Morphological Study of Glochidion obovatum under Heavy Browsing Pressure by Sika Deer

Shogo Takei, Kazuhiro Yoshioka, Satoru Yamada, Hiroshi Hayakawa, Jun Yokoyama, Katsura Ito, Shinichi Tebayashi, Ryo Arakawa, Tatsuya Fukuda

Faculty of Agriculture, Kochi University, Kochi, Japan.
Faculty of Science, Yamagata University, Yamagata, Japan.

DOI: 10.4236/ajps.2014.59148                

Abstract

To clarify the modification of physical defences of Glochidion obovatum Sieb. et Zucc., we compared the length of spine-like branches and frequency of lateral branches of G. obovatum between Kashima Island, which supports a high density of sika deer (Cervus nippon), and its neighbouring areas. The length of spine-like branches of G. obovatum in Kashima Island was not significantly longer than that of the neighbouring areas, but the frequency of lateral branches on the island was higher than that of the neighbouring areas. Since the branches of G. obovatum are heavily foraged by the sika deer, the shrub form of the species has evolved into the bonsai form, suggesting increased frequency of occurrence of lateral branches, which could develop as shoot-like branches. Thus, the observed features are facultative defence mechanisms of G. obovatum against heavy browsing in a small-sized island with very high density of sika deer.

