Showing papers by "Canadian Forest Service published in 2021"

Tree height and leaf drought tolerance traits shape growth responses across droughts in a temperate broadleaf forest.

Abstract: As climate change drives increased drought in many forested regions, mechanistic understanding of the factors conferring drought tolerance in trees is increasingly important. The dendrochronological record provides a window through which we can understand how tree size and traits shape growth responses to droughts. We analyzed tree-ring records for 12 species in a broadleaf deciduous forest in Virginia (USA) to test hypotheses for how tree height, microenvironment characteristics, and species' traits shaped drought responses across the three strongest regional droughts over a 60-yr period. Drought tolerance (resistance, recovery, and resilience) decreased with tree height, which was strongly correlated with exposure to higher solar radiation and evaporative demand. The potentially greater rooting volume of larger trees did not confer a resistance advantage, but marginally increased recovery and resilience, in sites with low topographic wetness index. Drought tolerance was greater among species whose leaves lost turgor (wilted) at more negative water potentials and experienced less shrinkage upon desiccation. The tree-ring record reveals that tree height and leaf drought tolerance traits influenced growth responses during and after significant droughts in the meteorological record. As climate change-induced droughts intensify, tall trees with drought-sensitive leaves will be most vulnerable to immediate and longer-term growth reductions.

Worldwide border interceptions provide a window into human‐mediated global insect movement

Abstract: As part of national biosecurity programs, cargo imports, passenger baggage and international mail are inspected at ports of entry to verify compliance with phytosanitary regulations and to directly intercept potentially damaging non-native species to prevent their introduction. Detection of organisms during inspections may also provide crucial information about the species composition and relative arrival rates in invasion pathways that can inform the implementation of other biosecurity practices such as quarantines and surveillance. In most regions, insects are the main taxonomic group encountered during inspections. We gathered insect interception data from nine world regions collected from 1995 - 2019 to compare the composition of species arriving at ports in these regions. Collectively, 8,716 insect species were intercepted in these regions over the last 25 years, with the combined international dataset comprising 1,899,573 interception events, of which 863,972 were identified to species level. Rarefaction analysis indicated that interceptions comprise only a small fraction of species present in invasion pathways. Despite differences in inspection methodologies, as well as differences in the composition of import source regions and imported commodities, we found strong positive correlations in species interception frequencies between regions, particularly within the Hemiptera and Thysanoptera. There were also significant differences in species frequencies among insects intercepted in different regions. Nevertheless, integrating interception data among multiple regions would be valuable for estimating invasion risks for insect species with high likelihoods of introduction as well as for identifying rare but potentially damaging species.

The development and implementation of a human-caused wildland fire occurrence prediction system for the province of Ontario, Canada

Abstract: We describe the development and implementation of an operational human-caused wildland fire occurrence prediction (FOP) system in the province of Ontario, Canada. A suite of supervised statistical ...

Joint effects of climate, tree size, and year on annual tree growth derived from tree-ring records of ten globally distributed forests

Abstract: Tree rings provide an invaluable long-term record for understanding how climate and other drivers shape tree growth and forest productivity. However, conventional tree-ring analysis methods were not designed to simultaneously test effects of climate, tree size, and other drivers on individual growth. This has limited the potential to test ecologically relevant hypotheses on tree growth sensitivity to environmental drivers and their interactions with tree size. Here, we develop and apply a new method to simultaneously model nonlinear effects of primary climate drivers, reconstructed tree diameter at breast height (DBH), and calendar year in generalized least squares models that account for the temporal autocorrelation inherent to each individual tree's growth. We analyze data from 3811 trees representing 40 species at 10 globally distributed sites, showing that precipitation, temperature, DBH, and calendar year have additively, and often interactively, influenced annual growth over the past 120 years. Growth responses were predominantly positive to precipitation (usually over ≥3-month seasonal windows) and negative to temperature (usually maximum temperature, over ≤3-month seasonal windows), with concave-down responses in 63% of relationships. Climate sensitivity commonly varied with DBH (45% of cases tested), with larger trees usually more sensitive. Trends in ring width at small DBH were linked to the light environment under which trees established, but basal area or biomass increments consistently reached maxima at intermediate DBH. Accounting for climate and DBH, growth rate declined over time for 92% of species in secondary or disturbed stands, whereas growth trends were mixed in older forests. These trends were largely attributable to stand dynamics as cohorts and stands age, which remain challenging to disentangle from global change drivers. By providing a parsimonious approach for characterizing multiple interacting drivers of tree growth, our method reveals a more complete picture of the factors influencing growth than has previously been possible.

