David I Forrester
Research interests
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InterestsForest Ecology, Silviculture, Forestry Research, Forest Management, Forestry
Publications
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3.13Impact points
The balance between facilitation and competition in mixtures of Eucalyptus and Acacia changes as stands develop.
Oecologia. 02/2011; 166(1):265-72.
The balance between facilitation and competition is likely to change with age due to the dynamic nature of nutrient, water and carbon cycles, and light availability during stand development. These processes have received attention in harsh, arid, semiarid and alpine ecosystems but are rarely examine... [more] The balance between facilitation and competition is likely to change with age due to the dynamic nature of nutrient, water and carbon cycles, and light availability during stand development. These processes have received attention in harsh, arid, semiarid and alpine ecosystems but are rarely examined in more productive communities, in mixed-species forest ecosystems or in long-term experiments spanning more than a decade. The aim of this study was to examine how inter- and intraspecific interactions between Eucalyptus globulus Labill. mixed with Acacia mearnsii de Wildeman trees changed with age and productivity in a field experiment in temperate south-eastern Australia. Spatially explicit neighbourhood indices were calculated to quantify tree interactions and used to develop growth models to examine how the tree interactions changed with time and stand productivity. Interspecific influences were usually less negative than intraspecific influences, and their difference increased with time for E. globulus and decreased with time for A. mearnsii. As a result, the growth advantages of being in a mixture increased with time for E. globulus and decreased with time for A. mearnsii. The growth advantage of being in a mixture also decreased for E. globulus with increasing stand productivity, showing that spatial as well as temporal dynamics in resource availability influenced the magnitude and direction of plant interactions.
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2.40Impact points
The influence of mixed tree plantations on the nutrition of individual species: a review.
Tree physiology. 09/2010; 30(9):1192-208.
Productivity of tree plantations is a function of the supply, capture and efficiency of use of resources, as outlined in the Production Ecology Equation. Species interactions in mixed-species stands can influence each of these variables. The importance of resource-use efficiency in determining fores... [more] Productivity of tree plantations is a function of the supply, capture and efficiency of use of resources, as outlined in the Production Ecology Equation. Species interactions in mixed-species stands can influence each of these variables. The importance of resource-use efficiency in determining forest productivity has been clearly demonstrated in monocultures; however, substantial knowledge gaps remain for mixtures. This review examines how the physiology and morphology of a given species can vary depending on whether it grows in a mixture or monoculture. We outline how physiological and morphological shifts within species, resulting from interactions in mixtures, may influence the three variables of the Production Ecology Equation, with an emphasis on nutrient resources [nitrogen (N) and phosphorus (P)]. These include (i) resource availability, including soil nutrient mineralization, N₂ fixation and litter decomposition; (ii) proportion of resources captured, resulting from shifts in spatial, temporal and chemical patterns of root dynamics; (iii) resource-use efficiency. We found that more than 50% of mixed-species studies report a shift to greater above-ground nutrient content of species grown in mixtures compared to monocultures, indicating an increase in the proportion of resources captured from a site. Secondly, a meta-analysis showed that foliar N concentrations significantly increased for a given species in a mixture containing N₂-fixing species, compared to a monoculture, suggesting higher rates of photosynthesis and greater resource-use efficiency. Significant shifts in N- and P-use efficiencies of a given species, when grown in a mixture compared to a monoculture, occurred in over 65% of studies where resource-use efficiency could be calculated. Such shifts can result from changes in canopy photosynthetic capacities, changes in carbon allocation or changes to foliar nutrient residence times of species in a mixture. We recommend that future research focus on individual species' changes, particularly with respect to resource-use efficiency (including nutrients, water and light), when trees are grown in mixtures compared to monocultures. A better understanding of processes responsible for changes to tree productivity in mixed-species tree plantations can improve species, and within-species, selection so that the long-term outcome of mixtures is more predictable.
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2.40Impact points
Assessing nitrogen fixation in mixed- and single-species plantations of Eucalyptus globulus and Acacia mearnsii.
