How Fern and Fern Allies Respond to Heterogeneous Habitat— A Case in Yuanjiang Dry-Hot Valley
Feng-Chun Yang 1, 2, 3, Chaya Sarathchandra4, 5, Jing-Xin Liu 6, Hua-Ping Huang7, Jian-Yong Gou 8, Ye Li7, Xiao-Ye Mao 1, Hui-Ting Wen1, Suthathong Homya 9, Kritana Prueksakorn 10 *, Jun Zhao 1, 3 and Ming-Fu Yang 3, 11
1 Yibin Vocational and Technical College, Yibin, Sichuan, 644000, China
2 School of Chinese Medicinal Material Resources, Guangdong Pharmaceutical University, Guangzhou, 510006, China
3 Yi Minority Culture Research Center of the Key Research Base of Philosophy and Social Sciences of Sichuan Province
4 State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
5 Department of Biological Science, Faculty of Applied Sciences, Rajarata University of Sri Lanka, Mihintale, 50300, Sri Lanka
6 Environmental Education Center, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla Yunnan, 666100, China; xtbg_liujx@qq.com
7 Environment and Plant Protection Research Institute, Chinese Academy of Tropical Agricultural Sciences,Haikou, 570100, China; hhp18@163.com
8 Honghe Meteorological Bureau, Yunnan, 661100, China; 125529676@qq.com
9 Department of Environmental Science, Faculty of Science and Technology, Phuket Rajabhat University, 83120, Thailand; suthathong.h@pkru.ac.th
10 Faculty of Environment and Resource Studies, Mahidol University, Nakhon Phathom, 73170, Thailand
11 Yanyuan Vocational Middle School of Liangshan Yi Autonomous Prefecture, Sichuan, 615500, China
First author: yangfengchun@gdpu.edu.cn
Co-first author: chayasarathchandra@gmail.com
Correspondence: kritana.pru@mahidol.ac.th
Abstract: The Yuanjiang dry-hot valley features hot and dry climate, low vegetation and soil degradation. It had lush vegetation in the past, but has become degraded in recent decades. Understanding the interrelationship between species and the habitat is necessary to explain this change. In this study, a link between fern and fern allies - a group that is hypersensitive to environmental factors and their circumstances is constructed. Intensive transects and plots were designed to be proxies for extant fern and fern allies, and their habitats. Fifty years of meteorological records of precipitation and temperature along altitude and river running direction (latitudinal) were employed. Alpha and beta diversity are used to access diversity. Species_estimated, Singletons, Uniques, ACE, ICE, and Chao2, which associate to abundance and rarity, are subscribed to the correlation between fern and fern allies, and their ecosystem. Eight species,Selaginella pseudopaleifera, Aleuritopteris squamosa, Adiantum malesianum, Pteris vittata, Davallia trichomanoides, Sinephropteris delavayi, Selaginella jugorum, and Lygodium japonicum are used as indicators of a typical xeric and sun-drying habitat. The results indicate (1) accompanied by dramatically shrinking habitats, fern and fern allies are in very low diversity and abundance, whereas the rarity is relatively high; (2) for fern and fern allies, environmental factors are positive when altitude goes up; and (3) eight indicator species are latitudinally correlated with fern and fern allies along the river running direction.
Keywords: diversity; dry-hot valley; fern; indicator; rarity
1. Introduction
The dry-hot valley is represented by high temperature and dry air throughout the year, and it is one of the arid ecosystems in the world influenced by climate change (Dong et al ., 2014; Wang et al ., 2016; Srivastava et al ., 2018). Climate change has resulted in extensive alteration of terrestrial ecosystems, including the change in biogeographic distribution and biological diversity, and the interaction between organisms and their living circumstances (Hea et al ., 2018). Understanding the interrelationship between plants and their environmental conditions in arid ecosystems is a preliminary step to interpret the mechanism of adaptation, or giving a feasible solution for saving earthbound environment (Jina et al ., 2019).
Yuanjiang dry-hot valley is located in the upper and middle region of Yuanjiang-Red River, an international river shared by China and Vietnam (6. GMS Operations Center, 2017). In the valley, the nature of soil, water and fertilizer are not in good condition (Su et al ., 2015; Yang et al ., 2018). The vegetation has changed gradually in the past 500 years, but has been degraded significantly in recent decades causing a dry and hot tropical ecosystem (Xu et al ., 1985). Broadleaf and evergreen plants have been shrinking, while it is currently dominated by montane savannah, covered with few trees and high grasses (Zhang et al ., 2009). To elucidate this change, it is necessary to understand a corresponding pattern between plants and environmental factors such as humidity, temperature and water availability. Fern and fern allies are traditionally considered hypersusceptible to environmental changes; their occurrence or disappearance is closely correlated to their living place (Abotsi et al ., 2020). In this study, the relationship between fern and fern allies and environments in the Yuanjiang dry-hot valley is investigated together with species population and environment factors.
2. Materials & Methods
2.1. Transect and plot designing
The research site is the core area of Yuanjiang dry-hot valley with a length of 105.26 km along the river channel, oriented northwest to southeast (Figure 1, A). Six transects were arranged randomly (Figure 1, B) with a concept of no interference by human activities, where three transects were set up altitudinally along a mountain slope, and the other three latitudinally along the riverside (Table 1). Altitudinal transects were in height vertically, with ten plots arranged equidistantly 20 m apart from the lower plot to the higher. The latitudinal transects were in length along the river channel, and ten plots were spaced at a distance of 100 m evenly (Figure 2). Plots were 2 m × 2 m squared. All fern species in the sampling sites were investigated and nomenclature following Flora Yunnanica (Wuet al ., 2006).
Table 1. Location, altitude and circumstance, and orient of each transect