Drought intensification increases extinction risk in the recalcitrant-seeded oak Quercus thorelii in the Indo-Burma biodiversity hotspot.
8 affiliations
- 1State Key Laboratory of Vegetation Structure, Function and Construction (VegLab); Ministry of Education Key Laboratory for Transboundary Ecosecurity of Southwest China; Yunnan Key Laboratory of Biological Adaptation, Conservation and Utilization; School of Ecology and Environmental Science, Yunnan University, Kunming, Yunnan, 650500, China.
- 2Germplasm Bank of Wild Species, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan, 650201, China.
- 3The key laboratory of Rare and Endangered Forest Plants of National Forestry and Grassland Administration & the Key Laboratory for Silviculture and Forest Resources Development of Yunnan Province, Yunnan, Academy of Forestry and Grassland, Kunming, Yunnan, 650201, China.
- 4Southeastern Center for Conservation, Atlanta Botanical Garden, Atlanta, GA, 30309, USA.
- 5Germplasm Bank of Wild Species, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan, 650201, China. [email protected].
- 6State Key Laboratory of Vegetation Structure, Function and Construction (VegLab); Ministry of Education Key Laboratory for Transboundary Ecosecurity of Southwest China; Yunnan Key Laboratory of Biological Adaptation, Conservation and Utilization; School of Ecology and Environmental Science, Yunnan University, Kunming, Yunnan, 650500, China. [email protected].
- 7The key laboratory of Rare and Endangered Forest Plants of National Forestry and Grassland Administration & the Key Laboratory for Silviculture and Forest Resources Development of Yunnan Province, Yunnan, Academy of Forestry and Grassland, Kunming, Yunnan, 650201, China. [email protected].
- 8CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan, 666303, China. [email protected].
Abstract
Background
Escalating anthropogenic disturbance and climate change are increasing extinction risks in the Indo-Burman region, yet the mechanisms driving rarity in many threatened trees remain poorly understood. Quercus thorelii, a low-elevation evergreen oak with only 11 known occurrences, exemplifies this pattern of rarity and vulnerability. This study combined seed-to-seedling trait assays with species distribution modeling (SDM) to identify the physiological and environmental mechanisms underlying its rarity. We assessed seed desiccation sensitivity, germination dynamics, and early seedling tolerance to drought and predation. We then identified key environmental factors influencing current habitat suitability and projected its future distribution under climate change scenarios.Results
Q. thorelii seeds are dispersed during the dry season but are highly desiccation-sensitive, with a broad germination temperature range and high tolerance to predation, suggesting that desiccation may be a primary constraint on seedling recruitment. Although its seeds germinate rapidly, thereby reducing exposure to drought, their large size restricts dispersal into moist microhabitats essential for successful germination. Despite a sequential seedling establishment strategy characterized by elongated cotyledonary petioles that position the embryo deeper in the soil, rapid allocation of cotyledon reserves to promote early taproot development, and temperature-regulated epicotyl physiological dormancy synchronized with the rainy season, successful recruitment remains constrained by seed desiccation. Habitat suitability for Q. thorelii was influenced more strongly by precipitation than by other environmental variables, including anthropogenic disturbance, highlighting precipitation as the dominant environmental predictor of its distribution. Under all future scenarios, total suitable habitat is projected to decline by > 80%, with only ~ 1% of future refugia located within protected areas. Based on these findings, Q. thorelii warrants reassessment as Critically Endangered under IUCN criteria. Assisted germination and reintroduction into climatically suitable refugia represent practical conservation strategies.Conclusions
Our findings highlight the exceptional vulnerability of recalcitrant-seeded trees to increasing drought and demonstrate how seed biology shapes extinction risk under climate change.
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BibTeX
@article{tu2026drought,
title = {{Drought intensification increases extinction risk in the recalcitrant-seeded oak Quercus thorelii in the Indo-Burma biodiversity hotspot.}},
author = {Yu Tu and Vyan and Hugh W Pritchard and Lin Lin and Qiansheng Li and Hongying Chen and Min Deng},
journal = {BMC plant biology},
year = {2026},
month = aug,
doi = {10.1186/s12870-026-09653-w},
url = {https://europepmc.org/article/MED/42958039},
note = {CC BY-NC-ND},
}
RIS
TY - JOUR
TI - Drought intensification increases extinction risk in the recalcitrant-seeded oak Quercus thorelii in the Indo-Burma biodiversity hotspot.
AU - Yu Tu
AU - Vyan
AU - Hugh W Pritchard
AU - Lin Lin
AU - Qiansheng Li
AU - Hongying Chen
AU - Min Deng
PY - 2026
DA - 2026/08/03
JO - BMC plant biology
DO - 10.1186/s12870-026-09653-w
UR - https://europepmc.org/article/MED/42958039
AB - Background Escalating anthropogenic disturbance and climate change are increasing extinction risks in the Indo-Burman region, yet the mechanisms driving rarity in many threatened trees remain poorly understood. Quercus thorelii, a low-elevation evergreen oak with only 11 known occurrences, exemplifies this pattern of rarity and vulnerability. This study combined seed-to-seedling trait assays with species distribution modeling (SDM) to identify the physiological and environmental mechanisms underlying its rarity. We assessed seed desiccation sensitivity, germination dynamics, and early seedling tolerance to drought and predation. We then identified key environmental factors influencing current habitat suitability and projected its future distribution under climate change scenarios.Results Q. thorelii seeds are dispersed during the dry season but are highly desiccation-sensitive, with a broad germination temperature range and high tolerance to predation, suggesting that desiccation may be a primary constraint on seedling recruitment. Although its seeds germinate rapidly, thereby reducing exposure to drought, their large size restricts dispersal into moist microhabitats essential for successful germination. Despite a sequential seedling establishment strategy characterized by elongated cotyledonary petioles that position the embryo deeper in the soil, rapid allocation of cotyledon reserves to promote early taproot development, and temperature-regulated epicotyl physiological dormancy synchronized with the rainy season, successful recruitment remains constrained by seed desiccation. Habitat suitability for Q. thorelii was influenced more strongly by precipitation than by other environmental variables, including anthropogenic disturbance, highlighting precipitation as the dominant environmental predictor of its distribution. Under all future scenarios, total suitable habitat is projected to decline by > 80%, with only ~ 1% of future refugia located within protected areas. Based on these findings, Q. thorelii warrants reassessment as Critically Endangered under IUCN criteria. Assisted germination and reintroduction into climatically suitable refugia represent practical conservation strategies.Conclusions Our findings highlight the exceptional vulnerability of recalcitrant-seeded trees to increasing drought and demonstrate how seed biology shapes extinction risk under climate change.
SN - 1471-2229
ER -