TerreWEB

Terrestrial Research on Ecosystems & World-wide Education & Broadcast || An Innovative Graduate Training Program

TerreWEB 1st Annual Open House

TerreWEB Open House

When: Tuesday, November 25th, 2014, 5:00-7:00 p.m.

Where: Agora Café (lower level of the H.R. MacMillan Building at UBC, 2357 Main Mall, Vancouver, BC V6T 1Z4)

TerreWEB (Terrestrial Research and Worldwide Education and Broadcast) is a NSERC CREATE 6-year graduate training program that began in 2011 and that supports graduate students, post-docs, visiting scholars and student internships in global change science research and novel communications of their discoveries.

The first annual TerreWEB Open House will showcase creative forms of science communication by graduate students. Using a modified poster session format, students will present their work on global change and science communication in 5-minute rotating sessions. Rather than a typical conference-style session, the open house will be interactive and attendees will be encouraged to engage with the presenters and with each other in creative ways. The event will include an overview of TerreWEB, a raffle drawing, and refreshments. It is free and open to the public. Hope to see you there!

Abstracts

Amanda Asay (UBC FCS), S. Simard (UBC FCS), S. Aitken (UBC FCS), D. Durall (UBC BIOL), S. Dudley (McMaster U. BIOL), B. Pickles (UBC FCS), and R. Wilhelm (UBC Microbiology/Immunology)

Mycorrhizal facilitation of kin recognition in interior Douglas-fir (Pseudotsuga menziesii var. glauca)

Insight into influences on successful seedling establishment could be essential to future regeneration of British Columbia’s interior Douglas-fir (Pseudotsuga menziesii var. glauca) forests, particularly as climate changes. Areas of harsh climatic conditions have low regenerative capacity and require management decisions leading to enhanced seedling establishment.  Variable retention harvesting and natural regeneration from residual trees, for example, may become increasingly important for their locally adaptive traits as climate changes. Kin recognition, mycorrhizal networks, or the combination of the two may be important mechanisms for enhanced seedling establishment in these regions. We examined the effects of relationship (kin vs. non-kin) and mycorrhizal networks on regeneration from seed in greenhouse and field settings. In the greenhouse, kin recognition was evident in differing foliar microelement (Fe, Mo, Al and Cu) and growth variables (total leaf area, volume and stem length) according to relationships between seedlings. Kin recognition was also weakly evident in the field, where it was expressed as differential survivorship among kin versus non-kin seedlings. Kin selection was evident in the greenhouse, where microelement content of kin was greater than non-kin. Greater mycorrhizal colonization of kin compared to non-kin as well as greater donor total leaf area, volume and stem length also suggest kin selection, although not consistently in all experiments. In the field, survivorship was greater among non-kin; however, detection of kin recognition may have been masked by the large effects of site and seed origin on germination and survival. Mycorrhizal networks and carbon transfer occurred within all greenhouse seedling pairs, and enhanced mycorrhization of kin suggests network colonization was involved in kin selection, but our data does not strongly support our hypothesis that kin recognition was facilitated by mycorrhizal networks. While the mechanism of kin recognition is still not well understood, we provided evidence of kin recognition in interior Douglas-fir seedlings, particularly those that originate from harsh climates, and observed subtle indicators of kin selection or reduction of competition due to a close genetic relationship.  Accounting for these phenomena in forest management could be helpful to successful regeneration of interior Douglas-fir forests as stresses associated with climate change increase.

 

Salome Buglass (UBC GEOG), S. Donner (UBC GEOG)

A study of the recovery of Tobago’s coral reefs after a mass bleaching event in 2010

In 2010, coral reefs across the Caribbean suffered from a mass coral bleaching event. This study evaluates the recovery of scleractinian coral communities across three major reef systems in Tobago that differ in their exposure to sediment deposition as a result of different adjacent land use practices. At two sites of each of the three reef systems assessments were done on 1) adult colony population structure, in 2010, 2011 and 2013 to analyse temporal changes among coral populations, 2) density and composition of coral juveniles (< 5cm in size) to characterise the levels of successful sexual recruitment, 3) sediment accumulation rates and composition to understand its potential impact on each reef. The study found that three years after the bleaching event, most of the adult coral population distributions became more positively skewed, due to an increase in smaller size colonies. By 2013, Siderastrea siderea and Agaricia spp. population distributions differed significantly and their mean size had significantly declined among most reef sites. Juveniles were found in low density (5.41±6.31 m-2), especially at sites nearest to urban developed land, and were dominated by brooding genera; broadcasting genera like Montastrea and Diploria, which predominate in the assessed adult community, were rare. Sedimentation rates were below <5 mg cm-2 d-1 at all sites but one, and sediment grain size distribution profiles differed per reef system. Overall we found that the number large size colonies are declining among most taxa and that Tobago’s coral reefs are probably not relying on sexual reproduction for post-disturbance recovery.

