Allometry of some woody plant species in a Brazilian savanna after two years of a dry season fire

Abstract

Studies of allometry are important in explaining effects of fire and herbivory, for estimating biomass in forests, and so on. There has been extensive research on plant allometry in temperate and tropical forests, showing that plant architecture often adjusts to the elastic similarity model, but not in Brazilian savannas (cerrado). We studied allometry of Dalbergia miscolobium, Diospyros hispida, Erythroxylum suberosum, Miconia albicans, M. ligustroides, Schefflera vinosa, and Xylopia aromatica in a cerrado sensu stricto area that was affected by a fire in August 2006. We expected that the study species would not adjust to any of the allometric models considered common for forest species ("constant stress", "elastic similarity", and "geometric growth"), and that there would be differences in allometry in burnt and unburnt patches. We sampled two species in 60 5 × 5 m contiguous plots placed in three transects, and five species in 100 5 × 5 m contiguous plots placed in five transects, where we measured the diameters at soil level (DSL) and the heights of all shoots. We used standardized major axis regressions on log-transformed data. The regression slope between the height and DSL was higher than 1.0 (p< 0.05) for four species, showing a greater height than would be expected under geometric growth, not predicted by theoretical models. We found significant differences (p < 0.05) in regression slopes and/or correlation coefficients between burnt and unburnt plots for five species, indicating that fire may influence plant allometry in the Brazilian cerrado, and that such a response is highly variable between species.

Effects of an accidental dry-season fire on the reproductive phenology of two Neotropical savanna shrubs

“…Thus, at the time of the study, burnt stems of M. albicans were in general smaller than burnt stems of S. vinosa at the study site (Dodonov et al, 2011), probably due to a slower resprout growth. The smaller resprout size of M. albicans may explain the smaller intensity of the reproductive phenophases of the burnt individuals as well as the failure of most of the burnt individuals to produce ripe fruits during the study period.…”

“…Schefflera vinosa (Araliaceae) may be either a shrub or a tree (Durigan et al, 2004), with thin bark, that reaches a maximum height of 4 m at the study site (Dodonov et al, 2011). This species is also evergreen (Lucena et al, 2015) and occurs in different cerrado physiognomes (Soares et al, 2006).…”

“…Miconia albicans (Melastomataceae) is a shrub or small tree with multiple stems that grows up to approximately 3.5 m tall at the study site (Dodonov et al, 2011). It is common in savanna and dry forest (cerradão) vegetation in Brazil (Oliveira and Batalha, 2005;Assunção and Felfili, 2004).…”

“…Fires may be spatially heterogeneous, resulting in a mosaic of burnt and unburnt patches within an area (Wrobleski and Kauffman, 2003;Werner, 2010;Dodonov et al, 2014). Spatial variation in fire incidence may lead to spatial variation in plant characteristics such as plant allometry (Dodonov et al, 2011), size structure and distribution of resprouts (Silva et al, 2009;Dodonov et al, 2014), seedbank (Xavier, 2011), and plant phenology (Lucena et al, 2015).…”

Germination and allometry of the native palm tree Euterpe edulis compared to the introduced E. oleracea and their hybrids in Atlantic rainforest

“…Allometric relationships between stem height and diameter usually follow one of the three different models: the geometric, elastic, and stress similarity, characterized by their slope values (respectively 1.0, 0.66, and 0.5) (McMahon and Kronauer, 1976;Dodonov et al, 2011). We calculated Pearson's correlation coefficient and performed a standardized major axis regression (SMA) (Warton et al, 2006) between log H and log D for the pooled data and for each ontogenetic stage separately, for the two species and their hybrids.…”