Chemical and Mechanical Changes during Leaf Expansion of Four Woody Species of a Dry Restinga Woodland

Abstract

Young leaves are preferential targets for herbivores, and plants have developed different strategies to protect them. This study aimed to evaluate different leaf attributes of presumed relevance in protection against herbivory in four woody species (Erythroxylum argentinum, Lithrea brasiliensis, Myrciaria cuspidata, and Myrsine umbellata), growing in a dry restinga woodland in southern Brazil. Evaluation of leaf parameters was made through single-point sampling of leaves (leaf mass per area and leaf contents of nitrogen, carbon, and pigments) at three developmental stages and through time-course sampling of expanding leaves (area and strength). Leaves of M. umbellata showed the highest leaf mass per area (LMA), the largest area, and the longest expansion period. On the other extreme, Myrc. cuspidata had the smallest LMA and leaf size, and the shortest expansion period. Similarly to L. brasiliensis, it displayed red young leaves. None of the species showed delayed-greening, which might be related to the high-irradiance growth conditions. Nitrogen contents reduced with leaf maturity and reached the highest values in the young leaves of E. argentinum and Myrc. cuspidata and the lowest in M. umbellata. Each species seems to present a different set of protective attributes during leaf expansion. Myrciaria cuspidata appears to rely mostly on chemical defences to protect its soft leaves, and anthocyanins might play this role at leaf youth, while M. umbellata seems to invest more on mechanical defences, even at early stages of leaf growth, as well as on a low allocation of nitrogen to the leaves. The other species display intermediate characteristics.

Key words

Leaf defences - coastal forests - leaf nitrogen - leaf mass per area - anthocyanins - leaf strength - penetrometer.