 

Megan Callahan (UBC IRES), and T. Satterfield (UBC IRES)

The Long Hop Home

Given habitat loss, pollution, poaching, and climate change, it is clear that wildlife populations are struggling. It is estimated that around 20% of all mammals and 30% of all amphibians are threatened with extinction. Human activity lies at the root of many of these threats. Since attitudes inform actions, investigating attitudes towards animals as well as their origins and potential for change can have impacts on wildlife conservation. My Masters work looked at the role of zoos in conservation. Species bias, the preferential treatment of certain species or taxonomic groups, was an integral part of that investigation. More fully investigating what is involved regarding this issue of human attitudes towards animals, in terms of applications to conservation, will be part of my ongoing doctoral work.

In previous communication work regarding my studies, I attempted to understand and engage the general public’s knowledge of zoo conservation efforts with an interactive blog, only to find that knowledge was limited and localized. To begin to address these issues as well as additional instances of animal-human interactions, I will be writing a series of books, beginning with the children’s book presented in part at the Open House. It will deal with a very successful conservation project in which a number of Canadian and American zoos are participating. The Oregon Spotted Frog, one of the most endangered frogs in Canada, has lost about 85-90% of its historic range. The Vancouver Aquarium, Seattle’s Woodland Park Zoo, and others are involved in a “head starting” program that aims to release zoo-reared animals into the wild. My book would trace the journey of a frog from the wild, to the zoo, and back to the wild once more, in an age appropriate yet informative manner. This would allow for an integrative education project that would link animals in zoos with wildlife. In addition, it would be able to focus attention on amphibians, the group of animals that are often most endangered, but often least appreciated by humans. After a prototype copy is available, I will offer a read aloud session to children enrolled in zoo camps run by Woodland Park Zoo. I would hope to use this and other classroom based readings to gather and evaluate the impact of the book on knowledge and attitudes, which will help inform subsequent projects.

Conservation efforts require interest and funds from the general public. In order to garner this support, attitudes towards conservation species and mechanisms must be addressed. As a way to both communicate and inform my own research, a series of books focused on varying age groups will be completed in order to appeal to a wide audience in an informative, yet entertaining manner. While the first book will be focused on the zoos and conservation, subsequent editions will look at other animal-human interactions and their roles in conservation as influenced by my current and future work.

 

Christopher J. Carter (UBC SCARP), L. Angeles (UBC SCARP), T. Barisky (UBC SCARP) E. Crego-Liz (UBC GEOG)

Paghahanda sa Pagbabagong Klima: Towards a local climate change action plan (LCCAP) in the aqua-cultural Municipality of Hagonoy, Philippines

In 2014, the Municipality of Hagonoy Philippines will develop a Local Climate Change Action Plan (LCCAP), which will help them assess their vulnerability to current and projected climate changes. In doing so they will identify and implement mitigation and adaptation strategies. As a starting point for this process, the Municipality engaged planning support from the University of British Columbia’s (UBC) School of Community and Regional Planning (SCARP) to assist in research and analyses.

Using a consultative approach the planning team engaged in policy and vulnerability analyses addressing four priority areas set forth in the National Strategic Directions for climate adaptation: Food Security, Water Sufficiency, Ecological Stability, and Human Security. The report details next steps the Municipality can take in order to ensure implementation, secure financing, and facilitate monitoring and evaluation for successful climate adaption. This policy document introduces the challenge of and the basis for local climate change planning as addressed through land use planning, ecosystem services management and social policy. Pursuant to the strategic and value focused approach set forth by the UN HABITAT, this completed document is the first step in the Municipality’s commitment to developing a formal LCCAP.

