Research

We conduct research to improve the understanding of tree biology, forest ecosystems and provide insights useful in management applications. We focus our research on field data and integrate those studies with climatological and spatial analyses to provide insights into both fine-scale ecological processes and broader regional patterns. The mechanisms driving global climate change and ecosystem response are numerous, therefore, the research questions we ask target understanding changing disturbance regimes and tree growth-climate responses. Looking back into the past and into the future, our research examines both the causes and consequences of environmental change in temperate forests with a special interest on the outcomes for forest structure, ecosystem function, resilience and management implications.

EDUCATION

2017

PhD, Geography, University of Victoria, Canada

2014

Visiting Scholar (6 months), University of Colorado, Boulder

2011

M.Sc., Geography, University of Victoria, Canada

2004

B.Sc., Geography, University of Victoria, Canada

RESEARCH

The Baltic Sea and its southern lowlands: proxy – environment interactions in times of rapid change

Forest ecosystem change is driven by both short-term, high-magnitude climate events and gradual changes in mean climate conditions. Expressed in forest ecosystems directly through event-caused growth depressions or mortality, and indirectly by event-induced disturbance activity, extreme climate events have a greater influence on plant physiological processes than gradual changes in mean climate. More frequent and intense climate events are expected highlighting research priorities that address ecosystem responses to events including ecological memory and the importance of contextualizing responses in both time and space.

The overarching goal of this research is to assess the spatial and temporal patterns of growth resilience of common forest tree species in response to extreme climate events, and to compare these findings across proxy records derived from annually-varved lake sediments. This will be accomplished by addressing three research questions:

(1) Do spatial patterns of growth resilience and recovery exist and are these patterns synchronous, asynchronous or independent?

(2) Are temporal patterns of growth resilience and recovery synchronous, asynchronous or independent?

(3) Can the expression of extreme climate events and resilience be compared across proxy records of tree rings and annually-varved lake sediments?

This project aims to synchronized multiple marine, lake and tree-ring- based proxies and is conducted with direct collaboration with the Leibniz Institute for Baltic Sea Research Warnemünde (IOW), Rostock-Warnemünde, Germany, Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences, Potsdam, Germany, Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Berlin, Germany, University of Szczecin, Szczecin, Poland, Polish Academy of Sciences (PAN – IGiPZ), Torun, Poland and the Deutsches Archäologisches Institut, Berlin, Germany.

Mixed-severity fire history at a forest-grassland ecotone in west central British Columbia, Canada

This study examines spatially variable stand structure and fire-climate relationships at a low elevation forest-grassland ecotone in central British Columbia, Canada.

Publication: Harvey, J., Smith, D., Veblen T.T. 2017. Mixed-severity fire history at a forest-grassland ecotone in west central British Columbia, Canada. In press: Ecological Applications

doi: 10.1002/eap.1563.

Interannual climate variability drives regional fires in west central British Columbia, Canada

Key Points:

Interannual climate variability, represented as PDSI, increasingly synchronized fire activity between 1600 and 1900 AD
Weak/inconsistent associations between regional fires and ENSO, PDO and PNA suggest these patterns exert little influence on fire activity
Small, localized fires were climatically associated with positive antecedent moisture conditions

Publication: Harvey, J., Smith, D. 2017. Interannual climate variability drives regional fires in west central British Columbia, Canada. In press: Journal of Geophysical Research Biogeosciences doi: 10.1002/2016JG00366.

Disturbance-climate relationships between wildfire and western spruce budworm in interior British Columbia

We compiled site-level and regionalized tree-ring chronologies of fire (AD 1600-1900) and western spruce budworm (AD 1600-2009) outbreaks for both lower montane forests adjacent to expansive grasslands and middle montane forests (regionalized grassland and non-grassland chronologies). At site and regional scales, the relation between fire years, outbreaks of WSB, reconstructed values of the Palmer Drought Severity Index and annual precipitation were examined using superposed epoch and bivariate event analyses. We also examined the interrelationships between fire years and WSB outbreaks.

Publication: Harvey, J., Axelson, J., Smith, D. 2018. Disturbance-climate relationships between wildfire and western spruce budworm in interior British Columbia. Ecosphere 9:1-21.

Biotic and abiotic factors influence Douglas-fir encroachment into grasslands in interior British Columbia

In this study we are investigating a suite of abiotic and biotic factors (e.g., climate, grazing, fire, facilitation) that have influenced conifer encroachment into grasslands in the Churn Creek Protected Area over the last 150 years.

Publication in progress: Harvey, J., Smith, D. Biotic and abiotic factors influence Douglas-fir encroachment into grasslands in interior British Columbia. Target journal: Forest Ecology and Management.

Little Ice Age glacier activity in the central British Columbia Coast Mountains

The Little Ice Age behaviour of glaciers in the central British Columbia Coast Mountains, Canada, was described by conducting lichenometric surveys of Rhizocarpon spp. found on recently deposited moraines in the Kitimat and Pacific ranges.

Publication: Harvey, J., and Smith D. 2013. Little Ice Age glacier activity in the central British Columbia Coast Mountains. Geographiska Annaler 95: 1-14.

Mid-Holocene glacier expansion between 7500-4000 cal. yr BP in the British Columbia Coast Mountains, Canada

The mid-Holocene behaviour of five glaciers in the British Columbia Coast Mountains was reconstructed from radiocarbon ages and stratigraphic analysis. Subfossil wood evidence at Canoe, Fyles, Jacobsen, Tchaikazan and Icemaker glaciers suggests these glaciers were expanding into standing forests prior to 6630, 4900 and 4200 cal. yr BP. Stratigraphically constrained woody detritus at Fyles Glacier records the progradational history of a Gilbert-type delta forming in response to glacial expansion between 7020 and 5470 cal. yr BP.

Publication: Harvey, J., Smith, D., Laxton, S., Desloges, J., Allen, S. 2012. Mid-Holocene glacier expansion between 7500-4000 cal. yr BP in the British Columbia Coast Mountains, Canada. The Holocene 22: 975-985.