Bill Freedman

The chemistry of streams in southwestern and central Nova Scotia, with particular reference to catchment vegetation and the influence of dissolved organic carbon primarily from wetlands

The percentage of wetlands in a catchment accounted for about half of the variance in transformed data for concentrations of dissolved organic carbon (DOC) in 42 Nova Scotian streams draining catchments with 11 different kinds of vegetation. Color increased with DOC, as did total dissolved nitrogen (TDN). Thecolor/DOC andDOC/TDN quotients also rose with increasing DOC, indicating a change in the quality of dissolved organic matter with increasing wetland influence. Dissolved Fe, and to a much lesser extent dissolved Al, showed a strong positive correlation with DOC. Stream pH showed a strong negative correlation with DOC, largely from wetlands, and a strong positive correlation with non- marine Ca2+ weathered from mineral soils. Non-marine SO42− from acid deposition had no apparent influence on stream pH and decreased with increasing streamwater DOC in summer, presumably owing to reduction processes in wetlands that mitigated the effects of acid deposition. Apparently, these reduction processes also produced small amounts of dissolved, non-ionic organic sulfur. Non-marine Ca2+ was related strongly to the percentage of upland hardwood forests in the catchments. Wetlands exert a profound influence on the chemistry of streams, principally through their export of DOC but also because of reduction reactions in their anerobic peats.

Aquatic vegetation of Nova Scotian lakes differing in acidity and trophic status

Abstract Aquatic macrophytes of the littoral zone were surveyed in 21 Nova Scotian lakes, and macrophyte composition was interpreted in relation to chemical and physical characteristics. The lake set included both nutrient-enriched and acidified lakes, and consequently had a wide range of water chemistry variables, notably pH (3.7–8.3) and total phosphorus (0.003–6.0 mg l −1 ). Using canonical correspondence analysis, we related differences in vegetation among lakes to 14 water chemistry and three physical variables. Alkalinity, total phosphorus, and total nitrogen were most strongly correlated with differences in vegetation between heavily enriched, moderately enriched and non-enriched lakes. Interestingly, macrophyte composition was not strongly correlated with pH. Even in a subset of lakes consisting of moderately enriched and non-enriched lakes, alkalinity, total phosphorus and total nitrogen remained strongly correlated with vegetation differences. By contrast, vegetation differences among non-enriched laks correlated most strongly with substrate slope, lake area, calcium, and alkalinity.

Conversion of natural, mixed-species forests to conifer plantations: Implications for dead organic matter and carbon storage

Aboveground carbon storage of stands of natural forest was compared with that of conifer plantations of various age in New Brunswick, Canada. The stands of natural forest were dominated by balsam f...

Effects of the herbicides 2,4-D, glyphosate, hexazinone, and triclopyr on the growth of three species of ectomycorrhizal fungi.

In recent years, herbicides have come into increasing use as a si lvicultural tool. However , little is known about their effects on important nonta rge t organisms such as mycorrhizal fungi. This information is required in order to ensure that forest ecosystems are hOt damaged by herbicide use. Here we report the results of studies of the toxici ty of four herbicides to representat ive species of ectomycorrhizal fungi that infect forest trees. The herbicides 2 ,4-D and glyphosate are presently used in silviculture in Canada, while t r ic lopyr and hexazinone are unregistered for forestry purposes. Ail four of the herbicides are registered for forestry purposes in the United States.

Effects of silvicultural use of the herbicide glyphosate on breeding birds of regenerating clearcuts in Nova Scotia, Canada

The effects of habitat changes caused by the spraying of herbicides on the breeding birds of regenerating clearcut woodland were studied for one pre-spray and four post-spray years. Aerial application of glyphosate caused large decreases in the abundance of vegetation. There was a substantial recovery of some plant taxa by the end of the second post-spray growing season, especially of Rubus spp. and various herbaceous angiosperms, and there was further recovery to the end of the fourth post-spray year. Between the pre-spray and first post-spray years, the densities of most common breeding species decreased on all treatment plots, including the reference

Use of lakes by black duck broods in relation to biological, chemical, and physical features

