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Analyzing Models of Community Ecology Using Tree Distributions

As a biologist, Christina loves exploring the sciences and applying them to everyday life.

Community Ecology Models: Gleason vs Clements

For each species, a distribution map was recorded. If an online distribution map couldn’t be found, but a distribution data was, a distribution map was that data was combined with the MapChart tool. A general description, including height, shape, and tolerance was also collected.

If Gleason’s community model is more accurate, each species’ distribution will be distinctly unique due to its unique tolerance. If Clements’ model of community is more accurate, then the distribution of each species will be primarily seen in different areas with similar climates. Due to latitude determining the amount of solar radiation at a location, relationships between latitude and distribution serve as evidence of the connection between climate and distribution.

Map of Maximum and Minimum Tree Latitudes

Data from Tree Distribution Maps was used to identify the maximum and minimum latitude in each species' distribution.

Data from Tree Distribution Maps was used to identify the maximum and minimum latitude in each species' distribution.

Distribution Patterns

Generally, many of the species’ distribution is centered either in the southern United States, like Quercus stellata and Quercus pagoda, or the northeastern United states, like Acer saccharum and Populus grandidentata. This is likely due to the drastic climate difference between the regions. Ptelea trifoliata is an exception to the climate region pattern, spanning from Southeast Canada to the Southern United States, likely due to its high tolerance in soil moisture and light. To distributions spanning to the west (like Q. pagoda and P.trifoliata ) the Great Plains appears to be a frequent border, which is likely due to all the selected species being trees. These observations point to Clement’s model as the best to describe the distribution and community organization of the group.

Distribution and Size

Size doesn’t appear to affect distribution. The three smallest species- F. Alnus, P. trifoliata, C. Speciosa, have widely different distributions; C. Speciosa having the smallest distribution while P.Trioliata has the largest. In contrast, the two tallest species- Quercus pagoda and Betula nigra- have distribution centered in southeastern United States. Intriguingly, the distribution of these species counters Hong Qian’s paper "A latitudinal gradient in large-scale beta diversity for vascular plants in North America, which analyzes latitude gradient and concludes increasing latitude decreases beta diversity. However, this is likely due each species being selected for its presence in Indiana, and not an indication of a global pattern. Qian’s paper explains that beta diversity with respect to geographical distance serves as evidence of dispersal limitation, further supporting the theory that many species are not distributed in the Western United States due to the Great Plains serving as an obstruction in tree dispersion.

Salix babylonica is an exception to many patterns in the other tree distributions, for example, having areas of distribution that are not completely contiguous. This is potentially due to the species being originally from Asia, not North America, and spread throughout the continent due to human interaction.

For Further Analysis

To further analyze the distributions of the group, populations throughout the distributions would be useful. In the distribution maps, where the species can live is quickly observed, but whether the population in a certain area is high or low cannot be determined. This provides difficulty in observing the exact limits a species can exist in and which regions in the distribution have a higher population. This ambiguousness in how large a population had to be to be recorded in the distribution map created difficulty in the distribution maps made with MapChart.

More detailed information about the role of each species in its ecosystem would also be helpful as this would make patterns that are not distribution-based easier to observe. For example, having more characteristics of each species available could allow for trait-based ecology to be used, as explained in Wilkes’ paper. Trait based ecology can used to analyze biodiversity responses to environmental change, providing another tool to study the relationship between distribution and climate, in addition to other combinations of factors.

Works Cited

Frangula alnus (alder buckthorn). (n.d.). Retrieved October 26, 2020, from

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Fragula Alnus EDDMapS Distribution [Map]. (2020, May 31). In Glossy Buckthorn Frangula Alnus Mill. Retrieved October 26, 2020, from

Native range of Acer saccharum [Map]. (2018). In Acer Saccharum. Retrieved October 26, 2020, from

Natural range of Catalpa speciosa [Map]. (n.d.). In Catalpa Speciosa. Retrieved October 26, 2020, from

North America distribution: Catalpa speciose [Map]. (n.d.). In Catalpa Speciosa. Retrieved October 26, 2020, from

Plant Database. (2015, October 13). Retrieved October 25, 2020, from

Post Oak. (n.d.). Retrieved October 26, 2020, from

Quercus pagoda. (n.d.). Retrieved October 26, 2020, from

Qian, H., & Ricklefs, R. E. (2007). A latitudinal gradient in large-scale beta diversity for vascular plants in North America. Ecology Letters, 10(8), 737-744. doi:10.1111/j.1461-0248.2007.01066.x

SPECIES: Betula nigra. (n.d.). Retrieved October 26, 2020, from

Weeping willow (Salix babylonica) - EDDMapS State Distribution [Map]. (n.d.). Retrieved October 25, 2020, from

Wilkes, M. A., Edwards, F., Jones, J. I., Murphy, J. F., England, J., Friberg, N., . . . Brown, L. E. (2020). Trait‐based ecology at large scales: Assessing functional trait correlations, phylogenetic constraints and spatial variability using open data. Global Change Biology. doi:10.1111/gcb.15344

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

© 2021 Christina Garvis

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