Regional Agroclimate Characteristic and Its Multiple Teleconnections: A Case Study in the Jianghan Plain (JHP) Region

Agricultural production depends on local agroclimatic conditions to a great extent, affected by ENSO and other ocean-atmospheric climate modes. This paper analyzed the spatio-temporal distributions of climate elements in the Jianghan Plain (JHP), Central China, and explored the impacts from teleconnection patterns, aimed at providing references for dealing with climate change and guiding agricultural activities. Both linear and multifactorial regression models were constructed based on the frequentist quantile regression and Bayesian quantile regression method, with the daily meteorological data sets of 17 national stations in the plain and teleconnection climate characteristic indices. The results showed that precipitation in JHP had stronger spatial variability than evapotranspiration. El Niño probably induced less precipitation in summer while the weakening Arctic Oscillation might lead to more summertime precipitation. The Nash-Sutcliffe efficiency (NSE) of the multifactorial and linear regression model at the median level were 0.42–0.56 and 0.12–0.18, respectively. The mean relative error (MRE) ranged −2.95–−0.26% and −7.83–0.94%, respectively, indicating the much better fitting accuracy of the multiple climatic factors model. Meanwhile it confirmed that the agricultural climate in JHP was under the influence from multiple teleconnection patterns.

Waterlogging tolerance evaluation of fifteen poplar clones cultivated in the Jianghan Plain of China

To provide references for poplar cultivation in waterlogged prone area of Jianghan Plain of China, the waterlogging tolerance of 15 poplar clones widely cultivated in these areas were evaluated based on their responses to 45-day waterlogging stress followed by 15-day drainage recovery in morphology, growth, biomass accumulation, leaf gas exchange and chlorophyll fluorescence parameters. The results showed that the normal watered seedlings (CK) of the 15 clones grew vigorously during the experiment, and no defoliation and death occurred. For the seedlings under waterlogging treatment (water 10 cm above the soil surface), its morphology changed markedly, including slowing growth, chlorosis and abscission of leaves, development of hypertrophied lenticels and adventitious roots etc. Waterlogging stress significantly inhibited the seedling growth of height and ground diameter, biomass accumulation, as well as leaf gas exchange and chlorophyll fluorescence parameters of the 15 clones with varying degrees. The net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), intercellular CO2 concentration/ environmental CO2 concentration (Ci/Ca), variable fluorescence (Fv), variable fluorescence/ initial fluorescence (Fv/Fo) and PS Ⅱ primary light energy conversion efficiency (Fv/Fm) decreased gradually with the prolonged waterlogging, and reached their bottom on day 45. During the terminal recovery stage, the leaf gas exchange and chlorophyll fluorescence parameters of the most clones increased, but their recovery abilities were significantly different. At the end of the experiment, the highest survival rates (100%) were observed in DHY, HS-1, HS-2, I-72, I-69, I-63 and NL-895, and the lowest (zero) occurred in XYY. Survival rates of the other clones ranged from 33.33% to 83.33%. Both results of cluster analysis and membership function analysis showed that HS-1, I-69, DHY, NL-895 and HS-2 had the strongest waterlogging tolerance, XYY and HBY were the worst, and the other clones were moderate. These results would provide guidance not only for the selection of cultivated varieties in Jianghan Plain, but also for the selection of hybrid parents for waterlogging resistance breeding.

Study on Initiation and Mechanism of Seepage-induced Slope Failure in Jianghan Plain, Central China

The problem of seepage erosion is widespread in occurrence, but is rarely recognized as one of landslide causes. This paper describes and explains one event of slope erosion in Jianghan plain and is focused on the role of seepage erosion. The laboratory test is performed to reconstruct the hydraulic processes leading to slope failure with the application of different hydraulic loads. The observation and measurement reveal that slope alteration experienced three stages under seepage, and hydraulic gradient played a key role during seepage erosion phase. Using these results, a CFD-DEM model is developed to investigate how the seepage-induced soil particle migration would affect the slope evolution. The geotechnical properties control the failure processes and cause a significant change to the toe erosion and loosened zone. Although the instability of slope is mainly attributed to seepage gradient force, the occurrence of seepage erosion affects the failure mode. This work provides new guidance for hydrodynamic landslide prevention.

Designing Ecological Security Patterns Based on the Framework of Ecological Quality and Ecological Sensitivity: A Case Study of Jianghan Plain, China

Researchers and managers of natural resource conservation have increasingly emphasized the importance of maintaining a connected network of important ecological patches to mitigate landscape fragmentation, reduce the decline of biodiversity, and sustain ecological services. This research aimed to guide landscape management and decision-making by developing an evaluation framework to construct ecological security patterns. Taking the Jianghan Plain as the study area, we identified key ecological sources by overlaying the spatial patterns of ecological quality (biodiversity, carbon storage, and water yield) and ecological sensitivity (habitat sensitivity, soil erosion sensitivity, and water sensitivity) using the Integrated Valuation of Environmental Services and Tradeoffs (InVEST) model and the Chinese Soil Loss Equation Function. Ecological corridors were obtained by the least-cost path analysis method and circuit theory. A total of 48 ecological sources (3812.95 km2), primarily consisting of water area, forestland, and cropland, were identified. Ninety-one ecological corridors were derived, with a total length of 2036.28 km. Forty barriers and 40 pinch points with the highest improvement coefficient scores or priority scores were selected. There were 11 priority corridors with very high levels of connectivity improvement potential and conservation priority, occupying 16.15% of the total length of corridors. The overall potential for ecological connectivity is high on the Jianghan Plain. Our framework offers a valuable reference for constructing ecological security patterns and identifying sites for ecological restoration at the regional scale.