Predicted distribution of Michelia lacei
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FIG. 6 Changes in future habitat suitability for Michelia lacei relative to current habitat suitability in Yunnan Province, China, under different Shared Socioeconomic Pathways. Expansion indicates that the future habitat is more suitable than it is at present, no change (unsuitable) indicates that the habitat is suitable neither in the future nor at present, stability (suitable) indicates that the habitat is suitable both now and in the future, and contraction indicates that the habitat is suitable at present but will not be suitable in the future. (Readers of the printed journal are referred to the online article for a colour version of this figure.)
predicted using species distribution models is often wider than the actual distribution range of a species (Cai et al., 2022; Yan & Zhang, 2022). When determining the distribu- tion of threatened plant species, additional factors such as pollinator numbers, self-breeding, seed dispersal, commu- nity competition, habitat destruction, reduced population and habitat fragmentation need to be taken into account. These, amongst other factors, all have a greater impact on the distribution of highly threatened species than on those less threatened (Chen, 2017).
Changes in habitat suitability under future climate change scenarios
Based on our modelling, we predict the distribution of M. lacei will gradually decrease in the future, with the highly suitable habitat shrinking in size as the climate warms. This is consistent with previous research on the distribution patterns of threatened species in south-eastern Yunnan (Cai, 2020). In the four future periods we modelled, highly and moderately suitable areas were predicted to become areas of low suitability as temperatures change. In particular, the moderately suitable areas in Xishuangbanna were pre- dicted to decline to almost zero. Under the worst-case scen- ario (pathway SSP585 during 2061–2080), the moderately and highly suitable habitats were predicted to be restricted to Dehong in western Yunnan, with a few small patches in Honghe and Wenshan in south-eastern Yunnan. In general,
rising temperatures will promote the migration of plant po- pulations into boreal forests (Boisvert-Marsh & de Blois, 2021; Behera et al., 2023). Such increases in temperature are likely to be accompanied by the movement of mountain plants to higher elevations. As a Plant Species with Extremely Small Populations, the migratory ability of M. lacei is limited compared to other,more widespread species, and its suitable habitat is gradually being reduced.
Protection and management of M. lacei
Some of the M. lacei individuals we recorded are growing in fengshui forests, preserved by local communities fromnearby villages who believe the forests can bring prosperity and good fortune (Coggins & Minor, 2018). Two large individuals growing near a village have been listed as ancient trees by the local forestry bureau, and some individuals are located in a nature reserve, providing some level of protection. However,we foundmost individuals growing near roadsides, fields or riverbanks, with no protective measures. These individuals are at high risk of being cut down or otherwise destroyed. We found only three seedlings during our field studies, and can infer from this that wild populations are struggling to reproduce naturally. We found these seedlings in a vegetable field, by a roadside and in farmland where black cardomom Amomum tsaoko was being cultivated. During our 2022 surveys of wild M. lacei populations we found only four adult plants that had fruited.
Oryx, 2024, 58(5), 631–640 © The Author(s), 2024. Published by Cambridge University Press on behalf of Fauna & Flora International doi:10.1017/S0030605323001783
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