Abstract
It is well-known that drought has considerable effects on plant traits from leaf to ecosystem scales; however, little is known about the relative contributions of various traits within or between tree species in determining the plant’s sensitivity or the tolerance to drought under field conditions. We conducted a field throughfall exclusion experiment to simulate short-term drought (∼67% throughfall exclusion during the dry season from October to March) and prolonged drought (∼67% throughfall exclusion prolonging the dry season from October to May) and to understand the effects of drought on two dominant tree species (Michelia macclurei and Schima superba) in subtropical forests of southern China. The morphological, physiological, and nutritional responses of the two species to the two types of drought were determined. There were significantly different morphological (leaf max length, max width, leaf mass per area), physiological (leaf proline) and nutritional (P, S, N, K, Ca, Mg) responses by M. macclurei and S. superba to prolonged drought. Comparison between the drought treatments for each species indicated that the trees responded species–specifically to the short-term and prolonged drought, with S. superba exhibiting larger plasticity and higher adaption than M. macclurei. M. macclurei responded more sensitively to prolonged drought in terms of morphology, proline content, and nutritional traits and to short-term drought with regard to soluble sugars content. The differential species-specific responses to drought will allow us to estimate the changes in dominant trees in subtropical forests of China that have experienced a decade’s worth of annual seasonal drought.
Highlights
Both global climate models (Fischer et al, 2013; Singh et al, 2013) and observed precipitation trends (Marvel and Bonfils, 2013) have revealed that climate change is intensifying the hydrologic cycle and is expected to increase the variation in precipitation regimes worldwide
Prior to the throughfall exclusion, there were no significant differences in the leaf traits (L, W, length to maximum width (L/W), and LMA) among the treatments in either S. superba or M. macclurei (Figure 1)
For S. superba, the two types of drought had no significant effects on morphological traits except that the extended dry season (ED) treatment notably decreased the leaf width
Summary
Both global climate models (Fischer et al, 2013; Singh et al, 2013) and observed precipitation trends (Marvel and Bonfils, 2013) have revealed that climate change is intensifying the hydrologic cycle and is expected to increase the variation in precipitation regimes worldwide. The variation in precipitation patterns at both regional and global scales will occur with great spatio–temporal. The amount of rainfall is predicted to increase at mid– and high–latitudes and to decrease at low latitudes, with notable changes in seasonal intensity and frequency (Greve et al, 2014). E.g., in south China, it will be drier in the dry season and wetter in the wet season with ongoing climate change (Zhou et al, 2013). The dry season has lasted longer and the wet season has had more intensive rainstorms in the last 10 years, despite the total annual precipitation amount not changing significantly, in some regions of south China (Zhou et al, 2011). Physiological properties of plant species (Coe and Sparks, 2014); encroachment of woody plants (Kulmatiski and Beard, 2013); tree mortality (Anderegg et al, 2015); forest structure (Hoeppner and Dukes, 2012); evapotranspiration dynamics (RazYaseef et al, 2012); plant community composition (Cleland et al, 2013); biomass and net primary productivity (Hovenden et al, 2014; Wilcox et al, 2015); litterfall (Travers and Eldridge, 2013); the availability, uptake, transport, and accumulation of plant nutrients (including N, P, S, K, Ca, and Mg) (Rouphael et al, 2012); soil respiration (Thomey et al, 2011); and soil microbial communities (Zeglin et al, 2013), have been well documented to be affected by the rainfall patterns
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