This action research engaged a mixed method approach to data collection. Quantitative methodology included spatial analyses using Social Vulnerability Indicators (SoVI) gathered from the Community Based Monitoring System, provincial geohazard assessments, municipal finance analyses and surveys of policy makers. Qualitative methods included document and legal analyses, semi-structured institutional interviews and participant observation. Analyses of proposed land use policy and flood mapping was undertaken using ARCGIS.

Spatial analysis using SoVI proved counterfactual to political discourse of equality in exposure to upriver and coastal flooding.  Certain barangays (counties) were more statistically vulnerable than others, most notably communities that were coastal and along the Lambongan channel of the Angat River. Land use planning under the 2021 Comprehensive Land use Plans propose future development using nodal development inland, retreating current human settlement at risk from coasts.  Further, “climate proofing” has begun to be mainstreamed albeit limited to hard infrastructure and is limited by fiscal constraints. Principles of disaster risk reduction management and planning (short term) are often conflated with climate adaptation planning (long term).  Completion of an LCCAP will give the Municipality access to provincial funding for climate adaptation funding under the Peoples Survival Act. Site specific accounting for vulnerable and sensitive ecosystem services and participation of disproportionately vulnerable populations (such as informal and coastal settlements) in plan creation is recommended as next steps in LCCAP creation.

Little has been done at the intergovernmental level to act on climate change local governments in coastal communities of the Philippines are tasked with creating relevant policy and strategies for adaptation.  Researching alongside these institutions brings a unique opportunity to consider how climate adaptation and action planning is tailored to human settlements and the impact of sea level rise on island states.

Vulnerability to climate change and disasters is often shaped by the formal planning institutions responsible for planning cities and regions. Use of Community Based Monitoring System and SoVI in the Philippines offers a unique example of using fine grain data to aid in more transparent and accurate vulnerability assessments.

 

Camille Defrenne (UBC FCS), L. Lavkulich (UBC LFS), and S. Simard (UBC FCS)

The memory of soil in the Pacific Spirit Park of British Columbia

Pacific temperate rainforests of British-Columbia have a considerable potential to sequester carbon in the soil, because of the climate and the traits of conifers litter. These forests have been influenced by a long history of human and natural disturbances. The overall objective of this study is to examine the effects of disturbance history on soil properties and carbon stocks by comparing three second growth forests (mixed conifers/deciduous forest, pure coniferous forest and alder forest) ecosystems at various stage of succession in the Pacific Spirit Regional Park of Vancouver, BC. We sampled the soil pedons in each forest by morphological horizon and determined soil texture, bulk density, pH, total nitrogen (N), soil organic matter (SOM), soil organic carbon (C), oxalate-extractable Fe, Al and P and exchangeable properties. Mixed forest store five times more carbon (40 kg C m-2) than the alder forest and approximately 10 kg C m-2 more than the pure coniferous forest. The mineral soil C stock accounts for around one third of the total stock for the mixed and pure coniferous sites. The alder forest soil records the narrowest C:N ratio in the mineral horizons compared to the others sites, suggesting that there was likely an increase in OM decomposition and maturation as a result of land use history along with a decrease of soil fertility in the mixed and coniferous sites. Podzolization processes (regarding the Fe and Al concentrations) have been maintained but the dynamic surface soil characteristics has changed considerably as a result of the disturbance history. But also as a result of the high degree of variability of the original parent material. This study suggests that the alder forest soil is no longer an orthic Humo-ferric podzol but has evolved to become a Sombric Humo-ferric podzol. The results emphasize the importance of determining site history when conducting comparative forest ecosystems studies.

 

Darrell Hoffman (UBC LFS), M. Krzic (UBC LFS, FCS), M. Schmidt (SFU GEOG), S. Nashon (UBC EDCP) and L. Lavkulich (UBC LFS)

The Forest Floor Tool: Bringing humus form classification and description online

Global environmental and social issues are placing increasing demand upon the world’s soil resources. In recognition of this the 68th UN assembly has declared next year, 2015, the International Year of Soils. The forest floor, sometimes overlooked in soil science, is a massive carbon sink and provides habitat for the majority of soil microorganisms and fauna. While changes to the mineral soil may occur very slowly, fluctuation in the forest floor can be an early signifier of ecosystem changes due to pollution, changes in climate, or management practices.

