Ecosystem and its importance in Landscape Planning and Design
Landscape architecture is the art, planning, design, management, preservation and rehabilitation of the land and the design of large-scale man-made constructs. Through the 19th century, urban planning became more important, and it was the combination of modern planning with the tradition of landscape gardening that gave landscape planning and design its unique focus. American society of Landscape Architects defines the profession as the art and science of organizing land and the objects upon it, for human use and enjoyment.
Landscape planning and design is not a decorative or additive art. It is an integral part of all total physical planning or design effort. Landscape planning and design is forming and interrelating of countless composition in space intended to be walked through, run through, driven through, played in, sat in, and freely used in general.
So landscape planning is the practical art and science of adapting land, based on the premises that land use and beauty are compatible. It includes the planned combination of living plants, such as flowers, grass, ground cover, shrubs, trees, and vines, as well as natural features such as rocks and stones; and may also include reflecting pools, fountains, outdoor artwork, gazebos, screen walls, benches or fences.
Biosphere and Ecosystem:
In order to arrive at a sustainable landscape planning and design, it is essential to know the intricate intra and inter relationship that exists between different living and non- living elements of our environment.
The biosphere is the life zone of the Earth and includes all living organisms, including man, and all organic matter that has not yet decomposed. The biosphere is structured into a hierarchy known as the food chain whereby all life is dependent upon the first tier (i.e. mainly the primary producers that are capable of photosynthesis). Energy and mass is transferred from one level of the food chain to the next with an efficiency of about 10%. All organisms are intrinsically linked to their physical environment and the relationship between an organism and its environment is the study of ecology.
Ecosystem is the part of ecology. Ecology may be defined as that branch of biology which deals with the inter-relationship between living organisms and their environment. Ecology may also defined as the study of structure and function of nature.- (E. Odum 1963). Some example of ecology may be human ecology, plant ecology etc. The main object of ecology is to study the relation among different ecosystems.
An ecosystem can be defined as an ecological unit consisting of a biotic community (an assemblage of plant, animal, and other living organisms) together with its abiotic environment (such as soil, precipitation, sunlight, temperature, slope of the land, etc.). The word ecosystem is an abbreviation of the term, “ecological system.” The word ecosystem is derived from Greek OIXOS meaning home, and it refers to a natural community of plants and animals living together in a particular climate and soil. The size of ecosystems varies tremendously. An ecosystem could be an entire rain forest, covering a geographical area larger than many nations, or it could be a puddle or a backyard.
Ecosystems are of two types:
Natural ecosystem- like ecosystem of forest, river etc. it is also divided into two category.
Man made ecosystem- like agricultural land, river dam etc.
Figure no 01: Aquatic ecosystem Figure no 02: Terrestrial ecosystem
Some basic components of ecosystem:
An ecosystem includes population, communities, habitats and environments and is specifically refers to the dynamic interaction of all parts of the environment. It focuses particularly on the exchange of materials between the living and non-living portions.
Habitat, population and community:
A habitat is the place where a population lives. It is the natural abode or locality of our animal, plants or person. A population is a group of living organisms of the same kind living in the same place at the same time. Thus it can be said that a population deer in a forest or the population of fish in a particular lake.
· All of the populations interact and form a community. So a community consists of the population of plants and animals living together in a given place.
· The community of living things interacts with the non-living world around it to form the ecosystem.
Major communities and minor communities:
Major communities are of sufficiently large sizes which are complete in themselves and independent of other communities. Here nothing passes out from them and nothing is received outside except solar energy.
Minor communities are more or less dependent on neighboring communities.
The structure of ecosystem:
Figure no 03: A graphical representation of the structure of ecosystem
Processes of Ecosystems:
Energy enters the biological system as light energy, or photons, is transformed into chemical energy in organic molecules by cellular processes including photosynthesis and respiration, and ultimately is converted to heat energy.
Elements such as carbon, nitrogen, or phosphorus enter living organisms in a variety of ways. Plants obtain elements from the surrounding atmosphere, water, or soils. Animals may also obtain elements directly from the physical environment, but usually they obtain these mainly as a consequence of consuming other organisms. These materials are transformed biochemically within the bodies of organisms, but sooner or later, due to excretion or decomposition, they are returned to an inorganic state. Often bacteria complete this process, through the process called decomposition or mineralization.
