Showing papers on "Productivity (ecology) published in 1968"

Net Primary Productivity of Terrestrial Communities: Prediction from Climatological Data

Abstract: Actual evapotranspiration (AE) is shown to be a highly significant predictor of the net annual above-ground productivity in mature terrestrial plant communities. Communities included ranged from deserts and tundra to tropical forests. It is hypothesized that the relationship of AE to productivity is due to the fact that AE measures the simultaneous availability of water and solar energy, the most important rate-limiting resources in photosynthesis.

Studies on the phytoplankton and other algae of Indrasagar tank, Udaipur, India

Abstract: A study has been made of the productivity and periodicity of phytoplankton of the Indrasagar tank, Udaipur, in relation to physicochemical characteristics. Variations in the physical and chemical characteristics of water over a period of one year are described.

Estimating productivity and apparent photosynthesis from differences in consecutive measurements of total living plant parts of an Australian heathland

Abstract: Estimates of productivity and apparent photosynthesis in a typical Australian heathland were obtained by harvesting monthly over a period of 2 years. Net productivity was small (400 g m-2 year-1 or less) while the rate of apparent photosynthesis was considerable (about 6000 g m-2 year-1), representing a photosynthetic efficiency around 5 %. Below-ground production exceeded production above ground 6-10 times. Root biomass was of the order of 6500 g m-2. Death and consumption of roots was large, and most of the products of community photosynthesis were diverted below ground to replace an annual root loss of some 5500 g m-2. Community growth was a reflection of the behaviour of the dominant, Leptospermum myrsinoides. Standing biomass above ground was sensitive to the activity of this species, which produces new shoots from spring to autumn in relation to available soil water. The annual occurrence of extensive leaf abscission and high mortality of roots is correlated with high temperatures, low humidity, and depleted soil moisture.

Flooded Meadow Communities An Analysis of Their Productivity in a Wet Year

Abstract: The productivity of three plant communities differeing in moisture conditions was studied in the river basin of the Dyje near the village of Lanžhot (Southern Moravia). The communities were as follows:Serratuleto-Festucetum commutataeBalatova-Tulackova 1963,Gratiola officinalis—Carex praecox-suzae subass.Galium borealeBalatova-Tulackova 1963, andGratiola officinalis—Carex praecox-suzae subass.Rorippa silvestrisBalatova-Tulackova 1963. The associationGratiola officinalis—Carex praecox-suzae subass.Galium boreale appeared as the most productive one, its biomass maximum W=400 g . m−2 and the maximum R=0.042 g . g−1 . day−1 C=4.84 g . m−2 . day−1. Owing to extreme moisture conditions in the year 1966, the associationSerratuleto-Festucetum commutatae was also highly productive, as it reached the following maximum of dry matter production: 240 g . m−2, R=0.0388g . g−1 . day−1 C=4.64 g . m−2 . day−1. The maximum value of dry matter in the associationGratiola officinalis—Carex praecox-suzae subass.Rorippa silvestris was 220 g.m−2. Changes in dry matter production of shoots were evaluated statistically. The dry matter in the underground parts of plants in 1 square metre, collected from the 0–25 cm layer varied from 1,000 to 2,000 g.m−2. Together with records of the increasing dry matter in the shoots the author kept records of the properties of dead material.