title: Mechanisms of interference between kahikatea and grey willow in the Waikato

authors: Coleman, Emma J.

subjects: Interference

abstract: Research was undertaken to determine the nature of the coexistence between kahikatea and grey willow in the Waikato Ecological Region. Three main questions were investigated. Is grey willow inhibiting recruitment of kahikatea? If this is occurring, which mechanisms (of interference) are involved? And does anthropogenic disturbance influence this interaction?
The first and third were addressed by measuring kahikatea and grey willow populations for age, stem frequency and diameter at six sites, to assess how populations were structured, to reconstruct the population histories at each site and to determine whether kahikatea is successfully regenerating and what possible factors influence regeneration. Results indicated grey willow was establishing after kahikatea populations at all but the Totara Park site, and that once grey willow had reached the canopy, no further recruitment of kahikatea into the canopy occurred. No kahikatea saplings were present in grey willow densities above two per 10m2 and sapling presence did not always result in canopy emergence. Sites containing the highest sapling frequencies were those most recently exposed to moderate to large-scale disturbance, and those closest to a large seed source, rather than those with long established kahikatea populations. This suggests anthropogenic disturbance of certain scale and frequency can promote the regeneration of both species.
The second question was investigated using a range of methods. Dendrochronology was employed to compare diameter growth rates between the species at each site and found grey willow only performed marginally better than kahikatea and its competitive advantage in reaching the canopy faster is likely exerted via more rapid height growth rates. Experimental methods involved measuring annual height and diameter growth rates of forty introduced and twenty naturally established seedlings in various grey willow canopy treatments and water table heights in Totara Park, Hamilton city. Hemispherical photography and water table measurements were used to quantify seedling microhabitats. The greatest seedling diameter and height growth rates were recorded in the open canopy introduced treatment and the lowest in the closed canopy naturally established treatment irrespective of water table height. The reduction in summer light levels from a grey willow canopy regularly caused apical stem death or reduced growth rates of kahikatea seedlings.
Interference effects from allelopathy were investigated as previous research indicated kahikatea litter is toxic to its own seedlings. A trial was set up using potted grey willow cuttings and Sinapus alba seedlings and regularly sprayed with kahikatea litter extract. Results were inconclusive and the natural concentrations of kahikatea litter found at Totara Park did not appear to affect the growth of either species.
Overall this research suggests grey willow is inhibiting kahikatea regeneration via overtaking kahikatea growth to the canopy, shading out further recruitment, and maintaining dominance through efficient vegetative reproduction. Active management is required to ensure the return to dominance of kahikatea in Waikato swamp forests and highly disturbed sites, close to abundant seed source may provide novel opportunities for restoration.

text: Mechanisms of interference between kahikatea and grey willow in the Waikato Research was undertaken to determine the nature of the coexistence between kahikatea and grey willow in the Waikato Ecological Region. Three main questions were investigated. Is grey willow inhibiting recruitment of kahikatea? If this is occurring, which mechanisms (of interference) are involved? And does anthropogenic disturbance influence this interaction?
The first and third were addressed by measuring kahikatea and grey willow populations for age, stem frequency and diameter at six sites, to assess how populations were structured, to reconstruct the population histories at each site and to determine whether kahikatea is successfully regenerating and what possible factors influence regeneration. Results indicated grey willow was establishing after kahikatea populations at all but the Totara Park site, and that once grey willow had reached the canopy, no further recruitment of kahikatea into the canopy occurred. No kahikatea saplings were present in grey willow densities above two per 10m2 and sapling presence did not always result in canopy emergence. Sites containing the highest sapling frequencies were those most recently exposed to moderate to large-scale disturbance, and those closest to a large seed source, rather than those with long established kahikatea populations. This suggests anthropogenic disturbance of certain scale and frequency can promote the regeneration of both species.
The second question was investigated using a range of methods. Dendrochronology was employed to compare diameter growth rates between the species at each site and found grey willow only performed marginally better than kahikatea and its competitive advantage in reaching the canopy faster is likely exerted via more rapid height growth rates. Experimental methods involved measuring annual height and diameter growth rates of forty introduced and twenty naturally established seedlings in various grey willow canopy treatments and water table heights in Totara Park, Hamilton city. Hemispherical photography and water table measurements were used to quantify seedling microhabitats. The greatest seedling diameter and height growth rates were recorded in the open canopy introduced treatment and the lowest in the closed canopy naturally established treatment irrespective of water table height. The reduction in summer light levels from a grey willow canopy regularly caused apical stem death or reduced growth rates of kahikatea seedlings.
Interference effects from allelopathy were investigated as previous research indicated kahikatea litter is toxic to its own seedlings. A trial was set up using potted grey willow cuttings and Sinapus alba seedlings and regularly sprayed with kahikatea litter extract. Results were inconclusive and the natural concentrations of kahikatea litter found at Totara Park did not appear to affect the growth of either species.
Overall this research suggests grey willow is inhibiting kahikatea regeneration via overtaking kahikatea growth to the canopy, shading out further recruitment, and maintaining dominance through efficient vegetative reproduction. Active management is required to ensure the return to dominance of kahikatea in Waikato swamp forests and highly disturbed sites, close to abundant seed source may provide novel opportunities for restoration.