The requirement educate the next generation of soil scientists is becoming imminent and has been highlighted by a variety of international organizations such as the Intergovernmental Panel on Climate Change (IPCC). Innovative teaching methods and increased outreach to students and the public are necessary to meet this requirement. With the knowledge that we live in an increasingly urban, “plugged-in” society, it seems astute to take advantage of the continual advances in IT and digital media. Web-based learning (WBL) affords advantages such as multimedia enhancement of material and flexibility in time and place (reaching students in their on-line environments). The Forest Floor Tool will give students access to streaming videos, text, photos, graphics and tutorial questions. Students will review videos featuring interviews with a forest floor expert in order to complete a basic description and classification of a humus form sample. They will then delve deeper into the topic, exploring the tool to complete a follow-up assignment requiring an understanding of the ecological importance of the forest floor. An online survey and focus group interviews will be used to assess student satisfaction with the tool – informing recommendations to future WBL projects and improvements to the Forest Floor Tool.

Web-based educational tools have the potential to create new opportunities for post-secondary teaching and learning. With important soil science knowledge being concentrated in the hands of few, the increasingly prevalent online environment provides an opportunity to spread this knowledge worldwide. Furthermore, combining classroom learning with WBL targets multiple ways of learning by providing hands-on experience (social and tactile experience) and multimedia enrichment (text, audio, visual). Producing cohorts of well-trained soil scientists will be integral to meeting the global environmental challenges we currently face. Educators should look to WBL as one of the tools to achieving this.

 

Meghan Laidlaw (UBC FCS), C. Prescott (UBC FCS), and S. Grayston (UBC FCS)

The development of soil structure under three vegetation treatments in reclaimed Alberta Oil Sands sites

Oil sands surface mining has currently disturbed 715 km2 of boreal forest in northern Alberta, which is only 15% of the total surface-mineable area in the oil sands that could be disturbed. During the extraction process, surface soil is removed and stored until it can be used as a capping treatment in reclamation. Upland mineral soils are mixed with organic soils from low-lying peatlands to form a peat-mineral mix that caps reclaimed areas and provides a clean substrate for vegetation establishment. However, pre-existing soil structure is disrupted during this process and structure that may have developed in reclaimed soils since placement has not been previously measured. Soil structure plays an important role in carbon sequestration, facilitating water movement and retention, providing a diverse habitat for macro- and microorganisms, and storing essential nutrients. Thus, assessing soil structure in reclaimed sites will provide insight into whether key soil processes and functions have been re-established. We investigated the abundance and size distribution of water-stable aggregates in reclaimed soils under coniferous, deciduous, and grassland vegetation treatments, and compared these results to naturally fire-disturbed sites located nearby. All reclaimed sites were between 20-40 years old, and all natural sites experienced a wildfire 20-40 years ago. The goal of this project was to address the following questions:

  1. Does soil structure differ between reclaimed and naturally fire-disturbed sites?
  2. How does vegetation treatment affect soil structural development at reclaimed sites?
  3. Does carbon distribution within the soil structure differ between reclaimed and naturally fire-disturbed sites, and between reclamation treatments?
  4. Do reclaimed and naturally fire-disturbed sites have a similar capacity to stabilize C in intermediate and stable C pools?
  5. Is soil structure a useful indicator for soil quality in reclaimed ecosystems?

 

Joey Lee (UBC GEOG), A. Christen (UBC GEOG), Z. Nesic (UBC LFS), R. Ketler (UBC GEOG), R. Kellett (UBC SALA)

With support by: Benedikt Groß, Stephan Bogner, and 47Nord Media.

Urban CO2 Explorer

Cities and the cumulative processes of urbanization are key drivers of local and global environmental change. As cities are the centers of ever-increasing population growth and resource consumption, they are also the dominant sources of greenhouse gas (GHGs) emissions – in particular carbon dioxide (CO2) – into the atmosphere. While cities are a major contributor to increasing GHG concentrations in the earth’s atmosphere – and thus climate change – they also where policy interventions, urban design, community participation, and behavioral change can be most effective for reducing emissions impacts.

However, the current tools monitoring our GHG emissions cannot give us feedback at the spatial scales we can relate to and plan around. Traditional methods operate at coarse spatial resolutions (e.g. measured from space over thousands of kilometers) or at sparsely located fixed points.

