Zhu Jing, Jin Xing, He Zhong-Sheng, Xiao Qian-Ru, Chen Jia-Jia, Xing Cong, Liu Jin-Fu, Shen Cai-Xia
College of Forestry, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
Key Laboratory of Fujian Universities for Ecology and Resource Statistics, Fuzhou 350002, China.
Ying Yong Sheng Tai Xue Bao. 2022 Aug;33(8):2129-2138. doi: 10.13287/j.1001-9332.202208.008.
When seeds fallen from the mother trees, their initial contact physical environment was litter or soil. The dispersal positions of seeds (seeds positioned on top of the litter, the soil surface and beneath the litter) determine the process of their natural regeneration. We simulated three different dispersal positions of , including seeds positioned on top of the litter (2 and 4 cm litter was placed below the seed layer), soil surface (without litter), and seeds beneath the litter (2, 4, 6 and 8 cm litter covers in the upper layer of seeds). We examined the effects of seed dispersal position on the chlorophyll fluorescence characteristics, non-structural carbohydrate, specific leaf area, leaf dry matter content and nutrient content of seedlings. The results showed that leaf nitrogen content per area of seedlings had significantly positive correlation with soluble sugar content, non-structural carbohydrate content, and negative correlation with specific leaf area across different dispersal positions. Seedlings of the moderate litter cover (2 and 4 cm) adopted resource acquisitive strategies by increasing relative chlorophyll content, soluble sugar content, non-structural carbohydrate content, leaf dry matter content, leaf nitrogen content and phosphorus contents per area, and decreasing specific leaf area to achieve their demands for rapid growth. Seedlings grew on soil surface and beneath the deep litter (6 and 8 cm) adopted the resource conservative strategies with higher leaf nitrogen content per mass and specific leaf area, lower leaf dry matter content, and non-structural carbohydrate content to intercept more effective light resources to compensate for the shady environment brought by deep litter. This would further decrease the probability of seedling mortality due to 'carbon starvation'. Seedlings under litter layer stored starch in leaf, and reduced the energy consumption of photosynthetic tissues (low PSⅡ maximum photochemical efficiency) to maintain seedling growth. Comprehensive analysis of entropy method indicated that low amount of litter cover (2 cm) significantly promoted seedling growth of . In the future, we could regulate the thickness of litter layer to promote the growth and regeneration of seedlings in natural forest.
当种子从母树上掉落时，它们最初接触的物理环境是凋落物或土壤。种子的散布位置（种子位于凋落物顶部、土壤表面和凋落物下方）决定了它们自然更新的过程。我们模拟了三种不同的种子散布位置，包括位于凋落物顶部（在种子层下方放置2厘米和4厘米的凋落物）、土壤表面（无凋落物）以及凋落物下方的种子（在种子上层覆盖2厘米、4厘米、6厘米和8厘米的凋落物）。我们研究了种子散布位置对幼苗叶绿素荧光特性、非结构性碳水化合物、比叶面积、叶片干物质含量和养分含量的影响。结果表明，在不同散布位置下，幼苗单位面积叶片氮含量与可溶性糖含量、非结构性碳水化合物含量呈显著正相关，与比叶面积呈负相关。适度凋落物覆盖（2厘米和4厘米）的幼苗通过增加相对叶绿素含量、可溶性糖含量、非结构性碳水化合物含量、叶片干物质含量、单位面积叶片氮含量和磷含量，并降低比叶面积来采用资源获取策略，以满足其快速生长的需求。生长在土壤表面和深厚凋落物（6厘米和8厘米）下方的幼苗采用资源保守策略，具有较高的单位质量叶片氮含量和比叶面积，较低的叶片干物质含量和非结构性碳水化合物含量，以拦截更多有效的光资源，补偿深厚凋落物带来的阴暗环境。这将进一步降低幼苗因“碳饥饿”而死亡的概率。凋落物层下的幼苗在叶片中储存淀粉，并降低光合组织的能量消耗（低PSⅡ最大光化学效率）以维持幼苗生长。熵值法综合分析表明，少量凋落物覆盖（2厘米）显著促进了[物种名称]幼苗的生长。未来，我们可以通过调节凋落物层厚度来促进天然林中[物种名称]幼苗的生长和更新。
