While horizontal gradients of biodiversity have been examined extensively in the past, vertical diversity gradients (elevation, water depth) are attracting increasing attention. We compiled data from 443 elevational gradients involving diverse organisms worldwide to investigate how elevational diversity patterns may vary between the Northern and Southern hemispheres and across latitudes. Our results show that most elevational diversity curves are positively skewed (maximum diversity below the middle of the gradient) and the elevation of the peak in diversity increases with the elevation of lower sampling limits and to a lesser extent with upper limit. Mountains with greater elevational extents, and taxonomic groups that are more inclusive, show proportionally more unimodal patterns whereas other ranges and taxa show highly variable gradients. The two hemispheres share some interesting similarities but also remarkable differences, likely reflecting differences in landmass and mountain configurations. Different taxonomic groups exhibit diversity peaks at different elevations, probably reflecting both physical and physiological constraints. Montane regions harbor more than half of the world's biodiversity hotspots and recent research on biodiversity patterns has been notable for an increase in research on elevational patterns on mountains 1 . Mountains provide unique opportunities as 'natural experiments' for testing ecological theories and in particular for studying the effects of climate change because they present gradients in key abiotic features such as temperature and available moisture. Recent efforts have generated interesting and sometimes conflicting results, and debates on the generality of the frequently observed unimodal (''hump-shaped'' 2 ) curves and the underlying mechanisms have not been fully resolved. Indeed, despite increased research in this area in recent years, employing markedly improved techniques and greater sampling intensity, much inconsistency and debate remains both in pattern description and interpretation. For example, surprisingly little effort has targeted how elevational diversity patterns might vary in the Northern and Southern hemispheres and across latitudinal zones [3][4][5][6][7] . To tackle these problems, detailed comparisons are needed over distinct (replicate) elevational gradients across the globe.The upper elevational limit for phanerogams varies as a function of latitude and generally reflects limits to physiologic tolerance 1 . Moreover, similar elevational ranges in different regions are likely to exhibit different underlying gradients 8 , reflecting regional climate and geography; cold-temperate mountains lack the warm climate characteristic of lower elevations at lower latitudes, and temperatures at a tropical treeline might reflect those at the base of cold-temperate mountains. Additionally, the effect of aspect is greatly reduced on tropical mountains relative to temperate ones. As a result of these latitudinal differences, structurally identical mountains locate...

The role of urban parks in improving public health has been analyzed in the context of urban design in developed countries, but has seldom been considered in developing countries such as China. Previous studies have found positive correlations between parks and residents' physical activity and mental health status. In this study, we conducted a questionnaire survey to investigate respondents' physical activity status and its relationship with urban parks. The impact of different activities engaged in during park use on positive mental health was examined. The average physical activity level of the sample was 92.7 min of moderate to vigorous physical activity per day. Park users were more active in all forms of physical activity, except transport walking, than non-users. The presence of a park within 500 m from home and park use were significantly associated with total physical activity. Physical activity in parks significantly restored visitors' moods and energy levels, and interaction with nature brought mental health benefits in terms of relaxation and self-perceived confidence. Overall, this study found a positive correlation of urban parks with public physical activity and positive mental health benefits. However, further research is needed to improve the understanding of this relationship in the context of China.

No abstract