Friday, October 16, 2009

Ecosystem services- a lesson about

I went to a preserved forest in Rannebergen, Göteborg, in a mission to guide a friend about ecosystem services. This is about what we did that day, but also a text how the relationship in nature carries the burden of human activites.

Imagine a forest and a small lake. It's fall and there is a low but bright sun in a blue sky. You see trees in different colours; red, green, yellow, you see bare rocks, you see grass and a small path. The water shine and move a little bit in the wind. This area is protected for more than the beauty.

The ecosystem
My friend asked me were the boundaries for an ecosystem is. I answered that an ecosystem can be a forest, a lake, the globe or just a stick on the ground. You can set the boundaries of what you want to measure, yourself. But you need three different thing to call it an ecosystem; producers, consumers and decomposers.

The producers uses the sun, water and carbondioxide to produce green mass in the process of photosynthesis, the producers also use this sugar itself and produce carbondioxide in the process to make fat or protein to store in the plant. Plants also need other nutritions for its growth, which can be found in the soil. The middle level of consumers do nothing else than eat the green mass. The decomposers break down both living and dead materia of producers and consumers and recycle it back as nutriens in soil, which the producers can use.

Energy flows in ecosystems 
Small example of energy flow in a ecosystem; if 100% of the energy is in the producers, 16.1% is in the next step of the herbivores, 1.8% of the producers energy can be fund in the primary carnivores and 0.1% in the top carnivores (carnivores that eat carnivores, for example eagles or foxes) 24.2% can be found in the detrivores and decomposers. This tells us why it is much more energyconsuming to have an eating habit of meat instead of vegetables. When growing food for crops, as much as 90% or the protien and 98% of the calories, would disappear to the animals own metabolism, which is the answer to why the world is running out of farming land even if the technics and biomass/areal is bigger than ever.

From bare rocks to a forest
From the very first beginning everything is a bare rock. Liches are the first to colonize and they produce organic matter where small plants can colonize. Myccorhiza helps the grasses with the nutrient uptake. Acids from the nutrient decompose will release nutrients from the rocks and more nutrients (macro and micro nutrients like P and Ca) will be available for the plants. From more plants it will be a deeper humus layer and soon we have wooden plants. When woody plants are there, spruce can colonize easy, creating acid soils from needles and thick canopy layer that restrain microbes activity in the soil, creating a large undecomposed layer.

Temperature, water conditions, the angle of inclination, vegetation and its influence with shade and other specialties also effect the succession stages and rate. The ericaceous plants also thrive from the beginning and makes a shortcut in the succession stages. Not to forget is also the high usage of land in the southern areas of Sweden to compare to northern areas, were humans have force the system to go back to the grass conditions, when we make fields, pastureland and meadows. Areas like this are often nowadays left to "take care of its own", where the succession now (less than 100 years) can continue.
The myccorhiza
As much as 9 of 10 of the terresteral plants on planet earth live in a close relationship to soil fungi, a symbioses called myccorhiza. The symbioses gives a much larger connection to the soil and therefore acess to more nutrients. As a trade gift the fungus get sugar from the tree.

Myccorhiza is very sensitive to pesticides, fertilizer, packed soil and ground making. When fertilize a forest its important to remember the myccorhiza, because if the myccorhiza disappears because of more nutrients in the soil, other nutrients as the micro nutrients might be in shortness later, when no myccorhiza can help to "find it".

Three different myccorhiza is grouped after how they penetrate the plant root:

  • Arbuscular myccorhiza is formed by various types of plants, but environmental parameters that is related to its presents are low availability of phosphates and rich in nitrogen. Arbuscular myccorhiza can be found where the soil-pH is high and use mostly inorganic nitrogen.
  • Ectomyccorrhiza is formed by woody trees and scrubs and can be limited both from nitrogen and phosphorus. Soil-PH is neutral to low. The myccorhiza use mostly organic nitrogen, i.e can decompose organic matter by itself.
  • Ericoid myccorhiza can be found in arctic tundra and heathland because of the extremely low nutrient level in the soil. The ERM might be the reson for many plants to live here, when it have the unique abilities to obtain nitrogen and phosphorus from "raw" humus. Temperatur, soil-pH and water level is low. The result is a soil with a large amount of organic matter but no mineralized nitrogen as NH3 and NH4.

Worms, microbes, insects and bacteria break down organic material to nutrients. They can also break down pesticides and other pollutions from air and water.

The worms also mix organic matter with the soil, taking it from the top into the soil where other decomposers can help. Worms makes paths in the soil which helps plants to grown their roots and to get oxygen in the soil. They also makes the soil structure which decide the ability to hold water.

Plants shed their leaves, needles, flowers, fruit, and cones, animal shed hair, skin, feathers, pupal cases, exoskeletons and silk which the decomposers can tranform the nutrients again to other plants. The animals also produce excrements and uninary wasted that cointain nitrogenous compounds.

Water is fantastic!
The lighest is the ice (0 C degrees) and the heaviest water have a temperatur of 4 C degrees which mean, it is in a lake almost always some unfrosen water in the bottom for fishes to live in.

Transforming air to food
Nitrogen fixation bacterias can transform the nitrogen in the air (nitrogen is the most abundand gas, about 78% of the composion of air) to nitrogen that plants can use (from N2 to ammonium, NH3). Legumnious plants store the nitrogen in special roots and use nitrogen to the peas in the plant. Some trees also have nitrogen fixation bacterias. For example, tree species in the genus Frankia are used more and more in Agroforestry.

The bacteria help the soil to have a greater microbial activity which makes the soil able to hold more water and the soil is more fertile for other plants. Nitrogen fixation plants can be mixed to the soil, just grown before or toghether with other plants or as the bacteria Azospirillum sp that can colonize sugarcan and maize which in the future might get a much greater role when less artificial (which is an oil depended process) fertilizer is needed.

Examples of ecosytem services and the cost (trillion $ U.S)
  • soil formation (17.1)
  • recreation (3.0)
  • nutrient cycling (2.3)
  • water regulation and supply (2.3)
  • climate regulation (temperature and precipitaion, 1.8)
  • habitat (1.4)
  • flood and storm protection (1.1)
  • food and raw materials production (0.8)
  • atmorspheric gas balance (0.4)
  • pollination (1.6)
  • other services (1.6)
Together to a value of a total 33.3 trillion $ U.S (example from Costranza, 1997), but other numbers says a dubble value of the worlds annual GNPs of all national economies.

Other ecosystem services not mention above is barrier for diseases, control for natural disasters, inspiration, biomedicine, genetic resourses, social relationships, cultural diversity, spiritual and religious relations, cultural history, esthics, knowledge and education.

Did you know that:
-Tokyo use 2.14 times the whole area of Japan to the citys supply.
-One citizen need 220 000 to 250 000 km2 viable ecosystems

Humans having a hard time to understand that we are a part of nature. We think we are outside the system, "decoupled" from it

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