The study compared plant and avian diversity and species composition between four habitats to review the potential implications of two distinct management practices on a forestry estate, namely to rehabilitate riparian zones to grasslands or woodlands as the two habitats that historically occurred on the property.The study habitats were Plantation (Pinus trees in riparian zone), Bushland (recently harvested), Grassland (cleared of broadleaf plants), and Woodland (control). At seven sampling sites per habitat, a vegetation assessment was conducted, while birds were caught with mist nests. Plant species richness increased from Plantation to Woodland, whereas most bird species and individuals were found in Bushland. Plant and bird species composition differed significantly between habitats. Bushland and Grassland birds were closely associated with exotic forbs. Grassland attracted birds with diverse habitat and nesting-site associations, and Woodland birds associated with woody plants. It is recommended that the majority of riparian zones be managed as grasslands, although the exact affect of the biennial summer burning and presence of exotic plants on birds needs to be investigated. To attract cavity-nesting birds to the Estate, some suitable riparian zones should be rehabilitated to Woodland by planting Ficus andAcacia trees, as these trees are the most abundant and frequently occurring in this habitat. Rather than manage avian diversity per se, the African stonechat in Grassland and lesser honeyguide in Woodland can be employed as indicators of the rehabilitation state of the riparian zones.

a b s t r a c t A periodic steady state is a familiar phenomenon in many areas of theoretical biology and provides a satisfying explanation for those animal communities in which populations are observed to oscillate in a reproducible periodic manner. In this paper we explore models of three competing species described by symmetric and asymmetric May–Leonard models, and specifically investigate criteria for the existence of periodic steady states for an adapted May–Leonard model: x˙ = r(1 − x − ˛y − ˇz)x y˙ = (1 − ˇx − y − ˛z)y z˙ = (1 − ˛x − ˇy − z)z. Using the Routh–Hurwitz conditions, six inequalities that ensure the stability of the system are identified. These inequalities are solved simultaneously, using numerical methods in order to generate three-dimensional phase portraits to illustrate the steady states. Then the “stability boundary” is defined as the almost linear boundary between stability and instability. All the mathematics discussed is suitable for advanced undergraduate mathematics or applied mathematics students, offering them the opportunity to incorporate a computer algebra system such as Mathematica, DERIVE or Matlab in their investigations. The adapted May–Leonard model provides a practical application of steady states, stability and possible limit cycles of a nonlinear system.

Diets of two zooplanktivores were studied in Lake Winnipeg: the non-indigenous rainbow smelt (Osmerus mordax) and the native cisco (Coregonus artedi). Gut contents of smelt (70-130 mm total length) and cisco (100-200 mm TL) were concurrently collected with zooplankton (integrated vertical tows) from pre-determined locations throughout Lake Winnipeg in 2010 and 2011. When spatially separated, both zooplanktivores showed similar shifts from preference for fast-moving copepods during low total zooplankton density to slow-moving large cladocerans (Daphnia spp. and Eubosmina sp.) during high total zooplankton density. When spatially overlapped in the North Basin, dietary overlap was high between smelt and cisco, but possible vertical segregation was apparent during daylight-dark trawls. Diel variation in smelt diet was minimal. Overall, impact of smelt on the food web seemed weaker than in other smelt-invaded lakes, potentially owing to the warm, shallow nature of Lake Winnipeg providing a poorer quality habitat than cooler, deeper lakes.

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Diets of two zooplanktivores were studied in Lake Winnipeg: the non-indigenous rainbow smelt (Osmerus mordax) and the native cisco (Coregonus artedi). Gut contents of smelt (70-130 mm total length) and cisco (100-200 mm TL) were concurrently collected with zooplankton (integrated vertical tows) from pre-determined locations throughout Lake Winnipeg in 2010 and 2011. When spatially separated, both zooplanktivores showed similar shifts from preference for fast-moving copepods during low total zooplankton density to slow-moving large cladocerans (Daphnia spp. and Eubosmina sp.) during high total zooplankton density. When spatially overlapped in the North Basin, dietary overlap was high between smelt and cisco, but possible vertical segregation was apparent during daylight-dark trawls. Diel variation in smelt diet was minimal. Overall, impact of smelt on the food web seemed weaker than in other smelt-invaded lakes, potentially owing to the warm, shallow nature of Lake Winnipeg providing a poorer quality habitat than cooler, deeper lakes.

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Thermodynamic modelling is a relatively new technique with which to study the interactions of ionic species in solution. Using the computer program PHREEQE, and the modified version PHRQPITZ, the effects of a range of reactive anions and cations on the components of cementitious systems are studied with respect to cement barrier performance in a nuclear waste repository. A review is made of the underlying thermodynamic theory, and of the development of the technique of thermodynamic modelling, before concentrating on the program PHREEQE and the method by which it performs calculations. The technique is then applied to the CaO-SiO₂-H₂O system under the influence of sulfate, carbonate, chloride, arsenite, Na₂O, K₂O, NaCl and MgSO₄. The effects of NaCl and MgSO₄ on certain sub-systems within the CaO-Al₂O₃-H₂O system are also studied. It is calculated that Ca(OH)₂ and CSH are the main pH maintaining phases, of which CSH has the greater stability under the influence of the species considered. AFm and AFt phases also act as pH buffers, but they are quantitatively less important. A review is made of solid solutions between members of the AFm and AFt groups of minerals. Experimental methods are used to study the extent of solid solution between monosulfoaluminate and Friedel's salt, and between monosulfoaluminate and C₄AH₁₃. In the case of the former, no solid solution is observed, but an intermediate phase, designated Kuzel's salt, is observed. In the latter case, two areas of solid solution at low and high sulfate content, separated by a miscibility gap, are detected. No evidence is found to support the existence of calcium hemisulfoaluminate.

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