Understanding Northern Latitude Vegetation Greening and Browning Proceedings of a Workshop (2019) / Chapter Skim
Currently Skimming:
Trends and Drivers of Greening and Browning
Trends and Drivers of Greening and Browning
Pages 7-14
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From page 7... ...
Berner and colleagues are developing a pan-Arctic assessment of plant productivity that compares Landsat satellite maximum normalized difference vegetation index (MaxNDVI) data and field measurements from select sites, including sedge aboveground net primary productivity (ANPP)
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From page 8... ...
Greening trends in the MaxNDVI Landsat record were significant when considered across the tundra biome as a whole for 2000-2016, but when bioclimatic zones were evaluated separately, only the southernmost tundra bioclimatic zone showed a greening trend. In total, about half the tundra biome showed no systematic trend toward greening or browning.
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From page 9... ...
Sylvie Gauthier, Natural Resources Canada, provided a more in-depth look at the impacts of fire and harvest disturbance on boreal forest productivity and recovery across Canada. Recent remote sensing work suggests that forest cover losses have been greater than gains in Canada between 2000 and 2012 (Hansen et al., 2013)
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From page 10... ...
, surficial geology, topography, proportion of open woodland, and observed fire frequency. The difference between potential and current productivity increases as the fire return interval decreases (i.e., fire occurs more frequently)
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From page 11... ...
Many disturbance types at high latitudes are either directly tied to climate warming, or warming indirectly alters conditions that then contribute to the disturbance. The workshop had a few presentations that explored a dominant disturbance types in detail and many other presentations provided some discussion other disturbances in the context of greening and browning.
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From page 12... ...
Land Cover Change Jonathan Wang, focused his remarks on the role of disturbance and associated land cover change in influencing trends in greening and browning. Trends in NDVI have been shown to depend on land cover history, where time since disturbance impacts the observed trend (Sulla-Menashe et al., 2018)
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From page 13... ...
As explained by Arjan Meddens, University of Idaho, there have been widespread insect outbreaks in North America in the past. For example, in the early 2000s a mountain pine beetle outbreak in British Columbia, Canada affected 12 million hectares and a spruce beetle infested about 0.2 million hectares in North America (Hicke et al., 2012)
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From page 14... ...
. During the general discussion about disturbance, some participants questioned whether disturbance events could be factored out of some analyses to allow for focused attention on other drivers and exploration of why trends may be seen in areas that have not experienced recent disturbance or identifiable land cover changes.
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