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Article Excerpt
L'evaluation de biodiversite dans les paysages naturels continue d'etre un point de mire. Pendant que certains chercheurs estiment la valeur des caracteristiques predictives, telles que des formes de relief, d'autres examinent les concentrations d'especes rares pour comprendre leur signification. Dans cet expose, j'examine deux concepts interelies. J'explore les distributions d'especes rares dans le paysage, evaluant les correlations entre les formes de relief, les nombres d'especes rares, et les sites proteges. J'examine aussi le role des sites proteges dans la conservation de biodiversite. La coincidence spatiale des plantes vasculaires rares, formes de relief, et sites proteges a ete analysee. L'analyse utilise, en partie, I'inventaire de collections de plantes rares pour une region dans le sud-ouest de I'Ontario. Cet inventaire a ete compile pour le projet Atlas of Rare Vascular Plants of Ontario. L'analyse totale combine cet inventaire avec (a) une carte des formes de relief dans le sud-ouest de l'Ontario et (b) les emplacements des sites proteges dans la meme region. Les resultats indiquent que les sites proteges sont fortement alignes avec la distribution d'especes rares. Alors que les sites proteges occupent moins que 2 pour cent de la region etudiee, environ 20 pour cent des 4379 plantes rares uniques analysees (representant 170 des 293 especes rares dans la banque de donnees ou 68%) se trouvent sur des sites proteges. De plus, alors que 42 pour cent des plantes rares se retrouvent sur un seul type de forme de relief (plaine de sable), ce type occupe seulement 18 pour cent de la region. Et alors que les plaines constituent 24 pour cent de la region, moins que 2 pour cent des plantes rares se retrouvent sur celles-ci. Fait revelateur, quatre formes de relief constituent 50 pour cent la region etudiee mais elles soutiennent plus que 80 pour cent des plantes rares.
Mots-cle: plantes vasculaire rares, forme de relief, regions naturelles, sud-ouest de l'Ontario, analyse spatiales
Introduction
The protection of biodiversity and significant natural areas is a global issue facing resource managers, ecologists and planners. Rare vascular plants are a key component of biodiversity protection, and knowledge of their spatial distribution is essential in order to ensure protection of as many species, species combinations and critical habitats as possible. In keeping with this, their distribution relative to known significant natural areas is important, as these areas are targeted by government agencies and conservation groups for protection priority, thus providing an avenue of protection for rare species. In addition, any correlation of the occurrence of rare vascular plant species with other natural features, such as landforms (e.g., McIntrye and Lavorel 1994), will help identify additional key geographical areas for protection. Such correlations may also signify the presence of unique or rare habitats, which in themselves require protection. Furthermore, systematic reserve selection procedures (Pressey 1994; Pressey et al. 1997; Brooks et al. 2001) may use an environmental surrogate, such as landform, in place of detailed species information, and the quality and usefulness of the results of such analyses depends entirely upon the relation between the surrogate and the species of interest.
Areas identified as significant natural areas (SNAs) in this paper are those areas which have been identified by ecologists, naturalists and government planners as containing high quality remnant representations of the variations of flora, fauna or vegetation of a region. Generally they support good examples of regional habitat types with an associated complement of plant and animal communities and, often, high numbers of rare species. In many instances, SNAs also coincidentally represent unique or significant landforms. This coincidence of the biological with the physical may be random in nature, or may in fact reflect a biophyscial concordance or a rarity of site type which benefits rare species.
In this paper, an examination will be made of the spatial correlations between rare vascular plants, SNAs and landforms in the Carolinian zone of Canada--a region which lies wholly within the Province of Ontario. A byproduct of this work may be the identification of new sites which will require protective efforts. Spatial analyses using GIS, with its inherent ability to overlay multiple sets of data, has in previous studies revealed new insights into resource management issues (e.g., Joy et al. 1994). This research complements the extensive amount of research conducted on gap analysis (e.g., Davis 1994; Stohlgren et al. 1997; Jennings 2000), in species mapping (e.g., Dobson et al. 1997) and on rare species themselves (e.g., Klinkenberg 1984), in species predictive modelling (e.g., Walker 1990; Wahlberg et al. 1996; Stone et al. 1997), and in traditional phytogeographical studies (Argus 1992; Catling and Catling 1993; Catling and Brownwell 1995; Pabst and Spies 1998), since this work takes both a broader perspective (e.g., a large number of rare vascular plants species are included in a study which encompasses a wide region) and a more pragmatic approach (e.g., the actual species' distributions are used in the analyses rather than theoretical range maps, the approach taken in many gap analyses).
The Carolinian zone is one of the most significant natural regions in the country, one that is biologically rich and that supports unusually high numbers of rare species (Allen et al. 1990). Documentation of species and habitats has been extensively carried out for the region (e.g., Bricker and Reader 1990; Campbell et al. 1990; Klinkenberg et al. 1990; Varga and Allen 1990; Bowles et al. 1993; Pearce 1995). Numerous biologically significant natural areas (SNAs) have been identified in the region at several levels, including regionally, provincially and nationally significant sites (Allen et al. 1990). These...
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