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Assessing the Impacts of Species Composition on the Accuracy of Mapping Chlorophyll Content in Heterogeneous Ecosystems

Author: 
Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2021-11-19
Abstract: 

Chlorophyll is an essential vegetation pigment influencing plant photosynthesis rate and growth conditions. Remote sensing images have been widely used for mapping vegetation chlorophyll content in different ecosystems (e.g., farmlands, forests, grasslands, and wetlands) for evaluating vegetation growth status and productivity of these ecosystems. Compared to farmlands and forests that are more homogeneous in terms of species composition, grasslands and wetlands are more heterogeneous with highly mixed species (e.g., various grass, forb, and shrub species). Different species contribute differently to the ecosystem services, thus, monitoring species-specific chlorophyll content is critical for better understanding their growth status, evaluating ecosystem functions, and supporting ecosystem management (e.g., control invasive species). However, previous studies in mapping chlorophyll content in heterogeneous ecosystems have rarely estimated species-specific chlorophyll content, which was partially due to the limited spatial resolution of remote sensing images commonly used in the past few decades for recognizing different species. In addition, many previous studies have used one universal model built with data of all species for mapping chlorophyll of the entire study area, which did not fully consider the impacts of species composition on the accuracy of chlorophyll estimation (i.e., establishing species-specific chlorophyll estimation models may generate higher accuracy). In this study, helicopter-acquired high-spatial resolution hyperspectral images were acquired for species classification and species-specific chlorophyll content estimation. Four estimation models, including a universal linear regression (LR) model (i.e., built with data of all species), species-specific LR models (i.e., built with data of each species, respectively), a universal random forest regression (RFR) model, and species-specific RFR models, were compared to determine their performance in mapping chlorophyll and to evaluate the impacts of species composition. The results show that species-specific models performed better than the universal models, especially for species with fewer samples in the dataset. The best performed species-specific models were then used to generate species-specific chlorophyll content maps using the species classification results. Impacts of species composition on the retrieval of chlorophyll content were further assessed to support future chlorophyll mapping in heterogeneous ecosystems and ecosystem management.

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Article
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WETMETH 1.0: A New Wetland Methane Model for Implementation in Earth System Models

Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2021-10-18
Abstract: 

Wetlands are the single largest natural source of methane (CH4), a powerful greenhouse gas affecting the global climate. In turn, wetland CH4 emissions are sensitive to changes in climate conditions such as temperature and precipitation shifts. However, biogeochemical processes regulating wetland CH4 emissions (namely microbial production and oxidation of CH4) are not routinely included in fully coupled Earth system models that simulate feedbacks between the physical climate, the carbon cycle, and other biogeochemical cycles. This paper introduces a process-based wetland CH4 model (WETMETH) developed for implementation in Earth system models and currently embedded in an Earth system model of intermediate complexity. Here, we (i) describe the wetland CH4 model, (ii) evaluate the model performance against available datasets and estimates from the literature, and (iii) analyze the model sensitivity to perturbations of poorly constrained parameters. Historical simulations show that WETMETH is capable of reproducing mean annual emissions consistent with present-day estimates across spatial scales. For the 2008–2017 decade, the model simulates global mean wetland emissions of 158.6 Tg CH4 yr−1, of which 33.1 Tg CH4 yr−1 is from wetlands north of 45∘ N. WETMETH is highly sensitive to parameters for the microbial oxidation of CH4, which is the least constrained process in the literature.

Document type: 
Article
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A Hierarchical Analysis of Ecosystem Classification With Implementing in Two Continental Ecoregions

Author: 
Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2021-10-01
Abstract: 

Background The ecosystem classification of land (ECL) has been studied for a couple of decades, from the beginning of the perfect organism system “top-down” approach to a reversed “bottom-up” approach by defining a micro-ecological unit. After comparing two cases of the ecosystem classification framework implemented in the different continental ecoregions, the processes were carefully examined and justified.Results Theoretically, Bailey’s upper levels of ECL (Description of the ecoregions of the United States, 2nd ed. Rev and expanded (1st ed. 1980). Misc. Publ. No. 1391 (Rev). Washington DC USDA Forest Service; 1995) were applied to the United States and world continents. For the first time, a complete ECL study was accomplished in Western Utah of the United States, with eight upper levels of ECOMAP (National hierarchical framework of ecological units. U.S. Department of Agriculture, Forest Service, Washington, DC. https://www.researchgate.net/publication/237419014_National_hierarchical... 1993) plus additional ecological site and vegetation stand. China’s Eco-geographic classification was most likely fitted into Bailey’s Ecosystem Classification upper-level regime. With a binary decision tree analysis, it had been validated that the Domains have an empty entity for 500 Plateau Domain between the US and China ecoregion framework. Implementing lower levels of ECL to Qinghai Province of China, based on the biogeoclimatic condition, vegetation distribution, landform, and plant species feature, it had classified the Section HIIC1 into two Subsections (labeled as i, ii), and delineated iia of QiLian Mountain East Alpine Shrub and Alpine Tundra Ecozone into iia-1 and iia-2 Subzones. Coordinately, an Ecological Site was completed at the bottom level.Conclusions (1) It was more experimental processing by implementing a full ECL in the Western Utah of the United States based on the ECOMAP (1993). (2) The empty entity, named as Plateau Domain 500, should be added into the top-level Bailey’s ecoregion framework. Coordinately, it includes the Divisions of HI and HII and the Provinces of humid, sub-humid, semiarid, and arid for China's Eco-Geographic region. (3) Implementing a full ECL in a different continent and integrating the lower level's models was the process that could handle the execution management, interpreting the relationship of ecosystem, dataset conversion, and error correction.