Tree physiology. 10/2007; 27(9):1319-28.
Mixtures of Eucalyptus globulus Labill. and Acacia mearnsii de Wildeman are twice as productive as E. globulus monocultures growing on the same site in East Gippsland, Victoria, Australia, possibly because of increased nitrogen (N) availability owing to N(2) fixation by A. mearnsii. To investigate w... [more] Mixtures of Eucalyptus globulus Labill. and Acacia mearnsii de Wildeman are twice as productive as E. globulus monocultures growing on the same site in East Gippsland, Victoria, Australia, possibly because of increased nitrogen (N) availability owing to N(2) fixation by A. mearnsii. To investigate whether N(2) fixation by A. mearnsii could account for the mixed-species growth responses, we assessed N(2) fixation by the accretion method and the (15)N natural abundance method. Nitrogen gained by E. globulus and A. mearnsii mixtures and monocultures was calculated by the accretion method with plant and soil samples collected 10 years after plantation establishment. Nitrogen in biomass and soil confirmed that A. mearnsii influenced N dynamics. Assuming that the differences in soil, forest floor litter and biomass N of plots containing A. mearnsii compared with E. globulus monocultures were due to N(2) fixation, the 10-year annual mean rates of N(2) fixation were 38 and 86 kg ha(-1) year(-1) in 1:1 mixtures and A. mearnsii monocultures, respectively. Nitrogen fixation by A. mearnsii could not be quantified on the basis of the natural abundance of (15)N because such factors as mycorrhization type and fractionation of N isotopes during N cycling within the plant confounded the effect of the N source on the N isotopic signature of plants. This study shows that A. mearnsii fixed significant quantities of N(2) when mixed with E. globulus. A decline in delta(15)N values of E. globulus and A. mearnsii with time, from 2 to 10 years, is further evidence that N(2) was fixed and cycled through the stands. The increased aboveground biomass production of E. globulus trees in mixtures when compared with monocultures can be attributed to increases in N availability.
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Growth and physiological responses to silviculture for producing solid-wood products from Eucalyptus plantations: An Australian perspective
Forest Ecology And Management. 259:1819-1835.
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Effect of thinning, pruning and nitrogen fertiliser application on transpiration, photosynthesis and water-use efficiency in a young Eucalyptus nitens plantation
Forest Ecology and Management. 266:286-300.
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A comparison of four process-based models and a statistical regression model to predict growth of Eucalyptus globulus plantations
Ecological Modelling. 220:734-746.
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Photosynthetic capacity of Eucalyptus globulus is higher when grown in mixture with Acacia mearnsii
Trees Structure and Function.
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Individual-tree radial growth in a species-rich subtropical forest: the role of local neighbourhood competition
Forest Ecology And Management. 261:499-507.
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A comparison of four process-based models and a statistical regression model to predict growth of Eucalyptus globulus plantations
Ecological Modelling.
In forest management and ecological research, consideration of the impacts and risks of climate change or management optimisation is complex. Computer models have long been applied as tools for these tasks. Process-based forest growth models claim to overcome the limitations of empirical statistical... [more] In forest management and ecological research, consideration of the impacts and risks of climate change or management optimisation is complex. Computer models have long been applied as tools for these tasks. Process-based forest growth models claim to overcome the limitations of empirical statistical models, but the capacity of different process-based models and modelling approaches have rarely been compared directly. This study evaluates stepwise multiple regression models in comparison to four process-based modelling approaches (3-PG, 3-PG+, CABALA and Forest-DNDC) for greenfield predictions of Eucalyptus globulus plantation growth from 2 to 8 years after planting throughout southern Australia.The stepwise multiple regression models could not simulate plantation growth to a satisfactory level of precision over the entire simulation period, although 2 years after planting model efficiency was 0.46, greater than for any of the process-based models. The variables that were statistically important to predict early plantation growth were mean minimum temperature, stocking rate and the amount of applied N fertiliser. For plantations between 4 and 8 years of age, coefficients of model efficiency were between −0.55 and −0.99.Only process-based models provided the flexibility to realistically predict the impacts of the different growth conditions throughout of the simulation period. Amongst the process-based models, Forest-DNDC achieved the greatest model efficiency (0.28) at 2 years after planting and was the most consistent performing model (0.20–0.30), whereas CABALA achieved the greates model efficiency (0.70) after 8 years of plantation growth. Both 3-PG models performed best for 6-year-old plantations, but throughout the simulation period their predictive precision was strongly dependent on estimating site fertility. For 3-PG+, a statistical approach to estimate site fertility resulted in a model efficiency of 0.28 at 6 years after planting, whereas a subjective estimation of site fertility for 3-PG resulted in a model efficiency of 0.58. In general, the process-based models had difficulties in simulating very young plantations at less then 4 years after planting, plantations with high tree mortality rates and plantation response to extreme silvicultural management operations.
