Determinants of some leaf characteristics of Australian mangroves

Abstract

Leaf characteristics reflecting the size, lifespan (longevity), moisture content (degree of succulence) and complexity of structure of 20 mangrove species were studied over several years at 13 locations along the tropical and subtropical Australian coast. These characteristics were found to fall generally within the ranges of those for woody species from other ecosystems. With the exception of one species, it was found that leaf longevity was related inversely to leaf moisture content, increasing from nearly 6 months in more succulent species to over 2 years in less succulent species. This suggested that more succulent leaves are less complex in their structure because they have less well-developed ability to compartmentalize salt. There was a tendency also for leaf longevity to increase in species with larger leaves. These findings were consistent with the general view for land plants that leaf longevity is greater in species that have developed tolerance to environmental stress, salt particularly in the case of mangroves. Leaf tissue in such species is more robust or complex and requires greater metabolic resources in its construction; the plant is then advantaged by retaining the tissue for longer periods. Classification of the species considered here, based on their leaf longevity, moisture content and complexity, identified phylogenetically related species groupings that reflected these leaf longevity effects.

Functional Traits of Terrestrial Plants in the Intertidal: A Review on Mangrove Trees

“…The spectrum of values of major true mangroves ranges from 4 cm 2 (Lumnitzera racemosa) to ca. 70 cm 2 for some Rhizophoraceae (Rhizophora mucronata, Rhizophora apiculata, and Rhizophora lamarckii ;Ball, 1988;Saenger and West, 2016). Interestingly, another genus of Rhizophoraceae, Ceriops, represents the lower end of the spectrum (8-12 cm 2 in Ceriops tagal : Ball, 1988;Okello, 2014; 12 cm 2 in Ceriops australis: Saenger and West, 2016).…”

“…70 cm 2 for some Rhizophoraceae (Rhizophora mucronata, Rhizophora apiculata, and Rhizophora lamarckii ;Ball, 1988;Saenger and West, 2016). Interestingly, another genus of Rhizophoraceae, Ceriops, represents the lower end of the spectrum (8-12 cm 2 in Ceriops tagal : Ball, 1988;Okello, 2014; 12 cm 2 in Ceriops australis: Saenger and West, 2016). In general, the leaf area of Rhizophoraceae decreases along the order Rhizophora > Bruguiera > Kandelia > Ceriops.…”

“…Saenger and West (2016) identified a trend in leaf lifespan, leaf complexity, and leaf water content in mangroves where longer-lived leaves had a more complex structure and a tendency toward lower water content (<60%). Along this continuum, they clustered three groups of true mangroves: (1) shortlived succulent leaves (e.g., Sonneratia alba), (2) long-lived leaves with low water content (e.g., Ceriops tagal), and (3) leaves with intermediate water content and a large range of lifespans (Rhizophoraceae; e.g., Bruguiera exaristata, Bruguiera gymnorhiza, Rhizophora apiculata, Rhizophora mucronata, and Rhizophora stylosa) (Saenger and West, 2016). Our re-analysis of a larger dataset largely corroborates this pattern (Fig.…”

“…They do, however, store water in their well-developed, large-celled hypodermis and palisade mesophyll tissues (Saenger, 1982). More succulent leaves are less complex in their structure because they have a less well-developed ability to compartmentalize salt (Saenger and West, 2016), a capability that is essential for many mangrove species.…”

Do increasing respiratory costs explain the decline with age of forest growth rate?

“…Griffin (1994) summarized a number of studies of leaf construction costs that found light and water availability affecting them. Saenger and West (2016) found leaf construction costs in a number of species of Australian mangroves tending to be higher the more complex their anatomical structure. Niinemets (1999a) found increased construction costs with increases of leaf mass area due to increased water stress higher in the canopy of temperate hardwood forests in Estonia.…”