Harold A. Mooney and Richard J. Hobbs At present there is enormous concern about the changes that are occurring on the surface of the earth and in the earth's atmosphere, primarily as a result of human activities. These changes, particularly in the atmosphere, have the potential for altering the earth's habitability. International pro- grams unprecedented in scope, including the International Geosphere- Biosphere Program, have been initiated to describe and understand these changes. The global change program will call for coordinated measure- ments on a global scale of those interactive...

No other disjunct pieces of land present such striking similarities as the widely sepa- 1 rated regions with a mediterranean type of climate, that is, the territories fringing the Mediterranean Sea, California, Central Chile and the southernmost strips of South Mrica and Australia. Similarities are not confined to climatic trends, but are also reflected in the physiognomy ofthe vegetation, in land use patterns and frequently in the general appearance of the landscape. The very close similarities in agricultural practices and sometimes also in rural settlements are dependent on the climatic...

capable of providing at least a relative measure of stomatal aperture were first used shortly thereafter (Darwin and Pertz, 1911). The Carnegie Institution of Washington's Desert Research Laboratory in Tucson from 1905 to 1927 was the first effort by plant physiologists and ecologists to conduct team research on the water relations of desert plants. Measurements by Stocker in the North African deserts and Indonesia (Stocker, 1928, 1935) and by Lundegardh (1922) in forest understories were pioneering attempts to understand the environmental controls on photosynthesis in the field. While these...