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On the success and failure of mixed-species tree plantations: lessons learned from a model system of Eucalyptus globulus and Acacia mearnsii
Forest Ecology and Management.
Mixed plantations of a Eucalyptus species with a nitrogen-fixing tree species can produce significantly higher quantities of aboveground biomass than monocultures. However, if species or sites are not chosen correctly, one species may suppress the growth of the other and mixtures may be less product... [more] Mixed plantations of a Eucalyptus species with a nitrogen-fixing tree species can produce significantly higher quantities of aboveground biomass than monocultures. However, if species or sites are not chosen correctly, one species may suppress the growth of the other and mixtures may be less productive than monocultures. Based on a study of Eucalyptus globulus and Acacia mearnsii, this paper discusses the species attributes and site factors that should be considered to improve the probability of increasing biomass production using mixed-species plantations.In an 11-year-old mixed-species trial of E. globulus and A. mearnsii in southeastern Australia aboveground biomass production was twice as high in mixtures containing 50% E. globulus and 50% A. mearnsii than in E. globulus monocultures. There are three main types of interactions that led to this growth outcome: competition, competitive reduction and facilitation. Facilitation occurred as A. mearnsii fixed significant quantities of N, both in monoculture and when mixed with E. globulus. In addition, not only rates of N but also those of P cycling through litterfall were significantly higher in mixed stands than E. globulus monocultures, pointing to the importance of selecting a nitrogen-fixing species that is capable of N fixation and subsequent fast nutrient cycling through litterfall. Mixed stands developed stratified canopies, such that E. globulus eventually overtopped A. mearnsii after 9 years. This resulted in an increase in light capture at the stand level and a reduction in competition for light for E. globulus, a relatively shade intolerant species. This illustrates the importance of selecting species based on their height growth dynamics and relative shade tolerances, to ensure that neither species is suppressed by the other and that the less tolerant species is not overtopped by the more shade tolerant species.In addition to species attributes, site factors, such as soil nitrogen, phosphorus and water availability, play an important role in the interactions and processes occurring in mixtures. In a pot trial containing monocultures and mixtures of E. globulus and A. mearnsii, mixtures produced more biomass than monocultures of either species at low levels of N fertiliser. However, at high levels of N fertiliser E. globulus suppressed A. mearnsii and the biomass production of mixtures was not significantly different to that of E. globulus monocultures. This suggests that mixtures should only be planted on sites where the processes and interactions between species will increase the availability of, or reduce competition for, a major limiting resource for growth at that site.The accurate prediction of successful mixed-species combinations and sites is difficult due to the limited number of studies on mixtures. A mechanistic approach is required to examine the interactions and processes that occur in mixtures and to demonstrate why certain combinations are successful on some sites and not others.
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Growth and physiological responses to silviculture for producing solid-wood products from Eucalyptus plantations: An Australian perspective
Forest Ecology and Management.