Save Our Species: A Blueprint for Restoring Butternut (Juglans cinerea) across Eastern North America

Abstract: Butternut is a relatively uncommon hardwood tree native to eastern North America. The species' abundance has declined over the past 50 years, primarily because of an invasive pathogen (Ophiognomonia clavigignenti-juglandacearum [Oc-j]) and loss of suitable habitat for regeneration. Although genetic diversity of butternut is highest along the southern range edge, genetic diversity rangewide is fairly high, except in small and isolated populations. Although there is little evidence for even moderate resistance in native butternut, hybrids with Japanese walnut, a closely related species, display enough tolerance to infection to persist on the landscape and bear abundant nut crops year after year. Cryostorage of native embryogenic axes has yielded promising initial results as a strategy for gene conservation, but additional action is needed to conserve the remaining native gene pool. We describe a strategy for canker-resistance breeding in butternut using naturally occurring hybrids, hybrids in research orchards, and sources of native trees from as many regions as possible. Forest managers are encouraged to find surviving trees and collect seed for planting in suitable habitat to develop actionable knowledge that will enable the restoration of butternut with enough resistance to be self-sustaining on the landscape.

Optimizing the location of watercraft inspection stations to slow the spread of aquatic invasive species

Abstract: The accidental spread of aquatic invasive species (AIS) by recreational boaters is a major concern of state and county environmental planners in the USA. While programs for watercraft inspection to educate boaters and slow AIS spread are common practice, large numbers of boats and waterbodies, together with limited budgets, make program design difficult. To facilitate program design, we developed an integer programming model for allocation of scarce inspection resources among lakes. Our model uses species-specific infestation status of lakes and estimates of boat movement between lakes. The objective is to select lakes for inspection stations to maximize the number of risky boats inspected, where risky boats are ones that move from infested to uninfested lakes. We apply our model in Stearns County in central Minnesota, USA, to prioritize lakes for inspection stations and evaluate alternative management objectives. With an objective of protecting uninfested lakes within and outside Stearns County, the optimal policy is to locate stations at infested lakes having the most boats departing for uninfested lakes inside and outside the county. With an objective of protecting only Stearns County lakes, the optimal policy is to locate stations at both infested and uninfested lakes having the riskiest boats arriving from within and outside the county and departing to in-county lakes. The tradeoff between these objectives is significant.

Simulated winter warming has negligible effects on germination success of Acadian Forest tree species

Abstract: Dormant seeds that require long periods of cold stratification to become germinable may be most sensitive to increases in winter temperatures caused by anthropogenic climate change. In this study, ...

Forest Biosecurity in Canada – An Integrated Multi-Agency Approach

Abstract: In Canada, forest biosecurity is primarily under federal jurisdiction as the federal government is the signatory to the International Plant Protection Convention and other international trade agreements. The Canadian Food Inspection Agency (CFIA), which is Canada’s National Plant Protection Organization, has the mandate of analyzing risks, setting policy, and managing incursion responses related to forest biosecurity. Other federal government agencies play important roles; the Canada Border Services Agency (CBSA) enforces regulations at international ports of entry and the Canadian Forest Service of Natural Resources Canada conducts research and analysis in support of the development and implementation of phytosanitary regulations. The provinces and territories also manage invasive species through implementing regulations to prevent the spread of established forest pests. This paper outlines the regulatory framework for forest biosecurity within Canada, and provides case studies of species that have invaded Canadian forests or are anticipated to do so in the near future.

Evidence for Semiochemical Divergence Between Sibling Bark Beetle Species: Dendroctonus brevicomis and Dendroctonus barberi

Abstract: We investigated geographic variation in the semiochemistry of major disturbance agents of western North American pine forests, Dendroctonus brevicomis Le Conte and Dendroctonus barberi Hopkins (Coleoptera: Curculionidae: Scolytinae), species separated by the Great Basin in the USA that until recently were synonymous. At 15 sites in the western USA and northern Mexico, beetle populations were examined to determine (1) pheromone production by solitary, mining females, (2) male electroantennogram amplitudes in response to known semiochemicals for the genus, or (3) relative attractiveness of two female-produced pheromone components (endo- and exo-brevicomin) and two host odors (alpha-pinene and myrcene) to beetles in the field. Compared to female beetles collected east of the Great Basin (D. barberi), western females (D. brevicomis) produced a consistently higher proportion of, and male antenna were correspondingly more sensitive to, the exo- than the endo-isomer of brevicomin. With the exception of one sampling location (where no preference was observed), beetles west of the Great Basin were more attracted to exo- than endo- brevicomin trap lures, whereas eastern beetles displayed the reverse preference. In contrast, there was not a consistent difference between these populations regarding relative attraction or olfactory response to myrcene or alpha-pinene, although some geographic variability was evident. These data show that the semiochemical systems of D. brevicomis and D. barberi have diverged and corroborate genetic and morphological evidence that they are distinct, allopatric species.

