RESUMO
Quantitative identification of water utilization characteristics of xerophytic shrubs is an important prerequisite for the selection and optimization of a regional artificial sand-fixing vegetation system. In this study, a hydrogen (δD) stable isotope technique was used to study the changes in water use characteristics of four typical xerophytic shrubs, Caragana korshinskii, Salix psammophila, Artemisia ordosica, and Sabina vulgaris in the Hobq Desert under light (4.8 mm after 1 and 5 days) and heavy (22.4 mm after 1 and 8 days) rainfall events. Under light rainfall, C. korshinskii and S. psammophila primarily used the 80-140 cm layer of soil water (37-70%) and groundwater (13-29%), and the water use characteristics did not change significantly after the light rainfall event. However, the utilization ratio of A. ordosica to soil water in the 0-40 cm layer increased from less than 10% on the first day after rain to more than 97% on the fifth day after rain, whereas the utilization ratio of S. vulgaris to soil water in the 0-40 cm layer also increased from 43% to nearly 60%. Under heavy rainfall, C. korshinskii and S. psammophila still used the 60-140 cm layer (56-99%) and groundwater (~15%), while the main water utilization depth of A. ordosica and S. vulgaris expanded to 0-100 cm. Based on the above results, C. korshinskii and S. psammophila primarily use the soil moisture of the 80-140 cm layer and groundwater, while A. ordosica and S. vulgaris use the soil moisture of the 0-100 cm layer. Therefore, the co-existence of A. ordosica and S. vulgaris will increase the competition between artificial sand-fixing plants, while the combination of the two plants with C. korshinskii and S. psammophila will avoid competition between artificial sand-fixing plants to some extent. This study provides important guidance for regional vegetation construction and sustainable management of an artificial vegetation system.
RESUMO
BACKGROUND:Currently, the morphologic changes of the discoid lateral meniscus (DLM) remain unclear, and morphological indexes used to evaluate the injuries of DLM stil need to be explored. OBJECTIVE:To compare the MR imaging difference between symptomatic and asymptomatic DLM in adults, and to select reliablemorphologicalparametersfor assessing DLM. METHODS:A total of 36 patients (36 knees) with a symptomatic DLM (study group)and 34 patients (34 knees) with an asymptomatic DLM (control group) were included in this study. GE Healthcare Centricity RIS/PACKS System was used to measure the primary morphological parameters of two patients with DLM on coronal MR imaging. Intergroup comparison was performed with the Wilcoxon test. RESULTS AND CONCLUSION:On the coronal MR imaging, the width of the body portion and height of the free edge of the DLM was significantly increased in the study group compared with the control group (P 0.05). The width ratio of the body of the DLM to the lateral femoral condyle and the height ratio of height of the free edge to the middle of the DLM were significantly increased in thestudy group compared with the control group (P< 0.001), while the height ratio of the peripheral portion to the middle for the DLM was significantly decreased compared with the control group (P< 0.001). These findings suggest that compared with asymptomatic discoid lateral meniscus, the width of the body portion and the height of the free edge for the DLM are increased;however,the height of the peripheral portion which connects with the capsule of the DLM is decreased. The width ratio of the body portion of the DLM to the lateral femoral condyle and the height ratio of the free edge to the middle for the DLM may be reliable morphological parameters for the assessment of the DLM in adults.
