Showing papers by "Guy F. Midgley published in 2017"

Fire frequency filters species by bark traits in a savanna-forest mosaic

Abstract: Aims Savanna and forest biomes co-occur across many subtropical landscapes in Africa, and can be differentiated by their fire regime: fires are more frequent in savannas compared to forests. Bark thickness is a key trait of savanna trees, promoting their survival in this context. The rate of bark production (increment·yr−1) should therefore be critical for determining how quickly a developing sapling would be protected or bark could regenerate between two fires. Despite this, the rate of bark production has seldom been measured in studies of fire-tolerant vs fire-intolerant species. Location Hluhluwe-iMfolozi Game reserve, South Africa. Methods We examined the distribution of woody species in a South African park over 253 sites, stratified by biome. We described the bark traits of the 63 most abundant species and related them to the fire frequencies of the sites where they occur. Results Bark growth rate was a good predictor of woody plant persistence in fire-prone savanna ecosystems. A key exception was root-suckering species, which have their structure physically protected underground and can thus survive frequent fires while producing little bark. Conclusion Species of different forest types and savanna have different bark characteristics, highlighting the important role played by fire in shaping biome distribution.

Climate Change Impacts on Dwarf Succulents in Namibia as a Result of Changes in Fog and Relative Humidity

Abstract: The Succulent Karoo is well known for being rich in species with approximately 5,000 vascular plant species, and has a high floral endemicity. In this study, we investigate the current status of the dwarf succulents of Namibia, as represented by two genera in the Aizoaceae: Conophytum (restricted distribution) and Lithops (wider distribution) and examine possible climate change impacts on these genera by studying the effects on non-rainfall moisture availability (number fog days and relative humidity). Both genera show a contraction and loss of habitat, despite their drought resistant nature and adaptation to the current arid environment. This study demonstrates that climate-change induced alterations to the number of fog days in Namibia results insignificant changes in the distribution of the dwarf succulents, and shows the Atlantic coast and Orange River areas as potential refuge areas for dwarf succulents such as Conophytum and Lithops. KeywordsClimate Change; Conophytum; Lithops; Dwarf Succulents; Fog; Relative Humidity; Succulent Karoo; Namibia