Data for most nonmarketed goods are patchy and noncomparable among countries, while information on industrial raw materials is usually commercially sensitive. In the case of cash crops, many of these products can be, and increasingly are, supplied from nonforest environments, such as agroecosystems and plantations. The condition of forests is not necessarily relevant to their future supply. In the longer term, this may be true also of industrial roundwood and woodfuels but forests will remain the dominant source of supply of these commodities for the foreseeable future. The spiritual and aesthetic qualities of forests constitute perhaps the most important omissions from this study.
People commonly respond to forests with a sense of awe, exhilaration, and reverence.
Human values conferred on nature, however, cannot readily be captured by the kind of quantitative analysis presented here. Scattered data exist on tourism revenues and visitor numbers to forest reserves, which some analysts have used as proxy measures of human appreciation. Such exercises have not been considered here. The very concept of analyzing forest goods and services is essentially utilitarian, while appreciation of forests as objects of expressive power is essentially aesthetic. The two perspectives cannot logically be combined.