in ecosystems (such as water, nutrients) are organized in cycles and due to it the matter in ecosystems is partly or fully renewable.

Bio- and landscape diversity: Theme # 7 What is ecosystem diversity In the hierarchy of levels of biodiversity the ecosystem diversity is lying between the community diversity and landscape diversity genetic diversity species diversity community diversity ecosystem diversity landscape diversity The diversity of ecosystem is the variety and complexity of the relations between the elements composing the ecosystem. The diversity of an ecosystem is dependent on: Ш physical characteristics of the environment, the Ш diversity of species in ecosystem the Ш interactions that the species have with each other and with the environment. the Therefore, the ecosystems with complex physical environment which have many species, organized in a complex food web are more diverse than ecosystems having just few species in simple physical environment. The physical characteristics of an environment affect ecosystem diversity through many characteristics: air temperature, precipitation, air moisture, topography, rocks density and composition, soil physical and chemical properties.

Bio- and landscape diversity: Theme # 7 Factors of ecosystem diversity Climatic features: Temperature: there is a general trend for warm ecosystems to be richer in species than cold ecosystems. The more energy from the sun an ecosystem receives the more energy is accumulated at the first trophic level (primary producers) and more trophic levels could be supported with the energy coming from the primary producers. Precipitation is the main resource of water for ecosystems. The general tendency is that the wet ecosystems are normally more diverse. This is why the wetlands (ecosystems of bogs, marshes, seashores, river deltas etc) are very diverse and is the subject of a special attention of nature conservators.

Bio- and landscape diversity: Theme # 7 Factors of ecosystem diversity Topography: Generally the more complex topography increase the ecosystem diversity. For example, slopes with different and shape create variations in soil moisture, insolation, evaporation etc which in turn create various habitats within the one slope and diverse biotic communities.

Bio- and landscape diversity: Theme # 7 Factors of ecosystem diversity Rocks: influence ecosystem diversity through their density and chemical features. Too dense rocks (like granites) are not suitable for plants and animals and only few species of microorganisms and lichen could live on it. Too soft rocks (like sands) are also not very suitable for most plant species and only few species called psammophytes are living on sands and sandy rocks. Rocks that are not too dense and too soft are most favourable for rich ecosystem diversity. Poor diversity of ecosystems on solid rocks Rich diversity of ecosystems on loose sediments

Bio- and landscape diversity: Theme # 7 Factors of ecosystem diversity Soil characteristics: soils which are rich in organic matter (in soil humus) are favourable for rich biodiversity while poor soils could not support diverse vegetation and soil fauna. Soils having high content of salts; too high or too low value of p. H (acidity), too compact or too loose soils do not support ecosystem diversity.

Bio- and landscape diversity: Theme # 7 Stability and diversity Normally simple ecosystems are not stable while ecosystems having high diversity has higher stability both to changes in the natural environment and to human influences. Based on this general regularity some ecologists believe that more diverse ecosystems are more stable to natural and human disturbances. Robert Mc Arthur, famous American ecologist, proclaimed thesis: “Diversity makes stability”. Other ecologists leaded by Robert May denied this thesis saying that simple ecosystems could be very stable while many diverse ecosystems are fragile and unstable to both natural and anthropogenic disturbances. Robert May (born 1936), an Australian-English ecologist who contributed a lot to the development of mathematical modeling in ecology. His works played a key role in the development of theoretical ecology. The debate between ecologists who supported Mc. Arthur thesis and ecologists who denied it was one of the most intriguing in Ecology and helped to resolve many other theoretical issues. Finally it was found that the stability of ecosystems has three major forms, namely inertness (persistent), recoverability, and plasticity. Each of these forms depends on diversity of ecosystems differently. Robert Mac. Arthur (1930 – 1972), an American ecologist who made a major impact on many areas of ecology, including mathematical modeling and studying the relationships between stability and diversity of ecosystems.

Bio- and landscape diversity: Theme # 7 Fragile ecosystems Fragility of an ecosystem relates to a degree of change in ecosystem diversity following disturbance. Fragile ecosystems are the ecosystems whose diversity and other features could drop dramatically after even a little disturbance. Fragile ecosystems include deserts, semi-arid lands, mountains, wetlands, small islands and certain coastal areas. Fragile in English means easy to be damaged. Glass is fragile. International programs and conventions, e. g. Agenda 21, CBD (Convention on Biodiversity Conservation), pay special attention to fragile ecosystems. For some types of fragile ecosystems special international and national programs are developed to protect their diversity and stability. For example, for wetland ecosystems (areas where surface water and inlands meet, e. g sea shores, bogs etc) The Convention on Wetlands of International Importance (called the Ramsar Convention) is developed. Its aim is to identify the wetland ecosystems of World importance and to take actions needed to protect and to restore their ecosystems. 159 countries signed the Ramsar Convention with Ukraine among them. The goal of Earth Day in year of 2010 was to organize and to take 100, 000 actions to protect the world's most fragile ecosystems.

Bio- and landscape diversity: Theme # 7 Ecotones An ecotone is a transition area (zone) between two neighbouring ecosystems, such as forest and grassland; mountain and upland. Because many changes in the environment tend to be continuous, ecological transitions are often not sharp, but gradual. The gradual changes in environmental conditions create ecotones. Ecotone between forests with the holm oak Quercus ilex (red color) and with the downy oak Quercus pubescens (green color), Italy Linear border between forest and subalpine meadows, Italy

Bio- and landscape diversity: Theme # 7 Ecotones Within the ecotone species of two adjacent ecosystems are found together, and in addition, an ecotone often contains species not found in the neighbouring ecosystems. Due to this synergy the ecotone ecosystems are often more diverse then ecosystems, which create it. Ecotones are particularly significant for mobile animals, as they can exploit more than one set of habitats within a short distance. The ecotone contains not only species common to the communities on both sides; it may also include a number of highly adaptable species that tend to colonize such transitional areas. That is why in many cases, the number of species and the population density are greater within the ecotone than in the surrounding ecosystems, a phenomenon known as the edge effect. Examples of edge plants include many shrubs that are abundant along the boundaries of forest ecosystems in many parts of the world. Some animals are also more abundant in ecotones than in interior parts of ecosystems (white-tailed and mule deer, snowshoe hare, cottontail rabbit, blue jay, and robin) The ecotones play an important role in the biodiversity of many biomes, including the rainforests. For example, ecotones bordering rainforests and savannas are evolutionary hotbeds where evolutionary competition may lead to the rise of new species.

Bio- and landscape diversity: Theme # 7 New theme: Landscape diversity • What is landscape diversity • Measuring landscape diversity • Mapping landscape diversity • Landscape fragmentation

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