Standing crop

Under-grazing on the other hand will result in decreased utilisation of herbage by the animal, due to large amounts of senescent and wasted material. When a sward reaches full canopy, the rate of senescence will equal the rate of new leaf appearance and there will be no further increase in the weight of the standing crop (Fig. 2.2). 

The global average production rate of any nuclide, Q(t), at any time, t, will be primarily dependent on the cosmic ray intensity, I(t). If the intensity varies sinusoidally with a period T(u) = 2n/T), Q(t) will also vary sinusoidally. The standing crop of a nuclide in the sea water column for a production function, Q(t) = Q (1 + a cos tot), a being the amplitude, can be deduced to be 0... 

Once these nuclides deposit on the ocean floor they are likely to be subjected to particle mixing processes. In the following we discuss attenuation due to a simple case of mixing, in which the sedimentary particles are mixed to a constant depth, L, from the sediment-water interface [72,73]. For such a case the temporal variation in the standing crop (atoms/cm2) C, of the radionuclide in the mixed layer is given by ... 

Ecosystems subjected to oxidant air pollutants must be carefully observed and described individually if we are to understand and predict the complex consequences of chronic injury. Woodwell has summarized some of the expected effects of air pollutants on ecosystems elimination of sensitive species and reduction of diversity in numbers of species selective removal of larger overstoiy plants and a favoring of small plants reduction of the standing crop of organic matter, which leads to a reduction of nutrient elements held within the living system and increase in the activity of insect pests and in some diseases that hasten producer mortality. Many other effects can be suggested. 

One of the predicted effects of pollutants on eco stems suggested by Woodwell is a reduction in the standing crop of organic matter, which would lead to a reduction in nutrient elements held within the living system. The evidence discussed earlier definitely shows that primary production is much lower in an ozone>stressed conifer-forest ecosystem. This result would be anticipated in all similarly stressed natural ecosystems or agroecosystems. 

Chitin, the (l-4)-P-linked homopolymer of N-acetyl-D-glucosaminc is an immense renewable resource in the biosphere. Gooday (1) estimates both its annual production and standing crop to bt of the order of 10 to 100 billion tons. Annual production from Antarctic krill, Euphausia superba, alone, is estimated to be 5.8 -8.4 million tons. 

Standing-Crop Particles. Standing-crop, noncolloidal, particulate matter was sampled by using two techniques 1, niskin casts followed by filtration onto track-etched filters and 2, serial sieve fractionation in-line with continuous-flow centrifugation, which enabled the collection of gram quantities of suspended particles. 

Trap particles were size-fractionated in the laboratory in a manner similar to that described for the standing-crop particles. Four additional mesh sizes corresponding to those used in the pumping-system sieve unit were used to give complete correspondence with standing-crop size fractions. 

In summary, for each trap or standing-crop sampling point, eight particle-size fractions were created with nominal cutoffs of 508, 212, 114, 63, 19, 8.2, 1.0, and 0.4 pm. The 600 standing-crop and 1000 trap-mass fractions were chemically analyzed for phosphorus and major and trace elemental composition. Major particle types were identified and enumerated by optical microscopy. 

Chemical Analyses. Subsamples (<20 mg) of standing-crop-trap particulate matter were solubilized by acid digestion in sealed all-Teflon bombs (Bombco Inc.) in a procedure modified from Eggiman and Betzer (13). National Institute of Standards and Technology (NIST) standard reference materials River Sediment (SRM 1645), Urban Particulate Matter (SRM 1648), and mixed-element liquid spikes were used to check bomb performance. 

Figure 3. Particulate phosphorus concentrations (size-fractionated-standing-crop) integrated over the epilimnion.

Phosphorus settling rates were calculated as the ratio of P fluxes to standing-crop concentrations (Figure 10). Observed rates ranged from <0.1... 

Loss rates of total P from the stratified water column, based on changes in integrated standing-crop concentrations, ranged from a high of 5.5 mg/m2 per day (mid-July to late August) to a much lower rate of 0.74... 

Ferguson, R.L. and Rublee, P., 1976. Contribution of bacteria to standing crop of coastal plankton. Limnol. Oceanogr., 21 141-145. 

Maximum standing crop Algal biomass which results after cells have used up all available growth-stimulating nutrients under controlled experimental conditions. Volume 1(3). 

Curl, H., Standing crops of carbon, nitrogen, phosphorus and transfer between trophic levels in continental shelf waters south of New York, Rapp. Proc.-Verb. Cons. Int. Explor. Men, 153, 183, 1962. 

Hatcher, B.G. and Larkum, A.W.D., An experimental analysis of factors controlling the standing crop of the epilithic algal community on a coral reef, J. Exp. Mar. Biol. Ecol., 69, 61, 1983. 

Bledsoe, E.L., and Phlips, E.J. (2000) Relationships between phytoplankton standing crop and physical, chemical, and biological gradients in the Suwannee river and plume region, USA. Estuaries 23, 458-473. 

Steever, E.Z., Warren, R.S., and Niering, W.A. (1976) Tidal energy subsidy and standing crop production of Spartina altemiflora. Estuar. Coastal Shelf Sci. 4, 473-490. 

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