Leaf herbivory and decomposability in a Malaysian tropical rain forest.

There is accumulating evidence that similar suites of plant traits may affect leaf palatability and leaf litter decomposability. However, the possible association between leaf herbivory and litter decomposition rates across species in species-diverse natural ecosystems such as tropical rain forests remains unexplored, despite its importance in estimating the herbivory effects on carbon and nutrient cycling of ecosystems. We found no strong association between leaf herbivory and litter decomposition rates across 40 tree species in a Malaysian tropical rain forest, even though the leaf and litter traits were tightly correlated. This is because the leaf and litter traits related to herbivory and decomposition rates in the field were inconsistent. Leaf toughness accounted for only a small part of the variation in the herbivory rate, whereas a number of litter traits (the leaf mass per area, lignin to nitrogen ratio, and condensed tannin concentration) accurately predicted the decomposition rate across species. These results suggest that herbivory rate across species may not be strongly related to single leaf traits, probably because plant-herbivore interactions in tropical rain forests are highly diverse; on the other hand, plant-decomposer interactions are less specific and can be governed by litter chemicals. We also investigated two factors, phylogeny and tree functional types, that could affect the relationship between herbivory and decomposition across species. Phylogenetic relatedness among the species did not affect the relationship between herbivory and decomposition. In contrast, when the plants were segregated according to their leaf emergence pattern, we found a significant positive relationship between herbivory and decomposition rates for continuous-leafing species. In these species, the condensed tannin to N ratios in leaves and litter were related to herbivory and decomposition rates, respectively. However, we did not observe a similar trend for synchronous-leafing species. These results suggest that the relationship between herbivory and decomposition may be more greatly affected by functional types than by phylogenetic relatedness among species. In conclusion, our results suggest that well-defended leaves are not necessarily less decomposable litter in a tropical rain forest community, implying that herbivory may not generate positive feedback for carbon and nutrient cycling in this type of ecosystem.

[1]  V. Brown,et al.  Leaf palatability, life expectancy and herbivore damage , 1986, Oecologia.

[2]  P. Lucas,et al.  Leaf fracture toughness and sclerophylly: their correlations and ecological implications , 1992 .

[3]  John F. Muratore,et al.  Nitrogen and Lignin Control of Hardwood Leaf Litter Decomposition Dynamics , 1982 .

[4]  Hendrik Poorter,et al.  Differences in construction costs and chemical composition between deciduous and evergreen woody species are small as compared to differences among families. , 2006, Plant, cell & environment.

[5]  P. Reich,et al.  Leaf Life‐Span in Relation to Leaf, Plant, and Stand Characteristics among Diverse Ecosystems , 1992 .

[6]  D. Wainhouse,et al.  The role of lignin as a defence against the spruce bark beetle Dendroctonus micans: effect on larvae and adults , 1990, Oecologia.

[7]  T. Itioka,et al.  Variations in abiotic defense within myrmecophytic and non-myrmecophytic species of Macaranga in a Bornean dipterocarp forest , 2000, Ecological Research.

[8]  A. Gallardo,et al.  Leaf Decomposition in Two Mediterranean Ecosystems of Southwest Spain: Influence of Substrate Quality , 1993 .

[9]  P. Coley,et al.  Convergence in Defense Syndromes of Young Leaves in Tropical Rainforests , 2003 .

[10]  Sandra Díaz,et al.  Leaf structure and defence control litter decomposition rate across species and life forms in regional floras on two continents , 1999 .

[11]  Craig Loehle,et al.  Tree life history strategies: the role of defenses , 1988 .

[12]  J. A. Barone,et al.  HERBIVORY AND PLANT DEFENSES IN TROPICAL FORESTS , 1996 .

[13]  Terry V. Callaghan,et al.  Leaf digestibility and litter decomposability are related in a wide range of subarctic plant species and types , 2004 .

[14]  T. Whitham,et al.  Herbivory differentially alters plant litter dynamics of evergreen and deciduous trees , 2006 .

[15]  Nelson G. Hairston,et al.  Cause-Effect Relationships in Energy Flow, Trophic Structure, and Interspecific Interactions , 1993, The American Naturalist.

[16]  T. Aide.  Patterns of Leaf Development and Herbivory in a Tropical Understory Community , 1993 .

[17]  Sandra Díaz,et al.  Leaf traits and herbivore selection in the field and in cafeteria experiments , 2003 .

[18]  T. Yamakura.  Topography of a large-scale research plot established within a tropical rain forest at Lambir, Sarawak , 1995 .