year: 2010

title: Do benthic macrofauna functional groups or their key constituent species better predict variation in ecosystem functioning?

authors: Petersen, Grady

subjects: Marine science

abstract: Estuarine ecosystems are important zones for primary productivity and nutrient processing, have rich communities of plants and animals and support important fisheries and are fundamental to food webs. Intertidal habitats in estuaries are highly dynamic environments, subject to tidal variation and often have strong environmental gradients of salinity, turbidity and bed sediment grain size. These environmental factors contribute to the diversity of macrofaunal assemblages which vary over a range of spatial and temporal scales. This study was based in the Manukau Harbour, New Zealand, and aimed to investigate the spatial variation of nutrient processing within the harbour, and whether this variation is best explained by biotic or abiotic variables. Additionally, DistLM models were employed to find if either macrofauna functional groups or key species in these groups serve as better predictors of ecosystem function.
To provide empirical information to a project designing a whole-estuary nutrient mixing model, a team of ecologists deployed benthic incubation chambers (0.25 m2) to measure solute fluxes, and assessed the macrofauna community and sediment characteristics at 6 intertidal sandflat sites in the Manukau Harbour over a 4 day period in December 2016. Denitrification rates were measured at 2 sites to provide information on nitrogen removal from the harbour. This thesis deals specifically with how the macrofaunal communities and how they relate to and influence nutrient fluxes.
Macrofauna collected from the Manukau Harbour were assigned functional groups based on species specific traits. Multiple regression models were performed using functional groups and ecosystem variables as predictors, and dark chamber fluxes of O2, NH4+ and NOx- as response variables. Significantly correlated functional groups (p < 0.05) were substituted for their constituent species to determine whether functional groups or individual species served as better predictors of ecosystem functioning. 
The results indicated that while functional groups may provide redundancy in terms of multiple species carrying out similar functional roles, there are key species that dominate these roles. In addition to the macrofauna functional groups, several environmental variables (mud content, phaeophytin biomass and organic content) served as important predictors for changes in ecosystem functioning. 
This suggests that macrofauna functional groups form complex relationships with environmental variables which influence ecosystem functioning through benthic metabolism and excretion and macrofaunally-mediated such as bioturbation and irrigation of sediments. These biological processes alter the oxic-anoxic boundaries and facilitate the breakdown and remineralisation of deposited organic matter, fuelling primary productivity and nitrogen cycling.
At two sites where denitrification was measured, the total amount of nitrogen leaving the water column was similar (242.3 and 234.8 µmol N m-2 h-1), however the rates of denitrification of these sites was significantly (p = 0.0001) different, suggesting that permanent removal of nitrogen varies spatially across the harbour, which can have important connotations for ecosystem management.

