title: Influence of Vegetation Cover on Coastal Aquifer Fluctuation and Sand Transport on Matakana Island

authors: Muller, Joshua Alois

subjects: Coastal

abstract: The Bay of Plenty beaches on the east coast of the North Island, New Zealand are of significant physical, ecological and economic importance. Over the previous century, anthropogenic development and the introduction of non-indigenous coastal plant species has lead to a degradation of many of the Bay of Plenty regions’ coastal dune environments. Restoring these sections of coastline to their natural state strengthens the barrier they provide between coastal developments and the coastal ocean, whilst also promoting the growth of native plant species and improving habitat for local macro-invertebrate species. The influence of vegetation on aquifer levels and aeolian sediment transport in the dune and foredune was investigated at Matakana Island in the Western Bay of Plenty. Monitoring of the water table between March and November 2010 was undertaken at two adjacent sample sites, with different dominant overlying vegetation, Ammophila arenaria and Spinifex sericeus. During this time, aeolian sediment transport rates were also monitored through the deployment of sediment traps and two small climate stations. Results showed that aquifer levels beneath the dune face were highly variable. Fluctuations occurred at a range of time scales, stemming from variations in tide, rainfall and profile shape. Short-term fluctuation was primarily linked to tidal forcing. Tidal fluctuations were observed in the aquifer, and differed from tidal fluctuations directly offshore in their shape and amplitude, with some lag between tide and aquifer fluctuations also evident. Aquifer fluctuation shape and lag, and differences between sample sites were linked to the beach drainage capability through aquifer porosity and permeability; hydraulic conductivity; and transmissivity. Long-term change in beach profile shape further influenced aquifer levels, with an accreting beach resulting in an elevating average aquifer level and an eroding beach resulting in a diminishing aquifer level. Aeolian sediment deposition varied greatly across the cross-shore profile. Transport rates were limited by a small beach width when high tides combined with storm surge and wave run-ups limiting the source area. Rainfall further reduced transport potential when coinciding with high wind speed events. Sediment deposition was evenly distributed in the Spinifex dominated dune system, whilst deposition in the Ammophila dune primarily occurred at the seaward limit of vegetation growth. This pattern of deposition is linked to the characteristics of each species, primarily their average height and growth density. Sediment deposition differences between sites explain variances in sediment compaction which alters dune porosity and permeability at each site. Greater porosity and permeability in the Spinifex dominated dune saw the aquifer draining more readily. Lower beach aquifer levels aid accretion and greaten the source for onshore aeolian sediment transport. Spinifex dominated dunes are therefore suggested to provide healthier beach states on Bay of Plenty beaches.

text: Influence of Vegetation Cover on Coastal Aquifer Fluctuation and Sand Transport on Matakana Island The Bay of Plenty beaches on the east coast of the North Island, New Zealand are of significant physical, ecological and economic importance. Over the previous century, anthropogenic development and the introduction of non-indigenous coastal plant species has lead to a degradation of many of the Bay of Plenty regions’ coastal dune environments. Restoring these sections of coastline to their natural state strengthens the barrier they provide between coastal developments and the coastal ocean, whilst also promoting the growth of native plant species and improving habitat for local macro-invertebrate species. The influence of vegetation on aquifer levels and aeolian sediment transport in the dune and foredune was investigated at Matakana Island in the Western Bay of Plenty. Monitoring of the water table between March and November 2010 was undertaken at two adjacent sample sites, with different dominant overlying vegetation, Ammophila arenaria and Spinifex sericeus. During this time, aeolian sediment transport rates were also monitored through the deployment of sediment traps and two small climate stations. Results showed that aquifer levels beneath the dune face were highly variable. Fluctuations occurred at a range of time scales, stemming from variations in tide, rainfall and profile shape. Short-term fluctuation was primarily linked to tidal forcing. Tidal fluctuations were observed in the aquifer, and differed from tidal fluctuations directly offshore in their shape and amplitude, with some lag between tide and aquifer fluctuations also evident. Aquifer fluctuation shape and lag, and differences between sample sites were linked to the beach drainage capability through aquifer porosity and permeability; hydraulic conductivity; and transmissivity. Long-term change in beach profile shape further influenced aquifer levels, with an accreting beach resulting in an elevating average aquifer level and an eroding beach resulting in a diminishing aquifer level. Aeolian sediment deposition varied greatly across the cross-shore profile. Transport rates were limited by a small beach width when high tides combined with storm surge and wave run-ups limiting the source area. Rainfall further reduced transport potential when coinciding with high wind speed events. Sediment deposition was evenly distributed in the Spinifex dominated dune system, whilst deposition in the Ammophila dune primarily occurred at the seaward limit of vegetation growth. This pattern of deposition is linked to the characteristics of each species, primarily their average height and growth density. Sediment deposition differences between sites explain variances in sediment compaction which alters dune porosity and permeability at each site. Greater porosity and permeability in the Spinifex dominated dune saw the aquifer draining more readily. Lower beach aquifer levels aid accretion and greaten the source for onshore aeolian sediment transport. Spinifex dominated dunes are therefore suggested to provide healthier beach states on Bay of Plenty beaches.

year: 2011

title: Intraspecific trait variation can weaken interspecific trait correlations when assessing the whole-plant economic spectrum

authors: Laughlin, Daniel C.

