Barry R. Taylor

Rivers Research Laboratory

Barneys River at Avondale, Nova Scotia.  Retention of leaf litter in the arrow-straight, unstable channel is very poor because rocks on the bottom move and turn over during high flows.  Decomposition rates are exceptionally high here because of voracious consumption by leaf-shredding insects.

My principal research interest is the ecology of streams and small rivers in northern Nova Scotia. Within that field I have been following three lines of research: decomposition and transport of leaf litter; restoration of habitat for Atlantic salmon and other fishes; and ecology of rare floodplain plants.  I also curate the St. FX Herbarium.  I occasionally get distracted by projects on ponds, lakes and wetlands.  A brief explanation of each of these research directions is provided below.

Decomposition and Transport of Leaf Litter

Detrital carbon (plant litter) is at once the main structural material and the energy currency supporting aquatic ecosystems.  The quantity and quality of plant litter that a river receives determines the nature and productivity of the entire ecosystem, from bacterial and fungal decomposers to benthic invertebrates and fish.  Detrital carbon also creates a strong connection between streams and the terrestrial ecosystems through which they flow.

My research examines rivers in the Antigonish area, including the South, West, Rights, James, Pomquet, Barneys and Sutherlands rivers.  All these rivers are about the same size and run in parallel drainages into the sea.  They provide a neat set of natural replicates in which to compare detrital carbon dynamics.  Work to date reveals that the dynamics of litter decomposition are very different between streams and rivers and between summer and autumn.  Microbial growth is fostered by warmer temperatures, but leaf-feeding insects are largely confined to cool streams, creating a complex response of decomposition rate to temperature.

Right:  Effect of water temperature on decomposition of alder (Alnus incana) leaves in Nova Scotia rivers.  The rate declines above 14^oC, the upper lethal temperature for the leaf-shredding stonefly, Leuctra, which is confined to cool, woodland streams.

You can read a brief technical paper on this research.

Current and future work is aimed at learning how organic matter is retained and transported in small streams compared with rivers.  Retention in Nova Scotia rivers appears to be very poor, suggesting that much material is exported to the estuaries before it can provide energy to the river ecosystem.

Restoration of Habitat for Atlantic Salmon

Populations of Atlantic salmon are in decline worldwide.  Part of the cause of the decline may be loss of suitable spawning habitat in freshwater streams because of human alterations of the channel and the basin.  Continuing efforts to restore Brierly Brook, James River and other waterways in the Antigonish area suggest that spawning success of Atlantic salmon may be dramatically improved by restoration (MacInnis et al. 2009, Floyd et al. 2009).  The restoration method uses strategically placed logs and rocks to recreate the complexity of the stream channel and encourage the stream to return to its natural structure of pools and riffles.  More recent research examines the effects of restoration on other stream fishes, as well as the consequences for benthic invertebrates and litter retention and decomposition.

Left: A digger log lying across the stream and a bank deflector (rocks at left end of log) in a restored section of Brierly Brook, Antigonish County, Nova Scotia.  The log creates a plunge pool on the downstream side while the deflector directs water flow toward the far bank, encouraging meanders.  Redistributed fine sediments have created a sand bar in the lower left of the photograph.

(Photo by Trevor Floyd)

 Acknowledgement:  The Rivers Research Laboratory is funded by Department of Fisheries and Oceans, Nova Scotia Inland  Fisheries, St. Francis Xavier University, and when necessary, bake sales.

Ecology of Rare Floodplain Plants

As a sidelight to my work on the St. FX Herbarium, I have been studying the ecology of Triosteum aurantiacum (Wild Coffee, Tinker's Coffee-weed) in river floodplains.  This provincially rare plant is widely distributed along the lower South, West and Pomquet rivers.  The floodplain forests of the region are hot-spots of plant diversity, and harbour a number of infrequent or rare species which cannot survive in the base-poor, disturbed soils of the uplands. 

Field surveys of T. aurantiacum (Taylor and Tam 2012) suggest that periodic disturbance and limited seed transport (by birds) may be as important to the distribution of the plant as any special character of wetland soils.  We also found a surprising association between T. aurantiacum and mature white ash (Fraxinus americanus) trees.  Currently we're trying to determine the germination requirements of the tough seeds, and identify the birds or other organisms responsible for dispersing seeds.  Is limited seed dispersal the reason why T. aurantiacum is found in some regional river valleys and not in others?

Triosteum aurantiacum

Canada Lily (Lilium canadense) another rare plant restricted to floodplains in northern Nova Scotia

St. FX Herbarium

I act as Curator of the St. Francis Xavier University Herbarium (Acronym: STFX), and take responsibility for maintaining and expanding the vascular plant section of the collection. (Dr. David Garbary maintains the other half of the collection, devoted to seaweeds and other algae.)  Our vascular plant collection consists of about 4500 sheets, almost all representing species from northern Nova Scotia.  The collection is actively expanding.  The photograph on the right shows new specimens waiting to be labelled and catalogued.

I am especially interested in finding new occurrences for rare plants and establishing a better record of the flora of the tri-county area of northern mainland Nova Scotia (see the GAP Project, below).  This is an area where students or serious amateurs can make a real contribution to science and to the University.  We encourage anyone who is interested in field botany to lend a hand.

The flora of northern Nova Scotia is poorly known relative to that in other parts of the province.  Unstructured collecting to augment the STFX herbarium over the past few years has produced dozens of new records of plants that are either provincially rare or previously unknown from this region.  I have begun a long-term project to at once augment the vascular plant collection at STFX and fill in missing information concerning plant distributions in northern Nova Scotia.  The project concentrates on Guysborough, Antigonish and Pictou counties, so it seemed appropriate to call it the GAP Project.

Over the course of this open-ended project, the collecting effort will concentrate on specific habitats and locations where the probability of discovering overlooked species is greatest or where our present knowledge is least complete.  I hope to make repeated visits to the same or similar habitats over the course of the season, to follow the phenology of flowering plants and capture species that might be overlooked in a single visit.  The first priorities for the GAP Project are river flood plains and dolomite outcroppings.

The GAP Project is based entirely on volunteer work.  If you wander in the woods regularly and have a keen eye and some interest in botany, we would welcome your help.