Water-use efficiency (WUE) and the stoichiometry of plant-soil carbon (C), nitrogen (N), and phosphorus (P) are key indicators of plant growth, while stand quality is an important index for evaluating afforestation. Yet it remains unclear how WUE and stoichiometric characteristics respond to changes in stand quality in desert ecosystems. To that end, we studied the community characteristics of sand-fixing Caragana korshinskii stands differing in age (planted 10, 30, 50, and 70 years ago) in Mu Us Sandy Land, China, and measured their leaf water use efficiency (WUE) and leaf-soil C:N:P stoichiometry. The relations among the stand quality index, leaf WUE, and plant-soil stoichiometry were analyzed. After 70 years, WUE was at its lowest level, but only significantly lower than that of a 10-year-old C. korshinskii stand. Afforestation years had differential effects on C, N, and P nutrients and their stoichiometric characteristics in leaves and soil. For soil, its total P barely increased. Irrespective of stand age, the N:P ratio of leaves was > 16, which suggests P is the main factor limiting the development of C. korshinskii plantations. Notably, WUE decreased significantly as the stand quality index increased while soil stoichiometry responded more strongly than plant stoichiometry. These results can guide investigations into the role of C. korshinskii stands in plant and soil recovery effects, providing a scientific basis to evaluate the rational use of C. korshinskii sand-fixing forest in afforestation.

Leaf anatomical traits can reflect plant adaptation to environmental changes. However, whether the trade-offs among leaf anatomical traits can reflect the strategies spectrum of plant response to environmental changes and the strategic spectrum will shift with altitudes are not clear. In this study, 286 plant species from 19 altitudinal gradients from 1050 m to 3070 m on the eastern Tibetan Plateau were selected and 16 anatomical characters of blade, mesophyll and midrib were measured. The strategic and strategic spectra of leaf anatomical trait formation were by principal components analysis, followed by generalized additive models of the strategic spectra with shift in elevation to test the shift of strategy spectra along altitudes. Our results showed that the midrib xylem thickness of woody increased with increasing altitude, while other traits decreased; the upper and lower epidermis width, midrib parenchyma cell thickness and midrib lower epidermis cell thickness of herb increased with increasing altitudes, while other traits decreased. Blade strategic spectrum (BES), blade and mesophyll strategic spectrum (BMSS) and midrib strategic spectrum (MSS) were formed in the tissue of leaves, and the score of principal component one (PC1) was not significant between herbs and woody plants ( P>0.05).  There were mainly formed the spectrum of conservation and support strategies and the spectrum of resource acquisition and consumption, etc. With increasing altitudes, the habitat tended to become unsuitable for plant growth and the resources available to plants are reduced, plants shift from a “invest-fast-reap” acquisition strategy to a “invest-slow-reap” conservative strategy.