Research

Key questions:

    • How does the phenology of different native and non-native plant species respond to changes in fall growing season length?

    • Do plant responses vary based on geographic location?

Predictions:

    • Prediction 1: The more extreme the environment, like in the far north of Alaska or at high altitudes, the less likely native plants will be able to keep their leaves green or continue to make new leaves relative to non-native plants in years with extended fall seasons. In native plants, we anticipate a stronger senescence (or "shut down") response due to their adaptations to Alaskan photoperiod. We anticipate that non-native plants, which have typically been introduced from locations further south, will have a wider range of senescence triggers and a greater capability to take advantage of warmer falls.

  • Prediction 2: In more extreme environments, non-native plants will suffer greater losses from a late spring freeze or early fall freeze than native plants, thus incurring a higher risk from staying green late into the fall season.


Significance:

Finding the answers to these questions and more is extremely important to the arctic and boreal regions of the planet because here growing season has significantly increased in both length and variability in the past 100 years. This trend is expected to continue, and is bound to have impacts not just on plant communities but on entire ecosystems in the North.

Species of interest and study design:

Citizen scientists selected two species of plants to monitor, a native and a non-native, from within a single plant group. The one exception is the wintergreen / evergreen plant group in which there are no invasive populations present in the wild to monitor. In total there are eight possible plant groups that volunteers chose from. These plant groups were selected because they: 1) represent plants that are common in both rural and urban parts of Alaska, 2) represent families with lots of non-native plants, and 3) have a big impact on the environment (e.g., they are associated with nitrogen fixing bacteria).

After selecting two plant species, citizen scientists chose a study site and select and marked five plants of each species to monitor and record data on leaf, fruit and flower phenology with particular emphasis on the fall growing season. Citizen scientists then submited this data to Project BrownDown where it was collected and analyzed in order to address the BrownDown research questions.

Results, publications, presentations and products from this project:

  • Mulder, C.P., and K.V. Spellman. 2019. Do longer growth seasons give introduced plants an advantage over native plants in Alaska’s boreal forest understory? Botany 97: 347–362. DOI: 10.1139/cjb-2018-0209. [PDF]