Alves-Silva Estevão, Del-Claro Kleber
Institute of Biology, Federal University of Uberlândia, Ceará Str. 2D building, Umuarama Campus, Zip-code 38400-902, P.O. box 593, Uberlândia, Minas Gerais, Brazil.
Naturwissenschaften. 2013 Jun;100(6):525-32. doi: 10.1007/s00114-013-1048-z. Epub 2013 Apr 28.
Fires in the Cerrado savanna are a severe form of disturbance, but some species are capable of resprouting afterwards. It is unknown, however, how and whether post-fire resprouting represents a stressful condition to plants and how their rapid re-growth influences both the production of biochemical compounds, and interactions with mutualistic ants. In this study, we examined the influence of post-fire resprouting on biotic interactions (ant-plant-herbivore relationships) and on plant stress. The study was performed on two groups of the extrafloral nectaried shrub Banisteriopsis campestris (Malpighiaceae); one group was recovering from fire while the other acted as control. With respect to biotic interactions, we examined whether resprouting influenced extrafloral nectar concentration (milligrams per microliter), the abundance of the ant Camponotus crassus and leaf herbivory rates. Plant stress was assessed via fluctuating asymmetry (FA) analysis, which refers to deviations from perfect symmetry in bilaterally symmetrical traits (e.g., leaves) and indicates whether species are under stress. Results revealed that FA, sugar concentration, and ant abundance were 51.7 %, 35.7 % and 21.7 % higher in resprouting plants. Furthermore, C. crassus was significantly associated with low herbivory rates, but only in resprouting plants. This study showed that post-fire resprouting induced high levels of plant stress and influenced extrafloral nectar quality and ant-herbivore relationships in B. campestris. Therefore, despite being a stressful condition to the plant, post-fire resprouting individuals had concentrated extrafloral nectar and sustained more ants, thus strengthening the outcomes of ant-plant mutualism.
塞拉多稀树草原的火灾是一种严重的干扰形式，但有些物种能够在火灾后重新发芽。然而，火灾后重新发芽对植物来说如何以及是否代表一种压力状态，以及它们的快速重新生长如何影响生化化合物的产生以及与互利蚂蚁的相互作用，这些都尚不清楚。在本研究中，我们研究了火灾后重新发芽对生物相互作用（蚂蚁 - 植物 - 食草动物关系）和植物压力的影响。该研究在两组具花外蜜腺的灌木巴西远志（金虎尾科）上进行；一组正在从火灾中恢复，另一组作为对照。关于生物相互作用，我们研究了重新发芽是否影响花外蜜浓度（每微升毫克数）、蚂蚁粗壮弓背蚁的数量以及叶片食草率。通过波动不对称性（FA）分析评估植物压力，波动不对称性是指双侧对称性状（如叶子）偏离完美对称的程度，并表明物种是否处于压力之下。结果显示，重新发芽的植物中FA、糖浓度和蚂蚁数量分别高出51.7%、35.7%和21.7%。此外，粗壮弓背蚁与低食草率显著相关，但仅在重新发芽的植物中如此。本研究表明，火灾后重新发芽会引发高水平的植物压力，并影响巴西远志的花外蜜质量以及蚂蚁 - 食草动物关系。因此，尽管火灾后重新发芽对植物来说是一种压力状态，但重新发芽的个体具有浓缩的花外蜜并维持了更多的蚂蚁，从而加强了蚂蚁 - 植物共生关系的结果。
