Influence of Small Plot Size and Shape on Range Herbage Production Estimates

Dyne, George M. Van; Vogel, Willis G.; Fisser, Herbert G.

doi:10.2307/1933022

Cited by 40 publications

(22 citation statements)

References 8 publications

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“…This is well documented in studies estimating yield (e.g. Kalamakar 1932;Justesen 1932;Van Dyne et al 1963), abundance (Clapham 1932), and various forest parameters (Hasel 1938;Bormann 1953;Freese 1961).…”

Section: Univariate Estimationmentioning

confidence: 62%

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On sampling procedures in population and community ecology

1989

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In this paper we emphasize that sampling decisions in population and community ecology are context dependent. Thus, the selection of an appropriate sampling procedure should follow directly from considerations of the objectives of an investigation. We recognize eight sampling alternatives, which arise as a result of three basic dichotomies: parameter estimation versus pattern detection, univariate versus multivariate, and a discrete versus continuous sampling universe. These eight alternative sampling procedures are discussed as they relate to decisions regarding the required empirical sample size, the selection or arrangement of sampling units, and plot size and shape. Our results indicate that the decision-making process in sampling must be viewed as a flexible exercise, dictated not by generalized recommendations but by specific objectives: there is no panacea in ecological sampling. We also point to a number of unresolved sampling problems in ecology.

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Section: Univariate Estimationmentioning

confidence: 62%

“…Many plant species show a clumped pattern, however, and as a consequence plot size determination will be important in minimizing the sampling variance. Studies reporting on the effect of plot size on precision include Freese (1961), Van Dyne et al (1963), Wiegert (1967), andRam Babu et al (1981).…”

Section: Univariate Estimationmentioning

confidence: 99%

On sampling procedures in population and community ecology

1989

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“…Perimeter: area ratios also decrease as quadrat size increases. Van Dyne et al (1963) presented data indicating a positive bias in herbage weight associated with increasing perimeter: area ratios on several bunchgrass ranges in Montana. However, statistical and time efficiency must also be considered in selecting an optimum quadrat.…”

Section: Direct Harvest Methodsmentioning

confidence: 96%

Rangeland vegetation productivity and biomass

Pieper¹

1988

Vegetation Science Applications for Rangeland Analysis and Management

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Herbage weight or biomass is an important characteristic for range vegetation since it supports directly or indirectly all consumer groups. Plant biomass is also important as a measure of dominance in plant communities. Many methods have been devised to estimate plant biomass, but all have some limitations. Estimation techniques, either by plot or plant, often involve a double sampling procedure to improve on the estimates. Direct harvesting is a destructive sampling procedure which is often used when biomass is the response measured in research studies. Precipitation has been used as an independent variable to predict end-of-season biomass. However, considerable data are necessary to develop reliable relationships. Capacitance meters, biomass meters, and p-attenuation techniques have promise for specific situations, but have not received widespread support among range researchers and ecologists. All these techniques require considerable calibration before they can be used for specific situations. Plant biomass data are useful for establishing dominance of individual species, estimating livestock stocking rates, and determining range condition. IntroductionMeasurement of plant biomass or standing crop has been of interest to range workers for some time because herbivores depend directly upon plant biomass for their food. Interest in production ecology is of more recent emphasis by plant ecologists, particularly during the International Biological Program Studies during the 1970's (Milner and Hughes 1968). These studies illustrate the importance of plant biomass as an indicator of general ecological importance of individual plants and communities.