Keywords

Deer; Defence; Frequency; Herbivore; Island; Sika

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	Ehrlich, P.R. and Raven, P.H. (1967) Butterflies and Plants. Scientific American, 216, 104-131. http://dx.doi.org/10.1038/scientificamerican0667-104
[2]	Grubb, P.J. (1992) A Positive Distrust in Simplicity: Lessons from Plant Defenses and from Competition among Plants and among Animals. Journal of Ecology, 80, 585-610. http://dx.doi.org/10.2307/2260852
[3]	Myers, J.H. (1987) Nutrient Availability and the Deployment of Mechanical Defenses in Grazed Plants: A New Experimental Approach to the Optimal Defense Theory. Oikos, 49, 350-351. http://dx.doi.org/10.2307/3565772
[4]	Abrahamson, W.G. (1975) Reproductive Strategies in Dewberries. Ecology, 56, 721-726. http://dx.doi.org/10.2307/1935508
[5]	Bazely, D.R., Myers, J.H. and Burke da Silva, K. (1991) The Response of Number of Bramble Prickles to Herbivory and Depressed Resource Availability. Oikos, 61, 327-336. http://dx.doi.org/10.2307/3545240
[6]	Gibson, D., Bazely, D.R. and Shore, J.S. (1993) Responses of Brambles, Rubus vestitus, to Herbivory. Oecologia, 95, 454-457. http://dx.doi.org/10.1007/BF00321002
[7]	White, P.S. (1988) Prickle Distribution in Aralia spinosa (Araliaceae). American Journal of Botany, 75, 282-285. http://dx.doi.org/10.2307/2443895
[8]	Takei, S., Yoshioka, K., Yamada, S., Hayakawa, H., Yokoyama, J., Ito, K., Tebayashi, S., Arakawa, R. and Fukuda, T. (2014) The Length and Density of Prickles on Zanthoxylum ailanthoides (Rutaceae): A Comparison of Japanese Islands with Different Sika Deer Browsing Pressures. American Journal of Plant Science, 5, 332-337. http://dx.doi.org/10.4236/ajps.2014.53046
[9]	Pullin, A.S. and Gilbert, J.E. (1989) The Stinging Nettle, Urtica dioica, Increases Trichome Density after Herbivore and Mechanical Damage. Oikos, 54, 275-280. http://dx.doi.org/10.2307/3565285
[10]	Pollard, J.A. (1986) Variation in Cnidoscolus texanus in Relation to Herbivory. Oecologia, 70, 411-413. http://dx.doi.org/10.1007/BF00379504
[11]	Takatsuki, S. (1982) Ecological Studies on Effect of Sika Deer (Cervus Nippon) on Vegetation III: The Vegetation of Iyo-Kashima Island, Southwestern Shikoku, with Reference to Grazing Effect of Sika Deer. Ecological Reviews, 20, 15-29.
[12]	Takei, S., Ohga, K., Hayakawa, H., Yokoyama, J., Ito, K., Tebayashi, S., Arakawa, R. and Fukuda, T. (2013) Comparative Analysis of the Prickles on Rubus sieboldi (Rosaceae) Between Grazed and Ungrazed Areas in South-western Shikoku, Japan. Journal of Plant Studies, 2, 152-157. http://dx.doi.org/10.5539/jps.v2n1p152
[13]	Takei, S., Yoshioka, K., Yamada, S., Hayakawa, H., Yokoyama, J., Ito, K., Tebayashi, S., Arakawa, R. and Fukuda, T. (2014) Comparative Morphology of Prickles of Rubus croceacanthus H. Lév. (Rosaceae) in Kashima Island and its Neighbor Areas. Journal of Plant Studies, 3, 96-102. http://dx.doi.org/10.5539/jps.v3n1p96
[14]	Hashigoe, S. (1995) Flora of Kashima Island, Ehime Prefecture, Japan. Biology in Southern Ehime, 8, 22-32. (in Japanese)
[15]	Ohba, H. (1999) Glochidion J. R. Forest. and G. Forest. In: Iwatsuki, K., Bufford, D.E. and Ohba, H., Eds., Flora of Japan, Volume IIc, Kodansha, Tokyo, 9-11.
[16]	Okuda, T. (1987) The Phenotypic Variation of Glochidion obovatum Sieb. Et Zucc. in Relation to the Deer Browsing. Hikobia, 10, 13-19.
[17]	Kawahara, H. (1992) The Correlation between Browsing Behaviour by Sika Deer and the Changing of the Flora of Nozaki Island. Bulletin of Nagasaki Institute of Applied Science, 33, 137-144. (in Japanese)
[18]	Kawahara, H. (1997) The Influence of the Vegetation in Nozaki Island for Browsing by Sika Deer and the Management of Sika Deer. Bulletin of Nagasaki Institute of Applied Science, 15, 61-67. (in Japanese)
[19]	Takatsuki, S. and Saka, K. (1988) Recovery of Viburnum dilatatum after a Die-off of Sika Deer on Kinkazan Island. Ecological Review, 21, 177-181.
[20]	Inoue, M. and Kanemori, H. (2006) The Protection of Mountains and Fields from Sika Deer. Noubunkyou, Tokyo. (in Japanese)
[21]	Takatsuki, S. (2006) Ecological History of Sika Deer. University of Tokyo Press, Tokyo. (in Japanese)
[22]	Takatsuki, S. and Ito, T.Y. (2009) Plants and Plant Communities on Kinkazan Island, Northern Japan, in Relation to Sika Deer Herbivory. In: McCullough, D.R., Takatsuki, S. and Kaji, K., Eds., Sika Deer: Biology and Management of Native and Introduced Populations, Springer, Tokyo, 125-143. http://dx.doi.org/10.1007/978-4-431-09429-6_9
[23]	Terabayashi, S. (2006) Berberis L. In: Iwatsuki, K., Bufford, D.E., Ohba, H., Eds., Flora of Japan, Volume IIa, Kodansha, Tokyo, 342-343.
[24]	Kawahara, H. (1983) The Vegetation of Goto and Nozaki Islands. Bulletin of Nagasaki Institute of Applied Science, 24, 239-248. (in Japanese)
[25]	Seif el Din, A. and Obeid, M. (1971) Ecological Studies of the Vegetation of the Sudan. IV. The Effects of Simulated Grazing on the Growth of Acacia senegal (L.) Willd. Seedlings. Journal of Applied Ecology, 8, 211-216. http://dx.doi.org/10.2307/2402139
[26]	Young, T.P. (1987) Increased Thorn Length in Acacia depranolobium: An Induced Response to Browsing. Oecologia, 71, 436-438. http://dx.doi.org/10.1007/BF00378718
[27]	Milewski, A.V., Young, T.P. and Madden, D. (1991) Thorns as Induced Defenses: Experimental Evidence. Oecologia, 86, 70-75. http://dx.doi.org/10.1007/BF00317391