Treeline vegetation composition, structure and dynamics across the AD 1655 Burrell Lapilli deposit, Mt Taranaki, New Zealand

Research was conducted on Mt Taranaki, North Island, New Zealand, to examine how the composition, structure and dynamics of treeline vegetation has been influenced by the AD 1655 Burrell Lapilli eruption. Treeline is considered as “the connecting line between the uppermost forest patches on the mountain, with trees upright and at least 3 m in height and growing in groups”. The Burrell Lapilli was deposited at a thickness of 1–40 cm over c. 150 km² of the eastern flanks of Mt Taranaki, and is thought to have inflicted widespread mechanical and chemical damage to vegetation at the time of eruption. Isopach maps of the Burrell Lapilli distribution reveal an eruption axis exists south-eastwards from the summit towards somewhere between Dawson Falls and Stratford Mountain House; out from which the thickness of lapilli decreases in all directions. Vegetation at the treeline position (c. 1000–1100 m above sea level) was measured across this lapilli distribution with thirty-five 10 × 15 m quadrats and six variable length 5 × 35–120 m belt transects. An additional three quadrats were located on the treeline of the adjoining Pouakai Range, an area which has not suffered any recent volcanic disturbance. Across the survey area on Mt Taranaki, winter (24/7/2011–17/10/2011) temperature measurements were recorded using eighteen micro data loggers. The light requirements of selected treeline species (juveniles) were quantified in situ using canopy openness measurements made with hemispherical photography, in order to gain an insight into how species may have responded to increased light levels associated with vegetation damage by the Burrell Lapilli. Daily average minimum temperatures ranged from 0.64–1.26 °C, average daily maximum temperatures ranged from 5.37–7.24 °C, and average daily means ranged from 3.07–3.71 °C. No major temperature anomalies were detected across the survey area. Within the quadrats, a total of 57 vascular taxa were identified, all of which were indigenous and typical of either montane forest or shrubland vegetation types on the mountain. Quadrats were grouped based on the thickness of the Burrell Lapilli at the sites; quadrats where lapilli was 20–40 cm thick are referred to as ‘severe’, those with lapilli 1–20 cm thick as ‘minor’, and those outside the distribution of lapilli on Mt Taranaki as ‘outside’. Total basal area of trees >2 cm diameter at ground height (dgh) increased progressively from 165 to 265 m² ha⁻¹ across the severe, minor, outside, and Pouakai Range quadrat groups. Total density of trees displayed the inverse trend, with higher stocking rates in the severe (6615 stems ha⁻¹) and minor (8370 stems ha⁻¹) groups, compared with the outside (5422 stems ha⁻¹) and Pouakai Range (5822 stems ha⁻¹) groups. The contributions of four potential canopy/emergent species (Podocarpus hallii, Griselinia littoralis, Libocedrus bidwillii, Weinmannia racemosa) varied markedly at the treeline. Across the severe, minor, outside and Pouakai Range groups, basal area of Podocarpus was 30, 40, 26 and 20 m² ha⁻¹ respectively; Griselinia was 57, 58, 52, 6 m² ha⁻¹; Libocedrus was 10, 22, 93, 7 m² ha⁻¹ and Weinmannia was 0, 1, 24, 161 m² ha⁻¹. Vegetation of each group was accordingly classified as: Severe: Podocarpus / Griselinia scrub Minor: Podocarpus – Libocedrus / Griselinia scrub Outside: Libocedrus – Podocarpus / Griselinia – Weinmannia scrub Pouakai Range: Podocarpus / Weinmannia scrub Belt transect surveys across the treeline ecotone revealed that maximum tree diameters decreased markedly (c. 100 to 30 cm dgh) with increased elevation. Maximum tree heights also decreased with elevation, with emergent Libocedrus (c. 13 m) capable of attaining greater heights than emergent Podocarpus (c. 8 m) near the treeline position. Spatial configuration of trees implied that large canopy trees suppressed the number and size of stems in close proximity, and in areas away from canopy trees, clusters of smaller stems occurred (predominantly Pseudowintera colorata and Coprosma tenuifolia). Common treeline species were ranked in order from most shade-tolerant to least shade-tolerant (i.e., light demanding) using the 10th percentile of the distribution of light environments occupied by each species as an approximation of the minimum light levels tolerated: Coprosma tenuifolia > Pseudowintera colorata > Raukaua simplex > Griselinia > Podocarpus > Weinmannia > Libocedrus. Consequently, diameter frequency distributions of light demanding species tended to display cohort population structures, implying they were incapable of regenerating below a closed canopy; while more shade-tolerant species displayed all-sized or reverse “J” structures, indicating their ability to regenerate continuously. It is speculated that Libocedrus, being a tall emergent, was eliminated from the most severely affected areas because it suffered a direct impact from the lapilli and has poor resprouting capabilities. It did not successfully regenerate there because (1) seed dispersal did not occur, (2) it was competitively excluded, (3) or it could not tolerate the new substrate. Where the effects of the eruption were less severe, Libocedrus was more successful, with an even-aged population initiated due to the increased light levels on the forest floor. Griselinia was most successful in areas severely affected by the eruption, probably because it could establish epiphytically on brightly lit snags well before suitable substrate developed. Griselinia has maintained its dominance due to its in situ mode of regeneration, whereby seedlings establish epiphytically in parent trees, combined with its ability to basally resprout. Weinmannia was not capable of capitalising on the severely affected areas in the same way, because at this elevation it is very close to its upper altitudinal limit, and would not have tolerated exposure associated with open sites; then, following canopy closure, light levels would have been too low for it to establish. Podocarpus, being a more shade-tolerant species, probably established within the eruption zone sometime after the event, and continues to regenerate below a closed canopy. Seedling and sapling data suggest that in the absence of severe disturbance, the compositional differences observed around the treeline of Mt Taranaki are likely to persist. The explanation of vegetation patterns resulting from tephra eruptions elsewhere in the world may benefit from the findings that (1) emergent species suffer the most deleterious effects during a tephra eruption, (2) epiphytic regeneration may be an important mechanism for early arrivals into devastated areas, (3) light demanding species thrive as a result of openings created in the canopy, and (4) the successional trajectory of affected areas could be altered to the extent that vegetation patterns across tephra deposits may persist indefinitely