subjects: fine root tissue density

abstract: The worldwide plant economic spectrum hypothesis predicts that leaf, stem, and root traits are correlated across vascular plant species because carbon gain depends on leaves being adequately supplied with water and nutrients, and because construction of each organ involves a trade-off between performance and persistence. Despite its logical and intuitive appeal, this hypothesis has received mixed empirical support. If traits within species diverge in their responses to an environmental gradient, then interspecific trait correlations could be weakened when measured in natural ecosystems. To test this prediction, we measured relative growth rates (RGR) and seven functional traits that have been shown to be related to fluxes of water, nutrients, and carbon across 56 functionally diverse tree species on (1) juveniles in a controlled environment, (2) juveniles in forest understories, and (3) mature trees in forests. Leaf, stem, and fine root traits of juveniles grown in a controlled environment were closely correlated with each other, and with RGR. Remarkably, the seven leaf, stem, and fine root tissue traits spanned a single dimension of variation when measured in the controlled environment. Forest-grown juveniles expressed lower leaf mass per area, but higher wood and fine root tissue density, than greenhouse-grown juveniles. Traits and growth rates were decoupled in forest-grown juveniles and mature trees. Our results indicate that constraints exist on the covariation, not just the variation, among vegetative plant organs; however, divergent responses of traits within species to environmental gradients can mask interspecific trait correlations in natural environments. Correlations among organs and relationships between traits and RGR were strong when plants were compared in a standardized environment. Our results may reconcile the discrepancies seen among studies, by showing that if traits and growth rates of species are compared across varied environments, then the interorgan trait correlations observed in controlled conditions can weaken or disappear.

text: Intraspecific trait variation can weaken interspecific trait correlations when assessing the whole-plant economic spectrum The worldwide plant economic spectrum hypothesis predicts that leaf, stem, and root traits are correlated across vascular plant species because carbon gain depends on leaves being adequately supplied with water and nutrients, and because construction of each organ involves a trade-off between performance and persistence. Despite its logical and intuitive appeal, this hypothesis has received mixed empirical support. If traits within species diverge in their responses to an environmental gradient, then interspecific trait correlations could be weakened when measured in natural ecosystems. To test this prediction, we measured relative growth rates (RGR) and seven functional traits that have been shown to be related to fluxes of water, nutrients, and carbon across 56 functionally diverse tree species on (1) juveniles in a controlled environment, (2) juveniles in forest understories, and (3) mature trees in forests. Leaf, stem, and fine root traits of juveniles grown in a controlled environment were closely correlated with each other, and with RGR. Remarkably, the seven leaf, stem, and fine root tissue traits spanned a single dimension of variation when measured in the controlled environment. Forest-grown juveniles expressed lower leaf mass per area, but higher wood and fine root tissue density, than greenhouse-grown juveniles. Traits and growth rates were decoupled in forest-grown juveniles and mature trees. Our results indicate that constraints exist on the covariation, not just the variation, among vegetative plant organs; however, divergent responses of traits within species to environmental gradients can mask interspecific trait correlations in natural environments. Correlations among organs and relationships between traits and RGR were strong when plants were compared in a standardized environment. Our results may reconcile the discrepancies seen among studies, by showing that if traits and growth rates of species are compared across varied environments, then the interorgan trait correlations observed in controlled conditions can weaken or disappear.

year: 2017

title: Bilingual behaviour checklists: initiating a student, teacher and parent partnership in behaviour management.

authors: Glynn, Ted

subjects: bilingual education

abstract: Three bilingual (Maori and English) behavioural checklists formed part of a project designed to facilitate student, teacher and whanau collaboration in overcoming behavioural difficulties experienced by Maori students, (Hei Awhina Matua). The checklists assessed rankings by 163 students, 21 teachers and 96 whanau members of (1) contexts in which problem behaviours occur, (2) specific problem behaviours and (3) specific most valued behaviours. Data were gathered in three schools: a mainstream intermediate school with a Māori medium syndicate of three classes, a rural Kura Kaupapa Maori (Maori-controlled total immersion school) and a bilingual contributing primary school. While the three schools differed markedly in location, size, and in the proportion of Maori students enrolled, the rankings of settings and behaviours by students, teachers and whanau in each school were highly similar. The paper discusses how these data contributed to the design and development of the Hei Awhina Matua video and training manual, and provided a first step towards a collaborative student teacher and parent partnership in the management of student behaviour.

text: Bilingual behaviour checklists: initiating a student, teacher and parent partnership in behaviour management. Three bilingual (Maori and English) behavioural checklists formed part of a project designed to facilitate student, teacher and whanau collaboration in overcoming behavioural difficulties experienced by Maori students, (Hei Awhina Matua). The checklists assessed rankings by 163 students, 21 teachers and 96 whanau members of (1) contexts in which problem behaviours occur, (2) specific problem behaviours and (3) specific most valued behaviours. Data were gathered in three schools: a mainstream intermediate school with a Māori medium syndicate of three classes, a rural Kura Kaupapa Maori (Maori-controlled total immersion school) and a bilingual contributing primary school. While the three schools differed markedly in location, size, and in the proportion of Maori students enrolled, the rankings of settings and behaviours by students, teachers and whanau in each school were highly similar. The paper discusses how these data contributed to the design and development of the Hei Awhina Matua video and training manual, and provided a first step towards a collaborative student teacher and parent partnership in the management of student behaviour.

year: 2001