食物網中，掠食者對植物造成的跨食物鏈階層(trophic cascades)影響受到許多重視，本研究檢測水柳食物網中，鳥類掠食對水柳和樹上的節肢動物（分植食性、真菌食性與掠食者三群）豐度的影響。實驗樣地位於北臺灣新店溪岸，水柳以枝條為單位，使用細網隔絕鳥類20個月，並與有鳥類掠食的枝條比較其生長、繁殖、防禦性化學物質的表現以及節肢動物的豐度。無鳥類掠食的枝條生長與繁殖較差，但節肢動物群並未受到影響。防禦性化學物質以酚類配醣(phenolic glycosides)作為代表，無鳥類掠食的枝條其含量較少；葉子所受的植食損傷，無鳥類掠食的枝條在實驗開始約一年後損傷較高，但在第二年則與有鳥類掠食的枝條無異。實驗結果顯示，有鳥類掠食的水柳枝條生長與繁殖表現較好，其植食性損害也較低，證實了掠食者對植物有正向的跨食物鏈階層之影響。

Trophic cascades, defined as indirect effects of predators on plants via herbivores, play a crucial role in food web functioning. In this study I tested top-down trophic effects of avian predation on plants and arboreal arthropods in a willow (Salix warburgii) food web along a riparian zone of Xindian river in northern Taiwan. Bird predation was excluded by nylon netting around the branches for 20 months. The growth, reproduction and level of defensive phytochemicals of these branches were compared to that of control branches on the same trees; the abundance of arboreal arthropods and level of herbivory were also compared. The bird exclusion caused lower growth and reproduction in the willows but did not affect the abundances of 3 arthropod groups (i.e. herbivores, fungivores and predators) on them. The plant defensive phytochemicals, measured as the amount of phenolic glycosides, were lower for the bird exclusion branches. The level of herbivory was higher in the bird exclusion branches approximately one year after the treatment, but returned to a similar level as the control branches in the second year. This study demonstrated that avian predation has positive cascading effects on willows at branch level by improving their growth and reproduction, as well as reducing their herbivory.

Agrawal, A. A., J. A. Lau, and P. A. Hambäck. 2006. Community heterogeneity and the evolution of interactions between plants and insect herbivores. Quarterly Review of Biology 81:349-376.
Böhm, S. M., K. Wells, and E. K. Kalko. 2011. Top-down control of herbivory by birds and bats in the canopy of temperate broad-leaved oaks (Quercus robur). Plos One 6:e17857.
Boeckler, G. A., J. Gershenzon, and S. B. Unsicker. 2011. Phenolic glycosides of the Salicaceae and their role as anti-herbivore defenses. Phytochemistry 72:1497-1509.
Borer, E. T., E. W. Seabloom, J. B. Shurin, K. E. Anderson, C. A. Blanchette, B. Broitman, S. D. Cooper and B. S. Halpern. 2005. What determines the strength of a trophic cascade? Ecology 86:528-537.
Casini, M., J. Hjelm, J.-C. Molinero, J. Lövgren, M. Cardinale, V. Bartolino, A. Belgrano, and G. Kornilovs. 2009. Trophic cascades promote threshold-like shifts in pelagic marine ecosystems. Proceedings of the National Academy of Sciences 106:197-202.
Chang, W. F. 1985. A field guide to the birds of Taiwan. Taiwan: Bird Image Publication (in Chinese).
Coley, P. D., and J. A. Barone. 1996. Herbivory and plant defenses in tropical forests. Annual Review of Ecology and Systematics 27:305-335.
Crawley, M. J. 1989. Insect herbivores and plant population dynamics. Annual Review of Entomology 34:531-562.
Donaldson, J. R., M. T. Stevens, H. R. Barnhill, and R. L. Lindroth. 2006. Age-related shifts in leaf chemistry of clonal aspen (Populus tremuloides). Journal of Chemical Ecology 32:1415-1429.
Dudt, J. F., and D. J. Shure. 1994. The influence of light and nutrients on foliar phenolics and insect herbivory. Ecology 75:86-98.
Fine, P. V., I. Mesones, and P. D. Coley. 2004. Herbivores promote habitat specialization by trees in Amazonian forests. Science 305:663-665.
Fritz, R. S., C. G. Hochwender, D. A. Lewkiewicz, S. Bothwell, and C. M. Orians. 2001. Seedling herbivory by slugs in a willow hybrid system: developmental changes in damage, chemical defense, and plant performance. Oecologia 129:87-97.
Greenberg, R., P. Bichier, A. C. Angon, C. MacVean, R. Perez, and E. Cano. 2000. The impact of avian insectivory on arthropods and leaf damage in some Guatemalan coffee plantations. Ecology 81:1750-1755.
Griffin, C. A., and J. S. Thaler. 2006. Insect predators affect plant resistance via density‐ and trait‐mediated indirect interactions. Ecology Letters 9:335-343.
Hairston, N. G., F. E. Smith, and L. B. Slobodkin. 1960. Community structure, population control, and competition. The American Naturalist 94:421-425.
Haukioja, E., V. Ossipov, J. Koricheva, T. Honkanen, S. Larsson, and K. Lempa. 1998. Biosynthetic origin of carbon-based secondary compounds: cause of variable responses of woody plants to fertilization? Chemoecology 8:133-139.
Hjältén, J., L. Niemi, A. Wennström, L. Ericson, H. Roininen, and R. Julkunen-Tiitto. 2007. Variable responses of natural enemies to Salix triandra phenotypes with different secondary chemistry. Oikos 116:751-758.
