Sunday, 29 April 2012

Ways of Seeing Two

Take a look at this photo again, what do you see?

If you are wondering about the "again", then it might be worth reading Ways of Seeing One first.

Hopefully, you've zoned in on the different habitats here; woods, water, waterside, meadow and pathway. In addition, you'll have noted the fringes and transitions which support their own set of species. This is the major zoning method associated with foraging and identifying diversity in a local area, so what's next?

There are many factors which affect biodiversity. From a global perspective, climate is a huge distinguishing factor, so much so that if you were in a food library, climate zones would each have their own sections with almost no crossover, apart from at the transitions, of course. Climate is a sort of super habitat which is itself subdivided into the habitat zones we have learnt previously, albeit with some climate zone specific habitats.

An additional global modifier is altitude. With altitude, comes changes in temperature, moisture and prevailing weather, all of which affect plant growth. Here in lies the beginning of a huge area of study which we will sidestep for two reasons. The first is that in a recreational or survival foraging perspective, you're likely to be stuck in one of these super zones and have no real opportunity to change that, the other is that no matter where you are, the ways of seeing still apply. With that in mind, we'll stay local, but keep hold of altitude, more specifically how local altitude changes.

When we look around, local altitude makes the world stand up in three dimensions. A few specific features of altitude can give us many clues about the plant life and natural resources available. Let's start with Slope. Firstly, the direction of slope will define the direction of water flow. Water flows down hill, be it above or below ground. So if need water, follow the slope down, simple.

Unlike the contours on a map, which define a locus of points of common altitude, we will be taking a slightly different approach to zoning altitude. Let's start with the most simple case. If we keep walking up hill, eventually, we'll come to the top. This might seem like an over clarification, but at the top of a hill, all directions lead down. At this point, we are exposed to the elements from all directions. We are unlikely to find rich vegetation here, and often no trees either. Sometimes we don't even find soil. If anything, other than grass, we're likely to find hardy plants such as heather or gorse. Of course, if we walk up, we might get to the top of a hillock which is not actually that exposed as it has neighbouring higher hills. This is a local maxima, in mathematical terms, and though it has important qualities from a water flow perspective, it may not from a weather viewpoint. From a zoning perspective, you may wish to ignore minor local maxima.

The opposite of a local maxima or a local minima. This point on the landscape is a place where every direction is up hill. Chances are, of you're stood at a local minima, your feet are wet. If you're not stood in a lake or tarn, it's almost certainly going to be boggy and if not, a bit of digging may bring water. Open your eyes a little more and chances are you'll see another general trend down hill, this will lead to another local minima, likely larger and ultimately, if taken to its extreme, the minima which is the sea; global minima. There are regions of land which are below sea level, but these are likely to be marsh, such as the Fens in the UK (4m below) or parts of much wider arid regions which present a much more interesting survival challenge.

Typical Snowdonia
Ridges and Local Minima
Assuming we are not at one of these extremes, there will be a general trend down hill and one of three configurations. If we have slopes up on both sides, then we are in a Valley. A valley represents the most likely route for rivers and even if the valley floor is dry, then digging will generally expose ground water. There is likely to be lush vegetation in valleys.

The deeper and steeper the valley, the more shaded it will be. This will make for cold mornings and evenings. Additionally, valleys afford protection from the elements, unless of course, the wind direction is up or down it, in which case the wind can funnel, dramatically increasing speed, brrr! There are some temperature considerations with valleys, but they get quite nerdy, what with temperature inversions and all and deserves an article of its own.

The opposite of a valley is a Ridge, which is where there is a general trend up or down hill which drops off on both sides. This area of high exposure is normally the easiest route from one local maxima to another. Visibility is good here, but as with maxima, plant life can be limited.

Stick with me reader, this does have a point, I assure you. Our third and final situation is that we are merely mid slope, neither at the top or bottom in any direction. Some might argue that there is "flat", but in reality, that's just a special case of one of the above where the gradient is small. Gradient represent how steep a slope is. Where gradient is very high (steep), even at low altitude, soil doesn't hold and rocks are exposed. This can be seen clearly in the above pictures. Maximum gradient is represented by a cliff, which is essentially vertical. "Flat" zones, be they large or some small localised area, are often moist, since there is little chance for ground water to run off. They universally make poor sites for shelter. Better to find a slight gradient.

I promised a point, and so here it is. We don't need to concern ourself with actual altitude when zoning our vista, rather, we should be looking at whether or not areas are maximally high, like the tops of hills or ridges or low, like valley floors and dips. A ridge presents pretty much the same habitat factors at 100m as it does at 300m. It's not a matter of actual altitude, it's more about shape. Hill tops and ridges are exposed, valleys and dips are wet. In addition, we concern ourselves with gradient as this has an effect on soil. All of these factors have their own effect on vegetation.

Altitude Zones

Habitat and Altitude

We can now return to our original photo. I've zoned this area into high, middle, low, flood plain, waterside and basically, wet. This is because it's clearly visible, but at a distance, we might only see hight to low. We are not worried about the prevailing slope only that we can see the shapes of the area and understand what each feature presents. There are not many large areas of high gradient, but the meadow is really quite "flat".

Our original article allowed us to see the world in basic habitats. Now let's overlay a slightly improved version of that on our altitude zone map and see what we end up with.

Here you can see that altitude defines some habitat and the zones match, but elsewhere, the two form a patchwork across the landscape. Add in to this view the habitat fringes and transitions, together with extremes of steep and shallow gradient and you have a new way of looking at your environment.

In terms of recreational foraging or in a genuine survival situation, being able to make an assessment of the local environment is very important. Not only does it help us define what sort of plants might be available, but also sources of water, sites for shelter and routes to take, should be need to make a move. Basic Habitat and Altitude zones are two simple, visual dimensions which allow us to make assessments like "that meadow is going to be boggy", "there is likely to be a stream there and those trees very close are probably willow", "I bet there is rocks and pennywort over there", or "there's a section of land suitable for shelter building in those woods" all without taking a step.

Take time to notice the changes in trees and plants with respect to altitude shapes and see where water runs and settles. Combine all of this with the trees, plants and fungi we've covered on the course. A useful exercise is to take the knowledge you've learnt on your local patch and try to apply it to a brand new one. If you've made a concious effort to look and learn, your new environment will be much less unfamiliar.

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