text: Do benthic macrofauna functional groups or their key constituent species better predict variation in ecosystem functioning? Estuarine ecosystems are important zones for primary productivity and nutrient processing, have rich communities of plants and animals and support important fisheries and are fundamental to food webs. Intertidal habitats in estuaries are highly dynamic environments, subject to tidal variation and often have strong environmental gradients of salinity, turbidity and bed sediment grain size. These environmental factors contribute to the diversity of macrofaunal assemblages which vary over a range of spatial and temporal scales. This study was based in the Manukau Harbour, New Zealand, and aimed to investigate the spatial variation of nutrient processing within the harbour, and whether this variation is best explained by biotic or abiotic variables. Additionally, DistLM models were employed to find if either macrofauna functional groups or key species in these groups serve as better predictors of ecosystem function.
To provide empirical information to a project designing a whole-estuary nutrient mixing model, a team of ecologists deployed benthic incubation chambers (0.25 m2) to measure solute fluxes, and assessed the macrofauna community and sediment characteristics at 6 intertidal sandflat sites in the Manukau Harbour over a 4 day period in December 2016. Denitrification rates were measured at 2 sites to provide information on nitrogen removal from the harbour. This thesis deals specifically with how the macrofaunal communities and how they relate to and influence nutrient fluxes.
Macrofauna collected from the Manukau Harbour were assigned functional groups based on species specific traits. Multiple regression models were performed using functional groups and ecosystem variables as predictors, and dark chamber fluxes of O2, NH4+ and NOx- as response variables. Significantly correlated functional groups (p < 0.05) were substituted for their constituent species to determine whether functional groups or individual species served as better predictors of ecosystem functioning. 
The results indicated that while functional groups may provide redundancy in terms of multiple species carrying out similar functional roles, there are key species that dominate these roles. In addition to the macrofauna functional groups, several environmental variables (mud content, phaeophytin biomass and organic content) served as important predictors for changes in ecosystem functioning. 
This suggests that macrofauna functional groups form complex relationships with environmental variables which influence ecosystem functioning through benthic metabolism and excretion and macrofaunally-mediated such as bioturbation and irrigation of sediments. These biological processes alter the oxic-anoxic boundaries and facilitate the breakdown and remineralisation of deposited organic matter, fuelling primary productivity and nitrogen cycling.
At two sites where denitrification was measured, the total amount of nitrogen leaving the water column was similar (242.3 and 234.8 µmol N m-2 h-1), however the rates of denitrification of these sites was significantly (p = 0.0001) different, suggesting that permanent removal of nitrogen varies spatially across the harbour, which can have important connotations for ecosystem management.

year: 2018

title: A survey of psychologists’ opinions and behaviours on aspects of Maori mental health

authors: Sawrey, Richard

subjects: Maori

abstract: In the majority of settings where psychologists work, particularly in State health and justice settings, Maori people are substantially over represented relative to their numbers in the general population (Durie, 1987). This situation has raised serious questions about the adequacy of both mental health services and professionals in their provision of appropriate services for Maori people. (Hui Whakaoranga, 1984; Durie, 1985). Recommendations have been given to address these deficiencies. Te Hui Whakaoranga (l984) recommended a recruitment programme for Maori into health professions and training for health workers in Maori culture. The Committee of Inquiry into Procedures used in Psychiatric Hospitals (1988) pointed out that health professionals are rarely educated in taha Maori or the application of taha Maori to the service they provide. They stated that many current training programmes create a barrier to Maori people entering the health professions. They recommended that changes occur in both the in - service and basic training of health professionals.

text: A survey of psychologists’ opinions and behaviours on aspects of Maori mental health In the majority of settings where psychologists work, particularly in State health and justice settings, Maori people are substantially over represented relative to their numbers in the general population (Durie, 1987). This situation has raised serious questions about the adequacy of both mental health services and professionals in their provision of appropriate services for Maori people. (Hui Whakaoranga, 1984; Durie, 1985). Recommendations have been given to address these deficiencies. Te Hui Whakaoranga (l984) recommended a recruitment programme for Maori into health professions and training for health workers in Maori culture. The Committee of Inquiry into Procedures used in Psychiatric Hospitals (1988) pointed out that health professionals are rarely educated in taha Maori or the application of taha Maori to the service they provide. They stated that many current training programmes create a barrier to Maori people entering the health professions. They recommended that changes occur in both the in - service and basic training of health professionals.

year: 1993