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The long, rich history of lilac observations has led to a better understanding of plant responses to global change. Dedicated volunteers have been tracking the phenology of cloned and common lilacs since the 1950s. The observations have been invaluable in documenting plant responses to changing spring conditions.
This information has been used along with historical weather data across the country to capture the timing of Spring Indices, such as leaf-out and flowering that primarily vary with temperature. At the Gardens we are monitoring 29 individual lilacs, including the common lilac, Syringa vulgaris, and 25 S. vulgaris varieties.
Monitoring all of the varieties in one location provides the opportunity to determine how phenology varies among the varieties. In 2013 we also planted two cloned lilacs (Syringa x chinensis 'Red Rothomagnesis') which we received from the USA National Phenology Network (NPN). Data collected from these and other cloned lilacs allow phenological comparisons across the country without genetic variation contributing to differences in timing.
You can join in Denver Botanic Gardens lilac monitoring by entering your own observation data through NPN. Just log on to Nature's Notebook here with your own account (simple to set up if you don’t already have one). Once you have created an account:
- In “My Account Details” choose the “Edit” tab.
- Select “Denver Botanic Gardens” from the drop-down list of partner organizations.
- Click “Add”, then “Save” at the bottom of the page.
- Now go to your “Observation Deck,” and you will see Denver Botanic Gardens as one of your sites. Click on our group name and you will be able to enter data into our group’s observation data (“Enter Observation Data”).
The observations you submit will be part of a national database and freely available to everyone.