Climate change and human activities are strongly influencing the eco‐hydrological processes of the Chinese Loess Plateau. It is challenging to investigate the spatiotemporal changes of water and sediment yields and identify their potential causes. In this study, we used the annual runoff index (WI) and specific sediment yield (SSY) derived from 58 hydrological stations to quantify the changes and attempted to explain their potential causes. The WI exhibited significant (P < 0.05) decrease ranging from −0.1 to −2.6 mm yr−1 during 1957–2012 in 44 sub‐catchments. Similarly, the SSY in 52 sub‐catchments reduced in a range between −2.86 and −636 Mg km−2 yr−1. The region of Toudaoguai–Longmen has extremely high SSY ranging from 8000 to 41 000 Mg km−2 yr−1 during 1957–1969. Budget analysis suggested that the area of Lanzhou–Toudaoguai contributed limited sediment but extracted large amount of water. The areas with negative SSY were increasing and mainly distributed along the mainstream of the Yellow River. The Loess plateau was becoming drier and warmer since the 1950s, whereas the intensive human activities including water withdrawal, soil and water conservation projects and the operation of dams and reservoirs are the dominant factors for the decline in WI and SSY on the Loess Plateau. Copyright © 2016 John Wiley & Sons, Ltd.

a b s t r a c tHeavy metal-poisoning exerts the serious influence on crops growth, yield and quality. This research has focused on the impacts of HgCl 2 with different concentrations on the dynamic trends of photosynthesis, transpiration and water use efficiency (WUE) by using different wheat varieties as materials. The results showed that under 100 M HgCl 2 treatment, wheat leaf photosynthetic rate (Pn) and transpiration rate (Tr) exhibited significant changes, but photosynthetic characteristics presented no obvious regularity, and this kind of impact exerted the critical effects on different Hg 2+ concentrations. Similar changes sometimes appeared under low concentration and concentrations. WUE changed more regularly, and WUE of each wheat variety tended to drop after Hg 2+ treatments, except the individual concentration treatment. This change indicated that HgCl 2 treatment changed normal transpiration and photosynthesis, which led to the changes in leaf water use efficiency and related wheat eco-physiological parameters. All these results provide valuable information for establishing high-efficient stable agro-ecosystems in abiotic-stress area.

In order to find out if the inflorescences number variation has influences on the gender modification in plant species, we investigated the gender modification in a cultivated population of the monoecious species Sagittaria potamogetifolia. We also designed two nutrient levels to explore the impact of nutrient on gender modification in S. potamogetifolia. We found that the female and male flowers did not change with increasing plant size for each inflorescence at a low nutrient level. At a high nutrient level, the female flower numbers on each inflorescence did not increase with plant size; however, the male flower numbers had some positive correlation with the plant size. At the ramet level, the total male and female flower numbers increased with the plant size at both nutrient levels. The sex ratio (female to male flower ratio) decreased with the inflorescence numbers and the plant size (Midvein length). Although the nutrient variation had impact on the flower number production, it did not change the gender modification pattern. The high plasticity of inflorescence numbers, which caused the gender variation in S. potamogetifolia, and low plasticity of female and male flowers on a single inflorescence, indicates that the limited modification on gender in a single inflorescence may be compensated by inflorescence number variation at the ramet level.

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