CAS Key Laboratory of Forest Ecology and Silviculture, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, China.
Daqinggou Ecological Research Station, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, China.
Plant Cell Environ. 2024 Aug;47(8):2999-3014. doi: 10.1111/pce.14923. Epub 2024 Apr 21.
Crown removal revitalises sand-fixing shrubs that show declining vigour with age in drought-prone environments; however, the underlying mechanisms are poorly understood. Here, we addressed this knowledge gap by comparing the growth performance, xylem hydraulics and plant carbon economy across different plant ages (10, 21 and 33 years) and treatments (control and crown removal) using a representative sand-fixing shrub (Caragana microphylla Lam.) in northern China. We found that growth decline with plant age was accompanied by simultaneous decreases in soil moisture, plant hydraulic efficiency and photosynthetic capacity, suggesting that these interconnected changes in plant water relations and carbon economy were responsible for this decline. Following crown removal, quick resprouting, involving remobilisation of root nonstructural carbohydrate reserves, contributed to the reconstruction of an efficient hydraulic system and improved plant carbon status, but this became less effective in older shrubs. These age-dependent effects of carbon economy and hydraulics on plant growth vigour provide a mechanistic explanation for the age-related decline and revitalisation of sand-fixing shrubs. This understanding is crucial for the development of suitable management strategies for shrub plantations constructed with species having the resprouting ability and contributes to the sustainability of ecological restoration projects in water-limited sandy lands.
去除树冠可使在干旱环境中生长活力随年龄衰退的固沙灌木重新焕发生机；然而，其潜在机制尚不清楚。在这里，我们通过比较不同树龄（10、21 和 33 年）和处理（对照和去除树冠）下使用中国北方一种有代表性的固沙灌木（柠条锦鸡儿）的生长表现、木质部水力和植物碳经济，解决了这一知识空白。我们发现，随着植物年龄的增长而下降的同时，土壤水分、植物水力效率和光合能力也随之下降，这表明植物水分关系和碳经济的这些相互关联的变化是导致这种下降的原因。去除树冠后，快速萌生，涉及根非结构性碳水化合物储备的再利用，有助于重建高效的水力系统和改善植物的碳状况，但在较老的灌木中，这种效果变得不那么有效。碳经济和水力对植物生长活力的这种年龄依赖性影响为固沙灌木的年龄相关衰退和恢复提供了一种机制解释。这种对具有萌蘖能力的物种的人工林的管理策略的发展至关重要，并有助于在水资源有限的沙地上进行生态恢复项目的可持续性。