[19]  Thomas P. Clausen,et al.  DIVERSITY OF STRUCTURE AND ANTIHERBIVORE ACTIVITY IN CONDENSED TANNINS , 1997 .

[20]  T. Saitoh,et al.  Negative effects of acorns on the wood mouse Apodemus speciosus , 2003, Population Ecology.

[21]  J. A. Barone.  Host-specificity of folivorous insects in a moist tropical forest , 1998 .

[22]  L. Santiago,et al.  Extending the leaf economics spectrum to decomposition: evidence from a tropical forest. , 2007, Ecology.

[23]  K. Kikuzawa.  Leaf survival of woody plants in deciduous broad-leaved forests. 1. Tall trees , 1983 .

[24]  C. Gallet,et al.  Evolution of phenolic patterns in plants and associated litters and humus of a mountain forest ecosystem , 1995 .

[25]  R. Aerts.  Nutrient resorption from senescing leaves of perennials: are there general patterns? , 1996 .

[26]  R. Julkunen‐Tiitto,et al.  Phenolic constituents in the leaves of northern willows: methods for the analysis of certain phenolics , 1985 .

[27]  P. Coley,et al.  HERBIVORY AND DEFENSIVE CHARACTERISTICS OF TREE SPECIES IN A LOWLAND TROPICAL FOREST , 1983 .

[28]  L. Slobodkin,et al.  Community Structure, Population Control, and Competition , 1960, The American Naturalist.

[29]  Ken Thompson,et al.  Evidence of a causal connection between anti-herbivore defence and the decomposition rate of leaves , 1996 .

[30]  Thomas P. Clausen,et al.  Effect of nitrogen fertilization upon the secondary chemistry and nutritional value of quaking aspen (Populus tremuloides Michx.) leaves for the large aspen tortrix (Choristoneura conflictana (Walker)) , 1987, Oecologia.

[31]  N. Cobb,et al.  INSECT HERBIVORY INCREASES LITTER QUALITY AND DECOMPOSITION: AN EXTENSION OF THE ACCELERATION HYPOTHESIS , 2003 .

[32]  R. Hatfield,et al.  Extraction and isolation of lignin for utilization as a standard to determine lignin concentration using the acetyl bromide spectrophotometric method. , 2001, Journal of agricultural and food chemistry.

[33]  David A. Wardle,et al.  Linkages between plant litter decomposition, litter quality, and vegetation responses to herbivores , 2002 .

[34]  David A. Wardle,et al.  Can comparative approaches based on plant ecophysiological traits predict the nature of biotic interactions and individual plant species effects in ecosystems? , 1998 .

[35]  R. Dahlgren,et al.  Tannins in nutrient dynamics of forest ecosystems - a review , 2003, Plant and Soil.

[36]  D. Ackerly.  TAXON SAMPLING, CORRELATED EVOLUTION, AND INDEPENDENT CONTRASTS , 2000, Evolution; international journal of organic evolution.

[37]  D. Wardle,et al.  Herbivore-mediated linkages between aboveground and belowground communities , 2003 .

[38]  S. Hobbie.  Effects of plant species on nutrient cycling. , 1992, Trends in ecology & evolution.

[39]  K. Iiyama,et al.  Determination of lignin in herbaceous plants by an improved acetyl bromide procedure , 1990 .

[40]  Vojtech Novotny,et al.  Low host specificity of herbivorous insects in a tropical forest , 2002, Nature.

[41]  Thomas M. Lewinsohn,et al.  Insects on Plants: Diversity of Herbivore Assemblages Revisited , 2005 .

[42]  Daniel R. Lynch,et al.  Nonrandom Processes Maintain Diversity in Tropical Forests , 2006 .

[43]  D. Wardle,et al.  Linking above-ground and below-ground interactions: How plant responses to foliar herbivory influence soil organisms , 1998 .

[44]  J. Olson,et al.  Energy Storage and the Balance of Producers and Decomposers in Ecological Systems , 1963 .

[45]  J. Gosz,et al.  The Role of Carbon-Based Plant Secondary Metabolites in Decomposition in Terrestrial Ecosystems , 1988, The American Naturalist.

[46]  R. Naiman,et al.  Selective Foraging and Ecosystem Processes in Boreal Forests , 1992, The American Naturalist.

[47]  P. Ashton.  Toward a Regional Classification of the Humid Tropics of Asia. , 1991 .

[48]  J. Cornelissen,et al.  An experimental comparison of leaf decomposition rates in a wide range of temperate plant species and types , 1996 .

[49]  F. Stuart Chapin,et al.  Resource Availability and Plant Antiherbivore Defense , 1985, Science.