This literature review is a synthesis of recent publications and developments regarding the growing acceptance and potential of Alnus rubra (Bong) commonly called red alder. The project summarized some of the concerns and benefits of including red alder in coastal forest mixedwood management strategies. Some of the concerns include overtopping of conifers and competition for light. Some benefits include increases to site productivity, biodiversity, forest health and diversification of the coastal forest industry. It also examined past and current industry and government policies towards alder in mixedwood management and recent changes in some of these policies including the just released “Hardwood Management in the Coast Forest Region” policy paper. There is now recognition of the importance of alder management and there is a framework in place for patch mixedwood management in coastal BC. But before intimate mixedwood strategies are accepted and used operationally, further research and trials are required. There needs to be a better understanding of both the competetitive and beneficial effects of red alder in mixture with conifers for complex forests to in order to assist forest managers in making sustainable management decisions.

Five hundred eighty red alder along a 2.16 km portion of the Little Creek riparian zone were assessed for mortality following the 2009 Lockheed Fire near Davenport, California. The study area was divided into burn severity zones and every red alder within the riparian zone was observed and assessed for mortality. Height, diameter at breast height (DBH), and age were collected on selected trees. An estimation of red alder large woody debris (LWD) input to Little Creek since a 2010 LWD survey (Smith, 2010) was calculated using average red alder tree dimensions applied to Smalian’s formula (MLNRO, 2011). The mean proportion of dead red alder in the non-burn zone and burn-zone was .11 and .45 respectively. Volume of red alder LWD in Little Creek is estimated to have increased approximately 245% since the fire. Given other factors may have played a role in red alder mortality in Little Creek, the analysis reported here supports fire also contributed to accelerated mortality of red alder established following the catastrophic debris torrent in 1955 in Little Creek. This study provides useful information regarding fire and red alder and establishes baseline conditions of the Little Creek riparian zone following the 2009 Lockheed Fire.

Exotic species alter the streamside plant community by changing the resources available to the stream food web, causing cascading changes throughout the entire aquatic ecosystem. To better understand the impacts of exotic litter species on stream communities, investigations were made at global and local levels. A meta-analysis was performed to understand which environmental and litter quality factors impact native and exotic litter decay rates on the global scale. It was found that exotic species are likely to decay faster than native species at larger mesh sizes, and in warm temperature environments because high quality exotic leaves have a lower C:N ratio than native leaves. An urban litter decay experiment in Victoria, B.C. streams contrasting Alnus rubra, Salix sitchensis, Hedera sp., Rubus armeniacus and plastic trash found that trash decays more slowly than leaf litter, but leaf species all decay at the same rate, and stream invertebrates colonize all litter types equally. Significant differences in litter decay rates and invertebrate community alpha and Shannon diversities were also observed across the four different streams. The more that is learned about the impacts of exotic leaf litter, the better we are able to respond to keep streams as healthy and as biodiverse as possible. / Graduate / 2017-08-10 / 0329 / 0793 / kimkenn@uvic.ca