title: Waiwhakareke Natural Heritage Park 2021 Long-term monitoring: Report on ecological restoration progress

authors: Farnworth, Bridgette

abstract: This report was requested by Tui 2000 Inc. and the Hamilton City Council (HCC) as a means of tracking terrestrial restoration progress at Waiwhakareke Natural Heritage Park (WNHP). WNHP is a cutting-edge urban ecological restoration project in which ecosystems representative of the Hamilton Ecological District are being reconstructed from scratch on public land in Kirikiriroa Hamilton. Larger-scale projects of this nature are becoming more commonplace around the globe due to growing emphasis on restoring nature in urban areas. While this report quantifies the remarkable restoration success achieved at WNHP through investments by Tui 2000 Inc., HCC and the community since 2004, it also contributes to scientific theory. Restoration ecology is a newly developing scientific field and hence WNHP presents a unique opportunity for ecologists to improve restoration practice and also learn from the results.
Here we share results from data analysed from 25 permanent monitoring plots throughout WNHP, spanning planting years since the beginning of planting in 2004 through to 2017 (14 years of planting). These plots are located across the five main ecosystem types (i.e., planting zones) being restored. This information should be used to inform current management and future planning for WNHP.
In the 2021 monitoring, we measured key variables of forest development, including: canopy openness, native tree basal area, non-native herbaceous groundcover, leaf litter, dead trees, native tree seedling abundance and species richness, and epiphyte colonisation. Linear regression models revealed a statistically significant relationship between all (except dead trees and native tree seedling abundance) of these ecosystem variables and forest age. We note that there are several thresholds between 12 - 16 years since the initial restoration planting: basal area increased and the canopy openness decreased, reducing the light availability at the forest floor, thus reducing the non-native herbaceous groundcover from 100% to ~25% in 12 years (with one plot having 0% cover). With these ecosystem changes, important indicators of functioning forests appeared around the same time, such as leaf litter accrual (up to 95% groundcover) and an increasing number of dead trees (up to 37 dead small trees in one monitoring plot), native seedling recruitment (in abundance and species richness), and fern cover.
The results in the report generally signal positive restoration progress. Now a focus is required on non-native weed and invasive mammalian pest control management, paired with careful enrichment planting, and where needed, infill of mid/late-successional plants. Enrichment planting and weed/pest management will help secure the investment in initial plantings by starting the longer-term next phase of forest development, while also creating a more species-diverse ecosystem, resilient to the manifold pressures of the urban landscape, disease, and climate change.

text: Waiwhakareke Natural Heritage Park 2021 Long-term monitoring: Report on ecological restoration progress This report was requested by Tui 2000 Inc. and the Hamilton City Council (HCC) as a means of tracking terrestrial restoration progress at Waiwhakareke Natural Heritage Park (WNHP). WNHP is a cutting-edge urban ecological restoration project in which ecosystems representative of the Hamilton Ecological District are being reconstructed from scratch on public land in Kirikiriroa Hamilton. Larger-scale projects of this nature are becoming more commonplace around the globe due to growing emphasis on restoring nature in urban areas. While this report quantifies the remarkable restoration success achieved at WNHP through investments by Tui 2000 Inc., HCC and the community since 2004, it also contributes to scientific theory. Restoration ecology is a newly developing scientific field and hence WNHP presents a unique opportunity for ecologists to improve restoration practice and also learn from the results.
Here we share results from data analysed from 25 permanent monitoring plots throughout WNHP, spanning planting years since the beginning of planting in 2004 through to 2017 (14 years of planting). These plots are located across the five main ecosystem types (i.e., planting zones) being restored. This information should be used to inform current management and future planning for WNHP.
In the 2021 monitoring, we measured key variables of forest development, including: canopy openness, native tree basal area, non-native herbaceous groundcover, leaf litter, dead trees, native tree seedling abundance and species richness, and epiphyte colonisation. Linear regression models revealed a statistically significant relationship between all (except dead trees and native tree seedling abundance) of these ecosystem variables and forest age. We note that there are several thresholds between 12 - 16 years since the initial restoration planting: basal area increased and the canopy openness decreased, reducing the light availability at the forest floor, thus reducing the non-native herbaceous groundcover from 100% to ~25% in 12 years (with one plot having 0% cover). With these ecosystem changes, important indicators of functioning forests appeared around the same time, such as leaf litter accrual (up to 95% groundcover) and an increasing number of dead trees (up to 37 dead small trees in one monitoring plot), native seedling recruitment (in abundance and species richness), and fern cover.
The results in the report generally signal positive restoration progress. Now a focus is required on non-native weed and invasive mammalian pest control management, paired with careful enrichment planting, and where needed, infill of mid/late-successional plants. Enrichment planting and weed/pest management will help secure the investment in initial plantings by starting the longer-term next phase of forest development, while also creating a more species-diverse ecosystem, resilient to the manifold pressures of the urban landscape, disease, and climate change.

