Recent advances and future directions in soils and sediments research

Preface: proceedings of the 13th IASWS international conference

“…Harry Owen (Grahamstown, July 2014) This is the second IASWS proceeding to be published as a Special Issue of the Journal of Soils and Sediments (JSS); the previous meeting held in Dartmouth, UK, was also published in this journal in volume 10, issue 12 (see Wharton et al 2010). The themes of this meeting, and the papers contained in the published volume, closely match those of the host journal identified in their editorial by Owens and Xu (2011). We sincerely hope that this collaboration with JSS continues into the future as a mutually beneficial arrangement between our Association and JSS.…”

Impact of global climate change and fire on the occurrence and function of understorey legumes in forest ecosystems

“…Conversely, the modification of rainfall patterns, associated with higher temperatures, could decrease the intensity of wildfires in drier, fuel-limited forests where reduced moisture may lead to less biomass to burn (Allen 2007). Feedbacks between physiological stress driven by climate change and other forest disturbance processes such as fire are poorly understood (Allen et al 2010), especially because they intervene at different scales: whereas climate change acts at a global scale by increasing atmospheric CO 2 concentrations and temperatures, fire has a more local influence on forest ecosystems (Owens and Xu 2011).…”

“…Environmental changes such as elevated atmospheric CO 2 and temperature, atmospheric N deposition, land-use change or forest fires, have modified this fragile balance. How forest ecosystems are responding to these modifications is still unclear, and it is necessary to understand the underlying processes regulating these responses in order to be able to predict how C and nutrient cycles will be affected in the long term (Magnani et al 2007;Owens and Xu 2011).…”

“…First, trees should be able to adjust their physiological responses over time to gradually changing environmental conditions (Dawson et al 2011) but in the long term, gradual and step increases in atmospheric CO 2 concentration could generate negative effects on plant photosynthesis (Sun et al 2010). Because increased CO 2 did not occur in isolation but was accompanied by elevated N deposition and altered cycles of elements due to anthropogenic activities, the outcomes of global climate change are even more difficult to predict (Xu et al 2009;Owens and Xu 2011). Most studies conclude that elevated CO 2 concentration should increase photosynthesis by stimulating the carboxylation rate of Rubisco and reducing photorespiration (Schimel 1995;Atkin et al 1999), provided that available N and water are present in sufficient amounts (Liu et al 2010(Liu et al , 2011a.…”

Bedload sediment and nutrient losses in agro-ecosystems of the Brazilian semiarid region

“…Moreover, the removal of vegetation and frequent slash and burn management in the Caatinga have affected the physical quality of its soils, their nutrient cycle (Wick et al 2000;Aguiar et al 2006;Sousa et al 2012) and also changed the dynamics of the hydrological processes (Santos et al 2011;Rodrigues et al 2013). The management of native or cultivated vegetation alters the hydrological response to surface runoff, thereby producing sediment by drag, which results from a complex interaction of hydrological and geological processes (Puigdefabregas et al 1999;Grimaldi et al 2004;Owens and Xu 2011) naturally influenced by the geomorphology (Liying et al 2013) and human actions (Bartley et al 2006;Moreira et al 2011). It should be noted that although there are studies on the production and transportation of sediments, mainly for perennial rivers in temperate and humid climates, little is known about the watersediment process that occurs in semiarid regions (Reid et al 1996;Bautista et al 2007;Méndez et al 2010).…”