TITLE:
Assessing Spatial Patterns of Plant Communities at Varying Stages of Succession
AUTHORS:
Kevin Aagaard, Gregg Hartvigsen
KEYWORDS:
Ecological Succession, Fractal Dimension, Vegetational Chronosequence, Crown Shape, Statistical Modeling
JOURNAL NAME:
Applied Mathematics,
Vol.5 No.12,
June
26,
2014
ABSTRACT: There
is a well known connection between the structural complexity of vegetative
stands and ecosystem properties. Developing methods to quantify this structural
complexity is an important goal for ecologists. We present an efficient and
easily implemented field technique for calculating the shape of forest
canopies, and the shape of forest stands as succession occurs, using fractal
geometry. Fractal geometry can be used to describe complex, non-Euclidean
objects that are common in natural systems. We tested the use of this tool in
22 vegetative and forested plots in Western New York State, USA. We found an
asymptotic relationship for fractal dimension (D) as a function of basal area (BA;
r2= 0.68). In a randomization test to investigate the robustness of D to different tree canopy shapes, we
found that D was sensitive to canopy
shape switching, suggesting that the method is able to differentiate among
similar forests comprised of species having different shaped crowns. We
conclude that the shape is conserved in vegetative areas as they progress from
one stage of succession to the next (range of mean D: 2.56 to 2.68 across stages). Furthermore, we conclude that the
shape filling properties—i.e.,
distribution of trunks and limbs in a forested area, measured as mean
distance—are also conserved across vegetational chronosequences (F = 1.3189, df
= 8, 3, p = 0.3341).