Showing papers on "Productivity (ecology) published in 1974"

The Hubbard Brook Ecosystem Study: Forest Biomass and Production

Abstract: A small watershed in the White Mountains of New Hampshire bearing meso- phytic, cool-temperate, broadleaf-deciduous forests was studied. Acer saccharum, Betula lutea, and Fagus grandifolia are dominant, but toward higher elevations Picea rubens and A bies balsamea also occur and indicate the transition toward subalpine climate. The stands are young (following cutting in 1909-17) but contain older trees; stand composition is thought reasonably representative of the climax. For application of the Brookhaven system of forest dimension analysis, 93 sample trees of major species were cut and roots excavated. Mean dimensions of sample trees, and the constants for the system of logarithmic regressions relating volume, surface, mass, and growth to diameter at breast height and other independent vari- ables, show decrease in tree sizes and height/diameter ratios toward higher elevations. Stand characteristics, based on application of the regressions to forest samples, show trends of decrease for the elevation belts from low to high: stem basal area 26.3, 23.7, and 22.0 m2/ha, weighted mean tree height 16.9, 16.7, and 10.8 m, weighted mean age 124, 95, and 83 yr, stem wood volume 176, 155, and 103 m3/ha, aboveground biomass (dry matter) 162, 152, and 102 t/ha, estimated volume increment 379, 365, and 223 cm3/m2/yr, aboveground net primary productivity (1956-60) 1127, 1041, and 790 g/m2/yr, and leaf area ratio 6.2, 5.7, and 5.5 m2/m2. Biomass (and, presumably, production) of root systems is 18%-21% of that aboveground. Different estimations suggest that a mean climax biomass for the watershed may be around 350 t/ha, aboveground. Net ecosystem production (i.e., addition to the pool of woody biomass in the community) is estimated as 350 g/m2/yr aboveground and 85 below- ground for 1956-60, 238 and 52 g/m2/yr for 1961-65. Analysis of stem wood volume incre- ments reveals an abrupt and striking (18%) decrease in volume growth and productivity from 1956-60 to 1961-65. The net primary productivity of the former period, with a weighted mean for the watershed of 1110 g/m2/yr above and below the ground, is thought more nearly normal for the forest. Both drought and effects of increasing air pollution (notably increasing acidity of rainfall) may be responsible for the recent decrease in productivity.

Seasonal variation in composition, plant biomass, and net primary productivity of a tropical grassland at kurukshetra, india'

Abstract: The variation in composition, plant biomass, and net primary productivity was analyzed in a tropical grassland situated within the campus of the Kurukshetra University, India, at 290 58' N latitude and 760 51' E longitude. A study of life forms indicated a thero- cryptophytic flora. Detailed phytosociological values of constituent species of the vegetation were studied at monthly intervals (May 1970 to May 1971) through tiller analysis. Most of the species were found to be contagiously distributed. The changes throughout the year in the aboveground plant biomass, standing dead, litter, and belowground biomass showed a maximum aboveground biomass in September (1,974 g/m2) and maximum belowground biomass in November (1,167 g/m2) . Examination of vertical distribution of the aboveground biomass of total vegetation as well as of the individual species indicated that different layers of vegetation are dominated by different species in different months. The aboveground net primary production was maximum during the rainy season (1,706 g/m2), and the belowground maximum occurred during the winter season (785 g/m2). Total annual net primary production is estimated to be 3,538 g/m2. The system transfer functions revealed that productivity was more aboveground-directed during the wet period and more belowground-directed during the dry period. Annual efficiency of energy capture by the primary producers was calculated to be 1.66% on the basis of half total incident solar radiation.

