A study to explore the use of orbital remote sensing to determine native arid plant distribution

The author has identified the following significant results. It is possible to determine, from ERTS imagery, native arid plant distribution. Using techniques of multispectral masking and extensive fieldwork, three native vegetation communities were defined and mapped in the Avra Valley study area. A map was made of the Yuma area with the aid of ground truth correlations between areas of desert pavement visible on ERTS images and unique vegetation types. With the exception of the Yuma soil-vegetation correlation phenomena, only very gross differentiations of desert vegetation communities can be made from ERTS data. Vegetation communities with obvious vegetation density differences such as saguaro-paloverde, creosote bush, and riparian vegetation can be separated on the Avra Valley imagery while more similar communities such as creosote bush and saltbush could not be differentiated. It is suggested that large differences in vegetation density are needed before the signatures of two different vegetation types can be differentiated on ERTS imagery. This is due to the relatively insignificant contribution of vegetation to the total radiometric signature of a given desert scene. Where more detailed information concerning the vegetation of arid regions is required, large scale imagery is appropriate

Emotionality and perceptual defence

During the past decade, a number of experimental investigations have pro-gressively revealed the so-called "dy-namic, " or motivational, aspects of perceptual behavior. No longer do we view perception as organized solely in terms of the structural characteristics of stimulus objects or the frequency with which the individual has been ex-posed to these objects. Perceptions are structured not only with respect to the limiting stimulus conditions, but also with regard to the possibilities of re-ward (11, 12), need fulfillment (1, 7), attitudinal orientation (10), potentia

Yield of Three Range Grasses Grown Alone and in Mixtures with Legumes

Four legumes and 3 grasses in combination, and the 3 grasses alone were evaluated for forage yield and persistence for 9 years in north-central Colorado. Sicklepod milkvetch (Astragalus falcatus), alfalfa (Medicago sativa), sainfoin (Onobrychis viciifolia) or crownvetch (Coronilla varia) were planted in alternate rows with crested wheatgrass (Agropyron desertorum), Russian wildrye (Elymus junceus), or pubescent wheatgrass (A. trichophorum). Crownvetch failed to become established. Sainfoin, a short-lived species under Colorado range conditions, was gone within 5 years. Alfalfa persisted 7 years; it was killed by a combination of drought and pocket gophers. Sicklepod milkvetch persisted for the entire period. This site was too dry for pubescent wheatgrass and its stand declined rapidly. Crested wheatgrass with sicklepod milkvetch or alfalfa, and Russian wildrye with alfalfa produced the highest total yields. All grass-legume mixtures involving crested wheatgrass and Russian wildrye produced significantly more forage than the grasses grown alone in 30 cm row spacing. Crude protein content was higher for grass-legume mixtures than for the grass alone.This material was digitized as part of a cooperative project between the Society for Range Management and the University of Arizona Libraries.The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202