RESEARCH:

species distribution modeling

 
 

The freshwater diatom, Didymosphenia geminata, has recently and rapidly invaded New Zealand’s South Island. I am developing predictive models of invasion hotspots throughout New Zealand. These models incorporate dispersal through stream networks, as well as experimentally-derived environmental conditions that lead to successful invasions and bloom conditions.


By incorporating these important invasion mechanisms with environmental predictors, the models provide more robust predictions about existing and potential invasion hotspots. In addition to guiding management, these models help identify the biological and physical variables that are most important to successful invasions.

Species Distribution Modeling Research

  1. 1.Modeling invasions in stream networks

  2. 2.Habitat envelopes in species distribution modeling

  3. 3.See also: Climate Change and Communities

  1. 1.Modeling invasions in stream networks:         Didymosphenia geminata in New Zealand

Links

Collaborators:  Cathy Kilroy (NIWA), Philippe Gerbeaux (DOC), John Leathwick (DOC), Max Bothwell (Environment Canada)

funding:  NSF IGERT Ecosystem Informatics, National Institute for Water and Atmospheric Research, NZ Department of Conservation, Biosecurity New Zealand

  1. 2.Habitat envelopes, presence-only data, and indicator

    species:

    Northern goshawks and three-toed woodpeckers in

    Utah forests

Links

Relevant Papers:

Zarnetske et al. 2007. Habitat classification modeling with incomplete data: pushing the habitat envelope Zarnetske_Edwards_Moisen_2007.pdf

Zarnetske 2006a. Landscape-scale habitat classification modeling with incomplete data: the generation of ecologically-based pseudo-absence points Zarnetske_thesis_USU_2006.pdf

Zarnetske 2006b. Species distribution modeling of Three-toed woodpecker foraging sites Zarnetske_Three_toed_woodpecker_2006.pdf

Collaborators:  Thomas C. Edwards, Jr. (Utah State University), Gretchen Moisen (US Forest Service FIA)

funding:  USDA Forest Service Forest Inventory and Analysis Program, Utah State University Ecology Center

Species occurrence data often lack absence information and are usually limited to presence-only data, particularly at broad spatial scales. This lack of absences precludes the use of many robust statistical techniques in species distribution models (SDMs). Pseudo-absence points can be generated as substitutes for missing absences. However, traditional techniques generate pseudo-absence points at random across broadly-defined species ranges, often failing to include biological knowledge concerning the species-habitat relationship. This research developed a method for incorporating ecological knowledge about the species-habitat relationship into pseudo-absence points. These ecologically-based pseudo-absence points were generated within habitat envelopes, which are ecological representations of the observed distribution (i.e., realized niche of a species, or a feature (e.g., nest)), based on a single attribute, or the spatial intersection of multiple attributes.


Ecologically-based pseudo-absence points were paired with known presence data in SDMs. Forest Inventory and Analysis (FIA) and USDA Landfire map products (representing two different resolutions) were used as habitat predictor variables across forested regions of Utah for northern goshawk (Accipiter gentilis atricapillus) and American three-toed woodpecker (Picoides dorsalis) nest and foraging habitat. SDMs using ecologically-based pseudo-absence points outperformed SDMs using traditional pseudo-absence points, and were more ecologically relevant. Given some a priori knowledge of species-habitat relationships, ecologically-based pseudo-absence points can be applied to any species, ecosystem, data resolution, and spatial extent.
















Didymo in Waitaki River, New Zealand

West Matukituki River, New Zealand