Environmental control of seed dormancy and germination of Mimosa calodendron (Fabaceae): implications for ecological restoration of a highly threatened environment

Abstract

Rupestrian grasslands over ironstone outcrop, locally named canga, are montane ecosystems with restricted distribution known to harbor an unusually a large number of endemic plant species. These communities are highly threatened due to their high sensitivity to habitat conversions and extreme low resilience derived from anthropogenic pressure. Ecological restoration attempts on degraded rupestrian grassland areas have not yet been successful. Mimosa calodendron is an endemic canga shrub thought to play a facilitator role and, therefore, may enhance seedling recruitment in degraded areas. Since dormancy and slow germination are key factors of the biology of seeds and may hamper their use in ecological restoration, this study aimed to investigate the environmental control of seed dormancy and germination of M. calodendron seeds. We tested the effect of mechanical scarification, light and different incubation temperatures on seed germination. The effect of scarification on water uptake by seeds was also measured. M. calodendron seeds have physical dormancy and scarification was an effective treatment to promote high and rapid germination. Heat treatment also increased germination percentage of nonscarified seeds, but was less efficient than scarification. Once water uptake occurred, germination took place under a broad thermal gradient, regardless of light condition. Therefore, the germination profile of M. calodendron seems to be suitable for uncomplicated use in restoration projects, requiring only a pretreatment for dormancy release.

Biodiversity hotspots and Ocbil theory

“…Given the restricted geographic distribution of most plant species, the few conservation units created to protect the fragile campo rupestre are insufficient to achieve the 1992 Convention on Biological Diversity's and the derivative Global Strategy for Plant Conservation's goals. The Campo rupestre provides many important benefits to society, such as water provision, landscape for extreme sports, camping and adventure tourism, and efforts to overcome the barriers for ecological restoration are urgently needed (Le Stradic et al 2014a, b;Dayrell et al 2015).…”

“…Shearer et al (2012a) x Threatened flora susceptibility to Phytophthora cinnamomi. Shearer et al (2012b) x Modeling disturbance-based native invasive species control Allocasuarina huegeliana Shackleford et al (2013) x x All weeds Arianoutsou et al (2013) x glob Tree invasions into treeless areas Rundel et al (2014) x Grassland flora Le Stradic (2012) x Grassland flora Fernandes et al (2014) AtRf Inselberg floras de Paula et al (2015) glob Weeds of nutrient-poor soils Funk (2013) 9 (d) Minimising human disturbance x x Whole floras Arianoutsou et al (2013) x Sunbird pollinator limitation in the endangered geophyte Brunsvigia litoralis (Amaryllidaceae) Geerts and Pauw (2012) x Grassland flora Le Stradic et al (2014a) x Grassland flora Fernandes et al (2014) x Mimosa calodendron (Fabaceae) Dayrell et al (2015) 9 (e) Repair and restoration of OCBILS-an infant science and practice…”

Influence of pre-germination treatments on germination seed in Melanoxylon brauna Schott

“…Although mechanical scarification has been indicated as a good method to overcome seed dormancy in many Leguminosae species (Guedes et al, 2011;Dayrell et al, 2015), in this study it caused a decrease in brauna speed germination rate and percentage. Based on the results, it can be assumed that the seeds of Brauna do not have seed dormancy.…”

Influence of nutrient management on growth and nutrient use efficiency of two plant species for mineland revegetation

“…Due to iron ore mining, canga soils and oxisols are currently furthermore associated with a variety of man‐made substrates resulting from mining activities. Mineland rehabilitation activities are therefore not restricted to canga soils or oxisols, but include man‐made habitats such as pits and piles as well (Castro et al ; Dayrell et al ). Therefore, we selected two natural substrates (oxisols and canga soils) and iron mining waste to carry out our fertilization and nutrient omission experiments.…”