Two Harvard Forest Scientists share with us what spring looked like through the lense of their data.
From Ecologist Joshua Rapp:
Joshua Rapp is a plant ecologist interested in how life history influences the interactions of plants with their environments, and ecosystem processes. He is currently a Bullard Fellow at Harvard Forest, and will serve as the project Ecologist for the Our Changing Forests project Summer Institute for Teachers on August 25th.
Maple Syrup Season
From the maple tapper’s perspective it was an early spring. You can see a graph comparing the past few years at HF and my comments on the maple sugaring season here:
Some excerpts from Joshua's website related to the maple syrup research give a summary of what Spring looked like in the world of Maple Syrup.
I tapped the trees on February 1, the earliest I’ve tapped by more than 2 weeks, and collected sap throughout the first week of February.
March 30, 2016. The tapping season is officially over – cold nights and warm days of late have not resulted in dripping taps. This is not because the sap isn’t flowing in the trees; instead, the taps have become clogged with bacteria, which also clouds the little sap that does manage to drip from the taps. A warm spell 3 weeks ago caused the end of big flows, although sap continued to dribble out for a while, at least in the sugar maples. Overall, the early season was good for sap flow -second largest in the past 5 years, but only an average year for syrup since the sugar content of the sap was on the low side – second lowest in the past 5 years. I collected sap 25 times, the most I’ve done in a year. Most of the sap flows were low to moderate, but a few were quite high, including the 2 biggest one-day flows I’ve seen.
Maple and Oak Flowering:
Joshua Rapp's research is looking to see connections between maple tree's production of sugar and masting. Masting is a term that means synchronous production of seeds over large geographic areas. Think acorns or samaras. Flowering is the precursor of fruit production so that is looked as as well. It is thought that there is a tradeoff in energy the tree spends on sugar production vs. flower and seed production but it is not well studied.
Re: Flowering this spring: It was a slightly early and low-moderate flowering year for sugar maple. In the attached figure (below), a couple of sugar maples on the right side of the road are flowering, but the ones on the left side are not.
From what I observed, it was a very high flowering year for red oak, and the trees had many small 2nd year acorns. Red oaks take two years to mature acorns, so last year’s pollinated female flowers are small acorns this spring and will be full size by fall. This year’s fertilized ovules will become mature acorns next fall. It will be interesting to see if this results in two red oak mast years in a row (this year and next).
To see more about Joshua Rapp's Masting and Maple Syrup research go to his website at:
To see recent articles and radio stories about Joshua's research this winter and spring, see:
The Post-Tribune, Chicago Tonight, and Indiana Public Radio each did articles about Josh's newest sample site at the Indiana Dunes National Lakeshore.
The Worcester Telegram ran a story. Climate Central also published a piece. Also see: MassLive, WWLP-22News, the Westfield News and The Recorder.
To see more about the Our Changing Forests Schoolyard Ecology project, go to:
To begin the Our Changing Forests Schoolyard Ecology project for students in grades 7-12, see the flyer and registration form at:
From Buds, Leaves and Global Warming Project Ecologist, John O'Keefe:
John O'Keefe has been studying tree phenology at Harvard Forest for 26 years. He monitors when leaves emerge in the spring (bud break) and when the leaves drop in the fall (leaf fall) in order to determine whether the growing season is getting longer as a result of global climate change. In summarizing his spring 2016 tree phenology research, John O'Keefe had this to say:
I just finished entering this spring’s data and calculating the bud break dates. As I suspected, despite the record warm winter and early spring, the cool, cloudy April really slowed things down and we wound up with quite a late spring. Once the leaves emerged the weather warmed up and they developed fairly rapidly, so the 75% leaf development date wasn’t especially late. This points out that it is really the weather during April and early May that determines when leaf emergence will occur.
See graphs below from John O'Keefe:
Note that this graph shows the mean 75% leaf development over 26 years. This year seems to be later than average but not among the top 5 latest as was bud break.
This is a complex figure showing the Mean 50% budbreak, 75% leaf development and 50% leaf fall for 4 tree species all on one graph.
Notes to help interpret the key: Species ACRUBB stands for Acer Rubrum (Red Maple) bud break. The BEALBB is a birch species bud break. QURUBB is Red Oak, QUALBB is White oak budbreak...ACRU 75 is the 75%Leaf development for Red Maple, etc. The ACRUL50 depicts the leaf drop date for Red Maple, and so on.
It is helpful to see the overall trends all together here to see overall patterns. The bottom set of lines shows Spring data over time while the top set of lines shows the fall data over time.
To see more about John O'Keefe's own long term research go to:
To see more about the Buds, Leaves and Global Warming Schoolyard Ecology project for students in grades 4-12, go to:
To begin the the Buds, Leaves and Global Warming study, see our flyer and registration form for the Summer Institute for Teachers at: