The physical environment of an altitudinal gradient in the rainforest of Lamington National Park, southeast Queensland

Abstract

Climate and soil properties are key factors influencing vegetation and biota. As such, an understanding of the variability in climate and soil properties along an altitudinal gradient can be used to explain changes in vegetation and biota along the same gradient. Understanding these patterns can offer a powerful predictive tool with respect to changes in climate. The temperature, relative humidity and wind speed and direction were logged throughout the day and night for up to 333 days continuously at five different altitudes in the subtropical rainforest of Lamington National Park, Queensland, Australia. In addition, soil sampling was carried out at the same sites and elements of the physical, chemical and mineralogical characteristics of the soil tested. Temperature decreased with increased altitude, although less temperature variability was experienced at higher altitudes. All sites experienced relative humidity close to 100% for most nights throughout the year, although daily temperature increases reduced humidity at most sites. Increasing windiness at the highest (1100 m above sea level (a.s.l.)) altitude reflected meso-scale synoptic conditions. Soils demonstrated increasing moisture, organic matter and acidity as elevation increased. The macro- and micro-nutrients measured showed variable responses with nitrogen increasing and the other macro-nutrients decreasing with altitude. Aluminium increased exponentially with altitude. Moisture and temperature appear to be important drivers in soil parameters and therefore biological patterning along the transect. Future climate change resulting in atmospheric warming and drying are predicted to have a significant impact on moisture availability both in the canopy and soil environments.