Title: Fractal Analysis of Grass Patches Under Grazing and Flood Disturbance in an Alkaline Grassland
Abstract: A fractal analysis was
performed for grassland patterns on the Songnen plain in Northeast China, a region with
extremely heterogeneous vegetation because of alkalization. Four belt regions were selected
according to the different grazing intensity and the flood condition in 1994. Field measurements
on patch shape and size of plant communities were carried out along each region in 1997. The
perimeter area exponent and Korcak exponent were evaluated by regression method to
determine the fractal dimension of the patch boundary and patchiness of the grassland. 1. The
patchiness (Korcak exponent) of Leymus chinensis (Trin.) Tzrel, the dominant species of zonal
vegetation, increased with the grazing gradient. The perimeter area exponent (complexity of
boundaries) was the highest (0.64) in the lightly grazed grassland, and lower in the forage
grassland (0.56) and the heavily grazed grassland (0.59). 2. Both perimeter area exponent and
Korcak exponent of L. chinensis and two subdominant species (Puccinellia spp. and Aeluropus
littoralis (Gouan) Par1. var. sinensis Debeaux) of zonal vegetation were lower in the flooded
than in the non flooded grassland. The possible reason is that flood reduces the heterogeneity
of soil alkali. 3. In forage grassland, both Korcak exponent and perimeter area exponent of the
dominant species were lower than that of the sub dominant species, but showed converse
results in the heavily grazed flooded grassland. 4. Four of the six Durbin Watson tests of
regression evaluating Korcak exponent displayed significant autocorrelation in residuals. It can
be concluded that the dynamics of patchiness occurred on at least two scales in the present
data range. No significant autocorrelation was observed in residuals of regression evaluating
perimeter area exponent. It revealed that patchiness and complexity of boundary had different
scale regions.
Publication Year: 1999
Publication Date: 1999-01-01
Language: en
Type: article
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