title: Global patterns of insect herbivory in gap and understorey environments, and their implications for woody plant carbon storage

authors: Piper, Frida I.

subjects: shade tolerance

abstract: Insect herbivory is thought to favour carbon allocation to storage in juveniles of shade-tolerant trees. This argument assumes that insect herbivory in the understorey is sufficiently intense as to select for storage; however, understoreys might be less attractive to insect herbivores than canopy gaps, because of low resource availability and - at temperate latitudes - low temperatures. Although empirical studies show that shade-tolerant species in tropical forests do allocate more photosynthate to storage than their light-demanding associates, the same pattern has not been consistently observed in temperate forests. Does this reflect a latitudinal trend in the relative activity of insect herbivory in gap versus understorey environments? To date there has been no global review of the effect of light environment on insect herbivory in forests. We postulated that if temperature is the primary factor limiting insect herbivory, the effect of gaps on rates of insect herbivory should be more evident in temperate than in tropical forests; due to low growing season temperatures in the oceanic temperate forests of the Southern Hemisphere, the effect of gaps on insect herbivory rates should in turn be stronger there than in the more continental temperate climates of the Northern Hemisphere. We examined global patterns of insect herbivory in gaps versus understories through meta-analysis of 87 conspecific comparisons of leaf damage in contrasting light environments. Overall, insect herbivory in gaps was significantly higher than in the understorey; insect herbivory was 50% higher in gaps than in understoreys of tropical forests but did not differ significantly between gaps and understories in temperate forests of either hemisphere. Results are consistent with the idea that low resource availability - and not temperature - limits insect herbivore activity in forest understoreys, especially in the tropics, and suggest the selective influence of insect herbivory on late-successional tree species may have been over-estimated.

text: Global patterns of insect herbivory in gap and understorey environments, and their implications for woody plant carbon storage Insect herbivory is thought to favour carbon allocation to storage in juveniles of shade-tolerant trees. This argument assumes that insect herbivory in the understorey is sufficiently intense as to select for storage; however, understoreys might be less attractive to insect herbivores than canopy gaps, because of low resource availability and - at temperate latitudes - low temperatures. Although empirical studies show that shade-tolerant species in tropical forests do allocate more photosynthate to storage than their light-demanding associates, the same pattern has not been consistently observed in temperate forests. Does this reflect a latitudinal trend in the relative activity of insect herbivory in gap versus understorey environments? To date there has been no global review of the effect of light environment on insect herbivory in forests. We postulated that if temperature is the primary factor limiting insect herbivory, the effect of gaps on rates of insect herbivory should be more evident in temperate than in tropical forests; due to low growing season temperatures in the oceanic temperate forests of the Southern Hemisphere, the effect of gaps on insect herbivory rates should in turn be stronger there than in the more continental temperate climates of the Northern Hemisphere. We examined global patterns of insect herbivory in gaps versus understories through meta-analysis of 87 conspecific comparisons of leaf damage in contrasting light environments. Overall, insect herbivory in gaps was significantly higher than in the understorey; insect herbivory was 50% higher in gaps than in understoreys of tropical forests but did not differ significantly between gaps and understories in temperate forests of either hemisphere. Results are consistent with the idea that low resource availability - and not temperature - limits insect herbivore activity in forest understoreys, especially in the tropics, and suggest the selective influence of insect herbivory on late-successional tree species may have been over-estimated.

year: 2018

title: Assessment of the ecohydrological functioning of Otakairangi Wetland, Northland

authors: Campbell, David I.

abstract: Otakairangi is the largest wetland remnant on the floodplain of Northland’s Wairua River near Hikurangi. Extensive peat deposits many metres deep accumulated over thousands of years on the valley floors of the Otakairangi and Riponui valleys, as they did elsewhere within the former Hikurangi “Swamp”. The present‐day Otakairangi Wetland, with an area of 2.6 km², represents around 20% of its former extent.
This report provides an assessment of the ecohydrological functioning of Otakairangi Wetland in its current state, based on information gathered during a field survey, discussions with landowners, and other sources. The wetland, which contains representative communities of rare peatland plants, is a good candidate for restoration, including re‐introduction of the now locally extinct climax peatland plant species Sporadanthus ferrugineus.  
Hydrological modification to Otakairangi over the past century has included a deep central drain that has largely eliminated the natural diffuse flows of the former Otakairangi Stream as it traversed the wetland, and lowered water tables. Deep drains bordering the wetland’s south western and south eastern edges have also contributed to a modified hydrological regime. Over much of the past century water table lowering and frequent fires led to dominance by tall manuka, reduced peatland biodiversity, and severe peat degradation.
There is good evidence of fairly recent changes to Otakairangi’s vegetation towards greater dominance, especially in the east, of the key peat‐forming plant and ecosystem engineer Empodisma robustum, including vigorous growth of raw fibrous peat. As the dense manuka cover has declined,
Empodisma and allied plants have been able to naturally colonise and spread. Despite encouraging signs of some natural vegetation recovery within Otakairangi Wetland, there remain many unanswered questions about the trajectory of this recovery and the ongoing effects of drainage, as well as inundation by flood flows from the highly modified upstream catchment. Also, fire remains a constant threat that could reverse this trajectory. A number of key research questions are provided in this report that will guide the development of a research plan in support of ongoing restoration and monitoring efforts.
A number of restoration options are presented that should be considered at Otakairangi. These include minor to more major hydrological manipulations, which will require careful investigation and flow modelling in addition to working closely with affected landowners. As a first step, detailed surveys are required of drain invert levels and wetland and farmland surface levels. Monitoring of drain and wetland water tables should be initiated as soon as possible, to support research into wetland hydrological regimes and to further understand the spatial effect of water table lowering