Ecological study of Barrett Domain, New Plymouth

An ecological survey of Barrett Domain (New Plymouth) was conducted by the Environmental Research Institute, University of Waikato, for the New Plymouth District Council. The main ecological features of the domain were mapped and described, preliminary ecological impact assessments of domain upgrades were conducted, and recommendations made for the future management of the site. Barrett Domain encompasses a regionally significant wetland habitat (Barrett Lake), several hectares of remnant semi-coastal forest and areas of well-established planted native species. Wetland vegetation around Barrett Lake comprised reedland (kuta, raupo) and flaxland, and the lake provides refuge to a number of indigenous water birds. Semi-coastal forest at the site was dominated by tawa, kohekohe and pukatea, with a diverse range of understory and epiphyte species. Planted natives included a significant kauri grove, and patches of pohutukawa and puriri. Swamp forest to the west of the lake comprised mature pukatea and swamp maire, and if acquired in the land transfer, the ecological value of the domain would be greatly enhanced. Four permanent i-Tree vegetation monitoring plots and a National Wetland Monitoring plot were established at the domain and should be re-measured at 5 yearly intervals. Any ecological impacts associated with the construction of a path around the perimeter of Barrett Lake could be offset by restoration planting at the southern lake margin. Management recommendations include: • Restoration planting with appropriate native species at the southern lake margin and several other key areas within the domain. • Removing/monitoring exotic species, including the gorse and grey willow on the lake margin, and wandering Jew and climbing asparagus in the forest remnants. • Fencing (stock proofing) the swamp forest at the west of the lake once it is acquired. • Continuing with pest control and monitoring. • Obtaining new interpretive signage

Ecological study of Hickford Park and coastal walkway route options

An ecological study of Hickford Park, (New Plymouth) was conducted by the Environmental Research Institute, University of Waikato, for the New Plymouth District Council. The main ecological features of the park were mapped and described and recommendations were made for the future management of the site. Hickford Park encompasses significant wetland habitat (Waipu Lagoons and oxidation ponds), sections of planted native species, an extensive duneland system, exotic plantation forest, grazed pasture, sports playing fields and the recently completed Taranaki Velodrome. The Waipu Lagoons represent a rare coastal lagoon ecosystem type in Taranaki, and host a diverse range of native wetland flora and fauna. The acclaimed coastal walkway currently extends half way through Hickford Park to St Andrews Drive. The environmental impacts of several proposed routes for the extension of the coastal walkway through the remainder of the park to Bell Block beach were assessed and recommendations made for the preferred route from an ecological perspective. In summary: • Indigenous vegetation and habitats of indigenous fauna should not be disturbed if an alternative option is available. Possible ecological impacts of the walkway development may include removal of native vegetation, impact on dune system, alteration to land contours and slope, soil disturbance and sediment input to waterways. • Construction of the coastal walkway along the originally proposed route option (1.1) would require both vegetation removal and re-contouring and would result in a decrease or degradation of natural dune habitat. • Route option 1.2 appears to be the most feasible option, as the Waitara sewer line has previously been installed in the same location and no vegetation removal would be required. • Route options 1.2, 1.3 and the proposed walkway links, provide an opportunity to enhance the public’s appreciation of the ecology within Hickford Park. • In all cases, the ecological effects of the preferred walkway route should be offset via enhancement and restoration plantings

