Anatomical and morphological analysis of legume trees in relation to fire

Abstract

The influence of fire on ecosystems and the adaptation of plants as a response to fire is still unclear. Cerrado is one of the Brazilian ecosystems prone to periodic fires; it is a complex, heterogeneous system with well-adapted flora. This biome is composed of several families of plants, including the Fabaceae family (legumes). The Fabaceae shows adaptations to fire, such as their underground systems, which play a crucial role in maintaining diversity in environments like Cerrado. The purpose of this project is to provide an anatomical and morphological description of the fire-related attributes in the underground systems of ten species of the Fabaceae family to identify which species tolerate fire and which strategies are involved in their permanence after disturbances. Fire experiments will be carried out in juvenile individuals located in the Teaching, Research and Extension Farm of UNESP, Ilha Solteira-SP. Five individuals of each species will be buried in field within 1m of each other, in three patches of experimental burn (17 x 17m). The bag containing each plant will be kept underground and the block of substrate will be positioned at ground level to expose the aboveground segment of the seedlings/young plants. After fire, plants will be removed and followed-up in a vegetation house for one year to verify their survival and/or resprouting capacity after the disturbance. After follow-up, the following items will be measured: (a) total length of aboveground and underground systems; (b) number of leaves and stems; (c) biomass of aboveground and underground systems after oven-drying at 60°C for two days. Same-aged, unburnt seedlings/young plants cultivated in the same conditions (controls) will be measured after one year. Follow-up before and after fire will be carried out by counting aboveground structures (leaves and stems) and underground structures (buds). Stems and roots will be fixed in FAA50 and preserved in ethanol 70% for anatomical studies. Cross-sectional and longitudinal cuts may be obtained via free-hand sectioning with shaving blades or sliding microtomes. Cross sections will undergo proper routine treatment and clarification/dying, and will later be placed on permanent slides. Part of the material will be dehydrated, added to historesin, sectioned in a rotating microtome and stained with toluidine blue. Starch and other carbohydrate reserves will complete the morphoanatomical assessment of underground structures. (AU)