ABSTRACT Sedimentation after wildfire is a profound disturbance to the biogeomorphic character of fluvial systems. Despite this significant alteration, field data focusing on the geomorphic processes and bed morphology that form the physical structure of habitat are limited, especially over a longer-term perspective. We report results of detailed field studies following two wildfires in the same steep fluvial system in the southern California Transverse Ranges three decades apart. Substantial channel sedimentation during storms following both fires altered physical elements of habitat, which included bed elevation, step height and spacing, pool depth and spacing, grain-size distribution (D 84), and transport capacity (τ o /τ c). The postfire sediment deposits buried bedforms, decreased D 84 , and increased τ o /τ c by an order of magnitude. Incision during subsequent storms initiated recovery that depended on the attributes of post-wildfire climate variability that characterize the semiarid Mediterranean-type environment. Step-pool bedforms reappeared or reformed during the decades between wildfires as the relatively fine gravel-sized post-wildfire sediment was transported downstream, thus reestablishing the physical elements of habitat characterizing the dynamic system.

Abstract Deep marine mineral deposits are mineral deposits that have been formed outside the continental slope. Currently three main types of deposits are generally recognized: polymetallic manganese nodules, massive seafloor sulfides and cobalt-rich crusts. The authors argue that marine mineral resource management must be holistic. Holistic marine mineral management requires a clear understanding of the objectives to be achieved through mining and to assess and ensure a proper balance between costs, risks, potential gains and losses. For decades there have been substantial uncertainties regarding the short- and long-term impact of deep-sea mining on international society and the economy and, more recently, environmental issues have become central to the debate over mining the deep seabed. If deep-sea mining is to play a constructive role in the green transition towards more environmentally robust energy production and e-mobility, more ambitious interdisciplinary research is needed to provide the knowledge needed to devise a holistic approach to management of marine minerals. This includes completing thorough baseline studies in conjunction with geological exploration and devising new means of handling financial and technological uncertainties when making investment decisions and when developing regulatory frameworks.