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African Journal of Basic & Applied Sciences 5 (1): 01-07, 2013 ISSN 2079-2034 © IDOSI Publications, 2013 DOI: 10.5829/idosi.ajbas.2013.5.1.1115 The Interrelation of Biodiversity Dynamics, Ecosystem Processes and Abiotic Factors: A Review 1 Olutoyosi Ayeni and 2Learnmore Kambizi Department of Environmental and Occupational Studies, 2 Department of Horticultural Sciences, Cape Peninsula University of Technology, Faculty of Applied Sciences, Cape Town 8000, South Africa 1 Abstract: The ecological consequences of wetland loss have aroused global interest in recent years. Major advances have been made in describing the relationship between species diversity and ecosystem processes, in identifying functionally important species and in revealing tolerant mechanisms. There is, however, uncertainty as to how results obtained in recent experiments scale up to landscape and regional levels and generalize across ecosystem types and processes. Under stress, a plant has minimal mobility and control of its environment; wetland plants are exposed to environmental conditions outside the range normally exposed due to natural or anthropogenic changes, such as exposure to environmental pollution. The mechanism of defense breakdown and the production of activated oxygen exceed the plant’s capacity to detoxify it, leading to deleterious degenerative occurrences as loss of osmotic responsiveness, wilting and necrosis. A future challenge is to determine how biodiversity dynamics, ecosystem processes and abiotic factors interact. The strengths and limitations of the various measures used to assess the successes of the interaction are now being discussed. This paper reviews the challenges of heavy metals, highlight on challenges of wetland loss and ecosystem processes in a changing environment. Key words: Abiotic factors Biodiversity Biodiversity dynamics INTRODUCTION Ecosystems processes Wetlands therefore expected that all ecosystems will undergo changes in some abiotic and biotic factors or both as the human population climax impacting on biodiversity dynamics [3]. The environmental risk associated with recalcitrant metal contaminants coupled with their recycling to the food chain through the biogeochemical cycling of metals is a limiting factor [18]. The degradation of South African wetlands and their vulnerability to humaninduced changes in catchments and in the sea is a concern recognized by governments and such requires attention. Environment consisting of balanced interaction between biotic and abiotic factors and often abrupt perturbations in abiotic factors such as urbanization alters both biotic and abiotic ecosystem properties within, surrounding and even at great distances from urban areas [1-3]. It is globally acknowledged over the last decade that the introduction of harmful substances into the environment has generated a colossus magnitude of detrimental effects on human health, agricultural productivity and natural ecosystems [4-6]. Heavy metal contamination ruins biological community; destroy landscape ecology and environmental functions [7-17]. Changes in the environment can have direct effects on the ecosystem processes through biotic controls or indirectly through effects on the physiology, morphology and behavior of individual organisms, the structure of populations and the composition of communities. It is The Impact of Wetland on Biodiversity Dynamics: Naturally, aquatic ecosystems undergo “natural stress” both from biotic (living) or abiotic (non-living) origins. Wetlands are constantly under threat due to a mix of social, economic and political factor. With the current rate of increasing anthropogenic impact on both natural and Corresponding Author: Olutoyosi Ayeni, Department of Environmental and Occupational Studies, Cape Peninsula University of Technology, Faculty of Applied Sciences, P.O. Box 652, Cape Town 8000, South Africa. 1 African J. Basic & Appl. Sci., 5 (1): 01-07, 2013 semi-natural wetland ecosystems, there is a growing interest in understanding factors controlling ecosystem processes. This would enhance our ability to manage and protect wetland ecosystems, as well as obtain the maximum benefits from its values and functions [19]. A noticeable potential effect of climate change would be the increased loss of biodiversity and natural habitats. The assessment of the interrelation of biodiversity dynamics, ecosystem processes and abiotic factors in a sustainable way has been and still is a subject of research and development of various debates among stakeholders. Ecosystems under stress usually cause species diversity to decrease and may result in an increase in numbers of the species capable of tolerating stress. The more diverse any population in a community, the more stable the community becomes and the knowledge of the species composition of communities can provide insights into the ecological function of these communities and assist in the choice of suitable methods for remediation of polluted system. Wetlands are key ecosystems for mitigating the effects of fossil fuel emissions on climate. Internationally and in South Africa context, the future of biodiversity conservation lies in the great progress that has been made in assessing the state of biodiversity as well as the development made so far with the development of biodiversity plans which set targets for future conservation needs. Irrespective of the nature of the ecosystem involved, maximum efficiency of resources is crucial. Wetlands management has being associated with the several functions and values commonly attributed to wetlands. The functions, classified into three main groups (hydrology, biogeochemistry and habitat) are linked