A study on the physical and mechanical properties of a granite outcrop for a quarry at Onikoko community, Oyo State, South-Western Nigeria

Purpose. To investigate the physical and mechanical properties of a granite outcrop for a quarry at Onikoko community in Oyo State, South-Western Nigeria. Methods. Samples of granite rock were collected from the outcrop for the laboratory determination of their physical and mechanical properties required for determining its suitability for construction and engineering purposes, and the desired properties were determined. Findings. Results from the tests conducted on the granite samples indicated the various values of physical and mechanical properties of the outcrop in the study area. The results obtained are found to be within the acceptable international standards. Hence, the granite outcrop is found to be suitable for establishing a quarry in the study area based on the results obtained. Originality.The results in this study have affirmed the fact that granite rocks must possess adequate physical and mechanical characteristics to make them suitable for construction and engineering purposes. The physico-mechanical properties of the granite outcrop evaluated in this study having their values within the international standards attest to high strength cha-racterization of the granite rock. The life span of the proposed quarry is established to be forty years, which is also an indication of rich mineralization of the area. Practical implications. Results of this study can be a useful source of information to potential investors and policy makers for the establishment of a quarry in the study area. Hence, government’s attention can be drawn to the needs of the host community for the provision of basic infrastructures. Keywords: granite outcrop, physical and mechanical properties, quarrying operation

Micranthes petiolaris variety shealyi: A New Variety of Micranthes (Section Stellares, Saxifragaceae) from South Carolina

A new variety of Micranthes is described from a low-elevation granite outcrop in Pickens County, South Carolina. It is similar to high elevation Micranthes petiolaris populations in leaf morphology and chloroplast DNA (cpDNA) sequences, but differs in its annual habit, floral morphology, phenology, and ecology. The variety is known only from the type locality, with most clusters of individuals occurring along the forested boundary of an open granite outcrop, associated with Juniperus virginiana L., and growing upon moist to saturated moss mats and/or shallow soils. A discussion comparing the proposed taxon with M. petiolaris is provided, with notes about the distribution, habitat, and taxonomy of the variety.

Description of Isoetes afloramientorum, sp. nov. (Isoetaceae), and a second record for Isoetes santacruzensis, two granite outcrop quillworts in Bolivia

A second population of the diploid Isoetes santacruzensis is reported. This extends the range of that newly described endemic of granite outcrop pools by approximately 100 kms southward into central Bolivia from its type location. Another distinct taxon has been detected in the vicinity of the new I. santacruzensis population. The morphology of probably tetraploid I. afloramientorum sp. nov. is described. A cluster of distinct taxa comparable to similar complexes seen in North America, Australia and northern Brazil may be present on Bolivian granite outcrops. There is an urgent need for field investigation of this unique and important habitat to determine the contemporary status and protection requirements of its rare and possibly endangered flora.

Precipitation seasonality promotes acquisitive and variable leaf water-economics traits in southwest Australian granite outcrop species

Southwestern Australia (SWA) is a global biodiversity hotspot characterized by a mediterranean climate and is among the world’s oldest and resource-poorest landscapes. Within this region, granite outcrops provide habitat complexity, and contribute to high levels of species diversity and endemism. Granite outcrop plant species are characterized by distinct anatomical, morphological and eco-physiological traits. So far, functional studies of SWA granite outcrop plants examined trait patterns along the stark aridity gradient that occurs in the region. Despite precipitation seasonality being an important climatic driver of plant species richness and distribution in mediterranean-type ecosystems, relationships between plant traits and precipitation seasonality remain understudied. Here, we investigated granite outcrop species’ responses to changes in precipitation seasonality in terms of average and variability values of leaf traits related to water use efficiency. We found that plants displayed more acquisitive and variable trait values with increasing precipitation seasonality. These patterns are likely associated with the long-term effect of the stable and predictable precipitation regime in the old SWA that may have fine-tuned plant water use strategies to maximize water acquisition during the most favourable season.

Fire dependency of a rock-outcrop plant Calothamnus rupestris (Myrtaceae) and implications for managing fire in south-western Australian forests

Granite outcrops embedded in south-western Australian forests provide habitat for unique biotic assemblages and refugia for fire-sensitive taxa. Discontinuous vegetation and natural barriers to fire spread enable outcrops to function as fire refugia, provided fires in the surrounding forest are not of high intensity. In Summer 2003, lightning started a fire in jarrah forest that had not been burnt for almost 20 years. The high-intensity fire burned the vegetation on Mount Cooke, a large granite outcrop, providing an opportunity to study the response of Calothamnus rupestris Schauer, a fire-sensitive serotinous plant. The population was killed by the fire, but readily regenerated from seed stored in woody capsules. The post-fire population reached maturity after ~7.5 years, whereas the seed bank is unlikely to recover to the pre-fire level until ~14 years. The likelihood of intense forest wildfires affecting outcrop communities can be reduced by frequent low-intensity prescribed burning in the surrounding forests to reduce fuel hazard and quantity. Low-intensity forest fires are unlikely to be lethal to sensitive granite-outcrop communities.