References

• 1 Archetti M.. The origin of autumn colors by coevolution.  Journal of Theoretical Biology. (2000);  205 625-630
• 2 Backes P., Irgang B.. Árvores do Sul - Guia de Identificação e Interesse Ecológico. Porto Alegre; Editora Clube da Árvore (2002)
• 3 Blundell A. G., Peart D. R.. High abscission rates of damaged expanding leaves: field evidence from seedlings of a bornean rain forest tree.  American Journal of Botany. (2000);  87 1693-1698
• 4 Coley P. D., Aide M.. Red coloration of tropical young leaves: a possible antifungal defence?.  Journal of Tropical Ecology. (1989);  5 293-300
• 5 Coley P. D., Kursar T. A.. Anti-herbivore defenses of young tropical leaves: physiological constraints and ecological tradeoffs. Mulkey S. S., Chazdon R., and Smith A. P., eds. Tropical Forest Plant Ecophysiology. New York; Chapman and Hall (1996): 305-336
• 6 Cornelissen T. G., Fernandes G. W.. Defence, growth and nutrient allocation in the tropical shrub Bauhinia brevips (Leguminosae).  Austral Ecology. (2001);  26 246-253
• 7 Demmig-Adams B., Adams III., W. W., Barker D. H., Logan B. A., Bowling D. R., Verhoeven A. S.. Using chlorophyll fluorescence to assess the fraction of absorbed light allocated to thermal dissipation of excess excitation.  Physiologia Plantarum. (1996);  98 254-264
• 8 Dominy N. J., Lucas P. W., Ramsden L. W., Riba-Hernandez P., Stoner K. E., Turner I. M.. Why are young leaves red?.  Oikos. (2002);  98 163-176
• 9 Eck G., Fiala B., Linsenmair K. E., Hashim R. B., Proksch P.. Trade-off between chemical and biotic antiherbivory defense in the southeast Asian plant genus Macaranga. .  Journal of Chemical Ecology. (2001);  27 1979-1996
• 10 Edwards C., Read J., Sanson G.. Characterising sclerophylly: some mechanical properties of leaves from heath and forest.  Oecologia. (2000);  123 158-167
• 11 Feild T. S., Lee D. W., Holbrook N. M.. Why leaves turn red in autumn. The role of anthocyanins in senescing leaves of red-osier dogwood.  Plant Physiology. (2001);  127 566-574
• 12 Hormaetxe K., Hernández A., Becerril J. M., García-Plazaola J. I.. Role of red carotenoids in photoprotection during winter acclimation in Buxus sempervirens leaves.  Plant Biology. (2004);  6 325-332
• 13 Iddles T. L., Read J., Sanson G. D.. The potential contribution of biomechanical properties to anti-herbivore defence in seedlings of six australian rainforest trees.  Australian Journal of Botany. (2003);  51 119-128
• 14 Jones H.. Plants and Microclimate. 2nd ed. Cambridge; Cambridge University Press (1992)
• 15 Kong J.-M., Chia L.-S., Goh N.-K., Chia T.-F., Brouillard R.. Analysis and biological activities of anthocyanins.  Phytochemistry. (2003);  64 923-933
• 16 Kursar T. A., Coley P. D.. Nitrogen content and expansion rate of young leaves of rain forest species: implications for herbivory.  Biotropica. (1991);  23 141-150
• 17 Kursar T. A., Coley P. D.. Delayed development of the photosynthetic apparatus in tropical rain forest species.  Functional Ecology. (1992 a);  6 411-422
• 18 Kursar T. A., Coley P. D.. Delayed greening in tropical leaves: an antiherbivore defense?.  Biotropica. (1992 b);  24 256-262
• 19 Kursar T. A., Coley P. D.. Convergence in defense syndromes of young leaves in tropical rainforests.  Biochemical Systematics and Ecology. (2003);  31 929-949
• 20 Lacerda L. D., Araújo D. S. D., Maciel N. C.. Dry coastal ecosystems of the tropical Brazilian coast. van Der Maarel, E., ed. Dry Coastal Ecosystems. Amsterdam; Chapman and Hall (1993): 477-493
• 21 Lucas P. W., Turner I. M., Dominy N. J., Yamashita N.. Mechanical defences to herbivory.  Annals of Botany. (2000);  86 913-920
• 22 Mediavilla S., Escudero A.. Relative growth rate of leaf biomass and leaf nitrogen content in several mediterranean woody species.  Plant Ecology. (2003);  168 321-332
• 23 Moles A. T., Westoby M.. Do small leaves expand faster than large leaves, and do shorter expansion times reduce herbivore damage?.  Oikos. (2000);  90 517-524
• 24 Read J., Gras E., Sanson G. D., Clissold F., Brunt C.. Does chemical defence decline more in developing leaves that become strong and tough at maturity?.  Australian Journal of Botany. (2003);  51 489-496
• 25 Ribeiro S. P., Pimenta H. R., Fernandes G. W.. Herbivory by chewing and sucking insects on Tabebuia ochracea.  Biotropica. (1994);  26 302-307
• 26 Sanson G., Read J., Aranwela N., Clissod F., Peeters P.. Measurement of leaf biomechanical properties in studies of herbivory: opportunities, problems and procedures.  Austral Ecology. (2001);  26 535-546
• 27 Sims D. A., Gamon J. A.. Relationships between leaf pigment content and spectral reflectance across a wide range of species, leaf structures and developmental stages.  Remote Sensing of Environment. (2002);  81 337-354
• 28 Steyn W. J., Wand S. J. E., Holcroft D. M., Jacobs G.. Anthocyanins in vegetative tissues: a proposed unified function in photoprotection.  New Phytologist. (2002);  155 349-361
• 29 Sun S.. Leaf expansion rate, final leaf size and leaf expansion period are not necessarily correlated.  Oikos. (2003);  100 200-201
• 30 Tiffin P.. Mechanisms of tolerance to herbivore damage: what do you know?.  Evolutionary Ecology. (2000);  14 523-536
• 31 Witkowski E. T. F., Lamont B. B.. Leaf specific mass confounds leaf density and thickness.  Oecologia. (1991);  88 486-493

Editor: M. Riederer