Lecture 11 Grasslands and Rare Plants Flashcards
What is a grassland?
An ecosystem where Poaceae dominates the natural vegetation
Could have a cold season, different dry seasons/wet seasons
Precipitation is not adequate for the development of forests with closed canopies
Natural disturbances are important: fire, grazing animals
Variation in topography at a small scale, and climate at a large scale, gives a great variation in plant communities
What are natural disturbances in the NA Prairies?
Bison wallows used continuously over many years, hence providing a high frequency disturbance regime that favours annual plants adapted for colonization of disturbed areas
Fires are less frequent (typically 3-5 years) but spread over wide areas, influencing regional diversity patterns
–> mix of frequencies maximized species diversity
What is the diversity of grass growth patterns?
Bunch grasses (not spreading by rhizomes or stolons) VS sod-forming (spreads and makes sods, has rhizomes or stolons)
Cool season grasses (C3 photosynthesis; active growth in spring and/or fall) VS warm season grasses (C4 photosynthesis, active growth in summer)
Why does fire favour herbaceous plants over trees and shrubs?
1) Location of growing points
- buds (growing points) of trees and shrubs are located above ground –> growing points not protected
2) Amount of biomass removed by burning
- several years lost in trees/shrubs in terms of productivity
3) Length of time to regain reproductive maturity
- herbaceous plants only losing 1 year of growth (better matched to have frequent fires coming through) –> they can be productive in the same year or the next which is not the case for trees/shrubs
What makes growth more difficult towards the Western regions of the Prairies?
Prairie regions’ soil and moisture regimes vary from East to West
In the West, there is less rooting depth and less precipitation
–> Western regions: shortgrass
–> middle: midgrass
–> Eastern regions: tallgrass
What are the 4 grassland ecosystems of Canada?
Aspen parkland
Oak savanna
Tallgrass prairie
Shortgrass prairie
What is oak savanna? Where is it found?
Grassland with some trees transitional between temperate forest and tall grass prairie
On the Eastern edge of North America grasslands (in Ontario) –> eastern side of the tallgrass prairie
What is aspen parkland? Where is it found?
A grassland with open areas, and areas of fairly dense Populus trees
Northern edge: where the boreal forest meets grasslands
What are tallgrass prairies? Where are they found?
More precipitation
Plants vigorously growing, no bare soil patches
Found to the East
What are shortgrass prairies? Where are they found?
Less precipitation
Plants more water-stressed –> shorter
To the West
What are prairie potholes?
Within the different grassland regions, these are shallow wetlands
Very important to waterfowl
Numerous small depressions from altered topography from past, colder landscape that included pingos and from uneven glacial deposits
Not drained by surface flows (i.e. rivers/streams)
Fed mainly by snowmelt, they may dry up (ephemeral)
Past glacial action/melt created the depressions
What are some plant adaptations to grasslands?
Deep rooting –> an adaptation to fire
Species have different times of active growth
- benefit is less competition
What kind of species in prairie wetlands?
Tall grasses
- same species that are characteristics of Eastern Canadian shorelines/marshes (ex. Phalaris arundinaceae)
What is the current state of grasslands in Canada?
Very, very little original prairie is left due to the steel plow –> most grasslands converted for agriculture
Why are standardized definitions important in the context of rare species conservation?
Standard definitions are needed to that laws relate to consistent levels of threat for species extinction within each legal jurisdiction
For conservation to be harmonized across the globe for each threatened species as much as is possible
For the application of international laws on the trade and movement of listed rare species
What are different assessments of species status from global, national, to provincial?
Global IUCN Red List
COSEWIC: Canada
CDPNQ: Quebec
What is the CDPNQ and what is its role?
Centre de donnees sur le patrimoine naturel du Quebec
Keeps track of rare species in Quebec, and updates their status depending on new populations, changes in taxonomy, and new evaluations. They publish their lists on their website
What is the threatened/vulnerable and endangered status of CDPNQ?
threatened: species is in a precarious situation, but it is not expected to disappear in the short term
endangered: the species is in decline and is expected to disappear
Why are species rare? What do we mean by rare species?
In the context of conservation, we are concerned with declines in the populations of species, such that they are predicted to disappear (become extirpated or extinct) in the near future.
Usually, this is linked to both natural rarity causes, and impacts on the species from direct or indirect human pressures, namely habitat loss and degradation, invasive species, disease, etc.
What are the 3 natural causes of rarity?
1) Naturally small population sizes
2) Uncommon habitats
3) Restricted geographic distributions
–> combinations of these three causes give 7 forms of rarity and commonness`
What is an example of a rare species due to uncommon habitat?
Species that grow in serpentine soils in the US
(also known as narrow habitat distribution or high habitat specificity)
What is an example of a rare species due to restricted geographic distribution?
Golden pothos endemic to a very small and isolate island in French Polynesia
Has since become an invasive species in most countries along the equator due to anthropocentric activity
- also a hardy houseplant
However, most geographically restricted species remain in their ‘home’ region though, giving a much greater chance to become extinct
What is an issue with rare species and iNaturalist?
Plant poaching leading to extinctions in the wild of many species
What is the main threat to rare species in Quebec?
Habitat loss due to privately or publicly owned land
Protected lands are scarce in the South. Here, the pressure from humans is the highest. Most land is modified, and invasive species/diseases are most common
What are the 4 types of distribution patterns in North America?
Peripheral
Disjoint
Sporadic
Endemic
What are the main causes of rarity in Quebec?
Northern peripheral distributions (52%)
- distributions which just make it into Quebec at the southern edge of the province account for about half of all rare plants in the province
- Ontario under the pro-development Ford government has recently moved to de-list all species that are common in other jurisdictions
- In other words, rarity in Quebec often encompasses locally rare species (that are more common in other areas of the range). Conservation status of species is often defined at the level of country, not planet. If a species if rare in your country, often it is protected even if it is more common elsewhere.
Narrow habitat preference (42%): plants that grow on high pH or heavy metal rich sites
Why is the conservation of isolated populations important?
Conserving the genetic diversity of a species
What is a calcareous rock?
A rock that has calcium carbonate (CaCO3) or a variant
Forms from sediments rich in shells and marine fauna
pH is high
Ex. lime and dolomite (sedimentary), marble, veins of calcite in other rocks (metamorphic)
What is serpentine?
A name used to refer to rocks that are:
- highly basic
- rich in magnesium silicate and iron
- may be high in other trace metals too
What are alvars?
Kind of calcareous habitat where flat rocks (the bed rock) is close to the surface, with a very thin organic layer overtop