Significance of nanoplankton in the Chesapeake Bay estuary and problems associated with the measurement of nanoplankton productivity

Abstract: Over a 2-year program of monthly cruises covering the entire Chesapeake Bay (USA), the phytoplankters which passed 35 μm mesh were responsible for 89.6% of the phytoplankton productivity. On a single summer cruise, the <35 μm phytoplankton fraction was responsible for 93.4% of the chlorophyll a and 100% of the primary productivity. The <10 μm fraction was responsible for 81.3% of the chlorophyll a and 94% of the productivity. The difference in biomass in the <35 μm and the <10 μm fractions was significant (P=0.025), but no significant difference in the productivity could be demonstrated. Laboratory experiments demonstrated that recently assimilated carbon can be lost with gravity screening. Considering both this and the effect of herbivorous zooplankters enclosed in productivity incubations, a prescreening rather than postscreening technique is recommended for studying nanoplankton productivity.

The primary productivity of marine macrophytes from a rocky intertidal community

Abstract: This study represents the first report of primary production rates for Southern California intertidal producers. The production rates of 18 marine macrophytes near Wilson Cove, San Clemente Island, are close to those for other marine algal communities. No apparent relationship was revealed between the productivity of an alga and the division to which it belongs; however, productivity was associated with growth form. Encrusting prostrate forms were the lowest producers in terms of g C/m2/h and g C/g dry weight/h; sheet-like and finely-branched forms showed a greater productivity than coarsely-branched forms. Gelidium pusillum and Ulva californica had considerably greater production rates than the other algae measured.

Productivity and Production: Biomass Ratios of Bivalve and Gastropod Populations in an Eastern Canadian Estuary

Abstract: In a narrow, shallow estuary on the east coast of Canada, the dominant intertidal invertebrates were bivalve and gastropod molluscs. On a sand flat Mya arenaria produced 11.6 g∙m−2∙yr−1 flesh dry weight with a production:biomass ratio of 2.54, whereas Macoma balthica produced 1.93 g∙m−2∙yr−1 with a P:B ratio of 1.53. On a Spartina marsh, Littorina saxatilis produced 3.25 g∙m−2∙yr−1 with a P:B ratio of 4.11. Approximate P:B ratios were applied to biomass figures for four other species to give the following estimates of productivity: Mytilus edulis on Zostera beds 19.7 g∙m−2∙yr−1 flesh dry weight; M. edulis on Spartina beds 3.5 g∙m−2∙yr−1; Nassarius obsoletus 1.15 g∙m−2∙yr−1; Melampus lineatus 1.1 g∙m−2∙yr−1; Lacuna vincta 0.06 g∙m−2∙yr−1. A total production of the molluscs in the estuary is estimated at 4.7% of the production of Spartina and Zostera (all measured in kcal). It is postulated that molluscs are the chief primary consumers in the inlet.

Primary production of edaphic algal communities in a Delaware salt marsh1

Abstract: Gross primary production of edaphic algae was estimated for five areas in a high salinity tidal marsh near Lewcs, Delaware. Salt pan and bare bank (free of angiosperms) algal production did not vary significantly from one part of the year to another. Algal productivity in the tall Spartina alterniflora and Distichlis spicata areas was greatest from midJanuary to mid-May. In the short S. alterniflora area algal productivity did not decrease in the warmest part of the year as it did in the two other grass areas. Annual cycles of light, tcmpcrature, and salinity were measured. Gross algal production was about a third of the angiosperm net production. Since much of the algal production occurs when angiosperms are dormant, it complements the pattern of angiosperm energy fixation. Primary production in the salt marsh has three components: angiosperms, planktonic algae, and attached algae. Many investigators have examined aerial angiosperm production (e.g. Keefe 1972). Phytoplankton productivity in the major stream channels of a Georgia marsh system was measured by Ragotzkic (1959) and Pomeroy ( 1959) examined the edaphic algal productivity in the same marsh. Production of the soil algae was greatest at low tide in winter and highest at high tide in summer, but total daily production (high and low tide values combined) was not significantly different at different seasons. WC believed that edaphic algal production in a more northern salt marsh would differ from that in Georgia. In addition to affecting algal activities directly, the differcnt climatic conditions would indirectly affect the algae through their influence on the angiosperms. This study was undertaken to measure the algal primary produc1 Part of a thesis submitted for the degree of Ph.D. at the University of Dclawarc. This rcscarch was supported in part by Pittman-Robertson funds made available to the State of Delaware’s Division of Fish and Wildlife, Department of Natural Resources and Environmental Control. 2 Present address : Marine Institute, The University of Georgia, Sapelo Island 31327. tion in a Delaware salt marsh and to examine the potential relationships between the algae and some environmental factors. Materials and rmthods Algal communities associated with five areas in Canary Creek near Lewes, Delaware, wcrc studied for a year. The areas were: a tall (ca. 145 cm) Spartina alterniflora Loisel. stand along a creek, a short (ca. 25 cm) S. alterniflora stand in the higher marsh, a bare bank between the two S. alterniflora stands, a Distichlis spicata L. Greene stand, and a salt pan. Randomly selected samples of the edaphic marsh communities were taken from each area 15 times during the year, and data on illuminance, temperature, salinity (surface and interstitial water ) , surface water pH, and the height of spcrmatophytc cover were collected using standard equipment. Soil for interstitial water salinity samples was obtained by coring with plastic tubing. Water movement during transport was not significant since the average water pcrcolation rates for these saturated soils (57% water) was 0.37 ml hr-l cm-2 (SE = 0.08). Evaporation was reduced by lightly stoppering the coring tubes. Interstitial water samples were obtained by wrapping soil in LIMNOLOGY AND OCEANOGRAPHY 390 MAY 1974, V. 19(3) Marsh edaphic algal production 391

