桂林毛村岩溶区典型植物叶片碳、氮、磷化学计量特征

Carbon,nitrogen and phosphorus stoichiometry of typical plants in karst area of Maocun,Guilin

植物的碳、氮、磷化学计量特征能反映植物对土壤营养元素的利用效率,岩溶区植物经过长期的进化形成了自身独特的生理生态和生态化学计量特征,通过岩溶区植物叶片碳、氮、磷化学计量可以揭示岩溶生态系统各组分之间的养分循环规律。该研究在桂林毛村岩溶区次生林中选择3个20m×20m的样方,采用多元统计方法分析了岩溶区森林12种典型植物叶片共186个样品的碳、氮、磷的生态化学计量特征,研究它们之间的相互关系,探讨碳、氮、磷化学计量学在岩溶生态系统中的生态指示作用。结果表明:(1)虽然岩溶区石灰土氮和磷的含量较高,但由于其有效性低,植物对养分的吸收和利用缓慢,岩溶区石灰土植物的生长仍然受到N和P的共同限制;(2)由于岩溶区植物叶片中N和P的含量显著偏低导致较高的(C:N和(C:P值((C:N的平均值为80.86;(C:P的平均值为639.65);(3)利用N:P<14表明氮受限制,N:P>16表明磷受限制,14<N:P<16表明N和P共同限制的标准判断植物叶片受N或P的限制在岩溶区不完全适合;(4)元素间相关性分析表明,叶片的(C和N呈极显著负相关关系(P<0.01),(C和P呈显著负相关关系(P<0.05),N和P之间呈现极显著正相关关系(P<0.01)。这体现了植物体内两营养元素含量需求变化的相对一致性。研究结果有助于了解岩溶区森林植物的适生机制及其生态地球化学过程,可为岩溶区生态治理提供理论依据。

The balance between various elements of the ecosystem has been the focus of research related to the ecology of global change and biogeochemical cycles. Ecological stoiehiometry is the study of the balance of energy and ele- ments in biological systems and based on the general laws of physics, chemistry and biology. Ecological stoichiometry provides an integrated approach to investigating the stoichiometric relationships and rules in biogeochemical cycling and ecological processes. The primary nutrient elements, carbon （C）, nitrogen （N） and phosphorus （P）, play an important role in plant growth and regulating various botanic physiological functions. The cycling of N and P are tightly coupled to C cycling in ecosystems, primarily through aspects related to ecosystem carbon primary production. Leaf C, N and P stoichiometry varies throughout many aspects of plant biology. The ratios of C ： N, C P and N ： P may reflect the balance between the plant demand in relation to N and P availability and may constrain various processes. Carbon, nitrogen, and phosphorus stoiehiometry of plants reflect the utilization efficiency of plants with regard to soil nutrient elements. After a long period of evolution, plants had form and their own unique ecophys- iology and ecological stoichiometry in karst landscapes. Carbon, nitrogen, phosphorus stoichiometry of plant leaves can reveal the regularity of nutrient cycling within karst ecosystems. Three quadrats, sized 20 m × 20 m, in a second- ary forest in the karst area of Maocun, Guilin were selected. A total of 186 samples of 12 plant types were collected. The ecological stoichiometry of carbon, nitrogen, and phosphorus were analyzed using multivariate statisti- cal analysis to study the relationship between them and explored ecological indicating functions of carbon, nitrogen, and phosphorus stoichiometry in karst ecosystems. The results were as follows： Firstly, C, N, and P values in the samples＇ plant leaves were （456.19±2.16） mg· g^-1, （7.71±0.26） mg · g^-1 , and （0.89±0.02） mg · g^-1, respective- ly. Carbon, nitrogen, and phosphorus values were all lower than China＇s and global averages. Although the higher contents of N and P in the karst limestone soil because of their low availability and their slow uptake and utilization efficiencies, nitrogen and phosphorus still presented as common limitations to plant growth within the karst area. Secondly, in this study, C ：N, C ： P, and N ： P in the plant leaves of the samples were 80.86±6.74, 639.65 ± 53.79, and 10.42± 0.89, respectively. Because the contents of N and P in plant leaves in the karst area were signif- icantly lower, it resulted in higher C ： N and C ： P values. Thirdly, the rules of N ： P was less than 14, indicating nitrogen limits; N ： P was more than 16,indicating nitrogen limits; and N ： P between 14 and 16 showed that nitro- gen and phosphorus limits were not entirely suitable for determining the limiting nutrient elements within the karst area. Lastly, correlation analysis between elements showed that there was a significant negative correlation between leaf C and N （P〈0.01）, and a significantly negative correlation between C and P （P〈0.05）, while there was a sig- nificant positive correlation between N and P （P〈0.01）. This correlation reflected the change of the relative consis- tency of nutrient elements of plants. The results contributed to the understanding of plant adaptive mechanisms and ecological geochemical process, providing the theory basis for ecological control of the karst area.