Autotoxicity as a cause for natural regeneration failure in<i>Nyssa yunnanensis</i>and its implications for conservation

Zhang, Shanshan; Fu-qiang, Shi; Yang, Wanqin; Zhen-yong, Xiang; Kang, Hongmei; Duan, Zongliang

doi:10.1080/07929978.2015.1064630

Cited by 20 publications

(9 citation statements)

References 67 publications

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“…yunnanensis seedlings, especially when autotoxicity is concerned. According to Zhang et al [ 30 ], the autotoxic effects of N . yunnanensis might be concentrated under lower water potential conditions, thereby further hindering seed germination and seedling establishment.…”

Section: Discussionmentioning

confidence: 99%

“…They were stored in a cold room (4°C) after drying at room temperature (20°C). In order to exclude the autotoxic effects of its pericarp, a seed-washing treatment was employed to break dormancy [ 30 ]. Before sowing, the seeds were selected based on size homogeneity and surface-sterilized to prevent decay by soaking in 5% Na-hypochlorite for five min, followed by washing five times with distilled water.…”

Section: Methodsmentioning

confidence: 99%

“…Nyssa yunnanensis is a critically endangered and range-restricted tree species known only from two small populations, consisting of five and three mature individuals respectively. It distributed in ravine rainforest and remained in the tropical forest region of southern Yunnan Province, southwestern China [ 29 – 30 ]. It has been delineated on the China's Flora Red List [ 31 ] and the IUCN Red List as a Critically Endangered Species.…”

Section: Introductionmentioning

confidence: 99%

“…yunnanensis [ 33 – 36 ] have not identified any physiological constraints to regeneration. However, Zhang et al [ 30 ] proposed that regeneration in N . yunnanensis may be negatively impacted by its autotoxicity.…”

Section: Introductionmentioning

confidence: 99%

“…Significantly, meteorological records since 1960 have indicated that annual precipitation in the natural distribution areas of N . yunnanensis has decreased significantly during the past half century [ 30 ]. However, the impacts of drought stress on the suppression of N .…”

Section: Introductionmentioning

confidence: 99%

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Climate change-induced water stress suppresses the regeneration of the critically endangered forest tree Nyssa yunnanensis

2017

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Climatic change-induced water stress has been found to threaten the viability of trees, especially endangered species, through inhibiting their recruitment. Nyssa yunnanensis, a plant species with extremely small populations (PSESP), consists of only two small populations of eight mature individuals remaining in southwestern China. In order to determine the barriers to regeneration, both in situ and laboratory experiments were performed to examine the critical factors hindering seed germination and seedling establishment. The results of in situ field experiments demonstrated that soil water potentials lower than -5.40 MPa (experienced in December) had significantly inhibitory effects on seedling survival, and all seedlings perished at a soil water potential of -5.60 MPa (January). Laboratory experiments verified that N. yunnanensis seedlings could not survive at a 20% PEG 6000 concentration (-5.34 MPa) or 1/5 water-holding capacity (WHC; -5.64 MPa), and seed germination was inhibited in the field from September (-1.10 MPa) to November (-4.30 MPa). Our results suggested that soil water potentials between -5.34 and -5.64 MPa constituted the range of soil water potentials in which N. yunnanensis seedlings could not survive. In addition to water deficit, intensified autotoxicity, which is concentration-dependent, resulted in lower seed germination and seedling survival. Thus, seed establishment was probably simultaneously impacted by water deficit and aggravated autotoxicity. Meteorological records from the natural distribution areas of N. yunnanensis indicated that mean annual rainfall and relative humidity have declined by 21.7% and 6.3% respectively over past 55 years, while the temperature has increased by 6.0%. Climate change-induced drought, along with a poor resistance and adaptability to drought stress, has severely impacted the natural regeneration of N. yunnanensis. In conclusion, climate change-induced drought has been implicated as a regulating factor in the natural regeneration of N. yunnanensis through suppressing seed germination and screening out seedlings in the dry season. Based on the experimental findings, habitat restoration and microclimate improvement should both be highlighted in the conservation of this particular plant species.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%