Hongguang Xiao

Variations in leaf functional traits among plant species grouped by growth and leaf types in Zhenjiang, China

Leaf functional traits are adaptations that enable plants to live under various environmental conditions. This study aims to determine the differences in leaf functional traits among plants grouped by growth habit, leaf life span, leaf lifestyle, leaf form, and origin. Specific leaf area (SLA) of perennial or evergreen species was lower than that of annual or deciduous species because longer-lived leaves of perennial or evergreen species require more investment in structural integrity and/or defense against disturbances, especially with any resource constraint. SLA of large individuals was lower than that of small individuals. The low SLA in large individuals can improve their response to changing light and water conditions because increasing plant height is advantageous for light competition, but it can also impose a cost in terms of structural support and water transport. Petioles of plants with compound leaves were significantly longer than those of simple leaves because branching is expensive in terms of gaining height. SLA of plants increased with increasing invasiveness accordingly, and SLA of invasive plants was higher than that of their native congeners because invasive plants should invest more biomass on leaf growth rather than leaf structures per unit area to achieve a higher growth rate. Overall, variation in leaf functional traits among different groups may play an adaptive role in the successful survival of plants under diverse environments because leaf functional traits can lead to pronounced effects on leaf function, especially the acquisition and use of light. Plant species with different growth and leaf traits balance resource acquisition and leaf construction to minimize trade-offs and achieve fitness advantages in their natural habitat.

Nitrogen Deposition Influences the Allelopathic Effect of an Invasive Plant on the Reproduction of a Native Plant: Solidago canadensis versus Pterocypsela laciniata

ABSTRACT This study aims to gain insights into the allelopathic effects (by using leaf extracts) of the notorious invasive Solidago canadensis L. on seed germination of the associated Pterocypsela laciniata (Houtt.) C. Shih under different nitrogen (N) forms added: inorganic (NO3--N and NH4+-N), organic (urea-N), and mixed N (a mixture of the three N forms at 1:1:1 ratio). Among the two used concentrations of S. canadensis leaf extracts the higher exhibited inhibitory allelopathic effects on seedling height and biomass, germination potential, germination index, and vigor index of P. laciniata. N demonstrated positive effects on seed germination of P. laciniata. The effects of mixed and organic N on the seedling biomass of P. laciniata were more pronounced than those of inorganic N and control treatment. The vigor index of P. laciniata under mixed N was significantly higher than those under single N form and control treatment. Thus, organic and mixed N showed higher ecological effects on seed germination of P. laciniata than inorganic and single N form. All N forms could alleviate the inhibitory allelopathic effects of S. canadensis on seed germination of P. laciniata. Overall, the inhibitory allelopathic impact of S. canadensis on seed germination of native species may be attenuated under increased and diverse N deposition, thus it could prevent its further invasion.

Insights into the Invasiveness of Non-Native Plants under Atmospheric Nitrogen Deposition

Many diseases in Africa such as malaria are known to be sensitive to climate factors there is a positive correlation between malaria, cholera and meningitis, and climatic elements. Regular limits of malaria allocation indicate that malaria could develop for several months in most areas of Sudan due to climate variables. The study found that the malaria cases related to temperature increasing was clearly recognized in the Northern State with 1.59% out of the state population. The highest endemic state was Blue Nile with 2.45% in the Rich Wet Savannah, and the lowest state of malaria infections was Western Darfur with 0.06% cases. The total of malaria infections in northern Sudan is 15.19% of 29 million population, the prevalence of malaria in southern Sudan was 24.5% of 9.5 million population (including 2004 and 2005 returnees) of those examined were infected. Whilst in Khartoum State the mean number of cases increased to reach 60869 in the study period 5.5 million of population as the largest inhibited state.