Spatial Analysis for Management and Conservation of Cactaceae and Agavaceae Species in Central Mexico

Abstract

Recognition of the accurate spatial distribution of species in the habitat is fundamental to analyze species interactions (positives as nurse plant interactions and negatives such as competition) and also to create viable conservation and management plans. We present here three study cases to illustrate the power of spatial analysis by distance indices (SADIE) as a tool to understand the ecological associations between the subject species and the associated flora: 1) We studied the positive and negative interactions of Ariocarpus kotschoubeyanus a small cactus with the dominant shrub species of a desert; since these interactions are crucial to understand the establishment, distribution pattern, and viability of their populations. A. kotschobeyanus distributes in gaps with Ia=2.144 and associated positively with Tiquilia sp (X=0.379, P<0.0001) and Opuntia meijmeri (X=0.2753, P<0.0001), and negatively with Karwinskia humboldtiana (X=-0.1948, P<0.9803) and Calanticaria bicolor (X=-0.2568, P<0.9982). 2) To improve the process of locating new populations of M. mathildae, because their location was indirectly detected by screening conspicuous associated tree species such as Bursera fagaroides and Lysiloma microphylla. For this study case we combine the SADIE analysis with GARP niche prediction models to improve the location for new populations. 3) We evaluated the spatial distribution of Agave americana and Agave salmiana under different traditional management strategies; the spatial distribution was predominantly aggregated in patches with average aggregation indices (Ia=1.09, sd=0.38). Agave species tend to be dissociated with each other and also to pine and juniper trees. The spatial distribution of agaves and associates species changes among different management strategies and in cultivars.