Flood tolerance in two tree species that inhabit both the Amazonian floodplain and the dry Cerrado savanna of Brazil

Abstract

Comparing plants of the same species thriving in flooded and non-flooded ecosystems helps to clarify the interplay between natural selection, phenotypic plasticity and stress adaptation. We focussed on responses of seeds and seedlings of Genipa americana and Guazuma ulmifolia to substrate waterlogging or total submergence. Both species are commonly found in floodplain forests of Central Amazonia and in seasonally dry savannas of Central Brazil (Cerrado). Although seeds of Amazonian and Cerrado G. americana were similar in size, the germination percentage of Cerrado seeds was decreased by submergence (3 cm water) and increased in Amazonian seeds. The seeds of Amazonian G. ulmifolia were heavier than Cerrado seeds, but germination of both types was unaffected by submergence. Three-month-old Amazonian and Cerrado seedlings of both species survived 30 days of waterlogging or submersion despite suffering significant inhibition in biomass especially if submerged. Shoot elongation was also arrested. Submersion triggered chlorosis and leaf abscission in Amazonian and Cerrado G. ulmifolia while waterlogging did so only in Cerrado seedlings. During 30 days of re-exposure to non-flooded conditions, G. ulmifolia plants that lost their leaves produced a replacement flush. However, they attained only half the plant dry mass of non-flooded plants. Both submerged and waterlogged G. americana retained their leaves. Consequently, plant dry mass after 30 days recovery was less depressed by these stresses than in G. ulmifolia. Small amounts of cortical aerenchyma were found in roots 2 cm from the tip of well-drained plants. The amount was increased by flooding. Waterlogging but not submergence promoted hypertrophy of lenticels at the stem base of both species and adventitious rooting in G. ulmifolia. Despite some loss of performance in dryland plants, flood tolerance traits were present in wetland and dryland populations of both species. They are part of an overall stress-response potential that permits flexible acclimation to locally flooded conditions.

Levantamento Florístico da Área de Proteção Ambiental (APA) da Lagoa da Maraponga, Fortaleza, Ceará, Brasil

“…No tocante ao hábito arbóreo da família Malvaceae, somente a espécie Guazuma ulmifolia Lam foi registrada na área de estudo, sendo que a espécie supracitada é conhecida por tolerar ambientes alagados como as Florestas de Várzea da Amazônia e os ecossistemas drenados do Cerrado (Pires et al, 2018). Neste mesmo sentido, Gerber et al (2020) atestaram que a espécie Guazuma ulmifolia Lam tem potencial para ser utilizada como sombreadora para o preenchimento do dossel, colaborando assim com projetos que se destinam a restauração florestal.…”

Cumulative Impacts of Land Cover Change and Dams on the Land–Water Interface of the Tocantins River

“…The installation of dams led to an increase in the total amount of riparian area of the Tocantins River through the creation of reservoirs. However, as these new riparian zones have been pushed far from the original free-flowing river and are bordering lentic reservoirs, they are dominated by vegetation that may not be well-adapted to periodic flooding (de Oliveira et al, 2015;Pires et al, 2018). Development of riparian forest with species composition adapted to periodic flooding along reservoir margins may take decades or longer, or may never happen, due to the changed hydrology of the lentic environment compared to the lotic (Nilsson et al, 1997).…”

Sensitivity of seed germination to water stress in high‐altitude populations of a threatened palm species

“…2017; Pires et al . 2018). However, very few studies have been conducted on Atlantic Rainforest species (Kolb & Joly 2010; Braz et al .…”

“…In contrast, seed viability may be facilitated by a strategy to escape floods, as when seed germination is resumed after the flood is over (Pires et al . 2018).…”

“…Seeds of different species may sink or float during flood events, which results in distinct germination capacity. In contrast, seed viability may be facilitated by a strategy to escape floods, as when seed germination is resumed after the flood is over (Pires et al 2018).…”