Archaeological sites are being lost or significantly degraded due to natural and cultural impacts that have greatest effect upon exposed or unconsolidated surfaces. Erosion has long been recognized as the mechanism which is most damaging, but in addition to the physical losses due to erosion mechanics there are other changes than can be detrimental to the remnant deposits. Soil properties, including morphological, physical, chemical, mineralogical, and biological characteristics, are thrown into disequilibrium resulting from mineral weathering, clay genesis, leaching, eluviation/illuviation, salt accumulation, pH fluctuation, and gain or loss of organic carbon.
While wind and water erosion, bioturbation, construction, and agriculture are typically cited as the sources of the problem, archaeological excavations themselves can lead to site erosion and negative effects on soil properties. Poorly chosen locations for excavations relative to natural or cultural threats, lining excavations with inappropriate materials, and backfilling without protecting the reconditioned ground surface can all contribute to rapid, immediate, and significant losses. There are also negative effects that take longer to occur as the rates of soil formation slow.
Revegetation is one of the most important, cost-efficient stabilization methods to counter these unwanted changes (particularly to halt the immediate catastrophic losses caused by erosion), but there is little data available to evaluate the longterm results on sites, artifacts, and other culturally deposited materials. Evaluating the long-term effects is important because environmental change at archaeological sites cannot be stopped, but an acceptable, knowable level of change can be achieved. Management decisions to plan and implement revegetation projects must consider a range of feasible alternatives, choose solutions based upon identified benefits, and undertake appropriate maintenance activities over a foreseeable time span.