Research
Recent Publications
Goldblum, D. and Rigg, L.S. (2005) Tree growth response to climate change at the deciduous/boreal forest ecotone, Ontario, Canada. Canadian Journal of Forest Research. 35: 2709-2718. Abstract
Diochon, A., L.S. Rigg,
D. Goldblum, and N.O. Polans (2003) The regeneration dynamics and genetic
variability of sugar maple (Acer saccharum [Marsh.]) seedlings at the species’ northern growth limit, Lake Superior Provincial Park, Ontario, Canada.Physical Geography, 24(5): 399-413. Abstract
Goldblum, D. and L.S. Rigg. (2002) Age structure and regeneration dynamics of sugar maple at the deciduous/boreal forest ecotone, Ontario, Canada. Physical Geography. In Press. Abstract
Enright, N.J. and Goldblum, D. (1999) Comparative demography of co-existing Hakea species (Proteaceae), H. decurrens (non-sprouter) and H. rostrata (resprouter), in fire-prone Eucalyptus woodlands, western Victoria, Australia. Plant Ecology 144: 71-82. Abstract
Goldblum, D. and S.W. Beatty. (1999) Influence of an old field/forest edge on a northeastern United States deciduous forest understory community. Journal of the Torrey Botanical Society. 126: 335-443. Abstract
Enright, N.J. and Goldblum, D. (1998) Stand structure of the emergent conifer Agathis ovata in forest and maquis, Province Sud, New Caledonia. Journal of Biogeography. 25: 641-648. Abstract
Goldblum, D.(1998) Regeneration in unmanaged conifer plantations, upstate New York. Northeastern Naturalist. 5: 343-358. Abstract
Enright, N.J., Goldblum, D., Ata, P., and Ashton, D. H. (1997) The independent effects of heat, smoke, and ash on emergence of seedlings from the soil seed bank of a heathy Eucalyptus woodland in Grampians (Gariwerd) National Park, western Victoria. Australian Journal of Ecology 22: 81-88. Abstract
Goldblum, D. (1997) The effects of treefall gaps on understory vegetation in New York, USA. Journal of Vegetation Science. 8: 125-132. Abstract
Recent Publication
Goldblum, D. and Rigg, L.S. (2005) Tree growth response to climate change at the deciduous/boreal forest ecotone, Ontario, Canada. Canadian Journal of Forest Research. 35: 2709-2718.
Abstract: We consider the implications of climate change on the future of the three dominant forest species, sugar maple (Acer saccharum Marsh.), white spruce (Picea glauca (Moench) Voss), and balsam fir (Abies balsamea (L.) Mill.), at the deciduous-boreal forest ecotone, Ontario, Canada. Our analysis is based on individual species responses to past monthly temperature and precipitation conditions in light of modeled (general circulation model) monthly temperature and precipitation conditions in the study area for the 2080s. We then consider the tree species sensitivity to past climate with predicted conditions for the 2080 period. Sugar maple, located at its northern limit in the study area, shows the greatest potential for increased growth rates under the predicted warming and altered precipitation regime. White spruce is likely to benefit less, while the understory dominant balsam fir is likely to experience a decrease in growth potential. These projected changes would enhance the future status of sugar maple at its northern limit and facilitate range expansion northward in response to global warming
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Abstract:
The transition from deciduous forest to boreal forest is abrupt regionally
and topographically in Lake Superior Provincial Park, Ontario, Canada. The
northern range limit of Acer saccharum is coincident with the forest transition
to boreal forest. The goal of our study was to characterize the distribution
of A. saccharum seedlings at the transition zone to determine if variability
in seedling demographics and genetics with topographic position and along
a short north-south gradient was evident. Seedling density, size, age, and
growth were evaluated in permanent plots across the regional transition zone,
and at the south-facing, ridge top and north-facing limits across the topographic
transition. Growth over five years was determined by measuring the distance
between terminal bud scars, and compared with regional climate data. Genetic
material was collected and analyzed from two of these sites. No significant
differences were detected in density or growth of Acer saccharum across the
regional transition, but mean age increased and height decreased as the limit
was approached. Across the topographic transition, ridge top seedling densities
were greater than south-facing or north-facing limits. Genetic variability
was substantial with no cohort preference for topographic position detected.
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Goldblum, D. and L.S. Rigg. (2002) Age structure and regeneration dynamics of sugar maple at the deciduous/boreal forest ecotone, Ontario, Canada. Physical Geography. In Press.