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“…The choice of sampler size is important because it may affect both the accuracy and precision of invertebrate ppulation estimates. Smdl smplers are thought to yield overestimates of variables such as plant biomass due to edge effects (Hanson 1930;Sufiatme 1947;Hendisks % 956;Wiegerl1962;Van Dyne et al .1963), while large samplers yield higher precision for the same level of replication (Smith 1938;Pechanec and Stewart 1948). Many ecologists have used large samplers to decrease smpling variability (Green 1979, p. 39), while other researchers have suggested that small samplers are the most cost effective (Smith 1938;Pechanec and Stewart 1940;Ursic and M c C l u r b 1959;Downing 1979;Green 1979, p. 38-39;John et d. 1980).…”

Section: (J7956)mentioning

confidence: 99%

Quantitative Estimation of Epiphytic Invertebrate Populations

Downing

Cyr

1985

Can. J. Fish. Aquat. Sci.

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LXpartement de Sciences Bislsgiques, biniversit6 de MsPier6al, C.P. 6 128, Succlsrsale "A", MontrCad, Qu6. M3C 317 Downing, 8 . A., and W . Cyr. 1985. Quantitative estimation of epiphytic inve~elarate populations. Can. I. Fish. Aquat. Sci. 42: 15768-E79. Quantitative comparisons were made of the relative accuracy, precision, and cost of various population estimation techniques for epiphytic invertebrates. Quadrat clipping was often more accurate than the Gerking, Macan, Minto, or KUG samplers, yielding population estimates an average of sevenfold greater where differences were found. All quadrat sizes (112 cm2 to 1 m2) usually yielded equal estimates of epiphytic invertebrate populations. The spatial variance of replicate epiphytic invertebrate samples increased with population density and decreased with the size of sampler employed ( R~ = 0.W; n = 497). AH samplers yielded equivalent levels of sampling precision. A method providing provisional estimates s f the requisite number of replicate samples for a given level of precision is presented. Greater replication is required at Iow invertebrate poputation densit or when small samplers are used. The most cost effective sampler size for the phytofauna is about 500crnX. Improved sampling design can result in u p t o fivefold reductions i n sampling effort. Taxa examined include Acari, Arnphipoda, Chironsrnidae, Cladocera, Copepoda, Gastropsda, Hirudinea, Lepidoptera, Nernatoda, Oligochaeta, Ostracoda, Trichoptera, and Turbellaria.Les auteurs ont effectue des comparaisons quantitatives de la precision, de i'exactitude et d u cs0t relatifs de diverses techniques d'estimation dgmographique d'invertebres bpiphytes. b'kchantillonage par quadrat s'est souvent r6vkl6 plus precis que les echantillonneurs Gerking, Macan, Minto s u MUG; en moyenne, cet 6chantillonnage fournissait des estimations demographiques sept fois plus &levees quand des differences ktaient pr6sentes. Toutes les tailles de quadrat (die 112 cm2 3 I m2) ont gbnkralement donne des estimations kquivalentes des populations d7nvertkbres epiphytes. La variance spatiale des echantil8ons r6p6t6s d'invertebrbs epiphytes augrnentait en fonction de la densite de la population et dirninuait en fonctisn de la taille de B'&chantillonneur utilis4 (@ -8'94; n = 497). Les auteurs ont sbtenu des taux equivalents de precision d'eckantillonnage avec tous les echantillonneurs. %Is presentent une methsde d'estimation provisoire d u nsmbre df6chantillons repet& nkcessaire A lPobtention d'un niveake donn6 de precision. U n plus grand nornbre df$chantiIions rkpetes est necessaire quand la densite des invertebr6s est faible o u que de petits echantillonneurs ssnt utilisks. Pour la phytofaune, l'echantillonneur le plus rentable est celui qui mesure environ 500cm2. Une conception arneBisr4e de l'echantillonnage peut permettre de diminuer I'effort df6chantillsnnage d'un facteur aliant jusqu'a cinq fsis. bes tawsns etudiks sont les suivants : Acari,

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Influence of Small Plot Size and Shape on Range Herbage Production Estimates

Cited by 40 publications

References 8 publications

On sampling procedures in population and community ecology

On sampling procedures in population and community ecology

Rangeland vegetation productivity and biomass

Quantitative Estimation of Epiphytic Invertebrate Populations

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