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Article
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Implement and Analysis on Current Ecosystem Classification in Western Utah of the United States & Yukon Territory of Canada

Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2021-10-11
Abstract: 

The study cases in western Utah of the United States and Yukon Territory of Canada have more natural land and conservative ecosystems in North America. The ecosystem classification of land (ECL) in these two ecoregions had been analyzed and validated through implementation. A full ECL case study was accomplished and examined with eight upper levels of ECOMAP plus ecological site and vegetation stand in Western Utah, the US. Theoretically, applying Köppen climate system classification, Bailey’s Domain and Division were applied to the United States, North America, and world continents. However, Canada’s continental upper level ecoregion framework defined the ecological Mozaic on a sub-continental scale, representing an area of the hierarchical ecological units characterized by interactive and adjusting abiotic and biotic factors. Using Bailey’s Domain as the top level of Canada’s territorial ecoregion was recommended. Eight levels of ELCs were established for Yukon Territory, Canada. Thus, the second study case recommends integrating the ecosystem approaches with Bailey’s upper level ECL, broad ecosystem classification, and objectively defined ecological site in different countries, or ecoregions. Our study cases had exemplified the implementations with a full ELCs in Bailey’s 300 Dry Domain and 100 Polar Domain.

Document type: 
Article
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Spatial and Temporal Patterns in Canadian COVID-19 Crowdfunding Campaigns

Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2021-08-23
Abstract: 

Online charitable crowdfunding has become an increasingly prevalent way for Canadians to deal with costs that they would otherwise not be able to shoulder on their own. With the onset of COVID-19 and related lockdown measures, there is evidence of a surge in crowdfunding use relating to the pandemic. This study gathered, classified, and analysed Canadian crowdfunding campaigns created in response to COVID-19 from GoFundMe.com, a popular crowdfunding platform. Spatio-temporal analysis of classified campaigns allowed for observation of emergent trends in the distribution of pandemic-related need incidence and financial support throughout the pandemic. Campaigns raising money on behalf of established charities were the most common in the sample, and accounted for the greatest portion of funding raised, while campaigns for businesses made up a small proportion. Dense metropolitan areas accounted for the vast majority of campaign locations, and total sample funding was disproportionately raised by campaigners in Ontario and British Columbia.

Document type: 
Article
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Methane emission dynamics among CO2-absorbing and thermokarst lakes of a great Arctic delta

Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2021-09-28
Abstract: 

Lake-rich Arctic deltas differ biogeochemically from tundra lakes, and their role as sources and sinks of greenhouse gases remains poorly understood. Under-ice and open-water changes in methane (CH4) storage (43 lakes, 2014), floating chamber measurements of total and diffusive CH4 evasion to the atmosphere (6 lakes, 2014-2015), and water-column CH4 oxidation (MOX) (6 lakes, 2014-2015) permitted evaluation of how CH4 emissions vary among lakes with differing river-to-lake connection times within the Mackenzie Delta. CH4 emissions during ice-out were considerable, followed by substantial declines as open-water progressed. Water-column MOX rates were highest after ice-out, and declined throughout open-water. After accounting for a strong effect of CH4 substrate levels, MOX rates were inversely related to pH, which can increase to high levels during open-water because of high macrophyte production. Comparisons of water-column CH4 storage versus open-water fluxes (6 lakes) showed that diffusive evasion plus MOX removed most CH4 in the water columns every 1-2 days with only modest changes in storage, suggesting that counter-balancing water-column replenishment is substantial. Lakes with short river-connection times (i.e. most strongly autotrophic and strongly CO2- absorbing in this delta) and thermokarst lakes contribute disproportionately to CH4 flux, relative to lakes with long river-connection times. Thus, this great Arctic delta represents an important system of greenhouse-gas emitting lakes despite prior work showing their net absorption of CO2 during open-water, and having a low landscape area of CO2-saturated thermokarst lakes. Autotrophically absorbed CO2 becomes labile carbon substrate, and is microbially shunted back to the atmosphere as the more potent greenhouse gas CH4.

