Monday, January 23, 2012

Soil is Vital

The other day I wrote about insectiverous plants and their response to nutrient poor soils. Soil is vital in so many ways and every ecosystem has its own soils. Each soil carries a particular challenge to plants. And to survive in the ecosystem, they must be able to survive on each particular soil.

A few years ago I was playing hooky during a conference in Orlando, Florida. I was determined to find some natural habitats among the endless subdivisions, highways, and strip malls. So I pulled out a map and did my best. 

I found a postage-sized nature reserve, one of many, a typical spot for the Florida uplands, which were once a chain of sandy islands. The sandy soil at this reserve has two important characteristics that you can perceive just by bending down and picking up a handful of it. First, as sand, it is almost devoid of nutrients. There is almost no organic matter in the soil, nothing for a root to take hold of. Second, the sandy soil is super porous. Any rainfall (and they get about 60 inches a year) sinks right into the layers beneath the soil. The sand, with no organic matter, holds onto almost none of it. 

In a way, this is a desert. What kinds of plants would you expect here?

Amazing to see a cactus growing in Florida, perhaps more so to see it growing in the vicinity of palm trees on a piece of land that gets so much rain. Yet, to the plants that grow here the conditions are more like a desert than what we perceive as a piece of subtropical paradise.

The little bit of organic matter, for example leaves or wood that fall from the trees, are utilized immediately and abundantly by organisms like lichens and other fungi.

As a grad student at San Francisco State University I was fascinated with unusual soil types and their specialized plant types, for example "islands" of acidic soil that showed up in the otherwise alkaline California environment contained very special groups of plants, often native to the island alone.

Speaking of islands figurative and otherwise, Janet and I traveled to Puerto Rico a few years ago. I was eager to see the Unesco dry forest on the south side of the island. I got what I bargained for and lots more. Imagine seeing cacti like these growing right on the shore.

Plants seem almost infinitely adaptable to their environments. Part of the key to this is their incredible diversity. The more species there are, the more they are able to fill every possible niche with all its variables...rainfall, temperature, and soil. From a design perspective plants give us something to think about. 

How can we design environments, urban spaces, nature reserves, even buildings, with a diversity of forms and purposes?

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