(604) 822-8927 (laboratory)
Department of Forest Sciences
3041 - 2424 Main Mall
University of British Columbia
Vancouver, BC, V6T 1Z4
Energy subsidies link headwater streams and riparian forests. Forest harvesting can shift stream community composition and ecosystem functions by altering these terrestrial inputs. This project examines a) how shifts in terrestrial inputs due to forestry may affect the diversity of stream invertebrates and rates of detrital processing in small headwater streams, and b) how shifts in the timing of stream invertebrate emergence might feed back into effects on riparian forest food webs.
In the first year of this project we have characterized the decomposition rates of deciduous (Alnus rubra) and coniferous (Tsuga heterophylla) leaf litter material in 10 headwater streams. These streams varied according to their proportion of deciduous and coniferous canopy cover. Preliminary results indicate that deciduous leaf material decomposes more rapidly in streams under a deciduous canopy while the decomposition rate of coniferous material does not respond. We are presently engaged in analyzing additional data from this experiment that will allow us to make connections between this pattern and the abundance and diversity of benthic invertebrates in these streams and the existing patterns of deciduous and coniferous leaf litter accumulation.
In the 2008 field season, we plan to conduct several experiments that will allow us to more explicitly explore the mechanisms behind this pattern as well as investigating how decomposition rates are altered when the type of leaf litter (deciduous versus coniferous) is reversed.
Theory, models and empirical examples all suggest that movements of organisms and material between habitats (resource subsidies) are ubiquitous energy pathways in natural systems. Understanding the factors that determine the response of consumers in a recipient community to a resource subsidy is essential in the development of landscape level approaches to open systems (or to theory in community ecology, or population dynamics). I use theory, analytical modeling and field experimentation to identify the factors enhancing or restricting the impact of ecosystem openness on the abundance, distribution and life histories of consumers in recipient habitats.
Marczak, L.B., and J.S. Richardson (in review). Growth and development rates in a riparian spider are altered by asynchrony between the timing and amount of a resource subsidy. Oecologia
Karst, J, L.B. Marczak, M. Jones and R. Turkington (in press). The mutualism-parasitism continuum in ectomycorrhizas: a quantitative assessment using meta-analysis. Ecology (manuscript accepted June 2007)
Marczak, L.B., T.M. Hoover and J.S. Richardson (2007). Trophic interception: how boundary foraging organisms alter the flow of subsidies between habitats. Oikos 116: 1651-1662.
Marczak, L.B., R. M. Thompson and J.S. Richardson (2007). A meta-analysis of the role of trophic position, habitat type and habitat productivity in determining the food web effects of resource subsidies. Ecology 88:140-148
Marczak, L.B. and J.S. Richardson (2007). Aquatic insect emergence determines abundance and distribution of riparian spiders in a high productivity temperate rainforest. Journal of Animal Ecology 76: 687-694
Marczak, L.B. and J.S. Richardson (2006). Life history of Cordulegaster dorsalis (Odonata: Cordulegastridae) in an ephemeral habitat of southwestern British Columbia. Canadian Field Naturalist 120(4).
Miller, L.B., N. Garside, and D. Bavington, 1997. The end of community? Forms, process and pattern. Research in Community Sociology 8:21-59.
Miller, L.B., 1996. Some short thoughts on morality, ecology and nature. UnderCurrents, 8:31-32