We review the main silvicultural interventions used when managing Eucalyptus plantations for solid-wood products, including fertilising, pruning and thinning. The growth of a plantation and the quality of the wood produced is closely linked to the development of the tree crowns. These silvicultural ... [more] We review the main silvicultural interventions used when managing Eucalyptus plantations for solid-wood products, including fertilising, pruning and thinning. The growth of a plantation and the quality of the wood produced is closely linked to the development of the tree crowns. These silvicultural interventions influence crown dynamics and can interact with each other, as well as the species, site and the age at which they are applied. This review focuses on the growth and physiological responses observed in Eucalyptus plantations, particularly from an Australian perspective. The implications for wood quality, while given some attention, are beyond the scope of this review.
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Enhanced water use efficiency in a mixed Eucalyptus globulus and Acacia mearnsii plantation
Forest Ecology and Management.
Significant increases in aboveground biomass production have been observed when Eucalyptus is planted with a nitrogen-fixing species due to increased nutrient availability and more efficient use of light. Eucalyptus and Acacia are among the most popular globally planted genera with the area of Eucal... [more] Significant increases in aboveground biomass production have been observed when Eucalyptus is planted with a nitrogen-fixing species due to increased nutrient availability and more efficient use of light. Eucalyptus and Acacia are among the most popular globally planted genera with the area of Eucalyptus plantations alone expanding to over 19 Mha over the past two decades. Despite this, little is known about how nutrition and light availability in mixed-species tree plantations influence water use and water use efficiency (WUE). This study examined to what extent water use and WUE have been influenced by increased resource availability and growth in mixed-species plantations. Monocultures of Eucalyptus globulus Labill. and Acacia mearnsii de Wildeman and 1:1 mixtures of these species were planted. Growth and transpiration were measured between ages 14 and 15 years. Aboveground biomass increment (Mg ha−1) was significantly higher in mixtures (E. globulus; 4.8 + A. mearnsii; 0.9) than E. globulus (3.3) or A. mearnsii monocultures (1.6). Annual transpiration (mm) measured using the heat pulse technique was also higher in mixtures (E. globulus; 285 + A. mearnsii; 134) than in E. globulus (358) and A. mearnsii (217) monocultures. Mixtures exhibited higher WUE than monocultures due to significant increases in the WUE of E. globulus in mixtures (1.69 kg aboveground biomass per cubic metre water transpired) compared to monocultures (0.94). The differences in WUE appear to result from increases in canopy photosynthetic capacity and above- to belowground carbon allocation in mixtures compared to monocultures. Although further studies are required and operational issues need to be resolved, the results of this study suggest that mixed eucalypt–acacia plantations may be used in water-limited environments to produce a given amount of wood with less water than eucalypt monocultures. Alternatively, because mixtures can be more productive and use more water per unit land area (but use it more efficiently), they could be utilized in recharge zones where rising water tables and salinity result from the replacement of vegetation (fast growing trees) that uses higher quantities of water with vegetation (shallow rooted annual crops) that use lower quantities of water.
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Growth responses to thinning and pruning in Eucalyptus globulus, Eucalyptus nitens, and Eucalyptus grandis plantations in southeastern Australia
Canadian Journal of Forest Research. 42:75-87.
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Nutrient cycling in a mixed-species plantation of Eucalyptus globulus and Acacia mearnsii
Canadian Journal of Forest Research. 35(12):2942-2950.
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Growth dynamics in a mixed-species plantation of Eucalyptus globulus and Acacia mearnsii
Forest Ecology and Management. 193(1-2):81-95.
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Nutrient cycling in a mixed-species plantation of Eucalyptus globulus and Acacia mearnsii
Canadian Journal of Forest Research. 35(12):2942-2950.
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On the success and failure of mixed-species tree plantations: lessons learned from a model system of Eucalyptus globulus and Acacia mearnsii
Forest Ecology and Management. 209:147-155.
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Carbon allocation in a mixed-species plantation of Eucalyptus globulus and Acacia mearnsii
Forest Ecology and Management. 233:275-284.
Following (3)
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William D Stock
Edith Cowan University -
Jerome K Vanclay
Southern Cross University -
Anna E Richards
The Commonwealth Scientific and Industrial Research Organisation
Topics (1)
