Monday, May 31, 2010

A look at conifer phenology

Torrey pines (Pinus torreyana) , one of the rarest conifers in North America,
were sending out new needles in mid-January, near San Diego.

With a cool rainy Memorial Day weekend it seems like new kinds of spring wildflowers have pretty much quit coming out, and we won’t see big changes in what wildflowers are out until we finally get some warm summer days. (its 50 degrees and raining right now). But conifers on the other hand are about as active in producing new Budburst observations as they are any time of the year. So this week I thought it might be useful to do a quick review of the somewhat odd phenology stages of this ancient plant group.

Conifers are pretty interesting group of plants. The conifers were some of the first plants to grow on land, going all the way back to the Carboniferous period more than 300 million years ago, or more than three times as old as as even the most ancient groups of flowering plants that we see today. So does this mean these are “living fossils” and on their way to extinction? Hardly! Conifers despite their long history are amazingly adaptable, and actually have greatly expanded their dominance in many places, thanks to the value people place on the many wood products (or cool year around shade) that can be derived from these fast growing trees. Also these trees can handle ice, snow, wind and other events with much less injuries than broadleaved trees. Here in the West they are often the dominant species in the forest. They occur also in the East and Midwest, but in these warmer humid forests they are typically associated with poor soils, high elevations, or disturbances such as logging or fire. For more tidbits on the natural history of conifers check out books written by Aljos Farjon*

In the spring and summer we are generally looking for a couple of key stages:

First Needles: This is kind of like “budburst” or “budbreak” for flowering plants. This is when you can first see individual needles in a swelling bud

First Pollen: This is similar to “first flower” for flowering plants. The male cones or pollen cones swell, turn the mature color then one day the pollen starts flying (and hay fever season for some observers!).

Full Pollen This is when 50% or more of the branches are dispersing pollen. It often happens within a few days of first pollen.

These stages look a little different depending on which kind of conifer you are looking at. So this year I took some photos of several different kinds. For those of you that live in an area where there are not a lot of native conifers, as in many parts of the Midwest and east, you can also look at shade trees and ornamentals. Since the same species are planted all over the country these can be really interesting and valuable ones to watch, especially if they are growing away from concrete or buildings (like in parks or parkways or a backyard).

Douglas-fir. This is one of the world’s most important trees for timber, and is also one of the most common ornamental trees, so this is a really important species to observe for Budburst. In our area these are always the first to disperse pollen, but are much later in sending out new needles. As you can see in this photo they usually turn bright red just before they disperse pollen. Most pollen cones (male cones) of conifers have bright colors just before they are ripe.

Spruces. These are one of the most poplar ornamental trees in the country. The most common species are the Colorado Blue spruce, Engelmann spruce (native to the West and Northwest), Norway spruce (with the largest cones) and white spruce (native to Alaska and most northern countries). They generally disperse pollen after the hemlocks in our area and send out their needles about the same time as they disperse pollen. Spruces generally have reddish pollen cones which then turn yellow or brown when they disperse pollen. All of the spruce species in our area actually have a "cap" of scales at the tip of the bud when they reach the first needles

Soon afterwar
ds as the needles grow the cap of scales falls off.

Pines. These are some of the most common conifers across the country. They have a more unusual pattern of development, depending on how fast or young they are. Instead of just having needles emerge from buds formed during the previous year they often form “candles” which are new twigs or stems, usually covered with new needles. Like the other conifers the “new needle” stage is defined by when you can see new individual needles. This usually means that you will see the needles emerging from the tips of scale-covered bundles, usually after the candles have formed.

Pines are generally the last group of conifers to disperse pollen and send out new needles in our area. Most of them have pollen cones attached just below the clusters of new needles at the tip of the branches, as in the white pine pictured above. Ponderosa pine also looks like this. In our area the northern European pine, Scots pine (Pinus sylvestris) is usually first to disperse pollen, then ponderosa pine, then finally bristlecone and foxtail pines are the last to pollinate, sometime in early summer.

Some pines like this Scots pine pictured to the left can develop long columns of pollen cones which look a little bit like a stem or needle candle. But the key difference is the color and shape. These are yellowish in color and rounded (as contrasted with the narrow pointed shapes of young developing clusters of needles. These just started pollinating today in my yard. New needles will emerge much later.

So there you have it. The spring stages are pretty easy to see on these trees as long as you know where to look, and as long as you choose a tree that has branches that droop down low, making it easier to see what is going on! Otherwise a good pair of binoculars may be needed to see when things are happening. Since conifers are so widely distributed data from them can be really valuable for phenology scientists. If you have not looked at the phenology of local conifers, give it a try. They can help provide you a whole new perspective on spring!

Look at all this pollen! This Scots pine is producing a lot of cones this year.
Conifers vary a lot in how many cones they produce each year. They usually have a
"big year" every 5-7 years.

Paul Alaback

*Alijos Barjon 2008. A Natural History of Conifers. Timber Press. Portland.