Document type: 
Article

“If You Have a Pain, Get on a Plane”: Qualitatively Exploring How Short-Term Canadian International Retirement Migrants Prepare To Manage Their Health While Abroad

Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2021-04-12
Abstract: 

Background

Every year, tens of thousands of older Canadians travel abroad during the winter months to enjoy warmer destinations that offer social and recreational opportunities. How do these Canadians prepare to manage their health while abroad? In this analysis we explore this question by developing a typology of preparatory strategies.

Methods

Semi-structured interviews were conducted with 19 older Canadians living seasonally in Yuma, Arizona (United States). Interviews were transcribed verbatim and thematically analysed to form the basis of a typology of preparatory strategies.

Results

Four distinct preparatory strategies form the typology that summarizes how Canadian international retirement migrants prepare to manage their health while abroad. First, some participants became thoroughly prepared by gathering information from multiple sources and undertaking specific preparatory activities (e.g., visiting a travel medicine clinic, purchasing travel health insurance, bringing prescription refills). Second, some participants were preparation-adverse and relied on their abilities to address health needs and crises in-the-moment. Third, some participants became well informed about things they could do in advance to protect their health while abroad (e.g., purchasing travel health insurance) but opted not to undertake preparatory actions. A final group of participants prepared haphazardly.

Conclusions

This typology can assist health care providers in international retirement migrant destinations to appreciate differences among this patient population that is often characterized as being relatively homogenous. More research is needed to determine if these preparatory strategies are common in other mobile populations and if they are found in other destinations popular with international retirement migrants.

Document type: 
Article
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Exploring the Sensitivity of Recurrent Neural Network Models for Forecasting Land Cover Change

Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2021-03-10
Abstract: 

Recurrent Neural Networks (RNNs), including Long Short-Term Memory (LSTM) architectures, have obtained successful outcomes in timeseries analysis tasks. While RNNs demonstrated favourable performance for Land Cover (LC) change analyses, few studies have explored or quantified the geospatial data characteristics required to utilize this method. Likewise, many studies utilize overall measures of accuracy rather than metrics accounting for the slow or sparse changes of LC that are typically observed. Therefore, the main objective of this study is to evaluate the performance of LSTM models for forecasting LC changes by conducting a sensitivity analysis involving hypothetical and real-world datasets. The intent of this assessment is to explore the implications of varying temporal resolutions and LC classes. Additionally, changing these input data characteristics impacts the number of timesteps and LC change rates provided to the respective models. Kappa variants are selected to explore the capacity of LSTM models for forecasting transitions or persistence of LC. Results demonstrate the adverse effects of coarser temporal resolutions and high LC class cardinality on method performance, despite method optimization techniques applied. This study suggests various characteristics of geospatial datasets that should be present before considering LSTM methods for LC change forecasting.

Document type: 
Article
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Mixed Reality Flood Visualizations: Reflections on Development and Usability of Current Systems

Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2021-02-18
Abstract: 

Interest in and use of 3D visualizations for analysis and communication of flooding risks has been increasing. At the same time, an ecosystem of 3D user interfaces has also been emerging. Together, they offer exciting potential opportunities for flood visualization. In order to understand how we turn potential into real value, we need to develop better understandings of technical workflows, capabilities of the resulting systems, their usability, and implications for practice. Starting with existing geospatial datasets, we develop single user and collaborative visualization prototypes that leverage capabilities of the state-of-the art HoloLens 2 mixed reality system. By using the 3D displays, positional tracking, spatial mapping, and hand- and eye-tracking, we seek to unpack the capabilities of these tools for meaningful spatial data practice. We reflect on the user experience, hardware performance, and usability of these tools and discuss the implications of these technologies for flood risk management, and broader spatial planning practice. 

Document type: 
Article
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Institutional Systems & Structures for Knowledge Mobilization: Bringing Worlds Together to Support Knowledge Mobilization

Peer reviewed: 
No, item is not peer reviewed.
Date created: 
2020-11-25
Abstract: 

In this roundtable, we explore developing structures for knowledge mobilization in two different institutional systems, a university and in health and social care. First, we will explore developing a knowledge mobilization hub at Simon Fraser University, exploring consideration for spaces, sources, and supports. We will discuss questions space in the context of remote working, of the future roles of institutional libraries, and how to assess the value and impact of knowledge mobilization supports. Next, will consider the delivery of safe, effective, person centred care and how a systems approach must be developed to maximise knowledge use. The structures, processes and culture change that are required to mobilize knowledge from research, experience and practice to develop into ‘learning systems’ will be explored.

Document type: 
Conference presentation