During decomposition these materials are not destroyed or lost, so the earth is a closed system with respect to elements (with the exception of a meteorite entering the system now and then). The elements are cycled endlessly between their biotic and abiotic states within ecosystems. Those elements whose supply tends to limit biological activity are called nutrients.
The Cycles of Nature:
Energy from the sun is constantly entering and passing through the earth’s ecosystem. But our ecosystems have no similar extraterrestrial source of carbon, nitrogen, potassium and sulfur and many other substances that are required for life. These substances must be continually recycled through the ecosystem if the ecosystem is to persist.
The main biogeochemical cycles are:
1. Carbon cycle
2. Nitrogen cycle
3. Hydrological cycle
4. Phosphorus cycle
5. Sulfur cycle
Energy flow through ecosystem:
Thus the flow of energy through this system is like a step-wise progression. Mainly three steps are involved in energy flowing. They are:
1. Ecological pyramid
2. Food chain
3. Food web
Landscape ecology is the science of studying and improving the relationship between spatial pattern and ecological processes on a multitude of landscape scales and organizational levels.As a highly interdisciplinary enterprise, landscape ecology integrates biophysical and analytical approaches with humanistic and holistic perspectives across natural and social sciences. The most salient characteristics of landscape ecology are its emphasis on the relationship among pattern, process and scale and its focus on broad-scale ecological and environmental issues. Landscape ecology has important links to application-oriented disciplines such as agriculture and forestry. Agriculture has always been a strong human impact on ecosystems. Landscape ecology has been cited as a contributor to the development of fisheries biology as a distinct biological science discipline, and is frequently incorporated in study design for wetland delineation in hydrology. Landscapes may become substitutes for biodiversity measures because plant and animal composition differs between samples taken from sites within different landscape categories.
The Domain of Landscape Ecology:
The Allerton Park definition makes clear that heterogeneity, or distinct spatial patterns, comprise the core research question in landscape ecology. The main themes comprising
Landscape ecology includes:
· the spatial pattern or structure of landscapes, ranging from wilderness to cities
· the relationship between pattern and process in landscapes, including the ecological implications of pattern for populations, communities, and ecosystems
· the effect of scale on landscape
· the processes involved in pattern formation, such as the physical (abiotic) environment, demographic responses to this, and disturbance regimes
· the relationship of human activity to landscape pattern, process and change (e.g. applications in land-use planning)
Important terms in Landscape ecology:
Landscape ecology not only created new terms, but also incorporated existing ecological terms in new ways. Many of the terms used in landscape ecology are as interconnected and interrelated as the discipline itself. Landscape can be defined as an area containing two or more ecosystems in close proximity.
Scale and heterogeneity:
A main concept in landscape ecology is scale. Scale represents the real world as translated onto a map, relating distance on a map image and the corresponding distance on earth. Components of scale include composition, structure, and function. A landscape with structure and pattern implies that it has spatial heterogeneity, or the uneven distribution of objects across the landscape.
Patch and mosaic:
Patches defined as a relatively homogeneous area that differs from its surroundings. Patches have a definite shape and spatial configuration, and can be described compositionally by internal variables such as number of trees, number of tree species, height of trees, or other similar measurements.
Matrix is the “background ecological system” of a landscape with a high degree of connectivity. Connectivity is the measure of how connected or spatially continuous a corridor, network, or matrix is. For example, a forested landscape (matrix) with fewer gaps in forest cover (open patches) will have higher connectivity. A network is an interconnected system of corridors while mosaic describes the pattern of patches, corridors and matrix that form a landscape in its entirety.
Boundary and edge:
Landscape patches have a boundary between them which can be defined or fuzzy. The zone composed of the edges of adjacent ecosystems is the boundary. Edge means the portion of an ecosystem near its perimeter, where influences of the adjacent patches can cause an environmental difference between the interior of the patch and its edge.
Ecotones, Ecoclines, and Ecotopes:
A type of boundary is the ecotone, or the transitional zone between two communities. Ecotones can arise naturally, such as a lakeshore, or can be human-created, such as a cleared agricultural field from a forest.
An ecocline is another type of landscape boundary, but it is a gradual and continuous change in environmental conditions of an ecosystem or community. Ecoclines help explain the distribution and diversity of organisms within a landscape because certain organisms survive better under certain conditions, which change along the ecocline.
An ecotope is a spatial term representing the smallest ecologically-distinct unit in mapping and classification of landscapes. Relatively homogeneous, they are spatially-explicit landscape units used to stratify landscapes into ecologically distinct features.
