Daniel Kneeshaw | Université du Québec à Montréal (original) (raw)

Papers by Daniel Kneeshaw

We describe the fire regime in the Gaspesian mixedwood boreal forest in order to improve our know... more We describe the fire regime in the Gaspesian mixedwood boreal forest in order to improve our knowledge of the maritime fire regime through time and the role of climate on changes in fire cycle. We also investigated the importance of coarse scale spatial factors, such as topography, altitude, soil-type and vegetation-type. Fire history was reconstructed for a 6480-km 2 area using Quebec Ministry of Natural Resource archival data and aerial photographs combined with dendrochronological data, collected using a random sampling strategy. Physiographic features were not found to significantly influence the fire cycle, but an increase in the cycle (from 89 to 176 years p 0.0001) was observed since the end of Little Ice Age (LIA) (1850). Relative agreement between the archival data (1920-2003) and the semi-parametric survival analysis approach for the 1850-2003 period provides greater confidence in our determination of a fire cycle situated between 170 and 250 years. An analysis of fluctuations in the Canadian forest fire Weather Index system, calculated for the period 1920-2003, showed a statistically significant decrease in extreme values. Given such a long fire cycle and in the context of forest management based on natural disturbance, even-aged management under short rotations should be questioned in these mixedwood boreal forests.

The Forestry Chronicle, 2000

Pierre Drapeau114, Sylvie ~a u t h i e r l~~, David F' ar6115, Richard Carignan6, Rene Doucet7, L... more Pierre Drapeau114, Sylvie ~a u t h i e r l~~, David F' ar6115, Richard Carignan6, Rene Doucet7, Luc Bouthillier2, and Christian ~e s s i e r l Within Canada, and internationally, an increasing demand that forests be managed to maintain all resources has led to the development of criteria and indicators of sustainable forest management. There is, however, a lack of understanding, at an operational scale, how to evaluate and compare forest management activities to ensure the sustainability of all resources. For example, nationally, many of the existing indicators are too broad to be used directly at a local scale of forest management; provincially, regulations are often too prescriptive and rigid to allow for adaptive management; and forest certification programs, often based largely on public or stakeholder opinion instead of scientific understanding, may be too local in nature to permit a comparison of operations across a biome. At an operational scale indicators must be relevant to forest activities and ecologically integrated. In order to aid decision-makers in the adaptive management necessary for sustainable forest management, two types of indicators are identified: those that are prescriptive to aid in planning forest management and those that are evaluative to be used in monitoring and suggesting improvements. An integrated approach to developing standards based on an ecosystem management paradigm is outlined for the boreal forest where the variability inherent in natural systems is used to define the limits within which forest management is ecologically sustainable. Sustainability thresholds are thus d e f i by ecosystem response after natural disturbances. For this exercise, standards are proposed for biodiversity, forest productivity via regeneration, soil conservation and aquatic resources. For each of these standards, planning indicators are developed for managing forest conditions while forest values are evaluated by environmental indicators, thus leading to a continuous cycle of improvement. Approaches to developing critical thresholds and corresponding prescriptions are also outlined. In all cases, the scale of evaluation is clearly related to the landscape (or FMU) level while the stand level is used for measurement purposes. In this view the forest should be managed as a whole even though forest interventions are usually undertaken at the stand level.

Journal of Vegetation Science, 1998

Small-scale canopy openings are being increasingly recognized for their importance in boreal fore... more Small-scale canopy openings are being increasingly recognized for their importance in boreal forest stand development. Yet more work is necessary to understand their effects on seedling growth. This study investigated the effect of different degrees of canopy opening (all trees cut, conifers cut, conifers girdled and control quadrats) in different stand types on Abies balsamea seedling recruitment, growth and architecture. The lack of a treatment effect on seedling establishment suggests that gaps primarily affect advance regeneration. In the first year after treatment the seedlings in the cut blocks (both conifer cut and all trees cut) responded with an increase in height growth. Changes in the leader to lateral branch ratio were also significant. Continued architectural change in terms of number of branches produced did not occur until after two years had passed. Although not significantly different from the control, increases can be observed in all measurements for the girdled treatment. It is therefore concluded that the growth response of advance regeneration is more important following canopy opening than new seedling recruitment and that seedling performance is greatest where degree of opening is greatest.