Evaluation of vegetation and stream health within sites supported by the Hamilton City Council Plants for Gullies Programme

Between August 2012 and March 2013, the Environmental Research Institute, University of Waikato, conducted a survey of randomly selected Hamilton gully sites which had received plants from the Hamilton City Council’s Plants for Gullies Programme. This survey assessed recent plantings, existing gully vegetation and stream health, along with property owner awareness and engagement with the key restoration principles. The Plants for Gullies Programme has been extremely well received by the Hamilton community and gully owners. Survey participants were actively restoring their gully sites with the most common goal (c. 40%) being the establishment of native plant dominance within 10 years. Gully owners have a good understanding of restoration theory and practise; on average, plant placement in the gullies scored 15.7 out of 20 with consideration of plant environmental requirements and the concept of ecosourcing was understood by c. 76% of landowners surveyed. Also, most of the interviewed participants (c. 80%) were active in seeking guidance from other gullies, often through organised tours. Current stream health was qualitatively assessed and characterised at each of the gully sites. Results provide baseline data for future monitoring. The majority of surveyed sites (c. 50%) had sand or silt substrate and the Bankwood gully had the best features for fauna habitat (e.g. debris and areas of low flow). At the time of visit, c. 60% of surveyed streams had clear water clarity. The poorest water clarity scores were in the Waitawhiriwhiri gully. When assessed on width, length and density, the average riparian buffer score was 12.8 out of 20 while the average stream shading score was 12.7 out of 20. The average bank stability score was 13.1 out of 20, reflecting an erosion problem that many gully owners talked about. Surveyed gullies were diverse in terms of native and exotic vegetation structure and composition; native species contributed between c. 30% to 100% of surveyed trees and shrubs, whereas groundcovers were predominantly exotic. This assessment of gully sites has shown that the Plants for Gullies Programme improves native species diversity through the re-introduction of species that are not naturally regenerating. The Plants for Gullies programme is a powerful tool for engaging private landowners and making cost-effective change to Hamilton City’s native biodiversity. There is now a community of willing gully owners who will continue to restore their gullies with the support of a programme or network. It is our recommendation that the Plants for Gullies Programme is reinstated before this community loses momentum

Environmental effects of the Manganui ski field, Mt Taranaki/Egmont

During May 2012, the environmental effects of the Manganui ski field were examined. Permanent quadrats first established in 1974 to monitor vegetation changes were re-measured, vegetation mapping was conducted, modifications to ground form and drainage were identified, soil compaction was examined, and stream water from the ski field catchment was tested for nutrient enrichment. This report focusses primarily on the lower Manganui ski field, as the upper Manganui ski field consists mostly of unmodified herbfield or gravelfield, protected by a sufficient snow base over the winter months. The lower Manganui ski field has a long history of modification spanning from the early 1900s. Vegetation types mapped on the lower field included unmown tussockfield, mown tussock-herbfield, shrubland and exotics. The re-measurement of vegetation in permanent quadrats on the lower field suggests that since the last re-measurement in 1994, several exotic species have increased in cover, including Carex ovalis, Poa annua, and Agrostis capillaris (percentage cover increases of up to 46.6%, 42.0% and 20.7% respectively). Vegetation mapping and historic photographs indicate that the lower ski field sits within the elevational belt of shrubland vegetation, little of which remains due to regular mowing conducted on the field since 1947. Shrubs which have been largely excluded from the field through mowing include Brachyglottis elaeagnifolius, Hebe odora, Ozothamnus vauvilliersii, Dracophyllum filifolium, Pseudopanax colensoi, Raukaua simplex and Hebe stricta var. egmontiana. Areas of the ski field dominated by exotic vegetation were predominantly associated with historic culvert construction and rock dynamiting. Compaction by machinery was confined to the sensitive mossfield area at the base of the lower field

Vegetation dieback as a proxy for temperature within a wet pyroclastic density current: A novel experiment and observations from the 6th of August 2012 Tongariro eruption

The 6th of August 2012 eruption of Te Maari (Mt Tongariro, New Zealand) generated wet pyroclastic density currents (PDCs) which caused widespread dieback of vegetation (singed, brown foliage) in their path. An absence of significant charcoal formation suggests that PDC temperatures were mostly below 250 °C. Textural evidence for liquid water being present in the matrices during emplacement (vesicles) suggests that temperatures were b100 °C. We determined a probable minimum PDC temperature using an experiment replicating the critical temperatures required to induce foliar browning in seven species affected by the eruption. In locations where all species exhibited browned foliage (or were defoliated), temperatures were probably ≥64 °C assuming a PDC duration of 60 s. In the more distal areas, where only the most susceptible species were browned while others remained healthy and unaffected, temperatures were probably around 51–58 °C. These results have relevance to volcanic hazard mitigation and risk assessment, especially on the popular Tongariro Alpine Crossing

Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570