Advances in rarity studies at the community level have brought new insights into community assembly. However, biological assemblages of rare species, such as tree communities, have received less attention. Moreover, almost no study has explicitly examined the response difference between rare and common species to niche and neutral variables. 

Researchers from Xishuangbanna Tropical Botanical Garden (XTBG) conducted a study to explore the relative contributions difference between niche and neutral processes to rare and common species by the topographic variables and distance‐based Moran eigenvector maps (db‐MEMs) . They used eight plots range in latitude from 9.15° N to 42.38° N in the worldwide network of forest research plots. 

The researchers calculated contribution ratio (CR) between space and topography to quantify their relative importance. They employed Kendall’s rank correlation to determine the relation between CR and commonness. 

They discovered that the response of rare and common tree species to topography and/or space are different from each other in tropical, subtropical and temperate forests. 

Specifically, the relative importance of space compared to topography increased with abundance. Space was identified as a predominant factor for tree assembly regardless of species abundance. At local scale, elevational ranges had no effect on the contribution by space/topography. The relations were cell‐size dependent. 

“Our results indicate that the mechanisms influencing rare and common tree species assembly differ significantly. As the relative importance of space to topography increases from rare to common species across forests, thus they assemble differently”, said Dr. HU Yuehua, the first author of the study. 

The study entitled “The relative importance of space compared to topography increases from rare to common tree species across latitude” has been published online in Journal of Biogeography.  

Contact 

HU Yuehua  Ph.D 

Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan 666303, China