A Holocene Sedimentary Record from Anangucocha in the Ecuadorian Amazon

Abstract

The stratigraphic, seddimentary pigment, loss—on—ignition, pollen, and radiocarbon data of a sedimentary record from Anangucocha, in the Ecuadorian Amazon, define three environmental episodes during the last 3100 yr. A swamp episode (<3100—1300 BP) was followed by regional flooding (1300—800 BP) and an open lake period (since 800 BP). Pollen data show that a Mauritia palm forest occupied the early blackwater swamp and was replaced by a riparian community dominated by Cecropia during the flooding episode. The pollen of Urticaceae—Moraceae taxa, especially Urtica, has increased in abundance since the flood. Past flooding was an important disturbance agent, which influenced the history of the plant community around Anangucocha. In the Amazon forest, such episodic flooding may be an important type of disturbance that promotes and maintains high species diversity. The Anangucocha record indicates that Amazonia experienced climatic fluctuation during the late Holocene.

Late Glacial and Holocene avulsions of the Rio Pastaza Megafan (Ecuador–Peru): frequency and controlling factors

“…Weng et al's (2002) palynological studies indicate that tropical rain forest has developed throughout the Holocene with minor climatic oscillations. According to these authors, severe droughts occurred in the period 8,700-5,800 Cal years BP, which should be correlated with other records from Amazonia, adjacent savannas and the Andes (Hastenrath and Kutzbach 1985;Frost 1988;Hooghiemstra 1998, 1999). This ''dry'' period was succeeded by more uniform and wetter conditions with alternating wetter and drier millennial-scale events (Weng et al 2002).…”

The Productivity of the C_4 Grass Echinochloa Polystachya on the Amazon Floodplain

“…Although the floodplain is a small proportion ("" 3%) of the Amazon basin by comparison to the rainforest of the terra firme (land above the maximum floodwater height), this difference may in part be compensated for by higher productivity. Further, sedimentary evidence suggests that the balance between floodplain and terra firme rainforest may have varied within the Holocene period (e.g., Frost 1988), and thus the relative importance of floodplain communities may fluctuate. The floodplain area of the central Amazon currently exceeds 60 000 km 2 (Forsberg et al 1988).…”

The vegetation history of an Amazonian domed peatland

“…However, a consensus on the regional palaeoclimatology is still lacking (Flantua et al, 2016a). For example, pollen records from northern Ecuador, including Anañgucocha, Lago Agrio, Limoncocha, and Lago Santa Cecilia (Frost, 1988;Colinvaux et al, 1988), have been interpreted as recording a period of increased rainfall and flooding c. 1100 cal yr BP (albeit with chronological uncertainties: Flantua et al 2016b). Similarly, several isotopic records of rainfall in Andean ice cores show no clear anomaly during this period (Thompson et al, 1986(Thompson et al, , 1995(Thompson et al, , 2013.…”