Given the physiographic variability, variation in socio-political landscapes, and differences in ... more Given the physiographic variability, variation in socio-political landscapes, and differences in connectedness of people and communities associated with boreal forest ecosystems, approaches to forest management that are flexible enough to accommodate this variation are needed. Moreover, to ensure sustainable forest resource use, we need to embrace the inherent complexity of boreal forest ecosystems rather than eliminate it, and be prepared to adapt and adjust as environmental conditions change. While ecological resilience may be a useful forest management objective to this end, developing general guidelines to integrate it into practice remains elusive. We address a number of questions often posed by managers when attempting to include ecological resilience into forest management planning. Our goal is to determine if the theoretical foundation of ecological resilience is sufficiently developed to provide a general framework that can be applied for boreal forest management.

Partial cutting has been proposed as a means to better conserve biodiversity in managed forest la... more Partial cutting has been proposed as a means to better conserve biodiversity in managed forest landscapes. However, partial cutting encompasses many forms of silviculture; some with implicit goals of maintaining biodiversity such as multicohort harvesting or others which may specifically focus on regeneration of stands but may still provide some additional benefits for biodiversity such as shelterwood harvesting. Here we compared ground beetle assemblages of clear cuts, shelterwoods, multicohort harvested stands and uncut stands collected using pitfall traps both 2 and 3-years post-harvest. We hypothesized that partial cutting treatments would maintain assemblages that were more similar to uncut stands than to clear cuts. We further hypothesized that among partial cuts the multicohort harvested stands, with relatively high levels of retention (66%), would maintain beetle assemblages that were more similar to uncut stands than would shelterwoods, which had lower levels of retention (50%). We collected 6692 individuals, representing 42 species. Catch rates of beetles were similar among all harvested treatments (shelterwood, multicohort and clear cuts) and lower than uncut stands. Species richness and composition was similar between shelterwood and multicohort stands. Both partial cut treatments fell between clear cuts and uncut stands in terms of species richness and compositional similarity. Compositional differences between uncut stands and partial cut stands were defined primarily by reduced abundances of forest associated species such as Agonum retractum (LeConte), Synuchus impunctatus (Say) and four Pterostichus species within partial cuts. Within partial cuts, beetle assemblages differed between machine corridors with 0% retention and adjacent partial cut strips (50% retention) and uncut vegetation corridors (100%). We conclude that both shelterwoods and multicohort harvesting stands provide at least initially similar benefits for biodiversity compared to clear cutting although neither maintains assemblages consistent with those found in uncut stands. We expect that these similarities will end once trees are removed from shelterwoods. The reductions in abundances within partial cuts may extend the time necessary for individual populations to increase to pre-harvest levels in partial cuts. For land-managers, similar initial responses of beetle assemblages in multicohort and shelterwood harvests may permit some flexibility for conservation planning whereby final removal of seed trees within shelterwoods could be delayed depending on the status of recovering beetle populations.

Silva Fennica, 2011

There are many issues that we now understand much better than 20 years ago. Evidently, the taxono... more There are many issues that we now understand much better than 20 years ago. Evidently, the taxonomic focus in forest biodiversity research has changed. Birds and mammals were previously widely studied, but now most studies focus on invertebrates, fungi, bryophytes, ...

Remote Sensing of Environment, 2008

Understanding a disturbance regime such as gap dynamics requires that we study its spatial and te... more Understanding a disturbance regime such as gap dynamics requires that we study its spatial and temporal characteristics. However, it is still difficult to observe and measure canopy gaps extensively in both space and time using field measurements or bi-dimensional remote ...

Journal of Vegetation Science, 2010

Questions: How does woody vegetation abundance and diversity differ after natural disturbances ca... more Questions: How does woody vegetation abundance and diversity differ after natural disturbances causing different levels of mortality? Location: Abies balsamea-Betula papyrifera boreal mixed-wood stands of southeast Quebec, Canada. Methods: Woody vegetation abundance and diversity were quantified and compared among three disturbance-caused mortality classes, canopy gap, moderate-severity disturbances, and catastrophic fire, using redundancy analysis, a constrained linear ordination technique, and diversity indices. Results: Substantial changes in canopy tree species abundance and diversity only occurred after catastrophic fire. Shade-tolerant, late-successional conifer species remained dominant after canopy gap and moderate-severity disturbances, whereas shade-intolerant, early-successional colonizers dominated canopy tree regeneration after catastrophic fire. Density and diversity of mid-tolerant and shade-intolerant understory tree and shrub species increased as the impact of disturbance increased. Highest species richness estimates were observed after catastrophic fire, with several species establishing exclusively under these conditions. Relative abundance of canopy tree regeneration was most similar after canopy gap and moderate-severity disturbances. For the sub-canopy tree and shrub community, relative species abundances were most similar after moderate-severity disturbances and catastrophic fire. Vegetation responses to moderate-severity disturbances thus had commonalities with both extremes of the disturbance-caused mortality gradient, but for different regeneration layers.

