Aerial Bud Bank and Structural Changes of Woody Species from Argentine Chaco in Response to Disturbances

The objectives of this work were to estimate the ABB (Aerial Bud Bank) size in small individuals of four native woody species and its relationship with structural changes of plants after disturbances. Study area was located in dry forests from Western Chaco region, Argentina. Three tree species: Aspidosperma quebracho-blanco (Apocynaceae), Schinopsis lorentzii (Anacardiaceae), Sarcomphalus mistol (Rhamnaceae) and a shrubby species, Schinus fasciculatus (Anacardiaceae) were selected for this study. Twenty (20) juvenile individuals (below 6 cm diameter) were randomly sampled from each species and plant height (m), diameter (cm) and plant cover (%) were recorded. ABB was estimated by counting of all growth modules (shoots/branches and thorns) identified in a 1 m length segment of main stem. Results of an ANOVA (Analysis of Variance) showed significant effects of species (p < 0.0001), number of shoots/branches (p < 0.05) and number of thorns (p < 0.05) on ABB. Schinopsis lorentzii and S. fasciculatus were categorized as high ABB species, S. mistol and A. quebracho-blanco as medium and low ABB species, respectively. ABB size diminished in all species studied when plant height (p = 0.0006) and plant cover (p < 0.0001) increased which could be related to most allocation of resources towards height growth and elongation of growth modules rather than to the differentiation of new shoots. A correspondence analysis of ABB size, growth habit, number of sprouts/resprouts, presence of thorns in studied species growing in forests with different disturbances history, showed that perturbations increased number of resprouts, shrubby growth habit but spinescence was only trait with significant association with disturbed areas. These results enhance the knowledge of resprouting pattern after disturbances of native woody species and open new research lines for futures studies.