to the self-maintenance of the wetlands and their surroundings [20]. Because wetlands are at the interface of land and water, they are strongly connected to both terrestrial and aquatic ecosystems. Therefore, the health of a wetland is strongly affected by what is happening upstream. This means that an unhealthy wetland will often be a good indicator of problems in its catchments. (ROS) are increasingly appreciated as down-stream effectors of cellular damage and dysfunction under natural and anthropogenic stress scenarios in aquatic systems. Oxygen free radicals induce damage due to peroxidation to bio-membranes and also to DNA, which leads to tissue damage. It is well understood that the generation of ROS beyond the capacity of a biological system to eliminate them gives rise to oxidative stress. Plants are vulnerable to various stress factors. e.g. oxidative stress from deleterious effects of reduced oxygen species such as superoxide and hydrogen peroxide. These oxygen species can form hydroxyl radicals (OH-), the most reactive species known to chemistry. Hydroxyl radicals cause lipid peroxidation, protein denaturation, DNA mutation, photosynthesis inhibition and so forth. In order to survive, aerobic organisms have evolved a defense mechanism against oxidative stress. Because hydroxyl radicals are far too reactive to be controlled easily, the defense mechanism is based on elimination of superoxide and hydrogen peroxide. The central role in the plant antioxidative mechanism is played by superoxide dismutase (SOD), an enzyme that converts superoxide into hydrogen peroxide, which is then broken down by either catalase or various peroxidases [22]. Accumulation and Challenges of Heavy Metals: Both technological and industrial advances are loading the environment with heavy metals [23-24]. Main heavy metal concern is the modification of river flows by damming, irrigation and pollution from land, marine and atmospheric sources. Degradation has become increasingly acute within the last 50 years, creating further losses of biological resources. Many researchers have revealed on how contamination might not only affect the microorganisms and plants in the environment but invariably, poses a threat to animals and human health through exposure through the food web [7-11, 13]. Wetland has been indicated to be very much used recently in the treatment of the contamination especially acid mine drainage (AMD), for the new use of water purification in constructed wetlands [25]. Scientists are continually expanding the number of plants found to be highly dynamic ecologically, physically tough and resilient with good root and rhizosphere structure and chemistry, for example, Phragmites [26]. However, the disruptions on the biodiversity dynamics, ecosystem processes and abiotic factors which these plants relate after receiving high concentrations of metals remain unclear. Oxidation Effects on Metal Uptake by Wetland Plants: Environmental management of biodiversity and ecosystem particularly, wetlands; requires an understanding of the linkage of management actions to biological response [21]. For instance, plants generally transform energy from sunlight to chemical energy by means of photosynthesis. During the process, plants fix carbon dioxide (CO2) and release oxygen (O2) while coping with the loss of water (H2O). Reactive oxygen species 2 African J. Basic & Appl. Sci., 5 (1): 01-07, 2013 The vulnerability of the wetland environment to chemical damage depends on several factors, including the: physical and chemical properties of the chemical and its transformation products; concentration of the chemical entering the ecosystem; duration and type of inputs; properties of the ecosystem that enable it to resist changes which could result from the presence of the chemical; and location of the ecosystem in relation to the release site of the chemical [27, 28]. Metal accumulated by wetland plants was mostly distributed in root tissues; suggesting that there is tolerance strategy. Numerous wetland plants have constitutive metal tolerance and mechanisms of resistance that enable most cells in plants experiencing metal toxicity to continue normal activities while sacrificing a few cells that accumulate large amounts of the metal [29-31]. Metals, when found in high concentrations, are potentially toxic inorganic pollutants that destabilize ecosystems because of their bioaccumulation in organisms, biomagnifications in food chains and toxic effects on biota. [23, 7] highlighted the relevance of knowing the processes of metal accumulation, removal, uptake and distribution in the wetland. Knowing these, researchers could understand these systems and ensure that wetlands do not themselves become sources of metal contamination. This is necessary due to the environmental risk associated with remobilization of metal contaminant and their recycling to the food chain, particularly by the infiltration into the ground water. in order to reap its full potential [34]. Biodiversity dynamic’s major challenges for the future include the consolidation of reserves in under represented regions, the improved management of natural plant resources outside reserves and the need to justify protected areas within the framework of major and far reaching sociopolitical change. However, the consequences are the possible loss of species, an altered species complement and ultimately an altered and less productive ecosystem [32]. It is a great challenge to measure large-scale biodiversity dynamics; therefore, biodiversity is generally evaluated using only one population metric (metric per species), however, single population metric may not precisely indicate the changing state of a target population [35]. The extent