Given improvements in technology and the growth of the opensource community, new opportunities exist to help benchmark our emissions at the local scale. Using a mobile approach to sensing and monitoring emissions, we can use cars and bikes to pervasively measure greenhouse gas concentrations at a street level in real-time. The purpose of this presentation is to showcase the work-in-progress prototype of the Urban CO2 Explorer – a lightweight web-based interactive tool for visualizing CO2 concentrations in cities. The goal is to highlight the future potential of a mobile sensing approach to monitoring emissions in cities and to springboard a discussion about what actions can be taken by individuals and communities to reduce urban emissions, particularly given access to such a granular environmental dataset.

 

Deon Louw (UBC FCS), and S. Simard (UBC FCS)

Growth dynamics of mixed conifer – broadleaf plantations

Little experimental work exists on the effects of tree species diversity on tree growth over time.  This project assesses the results of an experiment established to determine the effects of below-ground interactions between broadleafs and conifers across various planted tree densities in the southern interior of British Columbia.  In 1993, Paper birch and Douglas fir seedlings were planted at two densities (low, high) at three similar sites in the interior wet belt of BC.  Additionally, the rooting area of half of the trees at each density was isolated using polyethylene plastic in order to eliminate below-ground interactions between the trees.  Research questions of the current project include whether below- ground isolation or planting density affects present tree size or growth over time and how responses to drought stress vary across the historical treatments.  Finally, historical treatments are compared with current conditions affecting tree growth including current tree density and proportion.

Growth measurements and tree cores were collected from each site during the summer of 2013.  Tree cores were processed and measured using a high resolution scanner and CDendro software.   A summer heat to moisture index (SHM) was used to represent growing season conditions and was compared with the growth of each individual combination of tree species and historical treatment using Pearson’s moment correlation coefficient.  Regression trees and mixed effects modelling were used to assess the relative importance of historical treatments and current conditions on present tree size. Finally, general additive mixed modelling (GAM) was performed to analyse the effects of planted density and below ground interactions on growth over time.

Preliminary results suggest that the two tree species reacted differently to the historical treatments. Paper birch appears more sensitive to below ground isolation while Douglas fir reacts to planted density.  Below ground isolation appears to negatively affect paper birch growth over time while Douglas fir growth increases over time at low planted density.  Growth is negatively correlated with dry growing seasons but no significant relationship could be found between dry seasons and any other explanatory variables.  The historical treatments appear to have much less explanatory power on tree size than current conditions, such as neighbouring tree density or soil characteristics.

The choice of topic stems from an interest in the connection between forest diversity and stability as well as an interest in species dynamics over time.  This work appears to show distinct growth histories of paper birch and Douglas fir with respect to root isolation and planting density.  One potential reason for a positive growth response of birch to root contact with fir relates to the relative vigour of fir compared to birch in this study.  Relatively weak birch could be accessing excess fir nutrients and water through mycorrhizal (root associated fungi) networks or other means.  While fir growth in this study was limited by density, it did not appear to respond to increased below ground contact with birch.  One potential conclusion could be that a relatively weak species grown in a mixture gains some benefit from below ground contact with a stronger species over time regardless of density.  This conclusion may encourage the practise of planting conifer-broadleaf mixtures in the interest of maintaining forest stability.

 

Julia Amerongen Maddison (UBC FCS), S. Simard (UBC FCS), M. Krzic (UBC FCS), S. Grayston (UBC FCS), and R. Blok (UBC ISCI)

Investigating defense-related information transfer between Douglas-fir via ectomycorrhizal networks

“Mycorrhizae” are an oftentimes mutual association of fungi and plant roots in which fungi receive carbon from plants and plants receive soil water and nutrients from the fungi. These same fungi can link multiple plants together belowground in what are called “common mycorrhizal networks (CMNs).” Past and current work has shown that CMNs can transfer nutrients such as nitrogen and phosphorus as well as carbon. Recent work has suggested that other transfers can take place on CMNs, such as alellochemicals and defense-related information. Both defense-related studies focused on arbuscular mycorrhizae, which as part of their interaction with plants penetrate the plant cells and form small, high surface area “arbuscules” (they look like trees) for nutrient exchange. My project focuses on the ectomycorrhizal system, in which mycorrhizal fungi do not penetrate cells but surround the root in what is called a “hartig net.” I address two main questions:  (1) Do we see similar patterns of defense-related information transfer in an ectomycorrhizal system? (2) Can we elicit these patterns using a plant defense hormone, methyl jasmonate (MeJA), as opposed to “natural” pathogens or herbivores?

