Background information and definitions
In many cases after wildfire, burned trees are removed. The main reasons are that they may provide good wood fuel that increases the intensity of future wildfires. Removing the burned trees is often done by heavy machinery which compresses the soil and may affect the germination and regrowth of plants. Removing the dead organic matter may affect soil mineral content and plant composition. Removing burned trees may also influence the spatial pattern of germination and seedling establishment and change the forest structure and composition.
Supporting evidence from individual studies
A replicated, controlled study in 1989-1993 in Aleppo pine Pinus halepensis forest in Israel (Ne'eman, Lahav & Izhaki 1995) found that clearing burned trees increased plant species richness. The number of species was higher in cleared than untreated plots (cleared: 196; twigs remaining: 192; untreated: 185/0.49 ha plot). Data were collected in 1993 in five plots (0.49 ha) of each of three treatments: cleared (burned trees cut down, trunks and smaller twigs removed), twigs (smaller twigs left) and control (untreated). Plots were all in an area totally burnt down in September 1989. Treatments were carried out in September-November 1990.Study and other actions tested
A replicated, controlled study in 1991-1994 in maritime pine Pinus pinaster woodland in Spain (Pérez & Moreno 1998) found that removing burned trees increased the cover and species richness of legumes but not of all herbaceous plants, or of the dominant shrub gum rockrose Cistus ladanifer. Legume cover (removed: 7-29%; control: 3-26%) and species richness (removed: 3-6; control: 2-5/plot) were higher in removal plots. There were no differences between treatments for: total herbaceous cover (removed: 8-47%; control: 3-49%), species richness (removed: 5-16; control: 6-14), gum rockrose cover (removed: 8%-25%; control: 10%-46%) and gum rockrose density (removed: 1-5; control: 5-11/m2). Data were collected in 12 removal plots (burned trees removed after fire) and 12 control plots (trees not removed, 5 × 5 m). Treatments were three years after the entire study site was burned by wildfire fire in 1991.Study and other actions tested