2023-24 - NWT CIMP Final Report - Final Report - CIMP187

File Identifier: {02E9559E-9333-4958-B86A-93E8316CAE45}

Metadata Language: en

Responsible Party:

Organisation Name: NWT CIMP

Role: Point Of Contact

Contact Info:

E-Mail Address: nwtcimp@gov.nt.ca

Metadata Date: 2025-09-24

Metadata Standard Name: ISO 19139/19115 Metadata for Datasets

Metadata Standard Version: 2003

Abstract: Vegetation change in response to climate change is one hypothesis for the rapid decline of the Bathurst caribou herd. We explored this through range-wide monitoring of vegetation on an annual basis in conjunction with an updated analysis of herd distribution and range use. A time-series of images from NASA’s MODIS satellite sensor was generated to determine how annual productivity and phenology of vegetation changed from 2000 to 2021. Maximum annual enhanced vegetation index (EVI), annual growing season length, and annual time-integrated EVI increased significantly on approximately 40%, 30%, and 50% of the herd’s core annual range, respectively. Declines were minimal (often 1% or less), meaning that there was an overall directional increase in annual total production over the study period. Trends toward longer growing seasons were driven more heavily by earlier spring green-up than by later onset of senescence. Trends in wooded regions, which correspond primarily with the herd’s winter range, were overwhelmingly related to the influence of forest fires, which have burned more than half of the area below forest line since mapping began in 1965. Nearly 2000 tall shrubs (mostly Betula glandulosa) were measured and sampled from sites in central portions of the herd’s range where significant increases in productivity were observed as well as from sites where no changes were observed. Annual rings were counted and measured to generate age distributions and ring width chronologies. There was no significant difference in the age of shrubs between Greening and No Change sites, indicating that the differences in productivity trends detected between the two site types were not due to differences in tall shrub establishment. However, there was a significantly greater tall shrub canopy at Greening sites and a significantly greater proportion of dead stems at No Change sites. Shrubs at greening sites also had significantly wider annual growth rings during the period of satellite observation. Together, these results suggest that increases in satellite-observed productivity are partly attributable to increases in the growth of preexisting erect deciduous shrubs that have allowed them to support greater leaf area. Finally, available caribou location data was used to conduct seasonal range mapping for the herd. The maps indicate that the extent of the herd’s range shrunk substantially since the late 1990s, and that most seasonal ranges also declined in area. Centres of seasonal range tended to move northwards during the period of analysis. The timing of some annual life history periods also changed; the calving period trended toward an earlier start and the late summer period trended toward a later start. Analysis of annual habitat use between the period after calving and the return to winter range supports the observation that the herd has contracted to an area surrounding Contwoyto Lake. However, preliminary modeling results do not indicate a strong relationship between this range contraction and the changes in range productivity and phenology measured remotely.

Language: en

Citation:

Contact Info:

Title: 2023-24 - NWT CIMP Final Report - Final Report - CIMP187

Date:

Date: 2024-03-31

Date Type: Publication Date

Topic Category: Environment and Conservation

Keyword Collection:

Keyword: Bathurst caribou

Keyword: remote sensing

Keyword: dendrochronology

Keyword: vegetation

Keyword: climate change

Spatial Extent:

West Bounding Longitude: -121.593

East Bounding Longitude: -106.433

North Bounding Latitude: 67.256

South Bounding Latitude: 61.599

Transfer Options:

URL: https://nwtdiscoveryportal.enr.gov.nt.ca/geoportaldocuments/2023-24%20-%20Final%20Report%20-%20Queens(Danby)%20CIMP187%20-%20V1.0.pdf

Distributor:

Distributor Contact:

Organisation Name: Cumulative Impact Monitoring Program (CIMP)

Role: Point Of Contact