Aquatic Biological Diversity Responses to Flood Disturbance and Forest Management in Small, Forested Watersheds

We examined riparian system responses to an extreme rainfall event on 1–4 December 2007, in eleven small watersheds (mean area—13.2 km2) from 2008–2016 at debris flow, high flood, and low flood reaches (all extended overbank flows). Macroinvertebrate responses followed expected outcomes after extreme disturbance including increasing chironomids and other multi-voltine species. A core assemblage of twenty abundant and common species-maintained populations even after debris flow (likely by recolonizing quickly) with total richness during project of 253 including 183 rare species (<0.01 total abundance) supporting an annual turnover of species from 22 to 33%. Primary disturbance changes to habitat were declines in shade and in-channel wood at all reaches, more strongly at debris flow reaches. Macroinvertebrate communities across disturbance intensities became increasingly similar after the storm. Combined effects of the flood reducing channel complexity and previous logging decreasing in-channel wood recruitment from riparian systems, limits habitat complexity. Until this feature of forested watershed streams returns, there appears to be a ceiling on reach scale aquatic biological diversity.

First inland record of bull shark Carcharhinus leucas (Carcharhiniformes: Carcharhinidae) in Indonesian Borneo

An individual of bull shark Carcharhinus leucas (Müller & Henle, 1839) with c. 600-700 mm of total length was caught and photographed on 2019 in Barito River, South Kalimantan province, Indonesia. This finding is considered as a first inland record of C. leucas in Indonesian Borneo (Kalimantan). Collecting data using citizen science is needed to asses the occurence of C. leucas and evaluate the importance of riparian system in Kalimantan waters as nursery area or ranging habitat for this species.

The myth of abundance: water resources in humid regions

Water resources in humid regions are perceived as abundant, and water-governance systems are based on the expectation of consistent availability of water to meet all needs. In arid regions, in contrast, the operating assumption is that water is a scarce resource that must be allocated systematically to avoid conflict. The ‘myth of abundance’ common in humid regions is counterproductive to effective water governance. This paper provides an overview of the concepts of water scarcity and water security and explains how water governance in humid regions fits into these frameworks. It then addresses the riparian system for allocating water rights and how this system promotes the myth of abundance. Three case studies are presented from humid regions of the Anglophone world, highlighting the shortcomings of abundance-based water-governance systems in these regions. Finally, the water-security framework is advocated as an alternative that addresses fundamental flaws of the abundance-based approach, namely issues related to ecosystems, water quality, disasters, and conflict. Using a goal of water security, rather than a perception of abundance, as the basis for water governance will lead to improved outcomes, especially given future climate change and population growth.

Lidar-based approaches for estimating solar insolation in heavily forested streams

Methods to quantify solar insolation in riparian landscapes are needed due to the importance of stream temperature to aquatic biota. We have tested three lidar predictors using two approaches developed for other applications of estimating solar insolation from airborne lidar using field data collected in a heavily forested narrow stream in western Oregon, USA. We show that a raster methodology based on the light penetration index (LPI) and a synthetic hemispherical photograph approach both accurately predict solar insolation, explaining more than 73 % of the variability observed in pyranometers placed in the stream channel. We apply the LPI-based model to predict solar insolation for an entire riparian system and demonstrate that no field-based calibration is necessary to produce an unbiased prediction of solar insolation using airborne lidar alone.

Lidar-based modelling approaches for estimating solar insolation in heavily forested streams

Methods to quantify solar insolation in riparian landscapes are needed due to the importance of stream temperature to aquatic biota. We have tested two approaches developed for other applications of estimating solar insolation from airborne lidar using field data collected in a heavily forested narrow stream in western Oregon, USA. We show that a raster methodology based on the light penetration index (LPI) and a synthetic hemispherical photograph approach both accurately predict solar insolation, explaining more than 73 % or the variability observed in pyranometers placed in the stream channel. We apply the LPI based model to predict solar insolation for an entire riparian system, and demonstrate that no field-based calibration is necessary to produce unbiased prediction of solar insolation using airborne lidar alone.