year: 2021

title: Conservation status of New Zealand freshwater invertebrates, 2013

authors: Grainger, N.

subjects: New Zealand Threat Classification System

abstract: The conservation status of 644 freshwater invertebrate taxa, across five Phyla, 28 Orders and 75 Families, was assessed using the New Zealand Threat Classification System (NZTCS) criteria. Forty-six species were ranked Nationally Critical, 11 Nationally Endangered and 16 Nationally Vulnerable. One hundred and seventy-two taxa were listed as Data Deficient. A full list is presented, along with summaries and brief notes on the most important changes. This list replaces all previous NZTCS lists for freshwater invertebrates.

text: Conservation status of New Zealand freshwater invertebrates, 2013 The conservation status of 644 freshwater invertebrate taxa, across five Phyla, 28 Orders and 75 Families, was assessed using the New Zealand Threat Classification System (NZTCS) criteria. Forty-six species were ranked Nationally Critical, 11 Nationally Endangered and 16 Nationally Vulnerable. One hundred and seventy-two taxa were listed as Data Deficient. A full list is presented, along with summaries and brief notes on the most important changes. This list replaces all previous NZTCS lists for freshwater invertebrates.

year: 2014

title: Lake Rotokakahi: The kakahi (Hyridella menziesi) in a general framework of lake health

authors: Butterworth, Joseph

subjects: Rotokakahi

abstract: Lake Rotokakahi is a mesotrophic lake located within the Rotorua Lakes District, North Island, New Zealand. Under the legal guardianship of the Tuhourangi and Ngati Tumatawera tribes of Te Arawa it has remained closed to the public since 1948. 

Lake Rotokakahi was last monitored regularly in 1996 under the Environment Bay of Plenty (EBOP) water quality monitoring programme with only the lake outlet (Te Wairoa Stream) being monitored since that time. Water quality data collected up to 1996 suggests that there may be degradation of water quality in the lake, as indicated by declining levels of dissolved oxygen in the bottom waters.

 Lake Rotokakahi steeped in historical significance, as well as having major cultural and recreational values was well known for its abundant resources and as the name suggests, particularly for its massive supply of the freshwater mussel or kakahi (Hyridella menziesi). Freshwater mussel species worldwide are in decline however little is known on factors controlling kakahi abundance and distribution. 

The overarching objective of this thesis is update water quality data last monitored in Lake Rotokakahi in 1996 while also identifying key environmental variables thought to influence kakahi populations.  This objective is underpinned by a number of aims that include:
 	Establishment of a 12-13 month water quality programme within Lake Rotokakahi so that data is obtained for comparisons with previous water quality data (pre-1997) to allow assessment of whether there have been water quality changes in the lake.
 	Conduct a population survey of the resident kakahi population examining possible environmental factors influencing their populations.
 	Present an oral history of Lake Rotokakahi focusing on its historical significance, water quality, and collection of kairoto (food collected form lakes).

from the 18 September 2006 to 14 September 2007 monthly water sampling was carried out at a mid lake station, the lake outflow and inflow for measures of nutrients, phytoplankton, zooplankton and chlorophyll a. Vertical profiles of temperature dissolved oxygen and chlorophyll fluorescence were also taken on various part of Lake Rotokakahi.

