The use of understory species as indicators of landform ecosystem type in heavily disturbed forest: an evaluation in the Haut-Saint-Laurent, Quebec

Abstract

An ecological study of the Municipalit6 R6gionale de Comt6 (MRC) du Haut-Saint-Laurent area, a highly disturbed landscape located south-west of Montr6al (Qu6bec), was carried out. The aim of this study was to establish links between indicator species of ecosystems and geomorphological features in a heavily disturbed background. Analysis to obtain the ecological groups are based on the links of herbaceous plants and shrubs. This approach is defined as a sociological one where grouping is based only on the species' affinity. In order to obtain ecological groups, similarity measures using the chi-square coefficient were calculated on the relative cover values of the 150 retained species from 452 plots. An intermediate linkage cluster analysis was then performed on the similarity matrix thus created. By this procedure, 56 ecological groups were obtained. These groups were then characterized according to abiotic variables, especially the geomorphological data, by the use of binary discriminant analysis. Results indicate that 39 of these 56 groups were significantly associated specifically with one of 10 morphogenic features, while 13 of these 56 groups were associated with 2 or 3 features. The ecological groups which were associated with one specific geomorphological process showed a strong link to one texture and one specific drainage class. On the other hand, the groups which were associated with several features were linked with one drainage class, usually imperfect, and a certain topographic situation. However, ecological groups showing a strong association to more than one feature can be of cartographic use, provided soil texture is analysed to determine the origin of the deposit. Finally, the type of deposit becomes non determinant on vegetation where drainage and topographic variables indicate poorly or very poorly drained sites. Non-significant groups should be used as indicators of drainage and topographical conditions but not as indicators of geomorphological deposits. The ecological groups not associated with morphogenic features demonstrated mostly a heliophilic character. Thus, the ubiquitous character of ecological groups is not exclusive to species taking advantage of disturbances. 14

Factors Influencing the Abundance of Berry Plants for Black Bears, <em>Ursus americanus</em>, in Quebec

“…In Missouri, Lyon and Sagers (1998) found that soil texture only poorly explains variation in the vegetation of riparian forests. In the Haut-Saint-Laurent, in Quebec, Meilleur et al (1992) observed no effect of soil texture on vegetation. In a steppe in the USA, more shrub species were found in intermediate soil textures, whereas more herbaceous species were encountered when soil texture was finer (Dodd and Lauenroth 1997;Lane et al 1998).…”

“…However, even in these studies, soil texture did not have a significant effect on the aboveground net primary production (Lane et al 1998). According to Meilleur et al (1992), soil texture is less important than general drainage conditions. However, it is well known that soil texture can affect the water retention potential (Dodd and Lauenroth 1997;Lane et al 1998;Singh et al 1998).…”

The relation between geomorphology and forest community types of the Haut-Saint-Laurent, Quebec

“…To reduce the number of species and to integrate many important environmental factors, the flora was separated into ecological groups already presented in Meilleur et al (1992). The ecological group concept was developed by Duvigneaud (1946).…”

“…Considered as distinct entities were, on the one hand, the herbaceous and shrub species that made up ecological groups as defined by Meilleur et al (1992), and, on the other hand, individual tree species. Great importance was given to geomorphological variables because they are one of the most stable ecological factors of the region.…”

Understory vegetation as environmental factors indicator in forest ecosystems

“…As plant coverage exposes different environmental factors such as microclimate, soil, light and physiographic properties, the direct measurement of these factors needs a costly plan (Daubenmire, 1976). To overcome this issue at low cost and within a short time, determination of ecological groups throughout a region is applied (Meilleur and Bergeron, 1992). In other words, plants reflex a complex of environmental properties, including climate and soil variables (Ellenberg, 1992).…”