喀斯特高寒干旱区不同经济树种的碳氮磷钾生态化学计量特征

探讨喀斯特高寒干旱区不同经济树种碳(C)、氮(N)、磷(P)、钾(K)含量及生态化学计量特征,丰富对"内稳态理论"、"生长速率理论"和生态系统养分限制状况的理解,为改善喀斯特生态环境提供理论支撑。本文以毕节市七星关区撒拉溪示范区的刺梨(Rosa roxburghii)、核桃(Juglans regia)2种主要经济树种作为研究对象,分析比较不同经济树种的养分含量特征、生态化学计量特征以及"叶片-凋落物-土壤"C、N、P含量和计量比之间的关系。结果表明:(1)2种经济树种不同组分中,核桃叶片有机C含量最高(均值为436.73 mg/g),刺梨叶片全N、全P含量最大(均值为20.77、2.10 mg/g),全K含量则为核桃根区土壤中最丰富(均值为17.07 mg/g)。核桃根区土壤速效K含量高于刺梨,表明核桃具有较好的耐旱性。(2)刺梨N再吸收率(19.23%)显著高于核桃N再吸收率(4.05%),表明与核桃相比,刺梨根区土壤N元素匮乏。(3)生态化学计量特征总体呈现出凋落物叶片根区土壤的规律。刺梨叶片N∶P低于14,说明刺梨生长时主要受N限制。刺梨叶片C∶P、N∶P低于核桃,推测栽种年限相同时,刺梨树种生长速率高于核桃树种。凋落物N∶P表现为核桃刺梨,故核桃凋落物能保留更多养分。核桃根区土壤C∶N高于刺梨,说明核桃地保肥能力较好。(4)根区土壤全P与叶片全P呈极显著正相关,说明植物叶片中P主要来源于土壤。根区土壤全N与凋落物C∶N呈极显著正相关,可见根区土壤中N含量与凋落物分解密切相关。

Ecological stoichiometry characteristics of carbon, nitrogen, phosphorus, and potassium of different economic tree species in the karst frigid and arid area

In this study, we explored the characteristics of the carbon (C), nitrogen (N), phosphorus (P), and potassium (K) content, as well as the ecological stoichiometry characteristics of economically important tree species from frigid karst and arid areas. Our goal was to elucidate the growth rates, stochiometric homeostasis, and nutrient limitations of these species, which would provide theoretical guidance to improve the ecological environment of the karst area. The study area was in the Salaxi region in Bijie, Guizhou Province, China, which is home to two economically important tree species, Rosa roxburghii and Juglans regia. We compared the nutrient contents and ecological stoichiometry characteristics of these species, as well as the relationships among the C, N, and P contents and the stoichiometric ratio of leaf-litter-soil. The results showed that among the different components of these species, the soil organic C content was the highest in J. regia leaves, whereas total N and total P contents were the highest in R. roxburghii leaves, and total K content was the highest in the root zone soil of J. regia. The available K in the root zone soil was higher for J. regia than for R. roxburghii, indicating that J. regia has superior drought tolerance. The N resorption rate of R. roxburghii was higher than that of J. regia, indicating that the root zone soil of R. roxburghii lacked N elements compared with J. regia. The ecological stoichiometry characteristics exhibited the trend of litter > leaves > root zone soil. The leaf N:P ratio of R. roxburghii was <14, indicating that the growth of R. roxburghii was mainly affected by N. The C:P and N:P ratios of leaves were lower in R. roxburghii than in J. regia given the same planting period; the growth rate of R. roxburghii was higher than that of J. regia. The N:P ratio of litter was higher in J. regia than in R. roxburghii, indicating that the litter of J. regia retained more nutrients. The C:N ratio of the root zone soil was higher in J. regia than in R. roxburghii, indicating that J. regia had a greater ability to retain fertilizer. There was a significantly positive relationship between the total P content of root zone soil and the total P content of leaves, which revealed that the P content in plant leaves was derived mainly from the P content in the soil. There was also a significantly positive relationship between total N content of the root zone soil and the litter C:N ratio, which indicated that the N content of the root zone soil was closely related to litter decomposition.