Disturbance and Fragmentation:
Disturbance is an event that significantly alters the pattern of variation in the structure or function of a system. Fragmentation is the breaking up of a habitat, ecosystem, or land-use type into smaller parcels. Disturbance is generally considered a natural process. Fragmentation causes land transformation, an important process in landscapes as development occurs.
Sustainable landscape design based on ecosystem pattern:
Landscape is a product of all process of nature and human culture, combining in varying proportion. Various critical factors should be assessed in landscape planning including several parameters of climate, geology, physiography, hydrology, vegetation, wildlife and land uses.
The ecosystem pattern-based design is the act of understanding the patterns of a region in terms of the processes that shape them and then applying that understanding to design and planning. By working with nature’s design, one can create landscapes that function sustainably.
Ecosystems come in different scales that are nested within each other. The boundaries are open and permeable leading to interaction or linkages between systems. Because of these linkages, modification or designing of one system affects surrounding systems, sometime adversely.
Figure no 04: Boundaries are open and permeable
One must examine these relationships between systems of different scales in order to analyze the effects of management. A disturbance to a larger system will affect smaller component systems within. For example, logging on upper slopes of an ecological unit may affect downstream smaller systems.
Using ecosystem pattern to design sustainable landscapes:
The patterns sensed do not occur randomly, but are linked to the processes that form them. For example, rocky reservoirs support pines within grasslands of the Great Plains.
The natural patterns and processes of a particular region provide essential keys to the sustainability of ecosystems, and can inspire designs for landscapes that sustain themselves. To be sustainable, a designed landscape should imitate the natural ecosystem patterns of the surrounding eco-region in which they are embedded. As seen before, trees signify rocky reservoirs of available water on the Great Plains. Planting these same trees on fine-grained plains soils, with only atmospheric precipitation to sustain them would kill the tree.
One must observe how regions function and try to maintain their functional integrity. The tropical rainforest, for instance, provides so much oxygen that it can be considered as a lung of the biosphere. So one should not use it only for massive lumbering, but instead, take advantage of its other resources, such as medicine.
Changing the natural pattern by adding subdivisions, roads, or other elements changes the ecological functions. For example, animals change their routes, water flows are changed in direction and intensity, erosion commences, etc. While designing the landscape, one should correlate these changes with their planning and design.
For landscaping an area one can use natural drainage instead of storm drains, wetlands instead of sewage treatment plants, and indigenous materials rather than imported ones.
Figure no 05: Natural drainage instead of storm drains Figure no 06: Indigenous materials for landscaping
Fundamentally, most natural systems are diverse. Therefore, good ecological design will maintain that diversity. Local ecosystems are dependent on the existence of other nearby ecosystems. Therefore, biodiversity depends on leaving some connections and corridors undisturbed.
The same type of forest growing in different eco-regions will occur in a different position in the landscape and have different productivity. For example, the height-age ratio of Douglas-fir varies in different climatically defined eco-regions. The eco-region determines which ratio to apply to predict forest yield. This is important, because if a landscape designer selects the wrong ratio, yield predictions and the forest plans upon which they are based will be wrong.
Historically, a high level of landscape heterogeneity was caused by natural disturbance and environmental gradients. Now, however, many forest landscapes appear to have been fragmented due to management activities such as timber harvesting and road construction. To understand the severity of this fragmentation, the nature and causes of the spatial patterns that would have existed in the absence of such activities should be considered. This provides insight into forest conditions that can be attained and perpetuated.
Figure no 07: This is a landscape illustrating the absence of trees on fluvial soils in the valley and alpine zone above a narrow band of forest dominated by spruce and sub alpine fir
Understanding the patterns of sites also can inspire design for urban and suburban landscapes that are in harmony with the region they are embedded within. Classifying metropolitan areas by eco-region forms a baseline for selecting native plants for landscaping or to restore natural conditions, as well as transferring information among similar cities which is also important in landscape planning and design. This information is an important guide to knowing which plants will thrive in a particular eco-region. Designing urban and suburban landscapes that mimic the native vegetation by using regionally appropriate plants is the safest course to ensure landscape sustainability.
Eco-regional analysis capitalizes by identifying climatic and landform factors likely to influence the distribution of species. This analysis uses these factors to define a landscape classification that groups together sites that have similar environmental character. Such a classification can then be used to indicate sites likely to have similar potential ecosystem character with similar groups of species and similar biological interactions and processes.
