Allocation of limiting resources, such as nutrients, is an important adaptation strategy for plants. Plants may allocate different nutrients within a specific organ or the same nutrient among different organs. In this study, we investigated the allocation strategies of nitrogen (N) and phosphorus (P) in leaves, stems and roots of 126 shrub species from 172 shrubland communities in Northern China using scaling analyses. Results showed that N and P have different scaling relationships among plant organs. The scaling relationships of N concentration across different plant organs tended to be allometric between leaves and non-leaf organs, and isometric between non-leaf organs. Whilst the scaling relationships of P concentration tended to be allometric between roots and non-root organs, and isometric between non-root organs. In arid environments, plant tend to have higher nutrient concentration in leaves at given root or stem nutrient concentration. Evolutionary history affected the scaling relationships of N concentration slightly, but not affected those of P concentration. Despite fairly consistent nutrients allocation strategies existed in independently evolving lineages, evolutionary history and environments still led to variations on these strategies.

No abstract

No abstract

No abstract

[1] Organic carbon storage in agricultural soils plays a key role in the terrestrial ecosystem carbon cycle. Paddy soils support important croplands in many parts of the world, especially in Asia. A thorough understanding of organic carbon storage in Chinese paddy soils would be helpful to both greenhouse gases emission and carbon sequestration studies. This paper examines soil organic carbon density (SOCD) and storage (SOCS) of paddy soils in China using the newly compiled 1:1,000,000 digital soil map of China as well as data from 1490 paddy soil profiles. Results show that paddy soils in China cover about 45.7 M ha, nearly 1.5 times more than the results of other studies. In China, the mean SOCD of paddy soils at a depth of 0-100 cm is 111.4 t C ha À1 , with a SOCS of 5.1 Pg. These results are 66-75% higher than studies from other scientists. However, the mean SOCD of paddy soils from 0 to 20 cm is 37.6 t C ha À1 , with a SOCS of 1.7 Pg, which is 89% higher than studies from other scientists.

No abstract

No abstract

Three-dimensional (3D) hierarchical self-supported NiCo 2 O 4 /carbon nanotubes/nickel foam (NiCo 2 O 4 /CNT/NF) electrode has been developed by electrodepositing NiCo layered double hydroxides (LDH) on self-supported CNT layer grown on macroporous NF substrate followed by a simple post-annealing process. The resulting 3D hierarchical self-supported NiCo 2 O 4 /CNT/NF electrode delivered high specific capacitances of 1533 F g -1 and 1335 F g -1 at current densities of 3 A g -1 and 30 A g -1 , respectively, vastly superior to those of NiCo 2 O 4 /NF electrode at same current density.The NiCo 2 O 4 /CNT/NF electrode also had good cycling stability and showed 102% initial capacitance retention after 2500 cycles at progressively varying current densities. The performance of NiCo 2 O 4 /CNT/NF electrode was further evaluated by two-electrode asymmetric supercapacitor device. The asymmetric device delivered a high energy density of 48.3 Wh kg -1 at a power density of 799.9 W kg -1 and still remained an energy density of 17.1 Wh kg -1 as power density increase up to 7995 W kg -1 . Remarkably, the asymmetric device also exhibited good cycling stability with capacitance retention of 78.9% after 2000 cycles at current density of 2 A g -1 ,indicating the promising applications in supercapacitors. Results of this study also provide an alternative strategy for constructing high performance supercapacitor electrode with high specific capacitance, good rate capability and cycling stability.