Aims
The response pattern of terrestrial soil respiration to warming during non-growing seasons is a poorly understood phenomenon, though many believe that these warming effects are potentially significant. This study was conducted in a semiarid temperate steppe to examine the effects of warming during the non-growing seasons on soil respiration and the underlying mechanisms associated therewith.
Methods
This experiment was conducted in a semiarid temperate grassland and included 10 paired control and experimental plots. Experimental warming was achieved with open top chambers (OTCs) in October 2014. Soil respiration, soil temperature and soil moisture were measured several times monthly from November 2014 to April 2015 and from November 2015 to April 2016. Microbial biomass carbon (MBC), microbial biomass nitrogen (MBN) and available nitrogen content of soil were measured from 0 to 20 cm soil depth. Repeated measurement ANOVAs and paired-sample t tests were conducted to document the effect of warming, and the interactions between warming and time on the above variables. Simple regressions were employed to detect the underlying causality for the observed effects.
Important Findings
Soil respiration rate was 0.24 µmol m−2 s−1 in the control plots during the non-growing seasons, which was roughly 14.4% of total soil carbon flux observed during growing seasons. Across the two non-growing seasons, warming treatment significantly increased soil temperature and soil respiration by 1.48°C (P < 0.001) and 42.1% (P < 0.01), respectively, when compared with control plots. Warming slightly, but did not significantly decrease soil moisture by 0.66% in the non-growing seasons from 2015 to 2016. In the non-growing seasons 2015–16, experimental warming significantly elevated MBC and MBN by 19.72% and 20.99% (both P < 0.05), respectively. In addition, soil respiration responses to warming were regulated by changes in soil temperate, MBC and MBN. These findings indicate that changes in non-growing season soil respiration impact other components in the carbon cycle. Additionally, these findings facilitate projections regarding climate change–terrestrial carbon cycling.
Backgrounds: Plant-animal interactions comprise the fundamental relationships of ecological research, and are sensitive to environmental change. However, The effects of pruning on animal-plant interactions have rarely been studied. Methods: We conducted field experiments to examine the impact of artificially-pruned shapes (e.g. cubic and spheroidal canopy) on the performance of the Box tree and the resulting aphid abundance at three sites; on a university campus, at a road green belt, and in a residential area. The differences of aphid abundance and plant morphology were determined with ANOVAs and paired-sample tests. Relationships between the investigated parameters were detected with simple regression and structural equation modelResult: Abundance was higher in plants with a cubic canopy than with a spheroidal canopy. Plants with a cubic canopy had lower leaf dry mass content and inflorescence numbers, but greater fresh twig length than the plants with a spheroidal canopy. The aphid abundance was negatively correlated with the leaf dry mass content and inflorescence numbers, and positively correlated with the fresh twig length. Conclusion: Our findings have proven that pruning shape can significantly affect the abundance of herbivores on the pruned plants. The results can provide data support for human actives can alter plant performance, and thereby to change insect preference.
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