Energy–water and seasonal variations in climate underlie the spatial distribution patterns of gymnosperm species richness in China

Abstract

Studying the pattern of species richness is crucial in understanding the diversity and distribution of organisms in the earth. Climate and human influences are the major driving factors that directly influence the large‐scale distributions of plant species, including gymnosperms. Understanding how gymnosperms respond to climate, topography, and human‐induced changes is useful in predicting the impacts of global change. Here, we attempt to evaluate how climatic and human‐induced processes could affect the spatial richness patterns of gymnosperms in China. Initially, we divided a map of the country into grid cells of 50 × 50 km2 spatial resolution and plotted the geographical coordinate distribution occurrence of 236 native gymnosperm taxa. The gymnosperm taxa were separated into three response variables: (a) all species, (b) endemic species, and (c) nonendemic species, based on their distribution. The species richness patterns of these response variables to four predictor sets were also evaluated: (a) energy–water, (b) climatic seasonality, (c) habitat heterogeneity, and (d) human influences. We performed generalized linear models (GLMs) and variation partitioning analyses to determine the effect of predictors on spatial richness patterns. The results showed that the distribution pattern of species richness was highest in the southwestern mountainous area and Taiwan in China. We found a significant relationship between the predictor variable set and species richness pattern. Further, our findings provide evidence that climatic seasonality is the most important factor in explaining distinct fractions of variations in the species richness patterns of all studied response variables. Moreover, it was found that energy–water was the best predictor set to determine the richness pattern of all species and endemic species, while habitat heterogeneity has a better influence on nonendemic species. Therefore, we conclude that with the current climate fluctuations as a result of climate change and increasing human activities, gymnosperms might face a high risk of extinction.

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

“…In general, the large geographic area could support more species and vice versa (Rosenzweig, 1995;Körner, 2003). Therefore, to explain the species richness patterns in plants, several hypotheses have been proposed, which concern the primary productivity (Bhattarai and Vetaas, 2003;Vetaas et al, 2019), temperature (Hawkins et al, 2003;Vetaas et al, 2019), availability of water (rainfall/precipitation) (Currie and Paquin, 1987;Hawkins et al, 2003;Kluge et al, 2017), potential evapotranspiration (Bhattarai et al, 2004;Vetaas and Ferrer-Castán, 2008;Geng et al, 2019), and seasonality (Gao and Liu, 2018;Pandey et al, 2020a).…”

“…On the other hand, climatic seasonality increases the level of tolerance in plant species and favors the wide spread of organisms. There are studies that support the use of temperature seasonality (TS) and precipitation seasonality (PS) in explaining the richness pattern of plant species, including gymnosperms (Gao and Liu, 2018;Pandey et al, 2020a). Finally, net primary productivity (NPP) is directly linked to biochemical oxidation processes (Rahbek et al, 2007;Vetaas et al, 2019).…”

“…China is one of the biodiversity hotspots of plant species on the earth, which can be proven by the presence of more than 25,000 species of flowering and non-flowering plants, including gymnosperms (Wu and Raven, 1999). There are 248 taxa of gymnosperms distributed in the ecoregions of China (Wu and Raven, 1999;Fang et al, 2011;Tang, 2015;You et al, 2017;Pandey et al, 2020a), where more than 80% are threatened, and around 50% are endemic species (Ying et al, 2004;Pandey et al, 2020a), demonstrating the hotspot of gymnosperm diversity. In this study, more attention was given to threatened and endemic gymnosperms because of their conservation priorities and geographical limitation, respectively (Vetaas and Grytnes, 2002;Ying et al, 2004;Kubota et al, 2015;Paudel et al, 2018).…”

“…On the other hand, endemic species are geographic range specific and are given more attention; however, little is known about the elevational pattern of endemic gymnosperms' distribution (Kubota et al, 2015). Moreover, southwest China and Taiwan are abundant in the diversity of gymnosperms (Pandey et al, 2020a). These regions are characterized by the presence of the mountain with an elevation range of more than 4,000 m. On the other hand, extreme and harsh climatic conditions in the North, Tibetan plateau, and Inner-Mongolian regions might be the limiting factor for the distribution of gymnosperms (Pandey et al, 2020a).…”

“…Moreover, southwest China and Taiwan are abundant in the diversity of gymnosperms (Pandey et al, 2020a). These regions are characterized by the presence of the mountain with an elevation range of more than 4,000 m. On the other hand, extreme and harsh climatic conditions in the North, Tibetan plateau, and Inner-Mongolian regions might be the limiting factor for the distribution of gymnosperms (Pandey et al, 2020a). Therefore, the ecoregions of China are suitable for the study on the EDG of gymnosperm species.…”