Sobrado M A, Medina E
Departamento de Estudios Ambientales, Universidad Simón Bolivar, Apto. 80-659, Caracas, Venezuela.
Oecologia. 1980 Jan;45(3):341-345. doi: 10.1007/BF00540202.
Species of the 'bana' vegetation in the Amazonas region of equatorial South America have scleromorphic leaves. This leaf type, which characterizes the vegetation of Mediterranean climates, among others, has apparently evolved in this community in response to the oligotrophic soils and widely fluctuating water table.Anatomically, the leaves have several features commonly found in xeromorphic plants, including greater leaf and cuticle thickness, pubescent leaves and sunken stomata, and a high incidence of sclerenchyma.Concentrations of K and P decrease with leaf age, while N remains nearly constant and Ca increases. Concentrations of N and P are lower than in other sclerophyllous species, but the amount of these nutrients recovered before leaf shedding are similar. The correlation between P and N as expressed per unit dry weight is high (r=0.87; p<0.01) as is the relation between leaf specific area (area/dry wt.) and N (r-0.83; p<0.01) and P (r= 0.82; p<0.01).Soils of this region are very acidic (extreme lowest value pH 3.6) and have high levels of exchangeable Al and Mn. Among the 'bana' plant species are some which accumulate high levels of Mn (>300 ppm) and Al (>1000 ppm).
南美洲赤道地区亚马孙区域的“巴纳”植被物种具有硬叶形态的叶子。这种叶型是地中海气候等地区植被的特征，显然在这个群落中进化形成，以适应贫营养土壤和大幅波动的地下水位。从解剖学上看，这些叶子具有旱生植物常见的几个特征，包括叶片和角质层更厚、叶片有毛、气孔凹陷，以及厚壁组织发生率高。钾和磷的含量随叶龄下降，而氮含量几乎保持不变，钙含量增加。氮和磷的含量低于其他硬叶植物物种，但在落叶前回收的这些养分数量相似。以单位干重表示的磷和氮之间的相关性很高（r = 0.87；p < 0.01），叶比面积（面积/干重）与氮（r = 0.83；p < 0.01）和磷（r = 0.82；p < 0.01）之间的关系也是如此。该地区的土壤酸性很强（最低pH值为3.6），可交换铝和锰的含量很高。在“巴纳”植物物种中，有些物种积累了高水平的锰（>300 ppm）和铝（>1000 ppm）。
