LTER: Carbon and Nutrient Relations Among Oligotrophic Forest Communities in the North Central Amazon Basin

营养限制似乎在亚马逊盆地里奥内格罗部分的少营养热带雨林生态系统中普遍存在。这项研究将检验关于这些森林的碳-养分关系和养分利用效率的几个假说。将研究四个离散的原始森林群落(每个群落都在不同的土壤类型上)，以及一个演替群落。这些群落之间的物种重叠很小，即使所有五个群落位于委内瑞拉圣卡洛斯·德里奥内格罗彼此相距1公里的范围内。对每个群落中的5个物种(总共25个物种)的个体进行了6年的监测，提供了关于产叶和叶片持续时间的基线数据。现在，将从叶片寿命、叶片衰老和土壤养分有效性方面研究养分和碳的关系。主要假设是群落(和物种)之间将出现明显的差异：1)由于生境资源可用性和物种演替生态位的变化，叶片形态和养分含量；2)二氧化碳同化能力，作为叶片养分含量和光合氮、磷利用效率的函数，3)由于光合作用养分利用效率、叶片寿命以及叶片养分保持和再转移随时间的变化，导致长期碳增益和养分利用效率的变化。

Nutrient limitations appear to be widespread in the oligotrophic rainforest ecosystems of the Rio Negro portion of the Amazon basin. This research will test several hypotheses regarding carbon-nutrient relations and nutrient-use efficiency for these forests. Four discrete primary forest communities (each on different soil type) will be studied, along with a successional community. Species overlap between these communities is minimal, even though all five communities are located within 1 km from each other at San Carlos de Rio Negro, Venezuela. Individuals from 5 species in each community (25 species total) have been monitored for six years, providing baseline data on leaf production and leaf duration. Now nutrient and carbon relations will be studied with respect to leaf longevity and leaf aging and soil nutrient availability. The main hypotheses are that distinct differences will emerge among communities (and species): 1) in leaf morphology and nutrient content, as a result of variation in habitat resource availability and species successional niche, 2) in CO2 assimilation capacity, as function of leaf nutrient content and photosynthetic nitrogen- and phosphorus-use efficiency, 3) in long-term carbon gain and nutrient-use efficiency, as a result of variation in photosynthetic nutrient-use efficiency, leaf longevity, and leaf nutrient retention and retranslocation over time.