Contrasting Gymnosperm Diversity Across an Elevation Gradient in the Ecoregion of China: The Role of Temperature and Productivity

Abstract

The species richness–climate relationship is a significant concept in determining the richness patterns and predicting the cause of its distribution. The distribution range of species and climatic variables along elevation have been used in evaluating the elevational diversity gradients (EDG). However, the species richness of gymnosperms along elevation and its driving factors in large geographic areas are still unknown. Here, we aimed at evaluating the EDG of gymnosperms in the ecoregions of China. We divided the geographical region of China into 34 ecoregions and determine the richness pattern of gymnosperm taxa along elevation gradients. We demonstrated the richness patterns of the 237-gymnosperm (219 threatened, 112 endemic, 189 trees, and 48 shrubs) taxa, roughly distributed between 0 and 5,300 m (above sea level) in China. As possible determinants of richness patterns, annual mean temperature (TEMP), annual precipitation (PPT), potential evapotranspiration (PET), net primary productivity (SNPP), aridity index (AI), temperature seasonality (TS), and precipitation seasonality (PS) are the major predictor variables driving the EDG in plants. We used the species interpolation method to determine the species richness at each elevation band. To evaluate the richness pattern of gymnosperms in an ecoregion, generalized additive modeling and structural equation modeling were performed. The ecoregions in the southern part of China are rich in gymnosperm species, where three distinct richness patterns—(i) hump-shaped, (ii) monotonic increase, and (iii) monotonic decline—were noticed in China. All climatic variables have a significant effect on the richness pattern of gymnosperms; however, TEMP, SNPP, TS, and PS explained the highest deviance in diversity-rich ecoregions of China. Our results suggests that the highest number of gymnosperms species was found in the southwestern and Taiwan regions of China distributed at the 1,600- and 2,800-m elevation bands. These regions could be under severe stress in the near future due to expected changes in precipitation pattern and increase of temperature due to climate change. Thus, our study provided evidence of the species–climate relationship that can support the understanding of future conservation planning of gymnosperms.

Precipitation and potential evapotranspiration determine the distribution patterns of threatened plant species in Sichuan Province, China

“…In the present study, a positive relationship was found between threatened plant species and temperature. This finding is consistent with that of previous studies on threatened species in protected areas of Finland 48 and threatened gymnosperms in China 38 . However, the temperature was the least expressed variable in the richness pattern of orchids 49 , Rhododendron 50 , and Gesneriaceae 29 in China.…”

“…PET was used as a surrogate of net available energy estimated using temperature, water, and solar radiation 44 . In previous studies, PET explained 33.87% deviance in the richness pattern of vascular plants in Nepal 11 , 35.6% in seeded plants in the Western Himalaya 45 , 48% deviance in woody plant species in the Iberian Peninsula 46 , and 75% in gymnosperm richness in Southwestern China 38 . Therefore, the Central region of Sichuan harboring a high diversity of threatened plant species could be directly related to the high PET of the region (Fig.…”

“…Namjagbarwa region, China 35 , Mt. Kenya, Kenya 36 , Los Tuxtlas, Mexico 37 , and the Himalayas also showed a hump-shaped species richness pattern of plant species along elevation gradients 11 , 14 , 38 , 39 . These regions resemble similar climatic and topographic characteristics with that of Sichuan, therefore, the findings of the present study agreed with the findings of most studies in the mountainous region around the world.…”

“…Five variables, namely, three climatic, one habitat heterogeneity, and one disturbance variable were used as a possible determinants of the large-scale pattern of threatened plant species in Sichuan. The climatic variables include the mean annual temperature (MAT), mean annual precipitation (MAP), and PET 6 , 8 , 11 , 29 , 38 , 45 , 51 . HHET was used as a range of elevation 18 .…”

Distribution and Assemblage Variation of Benthic Macroinvertebrates: A Uniform Elevational Biodiversity Pattern Among Different Groups?

“…Whatever the distribution pattern has shown, climatic, area, and local environmental variables are the most cited driving factors (Lomolino, 2001;Hawkins et al, 2003;McCain, 2004McCain, , 2007McCain, , 2009Birrell et al, 2020). Besides those explanatory factors above, biodiversity distribution along elevational gradient also varies due to specific taxonomic groups (Bryant et al, 2008;Kessler et al, 2011;Nunes et al, 2020;Pandey et al, 2021). Therefore, it is necessary to study elevational biodiversity patterns on different taxonomic groups.…”