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Forest dynamics in former plantations


Monday, July 23, 2012, by Anne Cervas
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This summer, I am working with my mentor, Audrey Barker Plotkin, to study former plantations at the Harvard Forest. We are working in the field to record the growth and changing vegetation dynamics as the former plantations grow back as native forest after a century of plantation forestry. We are also combining data from the Harvard Forest Archives to the data we collect in the field to study the growth and composition of the plantation forests compared to the native second-growth forest. 

Plantations were an important component of the Harvard Forest in the first fifty years after its founding in 1907. The plantations we’re studying were planted with several different tree species, mostly pine and spruce, between 1916 and 1944 on former farmland or pasture that had been abandoned throughout the 1800s. Plantations were created in an attempt to increase the productivity and value of the Harvard Forest, as well as experiment with various methods of planting and tending trees. Following the 1938 hurricane, which severely damaged a large portion of the forest, and the mixed success of the plantations in their first few decades, plantation management decreased around 1950. By 2007, approximately 135 acres of plantations remained at Harvard Forest, as the rest of the original 270 acres had been harvested or out-competed by native forest. Of the remaining plantation forests, about half were clear-cut in 2008 and 2009, and have been growing back as native early successional woodland. The other half was left untouched and remains as forested plantations.  

          

Along with my mentor Audrey, I am spending much of the summer out in the field, surveying the vegetation in the 22 plots that she set up in 2007 before half the plantations were cut down. Slightly less than half of the plots are in plantations that are still forested, while the rest are in former plantations that are now growing back as native forest following the clear-cutting. In each plot, we measure the diameter of the trees, stumps, and pieces of dead wood on the ground (any trees or large branches that have fallen or were left after clear-cutting), and record information about seedlings and saplings. We also record every type of plant aside from trees—shrubs, ferns, grasses, etc.—that is in the plot, and estimate how much space each plant covers inside the plot. From the data we collect, we can observe and quantify how these sites are changing over time.  

In addition to the fieldwork and data collection, I am also spending time this summer in the Harvard Forest archives, using information and data from the plantations over the years. By combining the data from our fieldwork this summer with the plantation and other forest data that exist from the last century, I will analyze the growth of the plantations over the last 100 years and answer questions about the plantations during and after the era of active tending. I am looking at how plantation growth, in terms of the average tree height, diameter, and volume, has changed in the decades after plantations were abandoned, and whether the growth in plantations over the last century has differed depending on the original composition of the plantation.  

In addition to the archival data on plantations, I’m using data from two different forest inventories, one from the peak era of plantation forestry and the other from about 40 years after plantations were abandoned. Using the forest inventories along with plantation data will allow me to look at plantation growth compared to the overall forest growth over time. By comparing various measurements, I am analyzing whether the growth of the plantations over the past century has differed significantly from the growth of the rest of the forest. 

Finally, I am looking at the differences in the other plant species present (aside from trees), both in the plantations over time and in plantations as compared to the forest as a whole. By analyzing the effects of different species, planting methods, and treatments on the growth of plantations, and comparing the growth and species richness of plantations to that of the forest as a whole, I hope to discover the impact and outcome of the plantations over the past century at the Harvard Forest.



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