Belowground productivity of two cool desert communities.

Abstract: A new technique based upon the dilution of C 14 /C 12 ratios in structural carbon of root systems during the course of the growing season was used to evaluate belowground turnover or productivity of two cool desert communities in northern Utah, USA. This technique provides a measure of turnover of the root system of established perennial plant communities avoiding many of the disadvantages of other techniques. Adjacent communities dominated by Atriplex confertifolia and Ceratoides lanata both exhibited belowground productivity values exceeding aboveground production by three-fold. The greater belowground turnover of the Atriplex-dominated community may be a factor contributing to the maintenance of a greater quantity of aboveground biomass and prolonged periods of active photosynthesis during the driest portions of the year when Ceratoides becomes largely photosynthetically inactive.

Depth distribution of photosynthetic activity in a Myriophyllum, spicatum community in Lake Wingra1

Abstract: Photosynthetic rates and productivity of Myriophyllum spicatum L. were examined in the littoral by incubating shoot sections at three rooting depths using a 14C technique. At a rooting depth of 240 cm, the interrelation of biomass and photosynthetic rates resulted in the production of 56% of the total photosynthetic productivity within 100 cm of the water surface in May. In August, 57% of the total productivity occurred within only 20 cm of the surface. Variations in the depth distribution of biomass, due to differing growth and sloughing patterns, resulted in different depth relations of photosynthesis at the other rooting depths. Light extinction and light adaptation of photosynthetic tissues were other factors determining the depth relations of photosynthesis.

Seasonal dynamics and productivity of Tanytarsus barbitarsis Freeman (Diptera: Chironomidae) in the benthos of a shallow, saline lake

Abstract: The chironomid Tanytarsus barbitarsis is the only abundant benthic species in Lake Werowrap, western Victoria, a small, shallow, highly alkaline lake in which high, fluctuating salinities (c. 36-56 g/l) impose an extremely low biotic diversity. Between successive Octobers in 1969 and 1970, the chironomids passed through about seven generations, attaining numerical densities in excess of 140,000/m². Seasonal fluctuations in density were attributed to emergence, available food, and predation by a dytiscid, Necterosoma penicillatum, occurring in high densities around the rocky marginal areas of the lake. Estimated annual net production, exclusive of mortality and first and second instar biomass, amounted to about 320 kcal/m²/yr. This is perhaps the highest estimate recorded for an inland aquatic macrobenthos community; it is especially remarkable in that evidence from salinity tolerance experiments suggests that the lake is not an optimal environment for the species.

