CONGRESO
LXV CONGRESSO NACIONAL DE BOTÂNICA
BOTÁNICA
XXXIV ERBOT - Encontro Regional de Botânicos MG, BA, ES 18 A 24 DE OUTUBRO DE 2014 - SALVADOR - BAHIA - BRASIL
Latinoamericano de
Botânica na América Latina: conhecimento, interação e difusão
XYLEM CONDUCTIVITY IS THE MAIN KEY FOR TREE
MORTALITY AFTER FIRE
AUTOR(ES):Amanda Thaciane dos Santos;Amanda Cristiane
Rodrigues;William Arthur Hoffmann;Amauri Alves de Alvarenga; João Paulo
Rodrigues Alves Delfino Barbosa;
INSTITUIÇÃO:
Instituto Federal de Minas Gerais – Campus Bambuí
Universidade Federal de Lavras
North Carolina State University - Raleigh - NC
The loss of phloem tissue has been considered the cause for tree mortality
after fire, mainly because of girdle of the trunk. Although, the speed trees
die after fire is not compatible with speed girdle cause tree mortality. Based
in observations of leaf desiccation after fire, we tested the hypothesis that
xylem loss of conductivity is the main key for tree mortality after fire. We
used as samples to our study, branches of Liriodendron tulipifera, submitted
to girdle, heated and control branches, with leaves and without leaves. The
heated treatment was based in applying a temperature of 75ºC using a 12V
battery and a datalogger to monitor the temperature inside the xylem. After
the temperature was applied, the xylem conductivity was measured using a
dye solution of methylene blue. We observed no conductivity after a week in
the heat treatment, in both branches, with and without leaves, when all the
heated branches presented signs of death, as desiccated leaves. We also
evaluated vulnerability curves in three conditions: combination of heat and
pressure together, heat first and after pressure and the control with only a
pressure gradient. The pressures used were 0, -0.5, -1.0, -2.0, -3.0 and
-4.0MPa. Our data suggest that the cause of the mortality after high
temperature events is the formation of embolisms. The vulnerability curves,
where the combination of temperature and low pressure potential were the
most dangerous when compared with the high temperature follow by the
gradient of pressure potential, suggesting that in a field with low water
potential soil conditions trees will probably be more susceptible to the
process of mortality. (CAPES, FAPEMIG, UFLA, IFMG)