Abstract:
Sugar maple reaches its northern limit along the eastern shore of Lake Superior
marking the transition from the deciduous forest of eastern North America
to a predominantly boreal forest community. In light of regional warming trends
over the past 100 years and projections for even warmer conditions in the
future we sought to characterize the current age structure and regeneration
status of both sugar maple and boreal tree species within this ecotone zone.
Within Lake Superior Provincial Park (Ontario, Canada) a series of west-east
trending hills create numerous deciduous-boreal transition zones as sugar
maple occupy uplands and boreal species occupy valley bottoms, then once north
of the sugar maple limit, boreal species dominate all topographic positions.
Unlogged forest stands were sampled in the transition zone on ridges and slopes
both north and south of the sugar maple limit. Overall tree density and basal
area in sugar maple and boreal stands was similar across the ecotone, but
seedling density was significantly higher in plots dominated by sugar maple.
Moreover, sugar maple seedlings, but not saplings, were found slightly beyond
the adult sugar maple tree limit indicating the potential for range expansion
may be limited by microclimatic variables, namely cold air drainage.
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Enright, N.J. and Goldblum, D. (1999) Comparative demography of co-existing Hakea species (Proteaceae), H. decurrens (non-sprouter) and H. rostrata (resprouter), in fire-prone Eucalyptus woodlands, western Victoria, Australia. Plant Ecology 144: 71-82.
Abstract: Population size-structures, seed production, canopy seed storage (serotiny), and recruitment were investigated in relation to fire, drought and disease for a pair of co-occurring resprouting and non-sprouting shrub species from the genus Hakea (Proteaceae) in fire-prone Eucalyptus woodlands in western Victoria, Australia. The non-sprouter species, Hakea decurrens, showed faster height growth, higher seed production and higher seed viability than the resprouter, Hakea rostrata. Population size structures in stands up to 24 years since last fire showed no evidence of inter-fire recruitment for either species. Following a fire in 1990 in a mixed species stand 15-20 years old, the estimated number of viable seeds released from canopy-stored seed banks was approximately equal for both species. However, the rate of seedling establishment in the first year was about 10 times higher, and seedling suvivorship over the first 5 years was seven times higher, for the non-sprouter. Seedlings of Hakea decurrens and resprouts of Hakea rostrata began to produce seeds within three years of the last fire, while the few surviving seedlings of Hakea rostrata showed no evidence of reproductive maturity after six years. Inter-fire recruitment was recorded for the non-sprouter, Hakea decurrens, in the oldest stand (burned in 1967) between 24 and 28 years since last fire. This was associated with an increased rate of seed release from serotinous fruits due to the onset of high rates of adult plant mortality. High adult mortality and increased seed release correlated with increasing stand age, the occurrence of severe drought, and the likely presence of Phytophthora cinnamomi, a fungal pathogen which damages the root system, reducing water and nutrient uptake. There were no new recruits for the resprouter Hakea rostrata in this stand, but old plants continued to resprout from basal lignotubers and no mortality was observed. While recruitment of strongly serotinous shrub species is commonly described as being restricted to the immediate post-fire period, the present study illustrates that other events (e.g., senescence, drought, disease) can lead to recruitment of serotinous non-sprouters and may be important in the maintenance of populations during unusually long periods without fire.
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Goldblum, D. and S.W. Beatty. (1999) Influence of an old field/forest edge on a northeastern United States deciduous forest understory community. Journal of the Torrey Botanical Society. 126: 335-443.
Abstract: We examined edge effects within a forest along old field boundaries in a mixed deciduous/hemlock forest community in upstate New York. Species composition and community structure of both forest understory and treefall gap vegetation were analyzed in two ways: first, we used belt transects to quantify changes in the understory community with distance from the forest edge, and second, we compared species composition of treefall gaps both near and distant from the edge. Exotic species and locally rare species were significantly more abundant at the forest edges than in the forest interior, while tree seedlings were less common at the forest edge. Species composition of treefall gaps near the old field/forest edge differed from composition of treefall gaps in the forest interior during most of the growing season. Treefall gaps at the forest edge, as a group, were compositionally more heterogeneous than treefall gaps distant from the edge.
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Enright, N.J. and Goldblum, D. (1998) Stand structure of the emergent conifer Agathis ovata in forest and maquis, Province Sud, New Caledonia. Journal of Biogeography. 25: 641-648.