to which biodiversity dynamics particularly plants exert an influence over ecosystem processes such as nitrogen cycles is largely unknown, it is also unclear how such processes may be dependent on abiotic factors. The ability of plant species to continue to influence ecosystem processes under a changing climate is unclear [36], which limits the ability to predict ecosystem responses to future environmental changes. Thus, the impact of biodiversity dynamics on some ecosystem processes may be primarily a result of change. Benefits of Biodiversity: A deep understanding of ecosystem processes is the best foundation for formulating good restoration and protection policies, which are multi sectoral and at multiple levels. Changes in biodiversity have the potential to either increase or reduce the incidence of infectious disease in plants and animals-including humans, because they involve interactions among species. At a minimum, this requires a host and a pathogen; often many more species are involved, including additional hosts, vectors and other organisms with which these species interact. [37] reviewed that reduced biodiversity affects the transmission of infectious diseases of humans, other animals and plants with a conclusion that biodiversity exerts a protective effect on infectious diseases is sufficiently strong to include biodiversity protection as a strategy to improve health [33]. Implications on Biodiversity Dynamics: The world is faced with the challenge of sustainable global food security. This seems to be more challenging as global climate is changing unpredictably. Worldwide, the production of food is being affected largely by myriads of environmental extremities and the sensitivity of plant due to pollution is a major limitation for high productivity [32]. The ever increasing population, whose majorities are children and women, are most vulnerable to dietary deficiency. Population growth, increased food demand, climate change, urbanization, rising health and environmental standards increasingly call for an integrated approach by all [33]. Many studies have quantified the contribution that biodiversity makes to people’s livelihoods in term of income [32]. A noticeable potential effect of climate change would be the increased loss of biodiversity and natural habitats. Healthy, functioning ecosystems are global defense against climate change and storm damage, so it becomes imperative to ensure conservation of wetland ecosystems Ecological Consequences of Wetland Loss: Human activities such as rural development, urbanization and the creation of hydro power reservoirs have influence plants and other sessile organisms by the destruction / reduction of available habitat. Mobile animals (especially birds and 3 African J. Basic & Appl. Sci., 5 (1): 01-07, 2013 mammals) retreat into remnant patches of habitat, which lead to crowding effects and increased competition. Also, agricultural development leaves small fragments of habitat which can only support small population of plants and animals, while small populations are more vulnerable to extinction. As available area is the primary determinant of the number of species in a wetland. The size of wetland will be influenced by number of species which were present when the wetland was initially created and influence the ability of these species to persist in the wetland. Minor fluctuations in climate, resources, or other factors would be unremarkable and quickly corrected in large populations can be catastrophic in small, isolated populations. Thus, fragmentation of habitat is an important cause of species extinction. The major influence is the loss, alteration and fragmentation of habitats, mainly through conversion of natural land for agricultural, aqua cultural, industrial or urban use; damming and other changes to river systems for irrigation or flow regulation. This has led to overexploitation of wild species’ populations, harvesting of animals and plants for food materials or medicine at a rate higher than they can reproduce. Another ecological consequence of wetland loss is through over-exploitation of resources which impacts on the livelihood, survival and food security [38]. Wetlands are sensitive to climate change, due to rising levels of greenhouse gases in the atmosphere, caused mainly by the burning of fossil fuels, forest clearing and industrial processes. Introduction of invasive species either deliberately or inadvertently to one part of the world from another can become competitors, predators or parasites of native species. Environmental impact assessments have been used as tools to identify the potential impacts of project activities on habitats of concern. Therefore, preservation of specific habitats (usually the remaining natural areas within the landscape) should be a priority for ecological functioning or species diversity of the ecosystem. The best understood examples of habitats critical to ecosystem functioning are wetlands. Environmental analyses through various researches’ have indicated that habitat alteration and destruction are among the greatest risks to ecological and human welfare. Ever-growing human demand for resources, however, is putting tremendous pressure on biodiversity. This threatens the continued provision of ecosystem services, which not only further threatens biodiversity, but also our own future security, health and well-being. It is important to harmonize the relationships between human population growth, regional economic development, environmental conservation and ecological restoration [39]. Limited understanding of the ecological regimes and the interactions between humankind and nature. Ecosystem Processes in the Changing Environment: Effective management of our