Interrelation between Landscape Planning and Ecosystem:
When landscapes are planned for an area ecosystem of the area plays a vital role.
If the landscape area is small and the required ecosystems are demanded, vertical gardens are best suited there. Because, vertical gardens create habitat for wildlife. As human infringe on natural spaces, the ecological landscape begins to change and shift. In urban environments with little space to plant horizontally, the natural element can be infused by exploiting unused vertical space. This will allow for a variety of insects, birds, amphibians, and other wildlife to colonize and utilize this newly, vegetated space.
Figure no 08: Pictures of vertical garden
The vertical garden is very efficient and aids in lowering energy consumption both in winter and summer. It is also an efficient way to clean up air. On the felt, polluting particles are taken in from the air and are slowly decomposed and mineralized before ending up as plant fertilizer.
Environmental habitat and landscaping:
Environment is an important factor in ecosystem and landscaping. Because, the survival and sustainability of the main element of landscaping, tree, largely depend on this.
The figure on the next page is showing the major terrestrial biomes. Each type of plants and animals cannot survive in every area. How the plants interact with their surroundings, in which type of soil they grow, what is the impact of that plant on that area; these are some important ecological question those we must know when designing any place. By knowing the ecosystem of any area, it is easy to select plants appropriate for that area which have no negative impact on that ecosystem.
|Figure no 09: major terrestrial biomes|
Elements of landscaping:
Even when using any hard elements of landscaping, like- fountain or, utilities like-water body, animals and birds are attracted there. This small change in landscape can bring a huge change in the food web of that area. This change could be positive or negative. Negative sides can be avoided by having a proper ecological knowledge.
Guiding principles for biodiversity conservation, ecological function and landscape:
Biodiversity conservation is needed in commodity production landscapes to sustain vital ecosystem services and to protect global biodiversity. Landscapes should include structurally characteristic patches of native vegetation, corridors and stepping stones between them, a structurally complex matrix and buffers around sensitive areas. These guiding principles provide a scientifically defensible starting point for the integration of conservation and production, which is urgently required from an ecological and a long-term economic perspective as well as landscape planning and design.
Strategy 1: Maintain and create large, structurally complex patches of native vegetation:
Larger patches tend to support more species than smaller patches. In addition to its area, the structure of a given patch of native vegetation is fundamentally important for biodiversity. The maintenance of large, structurally complex patches of native vegetation is particularly important in landscapes where many species are area-sensitive and confined to native vegetation, and where locations outside these patches are entirely uninhabitable for many native species.
Strategy 2: Maintain structural complexity throughout the landscape:
The area surrounding patches of native vegetation is often termed the “matrix” .The matrix is the dominant landscape element, and exerts an important influence on ecosystem function. A matrix that has a similar vegetation structure to patches of native vegetation will supply numerous benefits to ecosystem functioning. A structurally complex matrix will reduce negative edge effects at the boundaries of native vegetation patches. Edge effects are cascades of ecological changes that arise at the boundaries of patches of native vegetation because of a range of abiotic and biotic changes. For example, microclimatic changes near patch boundaries will affect the physical environment, making it more suitable for disturbance-adapted species.
Strategy 3: Create buffers around sensitive areas:
Features other than patches of native vegetation may also benefit from vegetation buffers around them. Aquatic ecosystems are obvious examples, and buffers are widely used to protect streams in forestry systems or to help preserve wetlands. Broadly speaking, buffers are particularly important where surrounding land exerts strongly negative influences on sensitive areas, such as providing a source of invasive species or chemical pollutants.
Strategy 4: Maintain landscape heterogeneity and capture environmental gradients
However, where humans do use landscapes for the production of agricultural or forestry commodities, there is widespread evidence that heterogeneous landscapes, which resemble natural patterns, provide greater biodiversity benefits than intensively managed monocultures.
Strategy 5: Minimize threatening ecosystem-specific processes
Although agriculture and forestry can threaten biodiversity, they are by no means the only threats; a range of other processes can be equally or more important in some landscapes. Examples include chemical pollution (Oaks et al. 2004) and hunting by humans. Such ecosystem specific threats need to be considered in the management of biodiversity in production landscapes, and situation-specific action taken to mitigate them.
