Ever wonder why certain plants are used in restoration work and not others?
Many factors are looked at when picking plants for any project; what kind of soil, how wet the soil stays during the year, and what plants are already thriving on the site.
This post looks at what the soil will tell us about the plants that should be included in our restoration.
Soil, or dirt, is very special stuff. To call it dirt does soil a great injustice. Gardeners know that soil is the basis for any good garden. Soil is a collection of a variety of granular material, minerals, micro-organisms, decomposing organic matter, and can have a wide pH range. Knowing what the soil is like is incredibly important for determining what kind of plants will do well on a site.
To figure out the composition of the soil you can look at how it feels. When you "feel" the soil what you are actually doing is evaluating the soil texture and structure. Soil can be described as being sandy, gritty, or clumpy. In restoration we take these descriptions a step further and determine what percentage of silt, sand, and clay. We also look at the structure of the soil, is it granular, single grain, rocky, prismatic. By figuring out the texture and structure we can determine factors like how well the soil drains water, and how nutrient rich the soil might be.
It is useful to note that water drainage can also be affected by the soil being compacted by development or heavy use. If compaction is an issue then the soil would have to be loosened before restoration activities could begin.
Micro-organisms in the soil are another factor in determining what plants should be planted. Some native plants require symbiotic fungus, mycorrhizae, to flourish. Some plants that require, or do best with mycorrhizae include: Red Huckleberry, and Western Red Cedar.
Organic matter in the soil also affects the pH, which dictates what kind of plants can be used. Many native plants love acidic soil. Other natives don't fair as well because they may have evolved in prairie, or water heavy areas. pH can also let stewards know if fixing the soil is in order if the pH of the area is extremely basic or acidic. Fixing the soil, or amending it, can be accomplished through mixing in compost, mulch, or special soil treatments. Knowing the pH can make a huge difference in the success or failure of a planting plan.
Carbon to nitrogen ratio can be important not only for picking out plants, but also could be used to determine if a restoration site has been disturbed too greatly to be planted without amending the soil first. By increasing organic material, like compost or mulch, at a site the carbon nitrogen ratio can be adjusted to make a site hospitable to plants after a severe disturbance.
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