Journal of Vegetation Science, 2007

To what extent do small-scale disturbances in the forest canopy, created by natural disturbance a... more To what extent do small-scale disturbances in the forest canopy, created by natural disturbance agents, affect stand development? Doubts exist as to whether small canopy openings have any real effect on the understory tree recruitment, especially in boreal forests. Location: Conifer and mixed stands in the Gaspesian region in eastern Québec. The main natural disturbance agents are recurring outbreaks of Choristoneura fumiferana (eastern spruce budworm) and winds. Methods: Linear transects in 27 sites were used to describe the gap (< 0.1 ha) regime parameters, including gap fraction, gap size and change in disturbance severity through time. Three stand types were distinguished, based on a gradient of abundance of tree host species for the eastern spruce budworm. The impact of gaps was evaluated on the basis of changes in the number, the period of recruitment, and the composition of tree saplings present within gap areas. Changes were measured along the gap size gradient, and according to the pattern of recent budworm epidemics. Results: The gap fraction is highly variable (18%-64%) and is on average relatively high (42%). Gap sizes have a positively skewed distribution. In most cases the growth rate among gap filling saplings increased sufficiently to date disturbance events. The composition and the structure of understory trees were affected by gap formation. The number of shade-intolerant tree species did increase during or following periods of particularly severe canopy disturbances. However, the establishment or survival of shade intolerant species was not restricted to larger gaps or more intensely disturbed periods. Conclusions: In sub-boreal forests of Eastern Canada, small scale disturbances in the tree canopy influence stand regeneration dynamics, but not to the extent that parameters such as sapling composition and recruitment patterns depend on gap regime characteristics.

Journal of Ecology, 2010

1. Mixed-wood boreal forests are often considered to undergo directional succession from shadeint... more 1. Mixed-wood boreal forests are often considered to undergo directional succession from shadeintolerant to shade-tolerant species. It is thus expected that overstorey gaps should lead to the recruitment of shade-tolerant conifers into the canopy in all stand development stages and that the recruitment of shade-intolerant hardwoods would be minimal except in the largest gaps. 2. We analysed short-term gap dynamics over a large 6-km 2 spatial area of mixed-wood boreal forest across a gradient of stands in different developmental stages with different times of origin since fire (expressed as stand 'age') that were affected differentially by the last spruce budworm (SBW) outbreak. Structural measurements of the canopy from lidar data were combined with spectral classification of broad species groups to characterize the gap disturbance regime and to evaluate the effect of gap openings on forest dynamics. 3. Estimated annual gap opening rates increased from 0.16% for 84-year-old stands to 0.88% for 248-year-old stands. Trees on gap peripheries in all stands were more vulnerable to mortality than interior canopy trees. 4. Due to recovery from the last SBW outbreak 16 years previously, gap closure rates were higher than opening rates, ranging from 0.44% to 2.05% annually, but did not show any relationship with stand age. There was, however, a continuing legacy of the last SBW outbreak in old-conifer stands in terms of a continued high mortality of conifers. In all stands, the majority of the openings were filled from below, although a smaller but significant proportion filled from lateral growth of gap edge trees. 5. Synthesis. The forest response to moderate-to small-scale disturbances in old-growth boreal forest counters the earlier assumption that the transition from one forest state to the next is slow and directional with time since the last fire. Overall, a small 6% increase in hardwoods was observed over 5 years, largely due to regeneration in-filling of hardwoods in gaps instead of successional transition to more shade-tolerant conifers. Gaps are vital for hardwood maintenance while transition to softwoods can occur without perceived gap-formation as overstorey trees die, releasing understorey trees.

Journal of Ecology, 2006

1 Traditional rankings of shade tolerance of trees make little reference to individual size. Howe... more 1 Traditional rankings of shade tolerance of trees make little reference to individual size. However, greater respiratory loads with increasing sapling size imply that larger individuals will be less able to tolerate shade than smaller individuals of the same species and that there may be shifts among species in shade tolerance with size. 2 We tested this hypothesis using maximum likelihood estimation to develop individualtree-based models of the probability of mortality as a function of recent growth rate for seven species: trembling aspen, paper birch, yellow birch, mountain maple, white spruce, balsam fir and eastern white cedar. 3 Shade tolerance of small individuals, as quantified by risk of mortality at low growth, was mostly consistent with traditional shade tolerance rankings such that cedar > balsam fir > white spruce > yellow birch > mountain maple = paper birch > aspen. 4 Differences in growth-dependent mortality were greatest between species in the smallest size classes. With increasing size, a reduced tolerance to shade was observed for all species except trembling aspen and thus species tended to converge in shade tolerance with size. At a given level of radial growth larger trees, apart from aspen, had a higher probability of mortality than smaller trees. 5 Successional processes associated with shade tolerance may thus be most important in the seedling stage and decrease with ontogeny.

