Leaf anatomy and chlorophyll content of 12 woody species in contrasting light conditions in a Bornean heath forest

Abstract

This paper reports the anatomy, chlorophyll content, and some optical properties of leaves of 12 tree species in sun and shade conditions in a tropical heath forest in Brunei (northern Borneo). These plants displayed some xeromorphic leaf features, e.g., relatively low stomata density compared with lowland rain forest plants and sun leaves usually with two or more layers of palisade cells. Most species displayed substantial plasticity in leaf structure and chlorophyll concentration in response to different light conditions. Dipterocarp leaves had thinner palisade mesophyll and greater spongy to palisade thickness ratios than non-dipterocarp leaves. The chlorophyll content per unit leaf area of the species studied was within the range quoted for American tropical rainforest trees. Their chlorophyll a : chlorophyll b ratios, however, were much lower than those for forest plants in humid temperate and subtropical regions. This could be attributed to the regular soil water deficits of this forest. Despite large variation in leaf structure and chlorophyll concentration among species and within species on the two distinct conditions, their absorptance of photosynthetic active light was similar. Chlorophyll concentration per unit weight was adversely and nonlinearly related to leaf thickness for the data pooled from all species in both light conditions (R2 = 0.49, P < 0.001).Key words: chlorophyll concentration, leaf anatomy, kerangas, light acclimation, leaf plasticity, tropical heath forest.

Leaf Morphological Plasticity of Tree Species from Two Developmental Stages in Araucaria Forest

“…The palisade parenchyma thickness varied more than spongy parenchyma between the stages, as observed in the ratio spongy/palisade parenchyma. In the adult stage, two species (A. edulis and L. divaricata) showed a ratio <1, due to an expressive palisade parenchyma increment in the adult stage, mainly in L. divaricata (44%), as observed in other studies (Vogelmann et al 1996;Cao 2000;Lee et al 2000;Hanba et al 2002;Sanches et al 2010). As expected, every species showed a spongy/palisade parenchyma ratio >1 in the young stages.…”

Leaf optical properties of two liana species Canavalia parviflora Benth. and Gouania virgata Reissk in different light conditions

“…In low irradiances, the structure of thylakoid changes; increases of the length of appressed to non-appressed membranes ratio are consistent with changes of chlorophyll a/b ratio due to relative composition of different pigments that compose both membranes (Anderson et al 1988). Indeed, most species grown under low irradiances present a decrease in chlorophyll a/b ratio (Lee 1988, Cao 2000, Evans & Poorter 2001). However, lianas were unusual with this trait; because, they generally exhibited enhancement of chlorophyll a, b and total (mass basis) under 10% and 1.5% PFD when compared with plants growing in full sun.…”

“…Although some studies stated that no pronounced differences were observed in leaf optical properties between sun and shade species, or between exposed and shaded leaves of a particular species (Lee & Graham 1986, Knapp & Carter 1998, Cao 2000, other works showed that, greater adjustments on leaf characteristics occurred, in shade tolerant species, which might increase light absorptance efficiency under limited light (Poorter et al 1995, Souza & Válio 2003b.…”

Comparação da morfologia foliar de espécies arbóreas de três estádios sucessionais distintos de floresta ombrófila densa (Floresta Atlântica) no Sul do Brasil

“…Vários estudos mostram que as plantas que crescem em solos arenosos, com baixa retenção de água e de nutrientes, possuem folhas com características xeromórficas, mesmo que pertençam a ambientes de florestas tropicais (Turner et al 1995, Medina et al 1990, Cao 2000. Algumas dessas formações vegetais, como por exemplo restinga e campinarana, possuem plantas com folhas espessas, textura coriácea, cutícula, hipoderme, parênquima paliçádico e esclerênquima bem desenvolvidos.…”