lecture 25- impacts of anthropogenic climate change on ecosystems 2 Flashcards
What is a common migratory response to warming climates?
Climbing to higher elevations in response to warming.
Many populations now isolated on “mountaintop islands”.
Explain the changes in biotic interactions between caribou and shrubs.
Increased shrub growth threatens caribou.
– Shrubs crowding out lichens (key winter food for caribou)
– Shrubs collect snow; deep snow makes it hard for caribou to reach lichens beneath
– Increasing shrubs also speeds up rate of warming:
* Snow trapped by shrubs insulates soil, keeping it warmer over winter.
* Arctic microbes increase the processing of organic matter in the soil, making soil even better for shrubs, further increasing the shrubs’ capacity to warm the soil.
Explain the changes in biotic interactions between polar bears and brown bears.
Polar bears are forced to move to terrestrial systems due to climate change. Ecology of brown bears in the arctic offers evidence that these habitats are unlikely to provide sufficient food for polar bears
Brown bears have been shown to displace polar bears from feeding sites.
Explain the changes in biotic interactions between birds and caterpillars.
The timing between the bird’s nesting period, the caterpillar stage, leafing, and flowering need to overlap for the species to thrive.
Changes in timing differ from species to species, so ecological interactions are disrupted.
- more leaf production
- caterpillars lay their eggs sooner due to spring coming faster
- small period of overlap for the bird nesting period
Explain the changes in biotic interactions between zooplankton and predators.
Zooplankton are important in lake ecosystem- they are the main herbivores and are important food resources for fish. Zooplankton can change their bodies to adapt to changes.
CO2 levels reduce the daphnia’s ability to perceive the presence of predators (decrease in defense expression)- if they can’t smell them, they can’t have morphological change so it will lead to worse levels of defensiveness.
Increased CO2 levels can reduce the population because they cannot enact the defense when faced with their predators.
Explain the changes in biotic interactions between plants and herbivores.
Elevated [CO2] reduces plant nutritional quality for herbivores by increasing leaf carbon-nitrogen ratios.
Consequently, herbivores will need to consume more plant tissue to meet their nutritional demands.
What are the eco-evolutionary feedbacks that impact
selection on plant traits?
1.) Higher temps -> higher insect growth rates, increasing plant damage
2.) Warmer winter temps reduce overwinter mortality among herbivores and increase foraging during prolonged growing seasons
3.) Climate change may disrupt herbivorepredator interactions
Explain the changes in biotic interactions between plants and pollinators.
- Droughts have a negative feedback effect on flower size.
- Climate change and elevated Co2 levels have a negative feedback effect on pollen production.
- Elevated Co2 levels have a negative feedback effect on nectar.
All of these impact pollinators.
Explain the changes in biotic interactions between plants and mycorrhizal associations.
Elevated CO2 has a positive influence on plant-mycorrhizal relationships.
With elevated CO2, potentially positive impact on plants = increase PS, which increases the nutrients they need.
It is not the CO2 that is limiting, it is the soil nutrients- we can get more nutrients with more CO2.
Potential that plants with fungi see a net positive impact.
What are the changes in disturbance regimes for wildfires, droughts, and insects?
Climate change increases the risk of fire in areas where decades of total fire suppression have resulted in the buildup of dead fuels.
Wildfires increasing in frequency, size, and season length:
– Longer, more intense summer droughts stressing trees
– Stressed trees are more susceptible to attacking beetles, which leave standing dead fuels in their wake
What are the changes in disturbance regimes for arctic wildfires and shrubs?
Wildfires consume lichens. The tundra used to never have fires. As we have more woody biomass increase in the tundra = more fire.
Climate change expands shrubs in the arctic, which has a negative impact on lichen (shading them, cant PS). Supporting the shrubs, which are declining in lichens and caribou.
Also, facilitate rapid increases in shrub cover through nutrient release and soil warming.
What are the changes in disturbance regimes for invasive desert grasses?
Outcompeting native grasses because they thrive under high CO2 conditions.
Invasive grasses are out-competing native grasses.
What are the changes in disturbance regimes for the mountain pine beetle?
Beetles prefer mature lodgepole pine. Because of fire suppression, we have lots of mature pine.
Beetle larvae are killed by severe (- 40oC) winter cold snaps - survival is enhanced by warmer winters (climate change).
With beetle: forests are a source of CO2
Creates a positive feedback loop:
- decomposition releases CO2
- temperatures rise
- increased beetle reproduction
- pine beetle infestation kills trees
Why have mountain pine beetles declined?
1- The amount of available habitat has diminished, as the beetle has already destroyed most of the mature lodgepole pine.
2- The rate of spread in other areas of the Interior has been somewhat varied, due to diverse terrain and forests with greater diversity of timber species.
What happens when species cannot adapt to new environmental conditions or move somewhere else?
- Decreases in populations
- Extirpation or even extinction