A lengthened period of anoxia in the bottom waters during thermal stratification was recorded with increased levels of chlorophyll a in winter and reduced secchi disk depth indicating an increase in phytoplankton biomass. Nutrient concentrations remain moderate relative to historical data. On going water quality monitoring on Lake Rotokakahi is recommended to further evaluate the extent of which water quality change is occurring. This will provide a better understanding of how Lake Rotokakahi can be best managed to further preserve the lake.

On 1 March and 20 April kakahi were sampled at five sites. Large kakahi densities were distributed predominantly in depths above the hypolimnion. Chlorophyll a fluorescence and dissolved oxygen were found to be the best correlates for kakahi density and biomass respectively. Low dissolved oxygen concentrations in the hypolimnion are thought to restrict kakahi distributions to above the thermocline in periods of hypolimnetic anoxia.

text: Lake Rotokakahi: The kakahi (Hyridella menziesi) in a general framework of lake health Lake Rotokakahi is a mesotrophic lake located within the Rotorua Lakes District, North Island, New Zealand. Under the legal guardianship of the Tuhourangi and Ngati Tumatawera tribes of Te Arawa it has remained closed to the public since 1948. 

Lake Rotokakahi was last monitored regularly in 1996 under the Environment Bay of Plenty (EBOP) water quality monitoring programme with only the lake outlet (Te Wairoa Stream) being monitored since that time. Water quality data collected up to 1996 suggests that there may be degradation of water quality in the lake, as indicated by declining levels of dissolved oxygen in the bottom waters.

 Lake Rotokakahi steeped in historical significance, as well as having major cultural and recreational values was well known for its abundant resources and as the name suggests, particularly for its massive supply of the freshwater mussel or kakahi (Hyridella menziesi). Freshwater mussel species worldwide are in decline however little is known on factors controlling kakahi abundance and distribution. 

The overarching objective of this thesis is update water quality data last monitored in Lake Rotokakahi in 1996 while also identifying key environmental variables thought to influence kakahi populations.  This objective is underpinned by a number of aims that include:
 	Establishment of a 12-13 month water quality programme within Lake Rotokakahi so that data is obtained for comparisons with previous water quality data (pre-1997) to allow assessment of whether there have been water quality changes in the lake.
 	Conduct a population survey of the resident kakahi population examining possible environmental factors influencing their populations.
 	Present an oral history of Lake Rotokakahi focusing on its historical significance, water quality, and collection of kairoto (food collected form lakes).

from the 18 September 2006 to 14 September 2007 monthly water sampling was carried out at a mid lake station, the lake outflow and inflow for measures of nutrients, phytoplankton, zooplankton and chlorophyll a. Vertical profiles of temperature dissolved oxygen and chlorophyll fluorescence were also taken on various part of Lake Rotokakahi.

A lengthened period of anoxia in the bottom waters during thermal stratification was recorded with increased levels of chlorophyll a in winter and reduced secchi disk depth indicating an increase in phytoplankton biomass. Nutrient concentrations remain moderate relative to historical data. On going water quality monitoring on Lake Rotokakahi is recommended to further evaluate the extent of which water quality change is occurring. This will provide a better understanding of how Lake Rotokakahi can be best managed to further preserve the lake.

On 1 March and 20 April kakahi were sampled at five sites. Large kakahi densities were distributed predominantly in depths above the hypolimnion. Chlorophyll a fluorescence and dissolved oxygen were found to be the best correlates for kakahi density and biomass respectively. Low dissolved oxygen concentrations in the hypolimnion are thought to restrict kakahi distributions to above the thermocline in periods of hypolimnetic anoxia.

year: 2008