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Landscape and Climate Controls on Terrestrial Ecosystems

Examining landscape and climate controls on ecosystem composition and function in a coastal-landscape mosaic.

Terrain and climate exert strong controls on the production and processing of the terrestrial organic matter that is available for export to the coastal waters. In support of the Kwakshua Watershed Program:

  • we are using remote sensing and field data to map and understand the distribution of key biophysical attributes across the landscape.
  • we are using a network of plots and sensors to examine spatial patterns and temporal dynamics of key ecosystem properties and processes in a complex coastal-landscape mosaic. 
Remote Sensing and Landscape Ecology

Our remotely sensed data sources include LiDAR, high resolution orthophotos, and satellite imagery. Field data include a combination of detailed ground plots and rapid visual checks from air and ground. To begin, we generated spatial datasets showing the distribution of biophysical properties such as soil drainage, stream networks, forest height and canopy openness. The remotely measured metrics have proved useful for locating and sampling sites of deep organic soil accumulation, for example. UVic researchers Shanley Thompson and Trisalyn Nelson (see SPAR lab website here) have used the remote sensing data in an unsupervised classification analysis to recognize and map 12 forested and 6 non-forested types on Calvert Island. At present, Gordon Frazer of GWF LiDAR Analytics is using the LiDAR data to examine topographic and spatial controls on forest biomass, which will help us understand landscape controls on the biogeochemical processes of central importance to the Kwakshua Watershed Program. In 2015, Paul Sanborn and collaborators will use field and remote sensing data to map the distribution of key soil properties within the study area.

Quadratic mean height of vegetation, with whiter areas representing higher values. Analysis by Gordon Frazer.

Landscape Gradient Studies

Sampling and sensor infrastructure: We have established 27 plots and four sensor nodes in contrasting terrestrial ecosystem types, from deep soil peatlands through relatively productive forests. We used combinations of LiDAR terrain metrics, ecosystem maps, and field reconnaissance to stratify the landscape and select plot locations. Vegetation biomass, structure and composition vary dramatically across a drainage gradient, from bryophyte and sedge dominated wetlands to forests of moderate productivity on better-drained soils. Soils vary from thin veneers over bedrock to peat accumulations of >2m. In three contrasting sites, we are using sensors to remotely monitor soil conditions in relation to seasonal and storm-driven weather patterns. Remotely monitored variables include water table depth, soil water content, soil temperature and soil redox potential. Mean water table depth varies spatially across and within ecosystem types. The soil environment is dynamic, tightly tied to storms and seasons. Several emergent studies are built upon the foundational plot network, involving soil microbial ecology, dendroecology, terrestrial laser scanning and biogeochemistry.

Microbiology across a drainage gradient: UBC scientists William Mohn, Colleen Kellogg and Thierry Heger are comparing soil Bacterial, Archaeal, Fungal (Mohn and Kellogg) and Protistan (Heger) communities along the environmental gradient from wetland through forest.

Soil ecosystem dynamics: Paired with the soil sensors described above, Colleen Kellogg and Allison Oliver are examining microbial communities and shallow ground water biogeochemistry across a range of microsite conditions (e.g., Sphagnum moss hummocks vs. sedge lawns) and vertical depth profiles, sampled across all seasons. The goal of this project is to understand how hydrology, specifically soil water table fluctuations, affects microbial community composition and function, soil properties and soil water biogeochemistry on Calvert Island. In collaboration with David D’Amore (USFS), we are pilot-testing the use of soil redox probes to as a means to monitor, in near real time, relative changes in soil redox status in relation to water table depth at the networked deep peat bog site. In addition to shedding light on the types of biogeochemical processes that may be occurring in the peat at any given time, these real-time measurements may also allow us to determine how quickly the microbial community responds to the dynamic hydrology characteristic of coastal temperate rain forests systems.

Tree age and growth rates across a drainage gradient: UVic scientist Andrew Trant is using tree rings to investigate how radial growth rates/climate sensitivities vary across the environmental gradient from forested wetlands or poorly drained sites through relatively productive forests on well drained sites. These data will give us a window into past ecosystem conditions and help us understand drivers of primary production across the landscape mosaic.

Terrestrial laser scanning and vegetation structure: University of Sherbrooke scientists Richard Fournier and Danny Blanchette used terrestrial laser scanning to characterize vegetation structure across the landscape gradient. Several test transects and sample plots were scanned, providing powerful datasets for visualization and measurement of fine scale vegetation structure, such as canopy height and volume. The image below shows a model of canopy height (CHM) along a transect.Terrestrial Laser Scanning (TLS) for ecological research

 

Related Research Element
Microbial Ecology Across a Land-Sea Gradient
Microbial communities and processes across a land-sea gradient in the hypermaritime coastal temperate rainforest.