To address these questions I preformed a greenhouse study in which I grew Douglas-fir trees in pairs, separated by mesh of different pore sizes. The smallest pore size (0.5µm) only allows water through, the second smallest (35µm) allows water and hyphae through), the biggest (250µm) happens to allow roots, hyphae, and water through (the expectation was that roots wouldn’t be able to grow through but that turned out to be false).  The soil was a 70/30 mix of wild/potting soil in which the wild soil was collected from our field sites in the Interior Douglas-Fir BEC zone near Kamloops.

After 11 months of growing the trees in the greenhouse, I began the experiment. This involved covering the trees with air-tight (ostensibly) bags aboveground and treating one of the pairs with either the CTL or treatment substance. The treatment involved dripping MeJA onto a q-tip and taping that inside the bag, the CTL involved taping a dry q-tip inside the bag.

24 hours later, half of the pairs were harvested, and 48 hours later, the other half of the pairs were harvested. “Harvest” involved clipping and preserving the stems and needles in liquid nitrogen, then transporting vials on dry ice to a -80 freezer for later gene expression work. The roots were cleaned and stored in a cold room for later morphotyping work.

After harvest, three main forms of analysis are being carried out:

(1)    gene expression work, in which I extract RNA from the stems, perform reverse transcription to make cDNA, and then perform qPCR to determine the relative expression of  2-3 target genes

(2)    morphotyping, in which I randomly sample 50 root tips per tree and group these root tips into same-species morphotypes for later molecular sequencing

(3)    foliar nutrient concentration, in which I dry and grind needle samples and send them to MOE to determine the concentrations of macro and micronutrients in the needles

 

Colin Mahony (UBC FCS), S. Aitken (UBC FCS), and S. Simard (UBC FCS)

Emergence of no-analog climates in British Columbia: Assessing degrees of novelty in climate change projections

The detection of novel climates in climate change projections is an open problem in ecological research. The primary task of novelty detection is identifying the climatic gradients that differentiate distinct and biologically relevant climate types. This task is increasingly challenging as the scale of investigation moves from global to regional, since the climatic gradients of interest become more subtle. Using the pioneering work of Williams et al. (2007) as our conceptual basis, we propose a supervised linear feature extraction method to detect ecologically significant gradients of climatic variation across the landscape of British Columbia. Within a climate space composed of these gradients, we use a distance metric to measure dissimilarity between projected climate conditions and current analog bioclimates.  Our preliminary results suggest that projected climate trends for the coastal region of British Columbia are towards novel climatic conditions not currently observed in North America. However, our methods have been unable to successfully differentiate the bioclimates of the continental interior of BC. These methods and results bring the challenges of novelty detection into focus.

 

Gesa Meyer (UBC LFS), Z. Nesic (UBC LFS), R. Jassal (UBC LFS), N. Grant (UBC LFS), A.L. Fredeen (UNBC), D.L. Spittlehouse (BC Ministry of Forests and Range), A. Christen (UBC GEOG), M.G. Brown (Carleton U. GEOG/ENVS), A. Mathys (UBC IRSS), C. Emmel (UBC EOAS), R. Bowler (UNBC ESM), T.A. Black (UBC LFS)

What have we learnt from carbon and water flux measurements following the recent mountain pine beetle epidemic in British Columbia?

The recent mountain pine beetle (Dendroctonus ponderosae) (MPB) outbreak in British Columbia (BC), which started in the late 1990’s, caused the loss of approximately 710 million m3 of commercial timber in an area of about 18.1 million hectares.

