PERMFILE100217 - Laserfiche WebLink

Home Browse Search

build up (illuviation). This horizon typically contains: (a) a concentration of salts, carbonates, • and colloidal clays either alone or in combination; (b) has a blocky or prismatic structure, and (c) coatings of iron and aluminum oxides may give it a darker, stronger, or redder color (Soil Survey Staff, 1998; Soil Survey Staff, 1999). Organic matter and root mass is significantly lower in the B-horizon. Microbial and mycorrhizal fungal activity is very low due to an alkaline pH, a significantly reduced organic substrate, and lower oxygen levels caused by higher concentrations of clays and salts and the resulting lower porosity. In many cases the B-horizon is a root- restricting zone because of the high clay content, increased salts and cazbonates, and low porosity. The C-horizon is the deepest layer in a soil profile. It consists of loose material or unconsolidated rock that has little soil development and is relatively unaffected by biological activity. However, in many instances the C-horizon may provide a superior rooting medium than the high clay and salt content B-horizon materials. Past mine land reclamation has documented that the mixing of topsoil and subsoil to create a maximum depth of replaced soil provides a suitable plant growth medium for promoting vegetation productivity. But, an increasing realization that this maximization of productivity has resulted in a minimization of diversity (at least beta diversity) and severe damage to soil microbial populations has brought into question past soil handling practices. With increasing scrutiny on species diversity, several studies have evaluated the affects of soil depth on diversity. The research strongly suggests that soil homogeneity and lack of landscape or habitat diversity results in vegetation stands generally populated with cool-season aggressive grasses with few fortis or shrubs (Allen, 1995; Munshower, 2000; Prodgers and Keck, 1996; Romig and Clark, 2000). In the semi-arid west, greater forb and shrub species diversity was • favored at topdressing depths between 9 and 12 inches with fewer species found at the shallow depth (<9") and deeper depth (>15") (Buchanan et al., 1999). These observations are supported in the native landscape when one considers the vegetation communities and compazes them to the soil depths occurring at various landscape positions and slope classes. Spatial redistribution of topsoils and subsoils is key to creating diversity of vegetation community types. Lands that receive topsoil favor the establishment of grasslands. Graded areas topdressed with suitable subsoil or spoil materials (i.e. no segregated topsoil) favor the establishment woody plant species. Sencindiver and Ammons (2000) thoroughly discuss the soil genesis and classification of soils formed on landscapes altered by human activities such as mining. These minesoils, many of which were leveled spoil materials, are undergoing relatively rapid soil formation processes, including accumulation of organic matter, horizon development and the development of soil structure. Establishment of native shrubs is particularly successful on selectively handled subsoil and spoil materials, especially those with higher rock contents (Buchanan et al., 1999). The key to successfully establishing plant species and vegetation community diversity within reclaimed ]ands is to create a landscape with a variety of aspects and slopes topdressed with appropriate soil types and depths. In summazy, soil salvage and reconstruction is critical for successful reclamation of drastically disturbed lands. Topsoil with its structure, organic matter, microbiology, living seeds and roots, and nutrient contents is a valuable resource that is difficult to duplicate using subsoil and amendments. Properly salvaged, handled and reconstructed topsoil and subsoil growth mediums • Appendix G 3 06/28/02