Plant growth in a fragmented forest is a consequence of top-down and bottom-up processes, but not their interaction

doi:10.1093/jpe/rtw067

Abstract

Abstract: Aims Habitat loss and fragmentation are the leading causes of global biodiversity decline. How fragmentation (leading to edge effects, increased isolation and declining habitat size) interacts with top-down processes like vertebrate herbivory, an important driver of vegetation structure and composition in many ecosystems, is poorly quantified. Interactions between fragmentation and changes in herbivory may exacerbate their individual influences on plant growth, with implications for management of native plant communities within fragmented landscapes. We examined the effects of habitat fragmentation on herbivore activity, and also how both fragmentation and mammalian herbivory influence growth of understorey plant species.
Methods This study was conducted at the Wog Wog habitat fragmentation experiment, located in south-eastern New South Wales, Australia. We use herbivore exclusion plots across an experimentally fragmented landscape to assess the interactive effects of fragmentation and herbivory on the growth of four plant species that vary in growth form and rarity in the landscape.
Important findings We observed species-specific responses to both herbivory and fragmentation, but no additive or interactive effects between these drivers. We show that a reduction in herbivore activity within fragments does not correspond with an increase in plant growth, even for the most palatable species. Rather, top-down processes continue to operate across the fragmented landscape. Although changes in habitat conditions within fragments appear to negatively influence both plant growth and mammalian herbivore activity, it is likely that alterations to bottom-up effects (i.e. fragmentation) may be more important than top-down effects (i.e. herbivores) for the species under investigation. The species-specific response of plants to herbivory or fragmentation may have implications for temporal and spatial population persistence in fragmented landscapes and ultimately fragment vegetation structure.

Key words: Wog Wog habitat fragmentation experiment, Pinus radiata, herbivory, understorey plants, plantation, eucalypt

摘要：
Aims Habitat loss and fragmentation are the leading causes of global biodiversity decline. How fragmentation (leading to edge effects, increased isolation and declining habitat size) interacts with top-down processes like vertebrate herbivory, an important driver of vegetation structure and composition in many ecosystems, is poorly quantified. Interactions between fragmentation and changes in herbivory may exacerbate their individual influences on plant growth, with implications for management of native plant communities within fragmented landscapes. We examined the effects of habitat fragmentation on herbivore activity, and also how both fragmentation and mammalian herbivory influence growth of understorey plant species.
Methods This study was conducted at the Wog Wog habitat fragmentation experiment, located in south-eastern New South Wales, Australia. We use herbivore exclusion plots across an experimentally fragmented landscape to assess the interactive effects of fragmentation and herbivory on the growth of four plant species that vary in growth form and rarity in the landscape.
Important findings We observed species-specific responses to both herbivory and fragmentation, but no additive or interactive effects between these drivers. We show that a reduction in herbivore activity within fragments does not correspond with an increase in plant growth, even for the most palatable species. Rather, top-down processes continue to operate across the fragmented landscape. Although changes in habitat conditions within fragments appear to negatively influence both plant growth and mammalian herbivore activity, it is likely that alterations to bottom-up effects (i.e. fragmentation) may be more important than top-down effects (i.e. herbivores) for the species under investigation. The species-specific response of plants to herbivory or fragmentation may have implications for temporal and spatial population persistence in fragmented landscapes and ultimately fragment vegetation structure.

Brad J. Farmilo, John W. Morgan, Dale G. Nimmo. Plant growth in a fragmented forest is a consequence of top-down and bottom-up processes, but not their interaction[J]. J Plant Ecol, 2017, 10(4): 601-609.