Sensors for Fire and Smoke Monitoring.

Abstract: Mastery of fire is intimately linked to advances in human civilization, culture and technology [...]

A Bi-Spectral Microbolometer Sensor for Wildfire Measurement.

Abstract: This study describes the development of a prototype bi-spectral microbolometer sensor system designed explicitly for radiometric measurement and characterization of wildfire mid- and long-wave infrared radiances. The system is tested experimentally over moderate-scale experimental burns coincident with FLIR reference imagery. Statistical comparison of the fire radiative power (FRP; W) retrievals suggest that this novel system is highly reliable for use in collecting radiometric measurements of biomass burning. As such, this study provides clear experimental evidence that mid-wave infrared microbolometers are capable of collecting FRP measurements. Furthermore, given the low resource nature of this detector type, it presents a suitable option for monitoring wildfire behaviour from low resource platforms such as unmanned aerial vehicles (UAVs) or nanosats.

Geocorrection of Airborne Mid-Wave Infrared Imagery for Mapping Wildfires without GPS or IMU

Abstract: The increase in annual wildfires in many areas of the world has triggered international efforts to deploy sensors on airborne and space platforms to map these events and understand their behaviour. During the summer of 2017, an airborne flight campaign acquired mid-wave infrared imagery over active wildfires in Northern Ontario, Canada. However, it suffered multiple position-based equipment issues, thus requiring a non-standard geocorrection methodology. This study presents the approach, which utilizes a two-step semi-automatic geocorrection process that outputs image mosaics from airborne infrared video input. The first step extracts individual video frames that are combined into orthoimages using an automatic image registration method. The second step involves the georeferencing of the imagery using pseudo-ground control points to a fixed coordinate systems. The output geocorrected datasets in units of radiance can then be used to derive fire products such as fire radiative power density (FRPD). Prior to the georeferencing process, the Root Mean Square Error (RMSE) associated with the imagery was greater than 200 m. After the georeferencing process was applied, an RMSE below 30 m was reported, and the computed FRPD estimations are within expected values across the literature. As such, this alternative geocorrection methodology successfully salvages an otherwise unusable dataset and can be adapted by other researchers that do not have access to accurate positional information for airborne infrared flight campaigns over wildfires.

Symptom development and mortality rates caused by Armillaria ostoyae in juvenile mixed conifer stands in British Columbia’s southern interior region

Abstract: Plots were established in 20 juvenile mixed conifer stands in the Interior Cedar Hemlock biogeoclimatic zone of British Columbia's southern interior region in western Canada to assess mortality and host response to infection in the form of basal lesions caused by Armillaria ostoyae. Western redcedar showed significantly lower mortality and a higher proportion of callused lesions at the root collar than Douglas-fir and western hemlock. Mortality decreased with increasing tree diameter for all species; however, the rate of decrease was markedly greater for western redcedar than Douglas-fir or western hemlock. Results from logistic regression analysis showed that the probability of Douglas-fir being killed is 14.6 times greater than western redcedar in these juvenile stands. Because western redcedar displayed significant resistance to A. ostoyae at both the root and stand level, this species represents an excellent choice as a significant stand component with more susceptible conifers. Should susceptible conifers succumb to Armillaria root disease, western redcedar will likely fill in the stand.

Animal Population Ecology: An Analytical Approach

Abstract: Animal population ecology comprises the study of variations, regulation, and interactions of animal populations. This book discusses the fundamental notions and findings of animal populations on which most of the ecological studies are based. In particular, the author selects the logistic law of population growth, the nature of competition, sociality as an antithesis of competition, the mechanism underlying the regulation of populations, predator-prey interaction processes, and interactions among closely related species competing over essential resources. These are the notions that are considered to be well-established facts or principles and are regularly taught at ecology classes or introduced in standard textbooks. However, the author demonstrates that these notions are still inadequately understood, or even misunderstood, creating myths that would misguide ecologists in carrying out their studies. He delves deeply into those notions to reveal their real nature and draws a road map to the future development of ecology.