Abstract: The size structure of the endemic New Caledonian conifer Agathis ovata is reported for sample stands in forest and maquis from three areas on ultramafic substrates in the south of the main island (Grand Terre). In closed forest Agathis ovata is typically represented by a low density of emergent adult trees with only limited evidence of seedling recruitment. In maquis, Agathis ovata is represented by individuals of all sizes, with seedlings and saplings abundant in most sample stands. Preliminary evidence from tree-ring studies indicates that rings may be annual. Estimated diameter growth rate is about 2 mm/yr for trees >10 cm dbh, and ring counts suggest tree ages of up to 400 years in maquis and 500 years in forest. Agathis ovata, and three other members of the Araucariaceae found in New Caledonia (Araucaria laubenfelsii, A. montana and A. rulei), are the only tree species which regularly occur scattered in maquis in this way, creating an unusual structural assemblage. No angiosperm tree species show this behaviour. The circumstances under which the Agathis ovata maquis stands arise and are maintained are the subject of further investigation. Preliminary evidence for tree ages indicates that these stands predate European arrival in New Caledonia and so are not the result of recent increases in the frequency and intensity of human disturbances. The presence of fire scars on many individuals, and location of most stands on slopes and spurs with outcropping laterite (cuirasse), suggests that this assemblage may owe its existence to the interplay of fire regime, topography and rockiness, and a resistance to fire in Agathis ovata which increases with plant size and age.
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Goldblum, D. (1998) Regeneration in unmanaged conifer plantations, upstate New York. Northeastern Naturalist. 5: 343-358.
Abstract: This study addresses the secondary succession of abandoned Pinus resinosa (red pine) and Picea glauca (white spruce) plantations in upstate New York. Both red pine and white spruce are not regenerating in the unmanaged plantations. Successful regeneration of hardwood tree species in the white spruce plantations occurred only within the 25-30 years following planting. Higher light levels in the red pine stands have led to a greater degree of subsequent hardwood invasion than in the white spruce stands. The impact of abandoned conifer plantations will have long-term effects, altering the forest species composition for several hundred years. However, the plantations will eventually return to a natural forest composition, and expansion of planted conifers into adjacent undisturbed forests is unlikely.
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Enright, N.J., Goldblum, D., Ata, P., and Ashton, D. H. (1997) The independent effects of heat, smoke, and ash on emergence of seedlings from the soil seed bank of a heathy Eucalyptus woodland in Grampians (Gariwerd) National Park, western Victoria. Australian Journal of Ecology 22: 81-88.
Abstract: The independent effects of smoke, ash, and wet and dry heat treatments on seedling emergence from the soil seed bank were tested for soils from fire-prone heathy woodlands in western Victoria. A total of 763 individuals from 56 species were recorded from the surface soil samples (which covered a total area of 1 m(2)). Both species richness and density of seedlings was greater for smoke- and heat-treated samples than for controls and ash-treated samples. However, only the density differences were significant. Mean seed bank densities for the smoke and heat treatments ranged from 855+/-70 m(-2) to 1080+/-58 m(-2) and are similar to estimates obtained elsewhere in Australia for heat-treated soils from dry sclerophyll communities. Of the 56 species recorded, 46 occurred in the smoke and heat treatments but only 33 in the control and ash treatments. The sudden increase in surface soil pH, exchangeable cations and extractable phosphorus which was associated with the ash treatment did not act as a trigger for germination in any of the species recorded here. Chemical constituents from smoke do appear to provide a stimulus separate from the effects of heat, but were not identified with any particular taxa.
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Goldblum, D.(1997) The effects of treefall gaps on understory vegetation in New York, USA. Journal of Vegetation Science. 8: 125-132.
Abstract: Treefalls are a common form of disturbance in northeastern United States forests. The resultant gaps contribute to a high degree of environmental heterogeneity in the understory of these forests. Plant density, plant cover, and species richness in understory plant communities were monitored for three years during the growing season, May - September. Differences between treefall gap and closed canopy vegetation were less pronounced early in the growing season for plant density and leaf cover. Species richness was significantly greater within treefall gaps during the entire growing season. Eight species were found in greater abundance within treefall gaps (i.e., gap-phase species), while one species was found more commonly under closed canopy. Ordination results suggest that time since gap creation and treefall gap size marginally affect the species composition of vegetation found within treefall gaps.
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