Showing papers on "Vegetation (pathology) published in 1975"

The Ecology of Serpentine Soils

Abstract: Publisher Summary The chapter provides details of the chemistry of the minerals frequently present in ultramafic rocks, and discusses the ecology of serpentine soil. Serpentine is used by biologists to describe a group of ultramafic rocks and the soils derived from them. Three principal polymorphic forms of serpentine are recognized: chrysotile, antigorite, and lizardite. The processes by which serpentine rocks develop into soils depend on climate, time, relief, and biotic factors along with the chemical composition of the parent material. As a result many types of soil occur on serpentines. The characteristics of serpentine are briefly discussed. Serpentine vegetation has two major characteristics: Physiognomic differences from the vegetation of surrounding rocks, and rare species and combinations of species. The vegetation of serpentines presents a wide range of appearances. Biologists have concentrated on the situations where serpentine vegetation is in sharp contrast with that of the surroundings. Such contrasts do not always occur and when this happens the serpentine vegetation is often not documented. The more closely studied serpentines have many vegetation features in common but the causes of these similarities can be very different. There is much scope for further work in many fields on serpentines.

Antarctic glaciation and early Tertiary vegetation

Abstract: PALYNOLOGICAL evidence obtained from drilling in the Ross Sea by the Glomar Challenger suggests that vegetation persisted in the area until the late Oligocene and results from the same drilling programme also suggest that ice-rafting of clastic debris commenced in the late Oligocene1. The vegetation reflected in the pollen spectrum therefore seems to have been contemporaneous with early phases of glaciation.

Palynology and Paleoecology of Postglacial Sediments from the Lower Fraser River Canyon of British Columbia

Abstract: The postglacial history of vegetation in the Yale area of the lower Fraser River Canyon is described from sediments of two lakes using percentage pollen analysis supplemented with macrofossil evide...

Presettlement Vegetation in the Sagebrush-Grass Area of the Intermountain West

Abstract: Highlight: Twenty-nine journals and diaries were reviewed for their vegetation descriptions of the sagebrush-grass area in an attempt to assess the relative importance of herbaceous plants and woody brush in the northern Intermountain West. The early writings suggest a pristine vegetation visual& dominated by shrubs. Stands of grass apparently were largely confined to wet valley bottoms, moist canyons, and mountain slopes, with more e.rtensive areas in eastern Oregon near the Cascade Range. The major area was apparently covered by thick stands of brush.

Impact of Leaf-Cutting Ants on Vegetation Development at Barro Colorado Island

Abstract: Invertebrates can influence vegetation development through modification of primary productivity, gene flow, and nutrient cycling. Invertebrate consumption of leaves, twigs, bark, and wood can reduce primary productivity. Selective consumption of these organs, selective seed predation, and selective pollination can alter the species composition of the vegetation. Invertebrate activities in detritus decomposition influence the pattern and rates of nutrient cycling.

The vegetation of Tertiary islands on the Ninetyeast Ridge

Abstract: Pollen from deep-sea drilling sites on the Ninetyeast Ridge which reflects island floras that flourished in the Palaeocene and Oligocene, shows pronounced similarity to Australian and New Zealand early Tertiary floras. Although they were closer to southern landmasses during the Tertiary, these islands were truly oceanic, and their colonisation occurred through long-distance dispersal mechanisms.

System for spraying and cooling vegetation

Abstract: Automated spraying system for misting and cooling vegetation, such as ornamental and food-producing plants, shrubs and crops. A sensor having a moisture evaporation rate similar to the particular vegetation and disposed among it forms part of a circuit that controls application of a cooling mist-like spray of water vapor to the vegetation whenever the moisture level drops below a preselectable value. The spray not only irrigates leaves and roots but also provides protection against damage to the leaves by insects and heat.

C. malvarum spore concentrate, formulation, and agricultural process

Abstract: Preparation of C. malvarum spores, spore concentrates and agricultural formulations for use as a mycoherbicide by application onto undesired vegetation; e.g., teaweed or to the situs of the undesirable vegetation, controlling the undesired vegetation in cropland and other locales where the presence of the vegetation is undesired.

A phytosociological classification of the Rustenburg Nature Reser ve

Abstract: I he vegetation of the Rustenburg Nature Reserve, situated on the Magaliesberg in Acocks’s (1953) Sour Bushveld veld Type ot South Africa, is classified by the Braun-Blanquet Method. Five major vegetation types, including mam subtypes, basic community types, variations and sub-variations are described floristically, physiognomically and in terms of habitat features. The vegetation is mapped at community tvpe and variation level, at a scale of 1 : 30 000.