Characteristics of 32 freshwater lakes in central and western Nova Scotia were quantified to determine the relative influence of various biological, chemical, and physical factors on habitat selection by black ducks (Anas rubripes Brewster) during brood-rearing. Acidity and trophic status varied greatly among the waterbodies, of which 20 were used by black ducks for rearing their young. Duck brood density was positively related to lake trophic status. The highest brood densities occurred on hypertrophic waterbodies with a large anthropogenic input of nutrients.Lakes with black duck broods had significantly higher concentrations of phosphorus and nitrogen, darker water with more dissolved organic carbon, and within the littoral zone, greater macrophyte cover, greater density and biomass of pelagic invertebrates, gentler slopes, and a softer, more organic substrate. Similar trends were observed within a subset of 17 acidic lakes (pH ≤ 5.5), 8 of which supported black ducks.The density of black duck broods was significantly correlated with 17 of 20 variables, most notably total phosphorus (r= + 0.81). Partial correlation (removing the effect of total phosphorus) revealed that brood density was significantly correlated with the abundances of pelagic (r= + 0.77) and benthic (r= + 0.68) invertebrates, macrophyte cover (r= + 0.52), and substrate score (r= + 0.57), but not with other chemical variables, including pH.Our results suggest that quality brood-rearing habitat is distinguished by a combination of factors, especially available nutrients, macrophyte cover, and invertebrates, subject to constraints imposed by physical characteristics of the littoral zone of the lake. The abundance of invertebrates, the primary food of young black ducks, emerged as the most important biological factor influencing the density of black duck broods.

Potential for carbon sequestration in Canadian forests and agroecosystems

The potential for carbon (C) sequestration was examined in selectedCanadian forest settings and prairie agroecosystems under severalmanagement scenarios. A simple C budget model was developed toquantitatively examine C sequestration potential in living biomass of forestecosystems, in associated forest-product C pools, and in displaced fossil-fuelC. A review of previous studies was conducted to examine C sequestrationpotential in prairie agroecosystems. In the forest settings examined, ourwork suggests that substantial C sequestration opportunities can be realizedin the short term through the establishment of protected forest-C reserves.Where stands can be effectively protected from natural disturbance, peaklevels of biomass C storage can exceed that under alternative managementstrategies for 200 years or more. In settings where it is not feasible tomaintain protected forest-C reserves, C sequestration opportunities can berealized through maximum sustained yield management with harvestedbiomass put towards the displacement of fossil fuels. Because there is afinite capacity for C storage in protected forest-C reserves, harvesting forestbiomass and using it to displace the use of fossil fuels, either directlythrough the production of biofuels or indirectly through the production oflong-lived forest products that displace the use of energy-intensive materialssuch as steel or concrete, can provide the greatest opportunity to mitigategreenhouse gas emissions in the long term. In Canadian prairieagroecosystems, modest C sequestration can be realized while enhancingsoil fertility and improving the efficiency of crop production. This can bedone in situations where soil organic C can be enhanced without relianceupon ongoing inputs of nitrogen fertilizer, or where the use of fossil fuelsin agriculture can be reduced. More substantial C offsets can be generatedthrough the production of dedicated energy crops to displace the use offossil fuels. Where afforestation or reconstruction of native prairieecosystems on previously cultivated land is possible, this represents thegreatest opportunity to sequester C on a per unit-area basis. However,these last two strategies involve the removal of land from crop production,and so they are not applicable on as wide a scale as some other Csequestration options which only involve modifications to currentagricultural practices.

Patterns and Importance of Dissolved Organic Carbon in Four Acidic Brownwater Streams in Nova Scotia, Canada

The temporal variation and importance of dissolved organic carbon (DOC) was investigated in four brownwater streams in Nova Scotia, Canada, in basins receiving approximately 20 kg/ha/yr wet deposition of sulfate. Organic anions contributed an average of 23% of total equivalents.Within each waterbody, correlations of H+ with DOC were insignificant, whereas they were significant with sulfate. DOC was consistently correlated with concentrations Ca and Mg, suggesting that they occur as organic complexes. DOC concentrations and thus organic anions were inversely correlated with stream flow.

Music and Environmental Studies.

The use of music in environmental education (EE) can help to inform students through ideas incorporated in musical lyrics, while also enhancing interest in environmental topics. Music can also enhance perceptions of the value of the natural world, especially when nature itself is recognized as being musical. This article discusses historical and contemporary connections between music and nature, including musical sounds in nature, the fusion of natural sounds and anthropogenic music, and anthropogenic music inspired by nature, with an overarching theme of harnessing these topics to teach about the natural world and to inspire conservation values.

Seasonal variations of water chemistry in oligotrophic streams and rivers in Kejimkujik National Park, Nova Scotia

The seasonal patterns of flow and the concentrations of color, Mg, Ca, H+, Na, Cl, organic anions, SO4, and Gran alkalinity are examined for five streams or rivers in Kejimkujik National Park (Lower Mersey River, Atkins Brook, Grafton Brook, Pebbleloggitch Brook, and Beaverskin Brook). These range in organic color and acidity from very darkwater Atkins Brook (average 191 Hazen units, pH 4.2) to clearwater Beaverskin Brook (5 Hazen units, pH 5.5). In general, most dissolved substances are present in a relatively large concentration during the high-flow period of winter-spring (most notably color, Mg, H+, Ca, Na, organic anions, and SO4). In contrast, Gran alkalinity generally occurs in its highest concentration during the lowflow period. These observations suggest that during the high-flow period, substances are “flushed” from the terrestrial watersheds of these rivers and streams.