In order to understand how climate change, urban development, and other factors are affecting species throughout the country, scientists need a lot of help monitoring populations. All of us can help collect data and send it on to be included for analysis. This is an especially good way to get children interested in the garden.
Here are some projects to consider joining:
Bumble Bee Watch
https://www.bumblebeewatch.org
Bumble bees are important pollinators but more needs to be learned about which species are where and which ones are in danger. You can help by sending in photographs, and by creating habitat for them.
The Great Sunflower Project
https://scistarter.org/the-great-sunflower-project
People from all over the United States are helping to establish baseline information on pollinator species, resources, and conservation concerns by collecting data on visitation rates to all plants (but especially sunflowers!) in their yards, gardens, schools and parks. (started in 2008)
The Lost Ladybug Project
http://www.lostladybug.org/
Many native ladybug species are disappearing and it isn't known why. Information about where native and introduced ladybugs are living may help save our natives.
More Citizen Science projects can be found on Wikipedia, on the National Geographic Society website, and on the LA Natural History Museum website. EarthWatch has a member-recommended project which involves the role of vegetation in cleaning the air.