Established in 1995, the Sustainable Forest Management Network (SFM Network) is an incorporated, ... more Established in 1995, the Sustainable Forest Management Network (SFM Network) is an incorporated, non-profit research organization based at the University of Alberta in Edmonton, Alberta, Canada.

Forest Policy and Economics, 2009

This research tested whether demonstration of the long term effect of different forest management... more This research tested whether demonstration of the long term effect of different forest management scenarios in a large forested area changes people's forest values and attitudes. Forestry professionals and other forest users in Central Labrador were shown simulation results of three alternative forest management scenarios illustrating possible long term effects on various indicators. Forest values and attitudes towards forestry were measured before and after the presentation. Our conception of values and attitudes is based on the cognitive hierarchy model of human behaviour which states that values are more enduring and more difficult to change than attitudes. It was thus hypothesized that attitudes would change but not values and that change in forestry professionals would be less than in other forest users since foresters are trained to think about long-term effects and large-scale processes of forest management scenarios. We also hypothesized that a greater number of people would have an opinion on forest management after the presentation. All three hypotheses were partially supported by the results. The results indicated that some attitude change occurred, but that values also changed somewhat. Most of the significant changes occurred when persons with no clear opinion on several forest-related questions formed an opinion. Long-term, landscape simulation results provide valuable information and enhance understanding of both forestry professionals and other forest users. However, being provided the same information, the two groups learned different things. While forest users gained more confidence in the current forest management plan and were motivated to further participate, professionals learned more specific things. This reflects differences between technical and local knowledge.

Environmental Reviews, 2003

Abstract: Old-growth forests have been identified as a potentially important stage of stand devel... more Abstract: Old-growth forests have been identified as a potentially important stage of stand development for maintaining biodiversity in the landscape, yet they have also been targeted by the forest industry in their drive to regulate the forest. We will attempt to propose a definition of old growth, ...

Ecoscience, 2005

A range of stands was sampled in the southern boreal forest of eastern Canada to determine the im... more A range of stands was sampled in the southern boreal forest of eastern Canada to determine the impact of forest development stages and light availability on the dynamics of an abundant understory shrub: mountain maple (Acer spicatum). Mountain maple was studied at both the population and individual stem levels. At the population level, a total of 190 1-m2 quadrats were sampled in five forest types representing a successional gradient (young aspen, mature aspen, mixedwood, shade-tolerant conifer, and old spruce budworm-affected conifer forests). At the individual stem level, a total of 100 stems of different sizes were harvested in a sub-sample of the quadrats. Mountain maple stem biomass, density, and population structure were found to be affected by forest composition, the coniferous forest being the least favourable. At the individual stem level, light availability and stem size were found to have an important impact on stem morphology and growth, suggesting a high level of plasticity in relation to canopy opening. From these results, four developmental phases of mountain maple population dynamics were identified: 1) following a drastic disturbance, a first phase of rapid growth, and potentially intense competition with aspen suckers, when present, takes place; 2) following the development of a closed aspen canopy, the overall density, biomass, and presence of mountain maple in the understory increase; 3) following recruitment of conifer trees into the overstory canopy, mountain maple enters a suppression phase associated with a decrease in light; and 4) following the occurrence of small scale disturbances, mountain maple quickly responds to rapidly dominate the openings, which further ensures its maintenance in the understory.

Ecology, 1998

This study identifies patterns in the gap disturbance regime along a successional gradient in the... more This study identifies patterns in the gap disturbance regime along a successional gradient in the southern boreal forest and uses this information to investigate canopy composition changes. Gaps were characterized in hardwood, mixed-forest, and conifer stands surrounding Lake Duparquet in northwestern Quebec. From 39 to 80 gaps were evaluated along transects established in each of these stands. The abundance of gap makers and gap fillers and total regeneration was evaluated by species, as well as the size of each gap encountered along the transects. The percentage of the forest in canopy gap was calculated directly from the proportion of the transect in gap and by using gap area and lineintercept techniques. Changes in composition were evaluated from gap-maker and gapfiller distributions and by using transition matrices based on species mortality and regeneration in canopy gaps.