Repeat burning affects species composition in degraded Cumberland Plain Woodland

Abstract

Cleared areas in Scheyville National Park, New South Wales, that formerly supported Cumberland Plain Woodland (CPW) now have a long unburnt mixed native and exotic grassland. To test whether re-introducing fire to these sites would benefit native species composition, and drive it towards that of neighbouring remnant woodland, an experiment was established in three grassy areas (grassy blocks) with prior agricultural land use, and one block in a remnant woodland. Replicate plots were established within blocks, and assigned to a repeat fire treatment, or unburnt controls. Plots in the fire treatment were burnt on all blocks in 2001, and in the grassy blocks only in 2005. Although the two fires did not result in recruitment of new native species on the grassy blocks, the successive fires had other beneficial effects. More native species were apparent in the above-ground vegetation on burnt than unburnt plots after both fires, and more summer-growing native grasses were apparent above ground and increased in abundance after the second fire. The large flush of exotic forbs that appeared after the first fire was not repeated after the second fire; many of these forbs had an obligate seeder fire response, and the short inter-fire interval may not have allowed replenishment of their seed bank. Burning did not result in recruitment of new native species in the grassy areas, and did not make the grassy areas more similar to the woodland in species composition. In the woodland, the first fire did not significantly affect species composition. Re-instating fire to degraded grassy sites will not by itself return the site to good quality CPW in the short term, but may contribute positively in the longer term through beneficial effects on natives and adverse effects on exotics.

Germinable soil seed bank of pasture, revegetation and remnant Cumberland Plain Woodland

“…The finding that the majority of exotic forbs in the seed bank of pasture and revegetated areas were annuals with the seeder fire response matches the large germination response of this group of species after a single fire on long unburnt former agricultural land at Scheyville National Park (Morris & Sanders 2021). The combination of higher seed production in seeder species compared with re‐sprouters (Clarke et al .…”

“…Only a small number of species responded positively to the fire treatment; of the four native species that did so, germination of one (Dichondra; Dichondra repens ) was also found to be stimulated by heat in the seed bank study of Hill and French (2004). Field observation of the post‐fire seedling flora in degraded CPW sites indicates that a wide range of both native and exotic species appear in burnt sites, and not in unburnt controls (Morris & Gibson‐Roy 2018; Morris & Sanders 2021). The species appearing in post‐fire field observations would include both germinants and re‐sprouters emerging from an intact and undisturbed soil profile, whereas the methodology of collecting soil and sieving it used in this study would have largely eliminated re‐sprouters and left only a thin layer of disturbed soil in the fire treatment, resulting in possible lethal effects on seeds.…”

“…A second fire three years after the first one at Scheyville did not result in another flush of annual exotic forbs. Morris and Sanders (2021) postulated that this functional group had not had sufficient time to build up a large seed bank in the inter‐fire period. Exotic annuals can build up their seed bank to pre‐fire levels with longer fire‐free intervals.…”

Smoke and Flame Identification Method for the Entire Process of Grassland Fire Based on YOLOv5m-D and Static and Dynamic Characteristics

“…In addition, due to the complex overall environment of grasslands, fires can spread in an irregular manner in all directions. Therefore, the development trend of grassland fires is usually unpredictable, and the fire is difficult to control, which brings great difficulty to subsequent firefighting work [4]. The current monitoring methods for grassland fires only include artificial, satellite remote sensing, and wireless sensors, but they all have low accuracy and cannot cover a large area.…”