Tree mortality due to MPB infestation is expected to significantly impact carbon (C) and water balances of forests. We made eddy-covariance (EC) measurements of CO2 and water vapor fluxes over the past eight years in two unharvested stands in the BC interior, which were attacked by the beetle in 2003 (MPB-03) and 2006 (MPB-06), respectively. MPB-03 was an open-canopy lodgepole pine (Pinus contorta var. latifolia) stand with considerable secondary structure (trees and understory not killed by the beetle), whereas MPB-06 was a pure lodgepole pine stand with little secondary structure. Following the attack, these stands became annual C sources, i.e., the decrease in gross ecosystem photosynthesis (GEP) exceeded the decrease in ecosystem respiration (Re). One year after the attack, in 2007, MPB-06 was a C source with annual net ecosystem productivity (NEP) of -81 g C m-2 yr-1, resulting from a GEP of 440 g C m-2 yr-1 and an Re of 521 g C m-2 yr-1. Four years after the attack, MPB-03 was still a C source with an NEP of -55 g C m-2 yr-1 (GEP = 430 g C m-2 yr-1 and Re = 485 g C m-2 yr-1). The two stands, however, recovered faster than expected with MPB-06 and MPB-03 becoming C neutral 3 and 6 years, respectively, after attack due to increasing uptake of CO2 by the remaining living trees and understory. Since then the two stands have been relatively weak C sinks with NEP values in 2012 (six and nine years after attack at MPB-06 and MPB-03) of 38 and 36 g C m-2 yr-1, respectively. Recovery was found to be much slower following clearcut harvesting with EC measurements in a clearcut in the same area indicating that it remained a growing season C source 10 years after harvesting.

Surprisingly, evapotranspiration (ET) in both unharvested stands changed little since the MPB attack with an annual average ET over the six years of 234 mm at MPB-06 and 284 mm at MPB-03. This indicates the important compensating effects of transpiration by the developing secondary structure and evaporation from the soil surface.

To study the effects of partial harvesting (the removal of all dead lodgepole pine trees), EC measurements were made between the fall of 2009 and 2013 in a mixed conifer stand that was attacked in 2005-06 and partially harvested in February and March 2009 (MPB-09). In the first three years after harvesting, this stand was an annual C source, but it has been steadily recovering and the C source weakened from an NEP of -121 g C m-2 yr-1 in the first year to an NEP of -52 g C m-2 yr-1 in the third year after harvesting. During the growing season of 2010, these measurements were supplemented with EC measurements in a nearby clearcut. This allowed the direct comparison of the effects of partial and clearcut harvesting on the C balance. MPB-09 was a small growing season C sink in 2010 (NEP = 9 g C m-2), due to CO2 uptake by the remaining trees and understory vegetation, whereas the clearcut remained a large C source (NEP = -103 g C m-2). To fully investigate the effects of such management strategies on C and water balances following insect outbreaks, we are currently modifying the process-based model (3-PG), and evaluating the model using our flux measurements. In the model we will also consider changes in heterotrophic respiration due to decomposition of increasing numbers of fallen dead trees at the unharvested sites as well as wind throw at MPB-09.

The observed and predicted recovery of the beetle-attacked stands is important for forest managers as well as policy makers to make informed decisions how to best manage forests following infestation

 

Matthew Zustovic (UBC FCS), and S. Simard (UBC FCS)

Regeneration potential of Interior Douglas-fir in response to canopy gap size and access to mycorrhizal networks

There is much concern about the long term productivity of the forests in British Columbia. Interior Douglas-fir, an economically valuable coniferous tree, has had little regeneration success in recent years as high summer temperatures cause drought stress to new seedlings and low winter temperatures induce frost damage to roots. Seeds of Interior Douglas-fir are able to establish after natural and man-made disturbances where resources such as light and water become more available, but the size of these disturbances which affects the amount of resources available, may determine the survival of the seedling.

I planted Interior Douglas-fir seed in different sized natural and man-made gaps within the IDF Biogeoclimatic zone near Kamloops, BC.  Above ground canopy gap factors such as light and temperature were monitored for 2 years until the seedlings were destructively harvested and measured for below ground factors such as nutrient concentrations, soil moisture, and access to mycorrhizal networks.

Preliminary results show that seedlings in larger gaps had significantly higher light availability and drought stress as well as higher variability in soil temperatures.  This would suggest that seedlings in larger canopy gaps would have increased stress and a therefore a decreased probability of survival. These findings build on the literature that small scale disturbances (both natural and man-made) create a micro environment better suited for regeneration of Interior Douglas-fir.

 

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