摘要：We evaluated the feasibility of using fractal geometry to measure the structural complexity innate to 11 species of temperate and tropical macrophytes. The efficacy of fractal dimension (D) as a surrogate of plant complexity was tested by using D values to predict the density of two dominant invertebrate taxa (Annelida and Odonata). Plants and invertebrates were collected from lagoons in the upper Paran River, Brazil, and from a lake in central Minnesota, USA. Fractal dimensions varied from 1.16 (SD=0.03) in Potamogeton illinoiensis to 1.68 in Najas conferta (SD=0.07) and Myriophyllum spicatum (SD=0.02). Spatial scale did not affect D values, since the results obtained for pictures taken at 25 cm 2 , 100 cm 2 and 600 cm 2 did not differ for five tropical species. Using the results of D recorded at 100 cm 2 , a positive and significant relationship between plant complexity and Annelida and Odonata densities was observed. The biological significance of the positive correlations between D and invertebrate densities and the feasibility in calculating D make this method a potential candidate for measuring plant complexities at small scales.
