![A forest damaged by pine beetles](/sites/default/files/styles/resource_card_image_360x300_/public/2019-09/pine-beetle-damage-forest.jpg?itok=rD_omerz)
How Do Introduced Species Affect Ecosystems and the Economy?
STEM Explained
When a species ends up outside of its natural zone, the consequences on other species, ecosystems and human industries can be severe. Climate change and human activities can introduce species into new zones.
![Lawn mower mowing grass](/sites/default/files/styles/resource_card_image_360x300_/public/2019-09/image%2C.jpg?itok=7Rfn7uh2)
How Do Plants Use Chemical Signalling?
STEM Explained
How do plants use scents? Learn how some plants use chemical signals to send messages to animals or other plants.
![Water Lily Water Lily](/sites/default/files/styles/resource_card_image_360x300_/public/waterlily.jpg?itok=nnvmuAjZ)
Flowers: Cup Shape
Picture Collections
8 images of some flowerheads such as roses and water lilies whose outer petals are longer than the petals in the centre of the flower
![Iris Iris](/sites/default/files/styles/resource_card_image_360x300_/public/blueiris.jpg?itok=dvud8S14)
Flowers: Irregular Shape
Picture Collections
3 images of some asymmetrical flowerheads such as an iris and an Orchis Sima or Monkey Orchid
![Sunflower Sunflower](/sites/default/files/styles/resource_card_image_360x300_/public/sunflowers.jpg?itok=pmiRVO51)
Flowers: Radial Shape
Picture Collections
7 images of some symmetrical flowerheads such as asters and sunflowers whose petals radiate from the centre of the flower
![Petunias Petunias](/sites/default/files/styles/resource_card_image_360x300_/public/petunias.jpg?itok=yMPRRNyK)
Flowers: Trumpet Shape
Picture Collections
5 images of some flowerheads such as petunias and lilies that start as a narrow base and widen to an open shape
![Green walls in Harvard University](/sites/default/files/styles/resource_card_image_360x300_/public/2020-05/Green_wall_Harvard_University.jpg?itok=_ivWsw8S)
Green Walls
STEM Explained
Green walls use plant processes to improve air quality in buildings.
![bees on frame held by beekeeper](/sites/default/files/styles/resource_card_image_360x300_/public/2019-11/Bees_at_work.jpg?itok=eCBFpn4d)
How are the World's Bee Populations Doing?
STEM Explained
Bees are important for agriculture. But bee populations face threats. This resource looks at Colony Collapse Disorder, herbicides & pesticides, and more.
![Massive algal bloom](/sites/default/files/styles/resource_card_image_360x300_/public/2019-09/massive-algal-bloom.jpg?itok=pqgXB2yc)
Eutrophication: Why you should care about pond scum
STEM Explained
When fertilizers from agriculture get into lakes and rivers, big problems can result for aquatic ecosystems, food chains & webs!
![Timea Filer - Urban Forestry Field Technologist](/sites/default/files/styles/career_image/public/2019-08/Timea%20Filer_28.jpg?itok=fEY8NK3Q)
Timea Filer (Video)
Career Profiles
Urban Forestry Field Technologist
![Timea Filer | Urban Forestry Field Technician Timea Filer | Technicienne de terrain en foresterie urbaine](/sites/default/files/styles/career_image/public/Timea%20Filer_26.jpg?itok=isJEd7as)
Timea Filer
Career Profiles
Urban Forestry Field Technician, City of Guelph
![Heather Dover | Arborist Heather Dover | Arboricultrice](/sites/default/files/styles/career_image/public/Heather%20Dover_13.jpg?itok=kijAxCZD)
Heather Dover
Career Profiles
Arborist
![Warren Bills | Digital Farming Business Development Warren Bills | Développement numérique des entreprises agricoles](/sites/default/files/styles/career_image/public/6204_13.jpg?itok=fsEVFRAi)
Warren Bills
Digital Farming Business Development
![Andrew Newman | Mechanical Tree Harvester Andrew Newman | Mechanical Tree Harvester](/sites/default/files/styles/career_image/public/6215_13.jpg?itok=oLEDX3iw)
Andrew Newman (Video)
Career Profiles
Mechanical Tree Harvester
![Lacey Rose - County Forester, County of Renfrew](/sites/default/files/styles/career_image/public/2019-08/6207_14.jpg?itok=GugzDZsy)
Lacey Rose (Video)
County Forester