Temperature And Betula Disribution On The Holy

Range, Massachusetts Essay, Research Paper

Temperature and Betula distribution on the Holyoke Range, Massachusetts

Abstract

In this study, it will be tested whether temperature affects tree densities in the genus Betula on different slopes of the Holyoke Range, specifically the north and south faces of the mountain range. My prediction is that the north face of the mountain will have a higher density of these trees than the south face of the range because of the temperature differences of the north slope being warmer than south slope for the range of growth for these trees. This experiment can be used to predict patterns of vegetation in other similar latitudes and slopes around the world. On September 20, 2000, the birch tree genus, Betula, density was measured on the north face of the Holyoke Range and on September 27, 2000, Betula..s density was also measured, but on the south face of the Holyoke Range. There were eight sites laid across a 150m transect line running across the slope starting from a subjectively chosen point. Based on the data collected on the Holyoke Range, the birch trees densities were not significantly higher on the north face than on the south face of the mountain range. Eight separate t-tests were performed, four on the density of the adult birch trees, and another four on the basal density of adult birch trees. From this data analysis it was possible to determine that the results were due to chance, not congruent with my prediction. From the results of my data, it can be concluded that temperature is not a factor in the tree density of Betula. In fact, temperature is not the only factor that can determine the growth of Betula, or other species of trees. Certain biotic and abiotic factors that can explain vegetation patterns of similar areas compared to this study.

Introduction

In this study, it will be tested whether temperature is one of the factors that affect tree densities in the genus Betula on different slopes of the Holyoke Range, specifically the north and south faces of the mountain range. In mid-latitudes in the Northern Hemisphere, northern-facing slopes are cooler than south-facing slopes because they receive less direct solar radiation. R. B. Livingston found that slope variation on the range exerts marked influence on all environmental factors (Livingston 1982). The upper, north-facing slopes are steep and abrupt (35.a to 40.a), while the south-facing slopes are more moderate (20.a). Accordingly, the angle of mid-day insolation is typically 55.a to 60.a greater on the south slopes than on the north slopes, except in late fall and winter when no direct light strikes the steep north-facing hill (Livingston 1982). Even though the area this experiment took place in does not exactly exhibit the same temperature variations discussed by Livingston, this can be still be used as a representation of north-facing slopes being warmer than south-facing slopes around the world.

On the Holyoke Range there are various species of Betula that have similar areas of optimal growth. The cherry birch, Betula lenta, can be found both in woods and in open and uplands on moist, protected, north-or east-facing slopes (Elias 1980). The yellow birch, Betula lutea, can also be found among cherry birch, but in the southern portion of its range, it can grow in cooler marshlands. The paper birch, Betula papyrifera, is found at lower elevations and often on north and east-facing slopes. Also the paper birch is one of the first species to occupy areas devastated by fire. Another species with similar traits to the paper birch is the gray birch, Betula populifolia, which occupies wide areas of abandoned fields and burned-over lands (Elias, 1980). These characteristics of these four Betula species are important because sometimes these trees are not in their optimal growth area, so implying that other factors are present affecting the growth of Betula on the Holyoke Range.

My prediction is that the north face of the mountain will have a higher density of these trees than the south face of the range due to environmental factors such as temperature.

Methods

On September 20, 2000, the birch tree genus, Betula, density was measured on the north face of the Holyoke Range and on September 27, 2000, Betula..s density was also measured, but on the south face of the Holyoke Range. There were eight sites laid across a 150m transect line running across the slope starting from a subjectively chosen point. The replicates were formed by taking eight random sites above the transect line, and eight below; then counting each as a single replicate giving a sample size of 16. Within these eight sites, the size, density of adults and saplings of other trees along with Betula. From the transect line, two 10×10m plots were measured, one above the transect line, one below the transect line. In the upper left corner of these plots, a 4×4m plot was also measured. Within the 10×10m plots, the species and the dbh (diameter at breast height, measured at about 1.5 above ground) of each adult tree was recorded. An adult was defined as an individual that had a dbh that was greater than 10cm. For trees with multiple trunks, the dbh of each trunk was recorded separately, noted the values of these as x+y+.K Also within the plot, dead trees were not counted. In the 4×4m plots the number of saplings of each tree sp