The relationship between standing crop in sedge meadows and summer temperature

Abstract: A major focus of ecology today, as indicated by the activities of the International Biological Program, is upon various aspects of ecosystem productivity. In order that productivity may be estimated over broader areas than can be encompassed by direct measurement, it is desirable that indirect methods (cf. Lieth 1965) be devised whereby easily measured environmental variables can be used to predict either productivity itself, or quantities such as standing crop which, for unexploited vegetation of similar life form, are closely related to productivity. Brylinsky & Mann (1973) have shown recently that energy-related variables, particularly mean air temperature, length of growing season, and latitude, are excellent global predictors of freshwater phytoplankton productivity, which itself is highly correlated with phytoplankton biomass. Bray & Gorham (1964) have likewise demonstrated a strong correlation between worldwide forest litterfall, a reflection of forest productivity, and latitude, which integrates the influence of insolation, temperature, and length of growing season. The sedge meadows with which this paper deals are of much less importance than forests and freshwaters, but they do constitute a common feature of northern and midlatitude landscapes. Hence it is of value to point out that the magnitude of their standing crop, measured over a wide range of habitats, is closely related to summer temperature. This energy-related environmental variable may therefore be used in broad-scale studies to estimate approximate standing crops for sedge meadows where actual data are lacking but where data for monthly mean temperatures are readily available.

Estimates of Above-Ground Biomass and Primary Productivity in a Missouri Forest

Abstract: For the ecologist, forest primary production and biomass have somewhat different connotations than they have for the forester. Ecologists are concerned with total forest primary production and biomass, whereas foresters, at least in the past, were concerned only with primary production of the merchantable portion of the forest (Ovington 1965). However, the forester's views have somewhat diversified as a result of the tremendous pressures put upon our remaining forests (Young 1968). They recognize that ecology is basic to forest land management and that all forest processes must be considered for optimization of forest productivity and biomass. Total dry matter production is considered to be a measure of the forest's efficiency to fix energy in all components of the ecosystem. Total dry matter production is also a measure of total energy input to the system with its subsequent dissipation of energy by respiring organisms. To maximize primary production and biomass accretion for fibre production, it is logical to consider all energy pathways of the ecosystem. The material presented in this paper is part of the data collected from June 1968 to June 1971 in order to gain some insight into ecosystem dynamics of an oak-hickory forest in central Missouri, U.S.A. Data are given for net primary productivity (NPP) and biomass of herbaceous vegetation, shrubs, saplings and trees. Root NPP and biomass are not considered here.

Comparison of Three Methods of Assessing Grassland Productivity and Biomass Dynamics

Abstract: Data from three different grassland communities were analyzed to evaluate the effectiveness of three methods of estimating net production of plant communities dominated by various mixtures of grasses, forbs and shrubs. The methods were: (1) peak standing crop, (2) summation of peak biomass for each species, and (3) incremental summation of biomass increases. Each method was applied to living biomass, standing dead biomass and litter. Comparison of the methods indicates that each has its application, but in most cases summation of positive biomass increases gave maximum estimates of community net productivity.

The plankton of Richards Bay

Abstract: A study of the plankton of the estuary system of Richards Bay in South Africa has been carried out by the plankton research group at the Port Elizabeth Museum This study in conjunction with other ecological studies provide an environmental survey of the site of the Richards Bay Harbour now under construction 2 Future studies will follow the changes that occur in the harbour and the new estuary being dredged for a nature reserve in the southern half of the bay 3 Two different plankton communities are involved In the channel area near the mouth a predominantly neritic marine plankton is found In the lagoon area further up a true estuarine plankton occurs dominated by the CopepodaPseudodiaptomus andAcartia 4 While species diversity is significantly higher in the channel area, the biomass of zooplankton is significantly higher in the lake area (up to 344 mg/m3) 5 A preliminary assessment of nett secondary zooplankton production gave a maximum value of 12 mg (dry wt)/m3/day 6 The pattern of distribution of zooplankton found in this study was found to bear very little relation to the distribution of the physical and chemical parameters conventionally investigated such as salinity, temperature, dissolved oxygen and various nutrients Tidal exchange appears to be the single most important factor controlling the distribution of zooplankton in Richards Bay The estuarine zooplankton only survives beyond a point where the rate of tidal replacement is not too great This boundary and areas of concentration appears to persist irrespective of the other environmental conditions prevailing Variations in population structure indicate how tidal replacement and vertical migration affect their survival and productivity

