‘OUT OF DOORS … PARKS AND TREES’
4.- THE TREE COMMUNITY
ECOLOGY - THE COMMUNITY OF THE TREE
All of us will explore the ecology of this place we're visiting. Ecology means the study of our home, so our job as ecologists will be to see how all the
different observations of the different groups fit together. A large part of this work will clearly have to be shared back in the classroom, but our task
while we're in the field will be to identify the basic component elements of the ecosystem being visited, take note of their main characteristics and
notice any inter- relationships that can be identified as typical of them or noteworthy. These elements can conveniently be reduced
to the following seven:
Earth - Water - Energy - Air - Plants - Animals - Combinations ('remains' of things).
Many interrelationships can be identified as manifestations of fundamental concepts such as:
Habitat - Population – Food chain – Cycle – Energy exchange – Community – Association
We'll find good examples of most of them in the Community of the Tree.
WELCOME TO THE COMMUNITY OF THE TREE
We say Welcome to the Tree COMMUNITY, because every sizeable tree is something like a town inhabited by lots of neighbours. To start with, it’s a huge
food factory, housed inside a tremendous, solid structure complete with its own equipment for pumping up water and keeping the air healthy and clean for
everyone who lives there! They all receive food, shelter and water, and also safety and comfortable quarters that are safe and easily accessible to use.
It has workers on duty night and day, receives visits from travelers who come and go, and distributes water and clean air for the benefit of everyone.
Nothing is wasted. Everything that’s left over gets converted back again into food for general use of the community and neighbourhood.
Trees are truly miraculous manifestations of nature. Imagine, if human beings could drink water through their feet, make wood out of water, soil and
sunshine, and house and feed as many friends as they wanted as long as they’re alive! Imagine, too, just how many times a tiny seed multiplies its weight
as it grows into a tree …
As if all this weren’t enough, the tree takes a long, long time to get tired. It’s capable of continuing to serve all the members of its community for
years, in some cases centuries and, believe it or not - even for thousands of years! The leaves we see today are made from processes uniting molecules
that come from many, often ancient, sources. They may be recycled from a dragonfly, clouds, a puma, or maybe even an ancient emperor or the breath or
scales of a dinosaur ... for billions of years this process of recycling has carried on continuously through permanent systems of exchange.
The energy that powers them and makes them work comes from our star, the sun. One of the easiest places to observe all this happening is in the
community of an adult tree.
TREES ARE … MAGIC
Trees are the largest and longest-lived living things of all. Some live up to 4,000 Y1ears. A tree is like a miniature universe – it uses energy from
outer space to make food from air, water and minerals in the earth. This food made by trees, and other green plants as well, is the source of life for
many animals – including human beings.
LET’S LOOK A LITTLE CLOSER AT THE TREE
We’ve already observed and climbed some trees, so now let’s look a little closer. What living beings live in and around this tree? Which of them actually
depend on it for their survival? Why do you think that’s so? Discuss this carefully. You may find out that all of them do, in one way or another. What do
you imagine these different beings eat. Which of them eat other beings you can see. Do you think that’s why they’re here? Questions like these lead us in
to understanding the interdependence of living beings. As we discuss them, let’s remember that’s exactly what we humans are as well. The tree you can see
in the drawing could be an tamarugo from the North of Chile, a quillay from the central zone, or a coigue or lingue from the South.
The idea of the
drawing is to give you an idea of some different animals you may find around a tree in any latitude of Chile. Your job when you’re outside nature
on your field trip will be to identify examples of animal life that live in the area youy not be able to see the animals, but perhaps you’ll see or hear
some signs of them. Local people may give you some information too. You may even see an animal you don’t recognize … draw it in your notebook so you can
identify it later. In the diagram are just 45 species of common Chilean animals. They’re numbered and include some mammals, reptiles, birds and insects.
Some are a bit hidden or disguised. Find out what you can about them all. Here's the key.
THE WORLD OF DECOMPOSERS
Let’s travel now from the world of large beings to the world of the smallest we can see. Let’s go hunting with hand lenses, for tiny living beings not more than a few millimeters high! What animals can we find in this old and rotting trunk? This ‘refuse’ of the forest forms a most important part of the community of the tree as well.
Inside this rotting trunk and all around it, live creatures which have a very special job, which is to help recycle the remains of everything that dies. Without them doing this essential work, no trees or other plants would find the necessary food in the earth to enable them to create new life and grow into new organisms.
Try and observe some of these ‘bugs’ carefully. What they’re doing is ‘decomposing’ or transforming the remains of living matter – that could be rotting wood, fallen leaves, remains of animals – and let’s not forget the tiny plants called mosses and lichens. (There are lots, lots more, that are so tiny we can’t see them even with our hand lens, to see them would need a microscope). Try and think, or ask your teacher, what’s the function of each one. Everywhere you go, if you look carefully and ask questions of this sort, most probably you’ll become aware that this process called ‘decomposition’ is going on all the time, and all over the place.
Here we can see a group of animals, some of which are eating others. Some of them move round the forest in search for food. Among them there are three ‘chains’ of predators and prey. We call them ‘food chains’, they show us who eats who. Try to find some of these chains. Then look for others which have animals in them that you often see. And don’t forget that plants, animals, and even old leaves and remains of animals are also used for food.
In this picture, which two of these animals are the only ones that can convert plants into meat? (That’s because they’re ‘vegetarians’ … we call them ‘ herbivores’ or ‘first order consumers’, because they consume plant matter directly. The animals that eat them, like the owl or snake, are ‘carnivores’ or ‘second order consumers’. The fox, which occurs in the community of the tree, is a good example of an ‘omnivore’. So, of course, are we human beings.
Here are some drawings of different kinds of birds. Each one is adapted to live in its own very special way, and in a certain kind of ‘habitat’, or living place … a particular combination of geography, climate and food resources. Try and guess what each one eats, and how it lives. What are those long legs useful for, and those fiercely curved beaks and talons?
Then look at the circle of birds. Do you know the name of any of them? Have you seen any bird like them here today? Notice how they fly. Do they fly fast in a straight line like an aircraft, or go gliding smoothly like a condor? What do you think they eat? Why do you think so? Think of other birds that have special adaptations, and add them to your list. It’s a good idea, and very interesting, to make your very own list of all the birds you’ve ever seen. Before too long, you’ll be surprised how long it gets.