text: Assessment of the ecohydrological functioning of Otakairangi Wetland, Northland Otakairangi is the largest wetland remnant on the floodplain of Northland’s Wairua River near Hikurangi. Extensive peat deposits many metres deep accumulated over thousands of years on the valley floors of the Otakairangi and Riponui valleys, as they did elsewhere within the former Hikurangi “Swamp”. The present‐day Otakairangi Wetland, with an area of 2.6 km², represents around 20% of its former extent.
This report provides an assessment of the ecohydrological functioning of Otakairangi Wetland in its current state, based on information gathered during a field survey, discussions with landowners, and other sources. The wetland, which contains representative communities of rare peatland plants, is a good candidate for restoration, including re‐introduction of the now locally extinct climax peatland plant species Sporadanthus ferrugineus.  
Hydrological modification to Otakairangi over the past century has included a deep central drain that has largely eliminated the natural diffuse flows of the former Otakairangi Stream as it traversed the wetland, and lowered water tables. Deep drains bordering the wetland’s south western and south eastern edges have also contributed to a modified hydrological regime. Over much of the past century water table lowering and frequent fires led to dominance by tall manuka, reduced peatland biodiversity, and severe peat degradation.
There is good evidence of fairly recent changes to Otakairangi’s vegetation towards greater dominance, especially in the east, of the key peat‐forming plant and ecosystem engineer Empodisma robustum, including vigorous growth of raw fibrous peat. As the dense manuka cover has declined,
Empodisma and allied plants have been able to naturally colonise and spread. Despite encouraging signs of some natural vegetation recovery within Otakairangi Wetland, there remain many unanswered questions about the trajectory of this recovery and the ongoing effects of drainage, as well as inundation by flood flows from the highly modified upstream catchment. Also, fire remains a constant threat that could reverse this trajectory. A number of key research questions are provided in this report that will guide the development of a research plan in support of ongoing restoration and monitoring efforts.
A number of restoration options are presented that should be considered at Otakairangi. These include minor to more major hydrological manipulations, which will require careful investigation and flow modelling in addition to working closely with affected landowners. As a first step, detailed surveys are required of drain invert levels and wetland and farmland surface levels. Monitoring of drain and wetland water tables should be initiated as soon as possible, to support research into wetland hydrological regimes and to further understand the spatial effect of water table lowering

year: 2017

title: Dialogue as a method for evolving Mātauranga Māori: Perspectives on the use of embryos in research

authors: Hudson, Maui

subjects: New Zealand

abstract: This paper explores the epistemological divide between mātauranga Māori (Māori knowledge) and science, and considers which cultural concepts have relevance when considering the use of embryos in research. We argue that empowerment is a necessary precursor for a dialogue process to be effective and to maintain the cultural dignity and confidence of the participants. Negotiating spaces to share ideas, concepts and values between different knowledge systems is an important exercise that creates opportunities for innovative thinking. The identification of cultural cues and indigenous reference points for considering how knowledge relating to embryo research might be located within a traditional knowledge schema is a necessary type of activity to ensure mātauranga Māori maintains its usefulness for Māori in a changing society while retaining its indigenous spirit and cultural tradition.

text: Dialogue as a method for evolving Mātauranga Māori: Perspectives on the use of embryos in research This paper explores the epistemological divide between mātauranga Māori (Māori knowledge) and science, and considers which cultural concepts have relevance when considering the use of embryos in research. We argue that empowerment is a necessary precursor for a dialogue process to be effective and to maintain the cultural dignity and confidence of the participants. Negotiating spaces to share ideas, concepts and values between different knowledge systems is an important exercise that creates opportunities for innovative thinking. The identification of cultural cues and indigenous reference points for considering how knowledge relating to embryo research might be located within a traditional knowledge schema is a necessary type of activity to ensure mātauranga Māori maintains its usefulness for Māori in a changing society while retaining its indigenous spirit and cultural tradition.

year: 2010