Some effects of dredging on populations of macrobenthic organisms

Abstract: Populations of epi- and infauna were studied from 10 mo before to 11 mo after a navigation channel was dredged through a small, shallow lagoon. A new sampler which penetrated 20·30 cm into the substratum was used. Current velocities and sedimentation patterns were changed due to an altered distribution of tidal currents, although flushing time was not appreciably altered. Values of certain particulate and dissolved nutrients changed after dredging, but no correlation was observed between animal populations and fluctuations in nutrients. Significant reductions in standing crop figures and species and specimen numbers occurred in both the bay and the dredged channel. Mercenaria mercenaria populations were reduced, but there was no evidence of mass mortality. Recovery of biomass in the channel was affected by sediment composition, but seasonal and sediment type variations were not significant in the bay as a whole. Goose Creek had a high predredging epi- and infaunal standing crop estimated at 36.83 g/m2 , but the number of organisms/m2 was relatively low, indicating a preponderance of large forms. Productivity of Goose Creek was calculated at 89.87 g/m'/yr before dredging and 31.18 g/m2/yr after dredging. Productivity figures for the mixed peripheral marsh were calculated and the annual loss due to replacement of 10.87 ha of marsh by spoil areas was estimated at 49,487 kg. Altered land usage patterns tended to fix this loss on a permanent basis. The unusually profound effects of dredging reported for Goose Creek are attributed to its small size and shallowness.

Small Mammal Productivity and Consumption in Spruce Forest and Reforestation in South Sweden

Abstract: Primary production, production of and energy flow through small mammal populations, as well as their consumption, was measured by IBP methods. In a mature spruce forest with mainly granivorous species the impact by small rodents was not appreciable. In a reforestation on a clear felled area there were large annual variations in productivity with 0.5-2% total and 1-3 % "useful" primary production being consumed by small rodents. The main small mammal consumer in this habitat was Microtus agrestis (L.). Production varied between 0.5 and 5% of the assimilated energy; the differences being due mainly to species and physiological properties.

Growth rates and productivity of Cladonia arbuscula and Cladonia impexa on the Sands of Forvie, Scotland

Abstract: Cladonia arbuscula (Walk.) Rabenh. and C. impexa Harm, were found to have annual growth rates of 4.6 mm and 5.1 mm respectively. These species together contribute about 470 kg/ha per annum of dry matter in a Calluna–Empetrum dry heath community.

Variation in zooplankton biomass with hydrological regime beneath the seasonal ice, mcmurdo sound, Antarctica

Abstract: Variations in zooplankton biomass are correlated with major hydrological features of south‐eastern McMurdo Sound (77° 50'S, 166° 30’ E). Biomass values fluctuate proportionally with tidal height and tide‐influenced current speed. There is a reversal in vertical distribution of zooplankton from open to sub‐ice waters: zooplankton is most abundant near the surface in open water areas, but in sub‐ice areas the greatest abundance is in the deepest water. A sub‐ice area of high zooplankton content is explained in terms of zooplankton productivity. High biomass associated with high tide in the south‐western part of the area studied is presumed to be due to the transport of enriched open‐sea water under the ice. There is marked depletion of the sub‐ice fauna in all water layers close to Ross Island, which is apparently correlated with the presence in this area of a warmer surface current. The deeper water layers are the emergent stream of a sub‐ice circulatory current.