[1]	Chen Hu, Jinyu Gong, Zhiyuan Ma, Linxuan He, Jingpin Lei, Hongxia Cui. Nitrogen and biochar interactions promote the stabilization of the temperature sensitivity of soil respiration [J]. J Plant Ecol, 2026, 19(1): 1-0.
[2]	Jinan Lu, Yaolin Guo, Yu-Jie Zhao, Jihua Wu, Bo Li, Christina L Richards, Rui-Ting Ju. Silicon mediates geographic variation of herbivory-related traits in a widespread plant invader [J]. J Plant Ecol, 2025, 18(6): 1-43.
[3]	Yuxi Liu, Jie Li, Junna Feng, Qiaoyan Chen, Siyuan Cheng, Ruiyu Fu, Xiaowei Guo, Yangong Du, Licong Dai, Zhongyi Sun. Conversion of tropical secondary forests into rubber plantations reduces network complexity and diversity of soil bacterial community [J]. J Plant Ecol, 2025, 18(6): 1-.
[4]	Lei Wang, Muhammad Hasnain, Zhanhui Tang, Kobayashi Makoto. Soil water availability alters plant‐soil feedback effects on invasive plant growth and foliar herbivory [J]. J Plant Ecol, 2025, 18(3): 1-13.
[5]	Juan Huang, Xi'an Cai, Runcheng Zhu, Juxiu Liu, Yuelin Li, Mianhai Zheng, Jiangming Mo. Responses of leaf traits of plantation tree species in South China under long-term nitrogen deposition [J]. J Plant Ecol, 2025, 18(3): 1-13.
[6]	Shuotian Lai, Björn Berg, Yongxin Lin, Haroon Rashid, Fuzhong Wu, Qiuxia Wu, Qiufang Zhang, Xinying Zhang, Jingjing Zhu, Xiangyin Ni. Chinese fir litter decomposition and its response to global change: a meta-analysis across China’s forests [J]. J Plant Ecol, 2025, 18(2): 1-15.
[7]	Lie-Wen Lin, Hua Huang, Wei-Wei Liu, Wei-Bang Sun. Cyclical drought and herbivore threats are potential causes of leaf variegation dimorphism in Cypripedium forrestii [J]. J Plant Ecol, 2024, 17(6): 1-14.
[8]	Cheng Zheng, Fei Zhang, Ziqi Lin, Liuhuan Yuan, Hongbin Yao, Gaohui Duan, Yandan Liu, Yangyang Liu, Haijing Shi, Zhongming Wen. Using the response–effect trait framework to disentangle the effects of environmental change on the ecosystem services [J]. J Plant Ecol, 2024, 17(5): 1-13.
[9]	Qiaoyan Chen, Ruiyu Fu, Siyuan Cheng, Dong Qiao, Zhongmin Hu, Zijia Zhang, Licong Dai. Effects of the conversion of natural tropical rainforest to monoculture rubber plantations on soil hydrological processes [J]. J Plant Ecol, 2024, 17(2): 0-rtae021.
[10]	Xikang Hou, Dan Kou, Mitsuru Hirota, Tong Guo, Tao Lang. Altitudinal variations of the rate and temperature sensitivity of soil nitrogen mineralization on the Qinghai-Tibetan Plateau [J]. J Plant Ecol, 2023, 16(5): 0-.
[11]	Zhenlu Qiu, Mei Zhang, Kefan Wang, Fuchen Shi. Vegetation community dynamics during naturalized developmental restoration of Pinus tabulaeformis plantation in North warm temperate zone [J]. J Plant Ecol, 2023, 16(4): 0-rtac102.
[12]	Ling-Ling Wang, Qing-Qiu Zhou, Wen-Hua Su, Yun-Jian Xu, Qin-Dong Qian, Xiong Yang, De-Yun Chen, Zhe Chen and Jian-Ping Wu. Responses of fungal community to forest fire are species-specific in Yunnan Plateau, southwest China [J]. J Plant Ecol, 2023, 16(1): 0-.
[13]	Rui-Fang Wang, Zhi-Yong Liao, Wei-Tao Li, Chun-Hua Zhang, Han-Bo Zhang and Yu-Long Zheng. Low-level expression of induced defences and increased compensation in Eupatorium adenophorum relative to its native congeneric plant to mechanical wounding and insect herbivory [J]. J Plant Ecol, 2023, 16(1): 0-.
[14]	Bin Lan, Xiaoli Hu, Ying Wang, Shucun Sun. The abundance effect on network nestedness is stronger for parasitic than herbivory interactions [J]. J Plant Ecol, 2022, 15(6): 1133-1141.
[15]	Adam Klimeš, Martin Weiser, Tomáš Koubek and Tomáš Herben. Evolution of herbs: key to the conundrum might be tolerance not avoidance [J]. J Plant Ecol, 2021, 14(5): 911-919.