Michael S. Watt

Scion

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Mark O. Kimberley

Statistics New Zealand

Euan G. Mason

University of Canterbury

Grant D. Pearse

Flinders University

Peter W. Clinton

Scion

Jonathan P. Dash

Scion

Darren J. Kriticos

CSIRO Health and Biosecurity

B. Richardson

Marshall Space Flight Center

Carol A. Rolando

Scion

Horacio E. Bown

University of Chile

Murray R. Davis

Massachusetts Institute of Technology

Cooperative Institutions

Scion

112

Future Forests Research

Rotorua Hospital

Manaaki Whenua – Landcare Research

University of Canterbury

Rwanda Development Board

Commonwealth Scientific and Industrial Research Organisation

Universidad Internacional de América

Universidad de la Integración de las Américas

Museum of New Zealand Te Papa Tongarewa

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Modelling the influence of environment on juvenile modulus of elasticity in Pinus radiata grown in Chile

Forest Ecology and Management (2017)

Michael S. Watt Guillermo Trincado

Pinus radiata

Radiata

Coefficient of variation

10.1016/j.foreco.2017.06.006

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Citations (6)

Mangrove Forest Regeneration Age Map and Drivers of Restoration Success in Gulf Cooperation Council Countries from Satellite Imagery

Midhun Mohan Abhilash Dutta Roy Jorge F. Montenegro Michael S. Watt John A. Burt

Natural regeneration

10.2139/ssrn.4833329

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Citations (1)

The influence of wind on branch characteristics of Pinus radiata

Trees (2004)

Michael S. Watt John R. Moore Brandon J. McKinlay

Pinus radiata

Radiata

10.1007/s00468-004-0363-6

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Citations (55)

Growth, biomass, leaf area and water-use efficiency of juvenile Pinus radiata in response to water deficits

New Zealand journal of forestry science (2015)

Matthew J. Waghorn David Whitehead Michael S. Watt Euan G. Mason Jonathan J. Harrington

As the frequency and severity of drought events are expected to increase globally, drought-induced reductions in plantation productivity are likely to become more important. Such reductions will be of concern to forest managers looking to improve forest productivity during the establishment and initial growth phases of plantation-grown Pinus radiata D. Don. The objective of this research was to assess how growth, biomass, leaf area and water-use efficiency in juvenile Pinus radiata responded to the timing and duration of water deficits. Two-year-old Pinus radiata seedlings (cultivated in a polyhouse) were subjected to various water deficit treatments. Needle water potential, tree growth, biomass partitioning, leaf characteristics and water-use efficiency were measured to assess the impact that the timing and duration of water deficits had on productivity. Cyclical re-watering of the early- and late-season drought treatments led to large fluctuations in needle water potential. The summer drought treatment resulted in a sustained low needle water potential over the summer months. Total water stress integral (S ψ ) was 41.4, 66.8, 55.2 and 97.6 MPa-days for the well-watered, early-season cyclical drought, late-season cyclical drought and summer drought treatments, respectively. In general, water deficits decreased tree growth, reduced crown size, reduced biomass accumulation and leaf area, and resulted in more enriched values of δ13C, all of which were significantly (P < 0.05) affected by treatment. Summer drought reduced height, diameter and basal area by 24.7%, 33.1% and 52.3%, respectively. Total biomass was reduced by 64.7% and total leaf area by 40.0%, compared with the well-watered treatment. The reduction in stem diameter growth was larger for the late-season treatment than the early-season treatment when compared with the well-watered trees suggesting that late-season drought is more detrimental than early-season drought to tree growth. The results provide insight for forest managers of Pinus radiata into the importance of managing water deficits in order to maximise forest production of juvenile trees. Results suggest that late-season drought is more detrimental to absolute growth and biomass accumulation than early-season drought.

Pinus radiata

Radiata

Basal area

Water Use Efficiency

Growing season

Water use

10.1186/s40490-015-0034-y

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Citations (18)

The Potential Global Distribution of Tall Buttercup (Ranunculus acris ssp. acris): Opposing Effects of Irrigation and Climate Change

Weed Science (2013)

Graeme W. Bourdôt Shona L. Lamoureaux Michael S. Watt Darren J. Kriticos

Tall buttercup, a native of central and northern Europe, has become naturalized in the United States and Canada, and in South Africa, Tasmania and New Zealand. In Canada and New Zealand it has become an economically significant weed in cattle-grazed pastures. In this study we develop a CLIMEX model for tall buttercup and use it to project the weed's potential distribution under current and future climates and in the presence and absence of irrigation. There was close concordance between the model's projection of suitable climate and recorded observations of the species. The projection was highly sensitive to irrigation; the area of potentially suitable land globally increasing by 30% (from 34 to 45 million km 2 ) under current climate when a “top-up” irrigation regime (rainfall topped up 4 mm d −1 on irrigable land), was included in the model. Most of the area that becomes suitable under irrigation is located in central Asia and central North America. By contrast, climate change is projected to have the opposite effect; the potential global distribution diminishing by 18% (from 34 to 28 million km 2 ). This range contraction was the net result of a northward expansion in the northern limit for the species in Canada and the Russian Federation, and a relatively larger increase in the land area becoming unsuitable mainly in central Asia and south eastern United States.

