Hydrological sentinels and the relative emergence of climate change signals in New Zealand river flows

Hydrological impacts of climate change are prompting water resource and flood hazard management to adapt to non-stationary conditions. Among the factors influencing these policy decisions is the question of timing: when are we likely to see climate change effects? Using a national climate-hydrology model cascade over the 21st century, times and extents of emergence of six hydrological metrics are evaluated across New Zealand rivers. While the stringency of the emergence criteria has a significant effect on timing and extent, emergence for all metrics generally occurs after mid-century, if at all, and in the country’s South Island. Looking at the first emerging metrics, in contrast, allows us to sidestep the high uncertainties of the time of emergence, revealing mean winter flows to be the most extensive sentinel of climate change in New Zealand rivers among the metrics considered. This has implications for hydrological monitoring to inform timely climate change adaptation

Self-organization of a biogeomorphic landscape controlled by plant life-history traits

Feedbacks between geomorphology and plants are increasingly recognized as key drivers shaping a variety of landscapes. Most studies of biogeomorphic interactions have focused on the influence of physical plant characteristics, such as stem and root density, on landscape morphodynamics without considering the role of life-history traits. However, pioneer plants can have very different colonization behaviours. Fast colonizers are characterized by a high number of establishing seedlings that produce homogenous vegetation patterns. In contrast, slow colonizers are characterized by a low number of establishing seedlings that are able to expand laterally, resulting in patchy vegetation patterns. Here we combine biogeomorphic model simulations and field observations in the Western Scheldt Estuary, the Netherlands, to show that colonization behaviour can influence the evolution of wetland landscapes. We find that colonization by fast colonizers favours stabilization of pre-existing channels and consolidation of the landscape configuration. In contrast, colonization by slow colonizers facilitates the formation of new channels and thereby actively facilitates further landscape self-organization. Our findings underline the key role of life-history traits in steering landscape self-organization across different biogeomorphic systems, and potentially the long-term resilience of these landscapes to disturbances