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Plant Dry Mass (plant + dry_mass)
Selected AbstractsPlant palatability and disturbance level in aquatic habitats: an experimental approach using the snail Lymnaea stagnalis (L.)FRESHWATER BIOLOGY, Issue 5 2002ARNAUD ELGER 1.,The palatability of aquatic macrophytes to the snail Lymnaea stagnalis was investigated in the laboratory. Eight species of macrophyte were selected from habitats that differed in either flood disturbance regime or nutrient status. 2.,In a non-choice test, single macrophyte species were offered to individual snails. The average amount of plant dry mass consumed per Lymnaea dry mass ranged from 3.6 ± 1.4 (±SE) to 63.6 ± 13.9 mg g,1 day,1 across plant species. In a choice test, all eight plant species were presented simultaneously to sets of five snails. The average total consumption was 66.1 ± 3.8 mg g,1 day,1 and the maximum average consumption for a single plant was 26.2 ± 3.6 mg g,1 day,1. 3.,In both tests, the amount consumed by snails differed significantly between the plant species. The species growing in undisturbed habitats were the least consumed. Habitat nutrient status was unrelated to plant palatability. 4.,These results suggest that macrophyte species growing in habitats that are rarely disturbed by floods allocate a greater proportion of their resources to resisting herbivory. [source] On the measurement of growth with applications to the modelling and analysis of plant growthFUNCTIONAL ECOLOGY, Issue 2 2000Roderick M. L. Abstract 1.,In this paper, a theoretical framework for the analysis of growth is described. Growth is equated with change in volume (V) and the growth rate is given by the equation; dV/dt = (dm/dt)(1/,) , (d,/dt)(m/,2) where m is the mass and , the density. The volume is inclusive of internal air spaces. 2.,The second term of the growth equation (see above) can be ignored if density is constant over time. Data for humans (and presumably other large animals) show that while composition changes over time, the density is approximately constant at about that of water. In that case, the growth rate can be estimated from measures of the rate of change of mass. However, the density of plants is variable (c. 0·4,1·2 g cm,3) and measures of mass and density are necessary to analyse plant growth. 3.,To use the theory as the basis of plant growth models, it is necessary to develop simple methods for estimating the surface area of roots, stems and leaves assuming that the mass and volume are known. A literature review found that the surface area to volume ratios of leaves and roots generally increase with the mass concentration of water. Theoretical arguments are used to predict that in woody stems, the situation should be reversed such that the surface area to volume ratio increases with the mass concentration of dry matter. Those relationships should be very useful in the development of plant growth models. 4.,Measures of plant dry mass and estimates of the rate of change in dry mass are shown to be very difficult to interpret because of differences in the mass concentration of dry matter between individuals and over time. 5.,It is concluded that measures of mass and density will be necessary before plant growth analysis can achieve its full potential. A framework for extending the theory to include the forces necessary for growth to occur is described. [source] Developmental shifts in watermelon growth and reproduction caused by the squash bug, Anasa tristisNEW PHYTOLOGIST, Issue 2 2002Maciej Biernacki Summary ,,Compared with leaf-feeding herbivores, little is known about how sap-feeding herbivores affect plant growth, morphology and reproduction. This study examines effects of the sap-feeding squash bug ( Anasa tristis ) on watermelon ( Citrullus lanatus ) root, leaf and reproductive structures. ,,Plants at the four-leaf stage were exposed to different densities of caged squash bugs for 67 d (to plant maturity). ,,Initial effects were on roots. Herbivory was associated with a significant reduction in mean total root length, root surface area and number of root tips, as well as an increase in root diameters. Herbivore-exposed plants had significantly more leaves, although leaf lifespan was decreased. Both total plant dry mass and fruit dry mass per unit leaf area were significantly greater in controls. Significant effects of herbivores on plant reproductive traits included delayed flower formation (by 7,12 d), change in floral sex ratio (in favor of femaleness), increased fruit abortion, and smaller fruit size. ,,Developmental consequences were related to changes in plant water relations, including decreased water-use efficiency. Water use in treated plants was three to nine times greater per unit of plant dry mass than in controls. [source] | ||||||||||