Chronology: Two Years in Review
Over the past two years we have received funding from South Park National Heritage Area (SPNHA) to conduct research on dendrochronology and herbchronology. Their generosity has allowed us to study the science related to these two disciplines, by measuring the growth patterns of trees and herbs, respectively. We are looking to complete a bio-chronology at Beaver Ponds this coming summer. A bio chronology is the ages and growth patterns of all species that add annual growth rings. Growth rings are displayed in several plants but there are animals that display growth rings such as fish and turtles. Some of the animals also show a climate signal in their growth rings. A climate signal is shown as a pattern of wide and narrow rings displaying the influence of precipitation rates.
During the summer of 2015, with help of Drs. Richard Guyette and Rose Marie Muzika from the Missouri Tree Ring Laboratory (MTRL) at the University of Missouri, we sampled trees at Beaver Ponds and on University of Colorado-Colorado Springs and Mountain Area Land Trust Land on nearby Pennsylvania Mountain. The impetus of the project was to determine growth rates and ages of trees at Beaver Ponds and on Pennsylvania Mountain. At Beaver Ponds, we collected increment cores from lodgepole pine and cross sections from old stumps. On Pennsylvania Mountain, we collected increment cores from several bristlecone pines. We found live trees on Pennsylvania Mountain near 2000 years old while the oldest tree at Beaver Ponds was a 215-year-old Engelmann Spruce. One of the cross sections collected at Beaver Ponds started growing in 1356 and was over 500 years old when it was cut down. Most of the lodgepole pine samples at Beaver Ponds gave us recruitment date 1870. This corresponds with the establishment of the Duquesne smelter. Our guess is that most of the larger timber in the immediate area of the smelter was harvested for fuel. More than half of the cores from the bristlecone pine on Pennsylvania Mountain showed increased growth rates over the past 100 years. This is counter intuitive; you would expect diameter growth to decrease over time due to competition with other trees and old age. What caused the increased growth is unknown but it could be due to increased temperatures and/or additional CO2.
In 2016 Dr. Mike Stambaugh, (MTRL) along with Beaver Ponds personnel and volunteers collected samples of various herbaceous alpine plants that display annual growth rings. At Beaver Ponds, we sampled two types of cinquefoil – an herbaceous plant of the rose family; and a pea we still must identify. We collected several samples of Whipple’s Penstemon a species that is known to have growth rings. To be able to see the growth rings, we needed to slice the roots with a microtome. A microtome is an instrument that can hold a sample in a vise as it is drawn over an extremely sharp blade. The result is a sample that is about the third of the thickness of a human hair. After slicing, we stained the sample so we can see the cells with lignin. Lignin gives plants the ability to be erect. During collection, we collected additional above ground information that might be used as predictors of the plants age. What we found is that the sum of the diameter of the rosette and plant height are good indicator of the age of Whipple Penstemon.
In 2017 we are seeking funds to cover the cost associated with collecting information related to shrub growth at Beaver Ponds and on Pennsylvania Mountain. Shrub-chronology looks at the growth rates of shrubby species. At Beaver Ponds, we are planning on sampling stream side willows, shrubby cinquefoil, mountain sagebrush and common juniper. On Pennsylvania Mountain, we will sample shrubby cinquefoil, common juniper and willows. These species show growth rings well and display a climate signal. In preliminary sampling, we found a juniper that is 114 years old and a sagebrush that is 45.
With the collection of the 2017 shrub age data along with the dendro and herb-chronology data we will have made the first pass on determining the vegetative portion of the bio-chronology at Beaver Ponds and Pennsylvania Mountain.