Central Asia

10.1614/ws-d-12-00106.1

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Citations (9)

Future wood productivity ofPinus radiatainNewZealand under expected climatic changes

Global Change Biology (2011)

Miko U. F. Kirschbaum Michael S. Watt Andrew Tait Anne‐Gaelle Ausseil

Abstract The physiologically based growth model CenW was used to simulate wood‐productivity responses of P inus radiata forests to climate change in N ew Z ealand. The model was tested under current climatic conditions against a comprehensive set of observations from growth plots located throughout the country. Climate change simulations were based on monthly climate change fields of 12 GCM s forced by the SRES B1, A1B and A2 emission scenarios for 2040 and 2090. Simulations used either constant or increasing CO 2 concentrations corresponding to the different emission scenarios. With constant CO 2 , there were only slight growth responses to climate change across the country as a whole. More specifically, there were slight growth reductions in the warmer north but gains in the cooler south, especially at higher altitudes. For sites where P . radiata is currently grown, and across the full suite of GCM s and emission scenarios, changes in wood productivity averaged +3% for both 2040 and 2090. When increasing CO 2 concentration was also included, responses of wood productivity were generally positive, with average increases of 19% by 2040 and 37% by 2090. These responses varied regionally, ranging from relatively minor changes in the north of the country to very significant increases in the south, where the beneficial effect of increasing CO 2 combined with the beneficial effect of increasing temperatures. These relatively large responses to CO 2 depend on maintenance of the current adequate fertility levels in most commercial plantations. Productivity enhancements came at the expense of some soil‐carbon losses. Average losses for the country were simulated to average 3.5% under constant CO 2 and 1.5% with increasing CO 2 concentration. Again, there were regional differences, with larger losses for regions with lesser growth enhancements, and lesser reductions in regions where greater productivity enhancements could partly balance the effect of faster decomposition activity.

Radiata

Pinus radiata

10.1111/j.1365-2486.2011.02625.x

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Citations (38)

The influence of nitrogen and phosphorus supply and genotype on mesophyll conductance limitations to photosynthesis in Pinus radiata

Tree Physiology (2009)

Horacio E. Bown Michael S. Watt Euan G. Mason Peter W. Clinton David Whitehead

Mesophyll conductance, gm, may pose significant limitations to photosynthesis and may be differentially affected by nutrition and genotype in Pinus radiata D. Don. Simultaneous measurements of gas exchange and chlorophyll fluorescence were made to determine gm, using the constant J method (Harley, P.C., F. Loreto, G. Di Marco and T.D. Sharkey. 1992. Theoretical considerations when estimating the mesophyll conductance to CO2 flux by analysis of the response of photosynthesis to CO2. Plant Physiol. 98:1429–1436), in a fast- and a slow-growing clone of P. radiata grown in a greenhouse with a factorial combination of nitrogen (N) and phosphorus (P) supply. Values of gm increased linearly with the rate of photosynthesis at saturating irradiance and ambient CO2 concentration, Asat (gm = 0.020Asat, r2 = 0.25, P < 0.001) and with stomatal conductance to CO2 transfer, gs (gm = 1.16gs, r2 = 0.14, P < 0.001). Values of gm were greater than those of stomatal conductance, gs, and the ratio (gm/gs) was not influenced by single or combined N and P additions or clone with a mean (±SE) value of 1.22 ± 0.06. Relative limitations to mesophyll conductance, Lm (16%) to photosynthesis, were generally greater than those imposed by stomata, Ls (13%). The mean (±SE) CO2 concentration in the intercellular air spaces (Ci) was 53 ± 3 μmol mol−1 lower than that in the atmosphere (Ca). Mean (±SE) CO2 concentration in the chloroplasts (Cc) was 48 ± 2 μmol mol−1 lower than Ci. Values of Ls, Lm and CO2 diffusion gradients posed by gs (Ca − Ci) and gm (Ci − Cc) did not significantly differ with nutrient supply or clone. Mean values of Vcmax and Jmax calculated on a Cc basis were 15.4% and 3.1% greater than those calculated on a Ci basis, which translated into different slopes of the Jmax/Vcmax relationship (Cc basis: Jmax = 2.11Vcmax, r2 = 0.88, P < 0.001; Ci basis: Jmax = 2.43Vcmax, r2 = 0.86, P < 0.001). These results will be useful for correcting estimates of Vcmax and Jmax used to characterize the biochemical properties of photosynthesis for P. radiata.

Pinus radiata

Radiata

10.1093/treephys/tpp051

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Citations (55)

The status of forest carbon markets in Latin America

Journal of Environmental Management (2024)

Austin Blanton Midhun Mohan G. A. Pabodha Galgamuwa Michael S. Watt Jorge F. Montenegro

Carbon offset

Deforestation

Carbon sink

Carbon credit

10.1016/j.jenvman.2023.119921

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Citations (12)

Assessment of herbicides for selectively controlling broom (Cytisus scoparius) growing with Pinus radiata.

Hai Anh Tran K.C. Harrington Alastair W. Robertson Michael S. Watt S. M. Zydenbos

Broom (Cytisus scoparius (L.) Link) is an invasive weed in many commercial radiata pine (Pinus radiata D.Don) plantations throughout New Zealand. As broom competes strongly with newly planted pine seedlings and has an abundant seed bank that persists longer than the forest rotation cycle, ongoing broom control is essential to prevent significant loss of production. A variety of herbicides are available to selectively control the established broom seedlings during the first year after planting pines but there is little published information describing which are safest for pines and most effective as the broom grows older. In this study, we evaluated the efficacy of six selective herbicides: (1) 450/300 g a.i. ha 1 clopyralid/ picloram, (2) 1500/300 g a.i. ha 1 clopyralid/triclopyr, (3) 1500/50/4/150 g a.i. ha 1 clopyralid/picloram/ triclopyr/aminopyralid, (4) 500 g a.i. ha 1 fluroxypyr, (5) 10 kg a.i. ha 1 terbuthylazine, and (6) 6 kg a.i. ha 1 hexazinone, applied at three rates (the recommended rate shown above, half this rate and double this rate) in controlling broom of various ages (3, 6, 9 and 12 months). Effects of these herbicides on 12-month-old P. radiata plants were also assessed, and all treatments were compared against untreated broom and pine plants. Broom seedlings were established from seed individually in 1.2 L planter bags of potting mixture at 3 monthly intervals prior to all plants being sprayed on 18 December 2008. Likewise, the pine seedlings were transplanted into planter bags as 9-month-old seedlings from a commercial nursery 3 months prior to spraying on the same date as the broom. All herbicide treatments were applied using a precision gas-powered plot sprayer at a rate equivalent to 300 L ha 1, and all treatments apart from the hexazinone were applied with an organosilicone surfactant. Damage to plants Assessment of herbicides for selectively controlling broom (Cytisus scoparius) growing with Pinus radiata

Triclopyr

Broom

Pinus radiata

Clopyralid

Picloram

Potting soil

Radiata

Source

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Citations (1)

Compensation in seasonal leaf area dynamics and leaf longevity after defoliation in Buddleja davidii

Weed Research (2008)

M M THOMAS Michael S. Watt Matthew H. Turnbull Duane A. Peltzer David Whitehead

Summary Buddleja davidii is a major invasive weed and its success is attributed to its ability to recover rapidly following defoliation. To quantify the impacts of defoliation on seasonal leaf area dynamics, we measured rates of leaf area growth and loss on cohorts of leaves on control plants and on plants that were defoliated by 66% repeatedly at monthly intervals throughout two growing seasons. The rate of leaf area growth was closely related to cumulative air temperature, but the maximum rate for the defoliated plants in the first season was 2.2 times that of the control plants. This compensational leaf growth resulted in 52% greater total emergent leaf area, attributable to increased node production (34%) and leaf size (35%), compared with control plants. Leaf longevity during the first growing season in the defoliated plants was 12% greater than that in the control plants. During the second season, the degree of compensation was greatly reduced, attributable to reduced leaf size in defoliated plants compared with the control. Total emergent leaf area over both seasons in the defoliated treatment exceeded control values by only 15%. The impact of leaf loss on the vigour in this invasive shrub may, in the short term, be less significant than would be predicted. However, the impacts of continued defoliation are likely to increase markedly in subsequent years. The study provides the basis for modelling leaf area dynamics and plant growth in response to defoliation associated with biocontrol release programmes.

Leaf size

Growing season

Specific leaf area

10.1111/j.1365-3180.2008.00637.x

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Citations (16)