All photos by Paul Alaback, taken mostly in western Montana and at Torrey Pines Reserve, near San Diego.

Friday, May 14, 2010

Redbuds and other spring beauties

We’re enjoying a lovely spring in Chicago this year. Our early spring flowers are starting to fade: lilacs, redbuds, and trillium are all past their peak. I just took a spin around the Garden and saw several species in full bloom, including red columbine, (Aquilegia canadensis), marsh marigold (Caltha palustris), wild hyacinth (Camassia scilloides), the incredible lady slipper orchid (Cypripedium candidum), shooting star (Dodecatheon media), strawberries (Fragaria virginiana), wild geranium (Geranium maculatum), prairie smoke (Geum triflorum), Jacob's ladder (Polemonium reptans), and golden Alexander (Zizia aurea). Just starting to show their pretty purple-blue flowers are spiderworts (Tradescantia ohiensis). They’ve been open a couple of days here at the Garden and I noticed the first one open in my yard yesterday.

Spiderwort (Tradescantia ohiensis)
Photo by Jennifer Anderson, USDA-NRCS PLANTS Database

On April 19, I drove from Chicago to St. Louis and it was a study in redbud (Cercis canadensis) phenology. In Chicago, the redbuds were just starting to open, they were in peak bloom around Bloomington, Illinois, and by the time I reached St. Louis they were just past peak. In redbud time, we’re about 15 days behind St. Louis. When I was in Boulder last week, I saw redbud in peak bloom there. I would estimate Boulder is about 7-10 days behind Chicago, according to the redbuds!

What is your spring looking like this year? It is May 14th, do you know what your redbud is doing?

Kay Havens

Wednesday, May 12, 2010

Rapid changes in plant phenology in the Rockies

Spring finally came to the northern Rockies in Missoula,
Montana in early May. Serviceberry and maples are in full bloom.

As mentioned in our blog a few weeks ago, spring has been coming early across the country over the past several decades. How early spring has advanced depends on what species (and what phenophases) you are looking at or where you are. Spring has advanced so rapidly in some places that it appears to be causing stress for some native plant species. A study just published in the Proceedings of the National Academy of Sciences even documents a bird species in Europe that has increasing numbers of its populations that have apparently quit migrating, in response to warming spring and winter weather (!). Recent studies have documented that plant species that are most flexible and that are changing dates of first flowers or first leaves emerging tend to be doing better than species that are not changing their dates of their phenological stages (phenophases). (spring creep). This effect varies by species and location, so is an active area of scientific research. Scientists still do not clearly understand the causes of this variation by species or location (see Korner and Basler, March 10, 2010 issue of Science )

A recent study (Lesica In Press, Journal of Arid Environments) documented that in semi-arid or dry areas, like here in the Missoula valley of western Montana spring may be advancing even more rapidly than what we have seen in the Midwest and East. Most studies have documented that spring wildflowers are appearing an average of 3 days earlier each decade for the past 30 years or so, or an average of about 10 days earlier than historical records. Most of these studies have been done in humid climates in the eastern US and northern Europe. The Lesica study, and budburst data in this region show that spring is advancing at a rate of 7 or more days per decade for the earliest species, or more than twice what has been reported in most other regions.

Sagebrush buttercups are local sign of spring in our area. They put out leaves in the fall, usually in response to fall rains. Then they put out more leaves and the first flowers usually within a week or so of consistent warm temperatures, usually in the middle of March. In just the past 14 years, Lesica found that these flowers are emerging an average of 1.6 days earlier each year, or more than two weeks over the study. More than seven years of data were available for thirty-two species, 75% of which are flowering earlier. The most rapid advance in dates of first flowers were noted for 10 of the earliest flowering herbs. Comparing budburst data with my monitoring data for these foothills around Missoula, many plant species are flowering earlier even in the summer or fall, another result that is much more dramatic than for many humid sites in the East.

This study highlights the importance of what we are trying to do with our network of volunteers in Project Budburst. While there are general trends of how plants are responding to changes in climate, there are significant differences in some regions. Scientists really need better information on how all parts of the country are changing in response to changes in weather and climate, and how changes vary by species and phenophase.

Keep those observations coming!

Budburst News

Over 10,000 observations submitted by Budburst volunteers! We broke this threshold in early May. Keep up the good work! It is especially valuable when you can make observations on the same sites and species from year to year.

Top 10 wanted! Also check if any of our top 10 species or closely related species occur in your area. These data are especially useful to us in documenting how phenology is changing for these species across the country.

Paul Alaback

Photos: Top-Mount Sentinel, Near Missoula, Montana on April 25th. The cool spring has extended the length of the flowering period for both western serviceberry (Amelanchier alnifolia) and for Norway maple (Acer platanoides)
Middle: Sagebrush buttercup (Ranunculus glaberrimus) in flower on Mt. Sentinel.
Bottom: Yellow Puccoon or yellow gromwell (Lithospermum ruderale), one of the herbs found to be flowering weeks earlier that was recorded in the early 1990's.

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