natural resources depends on accurate assessment of wetland processes and the functions they serve. In other words, different classes of wetlands have different functions with respect to water quality and these differences need to be recognized in our management strategies. Assessment of function provides an estimate of the capacity of a wetland to participate in a given environmental process. Wetland function often is divided into three major categories: hydrologic; biogeochemical; habitat and food web support. Function should not be confused with value, which is an estimate of worth to society. The integrity of the native biological components of a wetland is known to be a reflection of the condition or health of a wetland. One of the first indicators of reduced condition or health is a change in the wetland plant community. For example, plant species have different ranges of tolerance to a variety of environmental factors such as inundation, wetness, salinity, pH, sedimentation, physical alterations, etc. Healthy, functioning wetlands serve as environmental filters and protect aquatic systems. However, if the rates of addition exceed the capacity of the wetland to perform chemical transformations, toxic concentrations may result. The consequences may be twofold: deterioration of the wetland biotic system, causing a reduction in function; and elevated chemical concentrations in adjacent aquatic systems due to reduced wetland function. It is beginning to be evident that nearly all ecosystems will undergo changes in some biotic and abiotic or both as the human population climax, impacting on biodiversity dynamics [3]. Changes in the environment can have direct effects on the ecosystem processes directly through biotic factors or indirectly through effects on the physiology, morphology and behavior of individual organisms, the structure of populations and the composition of communities and the question that this Main Challenges Facing in Wetland Restoration: South Africa is a developing nation with nearly all its wetlands loss or degraded and diversified environmental conditions, strong drive for socioeconomic development. This explains that environmental quality, resources usability and ecological security are important concerns for the success of regional sustainable development? 4 African J. Basic & Appl. Sci., 5 (1): 01-07, 2013 paragraph tries to answer is what are the consequences of a changing environment on the ecosystem functioning and ecosystem services? A critical step in that challenge is to understand how changing environmental conditions influence processes across levels of ecological organization. Many ecosystem processes are affected by environmental changes such as changing climate, increasing CO2 and increasing nitrogen deposition. Water is essential as sustenance for organisms and as a driving force for physical changes to the environment. It also serves to transport energy, nutrients and biota themselves. To understand the biodiversity, production and sustainability of ecosystems, it is necessary to appreciate the central role of dynamically varying physical environments. Hydrologic patterns in aquatic ecosystems and their surrounding landscapes play a key role in these dynamics. The following major activities may cause the loss of habitats critical to ecological processes: Land conversion to industrial and residential land use, Land conversion to agriculture, Land conversion to transportation, Timber harvesting practices, grazing practices and mining practices, water management practices, military, recreational and other activities. Critical habitats such as wetlands are well known for their nutrient cycling and purification services. Habitats obviously support the species with characteristic genetic diversity, population dynamics and biotic interactions. The abundance and distribution of critical habitats affect the pattern and connectivity in ecological process, natural disturbance regimes and hydrologic patterns, effective maintenance of these habitats and their structural complexity regardless of the intellectual approach, integration of knowledge across disciplines will be vital because no single individual or discipline holds the key to understand regional- and global-scale behaviour. The fragmentation of habitat has been implicated in the decline of biological diversity and the ability of ecosystems to recover from disturbances such as habitat loss, habitat fragmentation, connectivity and soil erosion [40]. An understanding of how ecological thresholds might be best utilized to conserve biodiversity and sustainably manage natural resources requires further research. the geochemical cycle, hence, the protection and conservation of ecosystem is of paramount importance. A poor understanding of the value of wetland will continue to encourage resource overuse and degradation, thus further compounding threats to development. Wetland restoration will contribute to the stabilization and improvement of metal uptake. Strategies that balance use and development of wetland and protection of the catchments ecological function should be designed to limit ecosystem extraction. Trade-offs is inevitable between protecting wetlands (achieving ecological integrity) and achieving economic developments. The future of biodiversity conservation in South Africa rests on the progress that has been made in assessing the state of biodiversity and the setting of developmental targets for future conservation needs. Plant biodiversity in wetlands should be enhanced to benefit both purification efficiency and ecology. It can be concluded that there is a link between critical habitat and ecological processes. 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