Wednesday, April 20, 2011
Tuesday, April 19, 2011
I had the great pleasure of traveling to Philadelphia last week, during which there were nice sunny days and lots of new flowers and leaves coming out on trees and shrubs and even wildflowers. Compared to Colorado Philadelphia is a week or two ahead in its phenology. You can see this by looking at common ornamental plants like white flowered crabapples, cherries and saucer magnolias (Magnolia soulangiana) which are common in both places. In the city there were many spring colors, in more wild areas with native plants spring was a bit more subtle. While I was there black cherry (Prunus serotina) came into flower next to the house I was staying in, going from one flower on one branch the first day, then about 5 branches with flowers the next day, or the first flower stage (4/15) then all the way to the full flower stage (more than half the branches with flowers) by the time I was leaving on 4/17).
Normally when you travel the occasional observer protocol could be used to record budburst observations since it is hard to know if you are really seeing the first day that a given plant put out leaves or new flowers. But if you have a chance to observe the same plants even for a few days during a rapidly changing time of the year like Philadelphia and many other places last week you can actually make some good regular budburst observations as well.
I also had the opportunity to visit some places outside the city to see how it compared with what was happening in the city. Normally you would expect the first flowers to occur in the city because of the "urban heat island" effect, where concrete tends to capture heat more quickly than soil so it is a little warmer and plants should become active sooner. For example black cherry was just starting to flower in the city but was still in the bud stage in the country.
I also had a chance to see budburst in action with many elementary school classes coming to the John Heinz Wildlife Refuge on Friday, working on pollinator gardens and other projects which will include making budburst observations on the plants that are developing there. Wildlife refuges can make for great places to make budburst observations since they have a wide range of natural habitats and are often easy to access, and may even include nature centers where you can get more information on local plant species. The most obvious wildflower in bloom on Friday was the marsh marigold (see above).
Another highlight was being able to see the oldest and one of the most unique botanical gardens in the country. This is the garden of John Bartram, who was a naturalist and botanist that helped establish botany and other sciences in the US and whose writings in the late 1700's inspired Henry David Thoreau and many other naturalists and scientists then and today. These places can be great places to make budburst observations since you can then compare dates of flowering with historical records, in this case over 200 years ago!
Coming back to Colorado on Monday I saw several changes since I left, again showing how now is the time to be watching your plants for budburst - they may change every day! Sweet cherries (Prunus avium) are now in bloom, the first japanese crabapples are in bloom, and several more cottonwoods came into bloom while I was gone. Eastern redbud has just come into bloom as well.
A beautiful forest in Bartram's gardens, with some trees planted as much as 200 years ago. Here you can see redbuds (Cercis canadensis) and sweet cherries (Prunus avium) coming into bloom.
Tuesday, April 12, 2011
Thankfully, spring color has arrived here in the Colorado Front Range. LIke most gardeners and northern residents in general I always anxiously await the first colors of spring, and finally it is here! We have had a tiny fraction of the snow that we should this time of year, so things are still quite brown in wild areas. Spring is early because of the lack of snow, with some plants as much as two weeks earlier than last year.
The first flowers were weeds (dandelion and cross flower). Cross flower (Chorispora tenella) is an annual mustard that can
become quite weedy but has an unusual pretty violet color to its petals (most mustards are a well, mustard yellow). The first real wildflower, native to our local prairies was a new species for me, a beautiful white sand lily (Leucocrinum montanum), growing right on the ground.
It burst into flower this past week in dry rocky places in a local open space park (Devils' Backbone) in the foothills. Golden eagles were soaring above me at the same time! (they overwinter in the foothills here). Mountain mahogany (Cercocarpus montana) is putting out new leaves, and skunkbrush (Rhus triloba) is sending out new flowers in warm sunny spots, and sagebrush is sending out new basal leaves. So soon the prairie will have a tinge of green. Chokecherry (Prunus virginiana) is sending out new leaves in riparian areas or draws, so maybe we will see new flowers in a few weeks.
Back in town irrigation has made for lush green grasses, and for a wide variety of trees and shrubs which are flowering or budding out now. As I reported a few weeks ago there were a few wind pollinated maples in full flower. These early ones (silver maple, sibirian elm, and red maple) are now mostly covered with
young developing fruits (samaras). You can see tinges of green on the Sibirian elms, but in fact there are no leaves. These are all just the young fruits glistening in the light. Lilacs and honeysuckles have been sending out new leaves, and have both reached the first leaf stage, but it will be a while before we see flowers.
Young Developing fruits (samaras) on Sibirian elm trees (Ulmus pumila), a common urban tree in the Intermountain West
Short "species" tulips and hyacinth bulbs are providing the most spectacular colors these days. It is no wonder that gardeners have savored these plants over the millenia, not only to they provide virtually limitless variety in the colors of their blooms, but they are amazingly tolerant of alternating snow, sun, and freezing nights in part due to their heritage which long ago was
rooted in high mountain environments in Turkey and nearby mountains in Central Asia. They are basically alpine flowers, that like many natives are well adapted to the late winter early spring season in these northern places as well as high mountain
environments. But here in Colorado not only do these plants have to deal with freezing temperatures but this year also drought conditions since we do not have moisture from melting snow. This seems to result in a less spectacular show of spring colors.
In my travels up to coastal Alaska last week I could see some green from grasses but still not much sign of flowers. Snow is still piled up in shady places. But I could see some red elderberry bushes (Sambucus racemes) with swolling buds, so maybe things will change in a few weeks. In Seattle a greenish tinge was covering alders, and cottonwoods as they started to bud out. Our cottonwoods have just come into bloom this past week.
Now we are into the full intensity of spring, I hope you find many new and interesting things while making budburst
observations this spring. Now is the time to make frequent observations since things are often changing day by day. Let us know what you find!
Wednesday, April 6, 2011
Did you know spring green-up is a phenophase transition observable from space? Scientists are using satellite images to assess changes in timing of green-up. Unfortunately, we’ve only been collecting these images since 1972 so we don’t have a long historical record to which we can compare contemporary records. Nevertheless, satellite images are providing g a new tool for those who study phenology that will become even more valuable in years and decades to come.