Photosynthetic pigments and productivity in the upwelling region of NW Africa

Abstract: Analyse de l'Ecosysteme des "Upwellings", Deuxieme Conference : Analysis of Upwelling Systems, Second Conference, 28-30 May 1973, Marseille.-- 14 pages, 13 figures, 4 tables

Limnological Studies of a Subarctic Lake System

Abstract: A limnological study was carried out on a pair of lakes within the taiga forest of interior Alaska. These lakes, Ace and Deuce Lakes, are irregular in that one of them (Deuce Lake) is meromictic, never undergoing complete circulation, and the other (Ace Lake) has a spring circulation which is confined to the surface layers and autumnal mixing is attenuated. The ionic composition is similar to lakes in the surrounding area, with somewhat higher levels of dissolved ions. The unique features of the lake system are related to the meromictic tendencies and highly colored water with rather high ionic content. Primary productivity rates are relatively high by interior Alaskan standards, and nutrient levels are high. Primary productivity is confined to the surface meter, but even so annual productivity amounts to more than 70 g C/m2-yr.

Direct and indirect counts of fungi and bacteria as indexes of microbial mass and productivity

Abstract: Kinetics of microbial mass and productivity were calculated from direct microbial counts on two leaf species during their first year of composition at two contrasting sites. Maximum microbial mass on the Fo litter surface approached 25 g/m2 of forest floor or 10 percent of the substrate weight. Corresponding productivity was about 1 g/m2·day. Fungal mass averaged 40 times greater than that of bacteria. Related serial dilution plate counts indicated qualitative aspects of colonization.

Phytoplankton productivity in findley lake

Abstract: Findley Lake is a dimictic, oligotrophic, subalpine lake located in the western Cascade Mountains, Washington. The lake is snow covered for most of the year so that the growing season was 3.5 months in 1971 and 4.5 months in 1972. Rapid melt of the lake's snow cover in summer allowed the sudden development of a phytoplankton productivity maximum (as measured by the 14C tracer method) of 86 mg m−2 hr−1 and a peak of 48 mg chlorophyll a per m1 within two weeks of surface clearing in 1972, followed by a rapid decline of productivity and biomass. Annual production (between 10 October, 1971 and 21 October, 1972) was 36 g/m2 in the 27.5 m water column. Autotrophic carbon assimilation during the snow-covered period was insignificant. The total production for the lake in 1972 was 530 kg carbon. The concentration of available nitrogen (NO2 + NO3 + NH3 as N) at 15 m ranged from 12 to 76 mg/m3 while PO4-P ranged from 0.5 to 8.3 mg/m3. In vitro nutrient enrichment experiments with natural phytoplankton communities from the lake indicated that while N and P together were growth limiting, P alone produced a growth response while N alone did not. Contributions to production from net-, nanno-, and ultraplankton were determined by fractional filtration of 14C-labeled phytoplankton samples. The nannoplankton, dominated by diatoms, accounted for 58% to 94% of productivity.

Preliminary analysis of productivity of fruiting fungi on Strzeleckie meadows

Abstract: Analysis demonstrated that the fresh ahd dry weight as well as the ash content of fungal fruit bodies collected on a forest-surrounded unmown meadow ( Stellario-Deschampsietum Freitag 1957 and Caricetum elatae W.Koch 1926) were lower than the same values for a plot of exploited mown meadow and higher than on an exploited unmown meadow ( Arrhenatheretum medioeuropaeum (Br.-Bl.) Oberd. 1952).

Nutrients and Aquatic Vegetation Effects

Abstract: After eutrophication from natural and civilizational causes is explained, the term oligotrophication is defined as the (partial) reversal of the eutrophication process under the influence of decreased nutrient inputs. Potentially limiting nutrients such as phosphorus, nitrogen, carbon, silicon, and trace metals are listed and evaluated with respect to: (1) mechanisms of nutrient limitation of primary biological productivity; (2) sources and relative abundance; and (3) regeneration and re-use in lake ecosystems. High concentrations of manganese in epilimnic waters are correlated with low abundance of blue-green algae, but manganese-resistant Cyanophyta were also found. An increase in areal loading of phosphorus of 0.1 g/m²/yr, equivalent to waste from one person per 1.2 ha (3 acres) of lake surface (0.6 ha or 1.5 acres if phosphate detergents are banned), is considered “environmental impact.”