A Test for Spatial Pattern in Vegetation Using a Monte-Carlo Simulation

Galiano, E. F.; Castro, Isabel; Sterling, A.

doi:10.2307/2260303

Cited by 19 publications

(7 citation statements)

References 21 publications

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“…Markov data set #2). However, it also found the average of patch and gap values, as Pielou (1977) and Galiano et al (1987) predicted (e.g. Markov data sets #3 and #4).…”

Section: Simulated Datasupporting

confidence: 54%

Permutation of Two‐Term Local Quadrat Variance Analysis: General concepts for interpretation of peaks

Campbell

Franklin

Gibson

et al. 1998

J Vegetation Science

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. Many ecological studies use Two‐Term Local Quadrat Variance Analysis (TTLQV) and its derivatives for spatial pattern analysis. Currently, rules for determining variance peak significance are arbitrary. Variance peaks found at block size 1 and at > 50 % of the transect length are the only peaks whose use is explicitly prohibited. Although the use of variance peaks found at block sizes > 10 % of the transect length have also been warned against, many researchers interpret them regardless. We show in this paper that variance peaks derived from TTLQV are subject to additional ‘rules of thumb’. Through the use of randomization and permutation analyses on real and simulated data of species abundance in contiguous plots along a single transect, we show that variance peaks found at block sizes 1, 2 and 3 occur frequently by chance and thus likely do not indicate biologically meaningful patterns. The use of multiple replicate transects decreases the probability of Type II error.

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“…Markov data set #2). However, it also found the average of patch and gap values, as Pielou (1977) and Galiano et al (1987) predicted (e.g. Markov data sets #3 and #4).…”

Section: Simulated Datasupporting

confidence: 54%

Permutation of Two‐Term Local Quadrat Variance Analysis: General concepts for interpretation of peaks

Campbell

Franklin

Gibson

et al. 1998

J Vegetation Science

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“…For example, a block size of 5 has an area of 5 m 2. Monte Carlo simulations were used to generate confidence intervals for each block size (Galiano et al 1987). New local variance has several advantages over other blocked-quadrat techniques including insensitivity to starting position along a transect and fewer limitations on block size (Ludwig & Goodall 1978;Ludwig 1979;Carpenter &Chaney 1983;Galiano 1983).…”

Section: Methodsmentioning

confidence: 99%

Scale dependency and the expression of hierarchical structure in Delphinium patches

Kotliar

1996

Vegetatio

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Hierarchy theory has provided a valuable conceptual framework for studies of heterogeneity. However, there have been few empirical studies of hierarchical structure and little is known about how hierarchical structure originates or varies among systems. Here, I explore how scale dependency can influence the detection of hierarchical structure. Specifically, I compared how heterogeneity changed with scale in patches of larkspur (Delphinium spp). The distribution of Delphinium nelsonii inflorescences was quite uniform over the range of measured scales (1 m2-2500 m 2) and only a single level of patchiness was observed. Aggregations ofD. barbeyi inflorescences were much more pronounced and this patchiness was evident at many scales. The number of hierarchical levels and the scales at which patchiness occurred varied both within and between plots ofD. barbeyi. Because patchiness was not strongly scale-dependent for either species, discrete patch boundaries and well-defined hierarchical levels were not usually apparent even when multiple scales of patchiness were present. In several cases, the scales of detected patchiness depended on the difference in scale between grain (resolution) and extent. I predict that because of the lack of dominant and strongly scale-dependent processes, microlandscapes such as Delphinium meadows, may be less likely to exhibit well-defined hierarchical structure than larger-scale landscapes, especially those heavily altered by human activities.

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“…Greig-Smith's analysis of variance, for instance, only offers relatively rough measures of pattern as block-analysis only provides values of departure from randomness at l, 2, 4, 8... levels, omitting intermediate readings. Hill's (1973) Local Variances can be used with continuous intervals but clump sizes detected depend on interclump distances (see Galiano, 1982;Galiano et aL, 1984). So far no satisfactory or complete study of analytical methods of vegetation pattern has been carried out, although Ludwig (1979) and Cormack (1979) discussed several methods and recommended respectively Hill's Local Variances and Mead's (1974) randomization test.…”

Section: Methods Of Analysismentioning

confidence: 99%

The small-scale pattern of Cynodon dactylon in Mediterranean pastures

Galiano

1985

Vegetatio

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The abundance of Cynodon dactylon was recorded in 50 plots presenting different geomorphological conditions and along a transect of 16 500 2 x 2 cm contiguous quadrats within a small basin 330 m in length, in the granite pediment of the Sierra de Guadarrama (Central Spain). Soil analyses were undertaken on samples from the 50 plots and the soil information matrix obtained was analysed using Principal Components Analysis and Discriminant Analysis. Results showed that in the Mediterranean pastures Cynodon dactylon was restricted to deep, well developed soils with relatively high values of cations, conductivity and organic matter, and could be used as an indicator of such soil conditions in these grasslands. The spatial pattern of the species was analysed using New Local Variances which revealed the existence of a small-scale pattern, ranging from 8 to 18 cm, present at all levels of the analysis. The size of small-scale patterns was positively correlated with species abundance and was interpreted as a relation between plant vigour and favourable soil conditions.

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A Test for Spatial Pattern in Vegetation Using a Monte-Carlo Simulation

Cited by 19 publications

References 21 publications

Permutation of Two‐Term Local Quadrat Variance Analysis: General concepts for interpretation of peaks

Permutation of Two‐Term Local Quadrat Variance Analysis: General concepts for interpretation of peaks

Scale dependency and the expression of hierarchical structure in Delphinium patches

The small-scale pattern of Cynodon dactylon in Mediterranean pastures

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