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Ecology Essay

Patterns of plant successional change in Gatineau Park, Old Chelsea, were studied quantitatively. The relations between different successional stages of plant communities and abiotic factors were descried. To test these, we went to the fields, and worked on two transect in groups of 4. We counted the trees and measured the diameter at breast height (dbh) for tree with a dbh value greater than 2cm. The dbh measurements (cm), percentage of fern cover and percentage of bare ground were recorded and used to perform statistical analysis.

No significant variations in the distribution of abundant tree species using chi2 analysis and percentage of fern cover using t-test analysis were observed between the compared sites. No significant variations found in the interquadrat analysis, and mean dbh of abundant tree species and percentage of bare ground between the sites compared. The results verified the stated hypothesis and were supported by literature sources. Introduction

The purpose of this study is to quantitatively describe patterns of plant successional change in old-field succession in temperate mixed forest ecosystems and to describe the relation between abiotic factors and plant communities at different successional stages.

Succession is described as predictable patterns of change over time and specifically, in ecology, as the predictable pattern of change in the species structure of an ecological community over time. There are two types of succession; primary and secondary. Primary succession refers to the successional development of plant communities that takes place on a site formerly devoid of vegetation and usually lack well developed soil.

Secondary succession refers to the successional development of plant communities that takes place when a well developed ecological community is disturbed either by natural or anthropogenic factors. Secondary successions are typically faster than primary successions since well developed soil is already present (Kaufman & Franz, 2000). Old field succession is a type of anthropogenic secondary succession that refers to the successional development of plant communities on abandoned farmland (Cramer and Hobbs, 2007).

This lab looks at an old field succession in the temperate mixed forest biome, particularly an area along the main rail of Gatineau Park Visitor Centre in Old Chelsea. This study area consists of five different sites which have been divided into transects and subdivided into quadrats. Each transect has 3 quadrats, and each site has 4 transects. There are five sites overall: site 1, site 2, site 3a, site 3b, and site 4. Each site has a different location and has had different type of disturbance. Dbh measurements (cm) of all identified tree species, percentage of plot area bare ground and percentage of area covered by ferns were recorded within the assigned quadrats. The dbh measurements were grouped into two size categories; dbh ≥ 2cm and dbh ≤ 2cm. Null hypotheses to be tested:

HO1: there is no significant statistical difference between quadrats 1 and 2 of site 3a transect 2 HO2: there is no significant statistical difference between quadrats 1 and 3 of site 3a transect 2 HO3: there is no significant statistical difference between quadrats 2 and 3 of site 3a transect 2 HO4: there is no significant statistical difference between the three most abundant species of site 3a transect 2 and site 1 transect 2 HO5: there is no significant statistical difference between the dbh value for the three most abundant species at site 3a transect 2 and site 1 transect 2 HO6: there is no significant statistical difference between the percentage of bare ground at site 3a transect 2 and site 1 transect 2 HO7: there is no significant statistical difference between the percentage of plot area covered by ferns at site 3a transect 2 and site 1 transect 2 The alternate hypotheses for each of the null hypotheses state that there is a significant difference between what is being compared. Materials & Method

Refer to “Bio 2129 Ecology Lab Manual”, “Lab # 3 – Human modification of temperate forests: Disturbance and succession”, pages 4-6. Modification: Where it says to leave the string at the transect (bottom of page 5), was modified since we were given the measuring equipment before the lab began. Results

Figure 1 (a) shows that at site 3a (transect 2), sugar maple is the most abundant tree species among tree species with dbh ≥ 2cm. (b) shows glossy buckthorn is the most abundant tree species among tree species with dbh ≤ 2cm. Table 1 show no statistical significance to the t-stat, therefore no significant variation exists among the quadrats 1+2 and 2+3 for the mean dbh (cm) of sugar maple. So we fail to reject the null hypothesis. On the other hand, quadrat 1+ 3 shows variation according to the t stat, therefore the null hypothesis for that quadrat is rejected.

Figure 2 shows that among tree species with dbh ≥ 2cm, sugar maple, iron wood, red pine are the most abundant tree species at both sites 1 (transect 2), and site 1 (transect 2). Figure 3 shows that among tree species with dbh ≤ 2cm, sugar maple, glossy buckthorn and red ash are the most abundant tree species at site 3a (transect 2). Sugar maple, iron wood, and white ash are the most abundant tree species at site 1 (transect 2). Table 4 shows no statistical significance. We fail to reject the null hypothesis. Table 5 shows no statistical significance to the t-stats and therefore there is no significant variation in the mean dbh (cm) ≥ 2 cm. We fail to reject the null hypothesis. Table 6 shows no statistical significance. We fail to reject the null hypothesis.


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