Distribution Pattern of Gymnosperms' Richness in Nepal: Effect of Environmental Constrains along Elevational Gradients.

Bikram Pandey,Kaiwen Pan,Kaiwen Pan,Arbindra Timilsina,Arbindra Timilsina,Arbindra Timilsina,Arbindra Timilsina,Salina Tripathi,Mohammed A Dakhil,Mohammed A Dakhil,Mohammed A Dakhil,Mohammed A Dakhil,Nirdesh Nepal,Nirdesh Nepal,Nirdesh Nepal,Saroj Koirala,Saroj Koirala,Saroj Koirala,Meta F Justine,Meta F Justine,Meta F Justine,Kamal B Nepali

doi:10.3390/plants9050625

Abstract

Understanding the pattern of species distribution and the underlying mechanism is essential for conservation planning. Several climatic variables determine the species diversity, and the dependency of species on climate motivates ecologists and bio-geographers to explain the richness patterns along with elevation and environmental correlates. We used interpolated elevational distribution data to examine the relative importance of climatic variables in determining the species richness pattern of 26 species of gymnosperms in the longest elevation gradients in the world. Thirteen environmental variables were divided into three predictors set representing each hypothesis model (energy-water, physical-tolerance, and climatic-seasonality); to explain the species richness pattern of gymnosperms along the elevational gradient. We performed generalized linear models and variation partitioning to evaluate the relevant role of environmental variables on species richness patterns. Our findings showed that the gymnosperms’ richness formed a hump-shaped distribution pattern. The individual effect of energy-water predictor set was identified as the primary determinant of species richness. While, the joint effects of energy-water and physical-tolerance predictors have explained highest variations in gymnosperm distribution. The multiple environmental indicators are essential drivers of species distribution and have direct implications in understanding the effect of climate change on the species richness pattern.

Highlights

The elevational gradient of species richness is an ecological phenomenon widely used in describing the patterns of species richness at small geographical areas or the landscape level [1]
All our results corroborate previous findings and support that species richness pattern of any taxa in mountain gradients is determined by environmental variables [7,20], this is the first comprehensive work that prioritized the distribution of gymnosperms along elevation gradients in Nepal
(i) the present study identifies the importance of environmental factors in determining the species richness pattern of gymnosperms in Nepal along the elevation gradients, and (ii) elevational gradients of species distribution will be a baseline for comparing the range shift of a population and prioritized in the conservation

Summary

Introduction

The elevational gradient of species richness is an ecological phenomenon widely used in describing the patterns of species richness at small geographical areas or the landscape level [1]. At its core, is a substantial factor that regulates the distribution of organisms in the mountains; findings have reported that there is a strong variation in climatic conditions along elevational gradients [3,4]. The fact that makes mountains an ideal area for investigating the species richness pattern is the variation in the environment and topography within a small geographical region [1,3,5,6,7]. Most studies conducted in the mountains around the globe have reported the hump-shape or the high number of species at the mid-elevation pattern [2,8,10,11,15,17,18,19,20,21,22,23,24,25]

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