Ho, C.-K., and S. C. Pennings. 2008. Consequences of omnivory for trophic interactions on a salt marsh shrub. Ecology 89:1714-1722.
Hunter, M. D., and P. W. Price. 1992. Playing chutes and ladders: heterogeneity and the relative roles of bottom-up and top-down forces in natural communities. Ecology 73:724-732.
Hunter, M. D., G. C. Varley, and G. R. Gradwell. 1997. Estimating the relative roles of top-down and bottom-up forces on insect herbivore populations: a classic study revisited. Proceedings of the National Academy of Sciences 94:9176-9181.
Huryn, A. D. 1998. Ecosystem-level evidence for top-down and bottom-up control of production in a grassland stream system. Oecologia 115:173-183.
Jeppesen, E., M. Søndergaard, J. P. Jensen, E. Mortensen, A.-M. Hansen, and T. Jørgensen. 1998. Cascading trophic interactions from fish to bacteria and nutrients after reduced sewage loading: An 18-year study of a shallow hypertrophic lake. Ecosystems 1:250-267.
Julkunen-Tiitto, R., and S. Sorsa. 2001. Testing the effects of drying methods on willow flavonoids, tannins, and salicylates. Journal of Chemical Ecology 27:779-789.
Larsson, S., A. Wirén, L. Lundgren, and T. Ericsson. 1986. Effects of light and nutrient stress on leaf phenolic chemistry in Salix dasyclados and susceptibility to Galerucella lineola (Coleoptera). Oikos 47:205-210.
Letourneau, D. K., and L. A. Dyer. 1998. Density patterns of Piper ant-plants and associated arthropods: top-predator trophic cascades in a terrestrial system? Biotropica, 30:162-169.
Marquis, R. J., and C. J. Whelan. 1994. Insectivorous birds increase growth of white oak through consumption of leaf-chewing insects. Ecology 75:2007-2014.
Menge, B. A. 1995. Indirect effects in marine rocky intertidal interaction websL patterns and importance. Ecological Monographs 65:21-74.
Mooney, K. A. 2007. Tritrophic effects of birds and ants on a canopy food web, tree growth, and phytochemistry. Ecology 88:2005-2014.
Neilson, E. H., J. Q. Goodger, I. E. Woodrow, and B. L. Møller. 2013. Plant chemical defense: at what cost? Trends in Plant Science 18:250-258.
Oksanen, L., S. D. Fretwell, J. Arruda, and P. Niemelä. 1981. Exploitation ecosystems in gradients of primary productivity. The American Naturalist 118:240-261.
Orians, C. M., and R. S. Fritz. 1995. Secondary chemistry of hybrid and parental willows: Phenolic glycosides and condensed tannins inSalix sericea, S. eriocephala, and their hybrids. Journal of Chemical Ecology 21:1245-1253.
Persson, L. 1999. Trophic cascades: abiding heterogeneity and the trophic level concept at the end of the road. Oikos 85:385-397.
Power, M. E. 1992. Top-down and bottom-up forces in food webs: do plants have primacy. Ecology 73:733-746.
Rowell-Rahier, M., and J. M. Pasteels. 1990. Phenolglucosides and interactions at three trophic levels: Salicaceae-herbivores-predators. Insect-Plant Interactions, Vol. 2 (eds E. A. Bernay), pp. 75-94. CRC Press, Boca Raton, Florida.
Schmitz, O. J., E. L. Kalies, and M. G. Booth. 2006. Alternative dynamic regimes and trophic control of plant succession. Ecosystems 9:659-672.
Shurin, J. B., E. T. Borer, E. W. Seabloom, K. Anderson, C. A. Blanchette, B. Broitman, S. D. Cooper, and B. S. Halpern. 2002. A cross-ecosystem comparison of the strength of trophic cascades. Ecology Letters 5:785-791.
Sipura, M. 1999. Tritrophic interactions: willows, herbivorous insects and insectivorous birds. Oecologia 121:537-545.
Smiley J. T., J. M. Horn and N. E. Rank. 1985. Ecological effects of salicin at three trophic levels: new problems from old adaptations. Science(Washinton) 229:649-651.
Spiller, D. A., and T. W. Schoener. 1994. Effects of top and intermediate predators in a terrestrial food web. Ecology 75:182-196.
Stamp, N. E., and M. D. Bowers. 2000. Do enemies of herbivores influence plant growth and chemistry? Evidence from a seminatural experiment. Journal of Chemical Ecology 26:2367-2386.
Stolter, C. 2008. Intra-individual plant response to moose browsing: feedback loops and impacts on multiple consumers. Ecological Monographs 78:167-183.
Strauss, S. Y., and A. A. Agrawal. 1999. The ecology and evolution of plant tolerance to herbivory. Trends in Ecology and Evolution 14:179-185.
Tahvanainen, J., R. Julkunen-Tiitto, and J. Kettunen. 1985. Phenolic glycosides govern the food selection pattern of willow feeding leaf beetles. Oecologia 67:52-56.
Trussell, G. C., P. J. Ewanchuk, and M. D. Bertness. 2002. Field evidence of trait‐mediated indirect interactions in a rocky intertidal food web. Ecology Letters 5:241-245.
Huang T.C., D.E. Boufford, H. Ohashi, Y.P. Yang and S.Y. Lu. 1996. Flora of Taiwan, Secon Edition. Editorial Committee of the Flora of Taiwan, Secon Edition, Taipei, Taiwan, ROC.
Yoneya, K., M. Uefune, and J. Takabayashi. 2012. An apparent trade-off between direct and signal-based induced indirect defence against herbivores in willow trees. Plos One 7:e51505.