Landscape and ecosystemGeographically speaking, a landscape is the visible features of an area of land, its landforms and how they integrate with natural (water, air, stones, fauna, flora, etc.) or man-made (plantations, cities, infrastructures, etc.) features. The effects generated by these factors create a unique “mosaic” that can/must be observed using different interpretative keys. More in specific, Geography studies the landscape’s dominant aspects, which is modelled by the natural factors according to the preliminary geologic base. Every landscape is the result of the dynamic interaction among lithospheric nature of the substrate, climate factors and biospheric elements, which determine, all together, the landscape’s facies (lat. “aspect”). Scheme 1: Natural and antropic landscape factors
Source: Catellani L. , Landscape factors 2018
According to this, a natural landscape is a context where the human action did not alter neither the ecosystem structure nor the quality and quantity of the existing natural resources. The intervention of human factors varies from “light influence” to “deep impact”. In the last centuries the processes leading to human impact have grown in number and intensity, leading to a remarkable fragmentation and decay of the natural landscapes. According to the World Heritage Commitee, the landscape is a peculiarity of a given geographical area and it’s the result of the combination man/nature. The landscape is an important element determining the life standard of people living in the cities and well as in the countryside, in the deteriorated areas as well as in the well-preserved ones. This vision is very antropocentric. Both natural and human factors interact through uninterrupted flows of matter and energy, which, from an ecological perspective, are like “springs” and “wells”. Scheme 2: Springs and wells
Source: Limit to Growth. The 30-Year Update , D &D Meadows, J .Randers
The picture above shows the flows of raw material and energy that are, first, withdrawn from the global springs, then they pass through the man-nature system, and last they reaching the global wells, where wastes and pollutants gather. The atmosphere is, at the same time, the spring of oxygen and carbon dioxide, which are essential for life, and the well where exhaust gases, fine dust produced by fossil fuels and other climate-change emissions accumulate. The current economic system is exploiting the vast majority of the resources available, saturating the wells’ absorbing capacity and pushing the system to its sustainability limit. In this model the “springs” are intended the organic and inorganic stocks like the soil, water, air, raw materials and life forms, which are supported by the solar energy that reaches the ground and fosters the passage of energy (e.g. material energy) and matter (e.g. vegetal matter). The flows of matter and energy lie at the basis of the ecosystems and connect organic and inorganic components. The ecological dimension where springs, wells and economic and antropic system interact is the natural ecosystem, i.e. where a given community lives and fosters changes in the balance and in the short- and long-term ecological system indicators. In the ecosystem biotic (Greek “bios”, life) and abiotic elements are deeply connected, especially in the biogeochemical cycles of matter and the flows of energy. Whereas the energy can be dispersed in heat and light waves, the matter can’t be neither created nor destroyed. It changes while passing from abiotic to the biotic community through trophic relations. The primary producers, i.e. plants, take inorganic elements from the ground, such as potassium, phosphorus and nitrogen, and transform them into organic matter. Afterwards, the organic matter passes through all the trophic levels of the ecosystem and the food chain till becoming mineral once again, thank to the decomposition of dead organic matter performed by microorganisms the living in the ground. Even a single clump of dirt in a mild forest can be a natural ecosystem, where the abiotic elements are represented by the mineral and organic elements composing the ground, and the biotic part is composed of microorganisms and macroinvertebrates. A single spoon of fertile soil contains from 100 millions to 1 billion bacteria of – at least – 10.000 different species (Datasource http://eusoils.jrc.ec.europa.eu), which carry out the decomposition process of the organic matter and the transformation of carbon from organic to inorganic, in order to make it available to the primary producers again. Various classes of organisms living in the ground chop, mince and mineralise the organic waste, and they bring back carbon, nitrogen, phosphorus and umic acids to the inorganic form. Every year an earthworm can convert more that 1000 tons. dry soil, that is 20/30 times its weight, into fertile soil available for plants’ growth. Also Fungi play a key role in symbiotic relations with plants helping them to be more resistant to parassites enemy and to absorb substunces by the soil. Fungi exist in two different forms, either as single celled organisms called yeasts (4-5 μm), or in hyphal forms whereby they grown to form extensive branched networks. For example, the fairy rings which can appear in lawns and grasslands in summer and autumn are good examples of extensive fungal individuals, with the rings of darker grass marking the edges of the advancing mycelial front (Fig.3). Some of these can grow at rates of over 1 m a year and can form ring structures over 200 metres across! Fig. 3,4 Fungi hyphal net ; Hyphal cells at microscope
The decomposing organisms are the prey of several micro- and macroorganisms, such as protozoas, myriapods, spiders and so on. Concluding, the structure of an ecosystem is composed of producers and consumers of I, II and III grade, which are deeply intertwined in the so called “food chain”. Fig.5 Biodiveristy soil in number
As on the soil , the ecosystem can be tiny or huge: it can be a small pond where several aquatic vegetable species create habitats and ecological niches that host other animal species, or it can be a long river that includes several sub-ecosystems. From the ecological point of view, the landscape is like a “mosaic” characterized by ecosystems connectivity, dynamism and balance and above all by ecological fragility.