Shifting agriculture is an adaptation to tropical soil conditions in regions where long-term, continued cultivation of the same land, without advanced techniques of soil conservation and the use of fertilizers, would be extremely detrimental to the fertility of the land. One form of shifting cultivation is the slash-and-burn system in which an area of forest is cut and burnt (leaving only stumps and some large trees) while the ashes add to the enrichment of the soil. Shifting cultivation is central to the culture and livelihoods of millions of people worldwide, however, it is the balance between agriculture and forest conservation that is not always achieved. It is this form of cultivation that often contributes to the loss of forest biodiversity which frequently causes the demise of some conifer species in tropical regions of the world