Greenway corridors have been popular in American landscape design for decades and represent one of the connection points between land-use planning and landscape ecology. As preserved corridors that protect the environment and provide opportunity for outdoor recreation, greenways provide a well-established tool for protecting environments through spatial heterogeneity. Beyond their traditional use by land planners, greenways are now considered important to ecological structure and function.
|Figure no 10: Greenways along pedestrian path|
|Figure no 11: Greenways along canal|
According to Linehan, greenways address the “need…for methods that make the link between ecological structure and function at broad spatial and temporal scales in both basic and applied research”. Greenways incorporate conservation measures through elements such as “A wildlife corridor system that protects regional diversity which should be at the forefront of the greenway planning process and could serve as the skeletal framework of a regional greenway system”.
Landscape design for species conservation:
Wildlife that move or disperse across landscapes, including large carnivores, faces obstacles in the form of human encroachment and habitat fragmentation. These species require large tracts of land, which generally are not available, or corridors through developed areas and transportation networks in order to move from one area to another. Most protected areas are not connected with corridors and do not contain intact regional ecosystems. Protection or conservation of these species will depend not only on sound implementation of greenways, but on the incorporation of spatial pattern concepts into development and conservation plans. Good landscape designs will require a regional reserve network of core wilderness areas, multiple-use buffer zones, and connectivity among them.
Adapting to climate change: Putting a value in Landscape
Landscape provides the fundamental support system for life on earth. Our living environment reflects human habits of consumption and waste. Our attitude to the landscape shapes the wider environment in physical, economic, social and cultural terms. Planning, design and management of the urban landscape requires an understanding of the functionality and performance of the built environment as a total system. It involves far more than simply arranging and maintaining “green stuff”— the trees and vegetation—it includes the impacts of human activity on soils, water, vegetation, biodiversity, materials and energy use, as well as how we understand, value and interact with our environment over time.
All urban landscapes have the capacity to enhance and regenerate the natural benefits and services provided by ecosystems in their natural state. Single dwellings, housing estates, parks, industrial estates, shopping malls, infrastructure corridors or regional recreation areas have the potential to function as an integral part of this broader global life-support system.
The issue of climate change has brought a new urgency to questions of how we manage landscape across a range of scales. There is a critical need to develop a collaborative, equitable, co-ordinate and long-term approach to urban landscape planning, design and management which aims not merely to minimize damage to ecosystems but to proactively maximize opportunities for the enhancement and regeneration of natural resources. We must consider landscape systems in a more comprehensive manner, including the previously disregarded contribution of our urban ecosystems.
Ecosystem Services and Landscape Management:
Ecosystem services is the term used to describe the ‘free’ goods and services provided by the ecological processes of healthy landscape systems, ie. Those organisms and processes which clean our air and water, pollinate plants, filter and recycle nutrients, modify our climate and enhance potential for human flourishing through interaction with the natural environment. A genuinely ‘sustainable’ landscape (ie. one which is designed and managed against long-term sustainability indices/outcomes) can provide a range of valuable ecosystem services which actually improve environmental quality rather than simply minimise the damage to natural systems. On a practical level, we need to develop ways to assess and measure the value of ecosystem services preserved or increased through sustainable landscape practices. Equally critical is the need to refine and quantify current understanding of those often less tangible linkages between our sense of connection with the wider environment and human health/spiritual well-being. What is needed is a renewed focus on the potential for improved landscape ‘performance’—particularly within urban ecosystems—in the context of addressing broader issues of sustainability and adapting to climate change. The central issue here is how we might better manage our urban landscapes in order to reveal, enhance and regenerate the value of ecosystem services across a broader range of landscape scales.
“Every thing is related to every thing else”
by Barry Commener
The ecosystem comprises the biotic community and the non living environment. It is the basic functional unit as it include both the organism and its environment, each influence the properties of others and both necessary for the survival and maintenance of life. The continuity of the energy flow and matter cycle has to be established for nature protection which is the main subject of landscape planning. Biodiversity exists because of all the natural cycles, especially, water and carbon cycles. The importance of handling biodiversity and wetlands under the nature protection and management concept is especially well understood in a time when climate changes and climate extremities (earthquakes, floods, tsunamis, and drought) can be seen in local to global scales; its essential functionality is becoming clearer. Given the great diversity among organisms on earth, most ecosystems only changed very gradually, as some species would disappear while others would move in. Locally, sub-populations continuously go extinct, to be replaced later through dispersal of other sub-populations. So ecosystem has great importance in landscape planning and design.
Lecture sheet from Prof. Qazi A. Mowla, 2009
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