Abstract
Accumulation of Aluminium (Al) at concentrations far above 1,000 mg kg-1 in aboveground plant tissues of Arbor aluminosa (Symplocos) species is the main reason why traditional Indonesian weavers rely on their leaves and bark as a mordant for dyeing textile. Recently, Symplocos species have become a flagship species for the conservation efforts of weaving communities due to their traditionally non-sustainable sampling and increasing demand for Symplocos plant material. Here we investigated Symplocos odoratissima, S. ophirensis and S. ambangensis at three montane rainforest sites in Central Sulawesi to measure Al levels in different tissues and organs. The highest Al concentrations were found in old leaves (24,180 ± 7,236 mg·kg-1 dry weight, mean ± SD), while young leaves had significantly lower Al levels (20,708 ± 7,025 mg·kg-1). Al accumulation was also lower in bark and wood tissue of the trunk (17,231 ± 8,356 mg·kg-1 and 5,181 ± 2,032 mg·kg-1, respectively). Two Al excluding species (Syzigium sp. and Lithocarpus sp.) contained only high Al levels in their roots. Moreover, no difference was found in soil pH (4.7 ± 0.61) and nutrient (K, Ca, Fe, Mg) availability at different soil levels and within or outside the crown of Symplocos trees, except for the upper soil layer. Furthermore, a positive and significant correlation between Al and Ca concentrations was found at the whole plant level for Symplocos, and at the leaf level for S. ophirensis and S. ambangensis, suggesting a potential role of Ca in Al uptake and/or detoxification within the plant. Our results provide evidence for strong Al accumulation in Symplocos species and illustrate that both Al accumulation and exclusion represent two co-occurring strategies of montane rainforest plants for dealing with Al toxicity. Indonesian weavers should be encouraged to harvest old leaves, which have the most efficient mordant capacity due to high Al concentrations.
Highlights
One of the first observations of plants containing high concentrations of alum may have been made by Georg Eberhard Rumphius, when he described the Arbor aluminosa (“aluminium tree”) [1]
Al accumulation is found in a total of ca. 45 angiosperm families [5,6,13], the dyeing protocol of Indonesian weavers is based on the exclusive use of local species [12]
Our data support the old, pre-Linnean name given by Rumphius (Arbor aluminosa) to these Al accumulating trees, the values measured are not as high as the 72,240 mgÁkg-1 recorded for S. spicata [4]
Summary
One of the first observations of plants containing high concentrations of alum may have been made by Georg Eberhard Rumphius, when he described the Arbor aluminosa (“aluminium tree”) [1]. This tree was later identified as a species of Symplocos (Symplocaceae) [2], which includes ca. Aluminium (Al) had not been discovered yet during the time of Rumphius, the notion of high levels of alum in plants was based on the traditional use of plant material as a mordant for dyeing textile, a process that apparently involved alum in India and South-East Asia [1,3,4,5,6,7]. Modern chemical analyses of Al concentrations in Symplocos plant tissue, are limited and include only few tropical species from their natural environment [14,15,16]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
