Environmental changes in biodiversity hotspot ecosystems of
South Ecuador: RESPonse and feedback effECTs (FOR2730)

Abstract:

To reconstruct the environmental history including vegetation, fire and climate dynamics, from the Cajanuma valley area (3285 m elevation) in the Podocarpus National Park, southern Ecuador, we address the following major research question: (1) How did the mountain vegetation developed during the late Glacial and Holocene? (2) Did fire played an important control on the vegetation change and was it natural or of anthropogenic origin?. Palaeoenvironmental changes were investigated using multiple proxies such as pollen, spores, charcoal analyses and radiocarbon dating. Pollen data indicated that during the late Glacial and transition to the early Holocene (ca. 16 000–10 500 cal yr BP) herb páramo was the main vegetation type around the study area, while subpáramo and mountain rainforest were scarcely represented. The early and mid-Holocene (ca. 10 500 to 5600 cal yr BP) is marked by high abundance of páramo during the early Holocene followed by a slight expansion of mountain forest during the mid-Holocene. During the mid- to late Holocene (ca. 5600–1200 cal yr BP) there is a significant presence of páramo and subpáramo while Lower Mountain Forest decreased substantially, although, Upper Mountain Forest remained relatively stable during this period. The late Holocene, from ca. 1200 cal yr BP to present, was characterized by páramo; however, mountain forest and subpáramo presented significantly abundance compared to the previous periods. Fires became frequent since the late Holocene. The marked increased local and regional fire intensity during the wetter late Holocene strongly suggests that were of anthropogenic origin. During the late Glacial and early Holocene, the upper forest line was located at low elevations; but shifted slightly upslope to higher elevations during the mid-Holocene.

Abstract:

Late Pleistocene and Holocene vegetation, climate, and fire dynamics, as well as human impact, were studied in the El Cristal region, which is part of the Andean Depression in southeastern Ecuador. The sediment core from a small basin at 2056 m a.s.l. was analyzed by pollen and charcoal analysis and dated by six radiocarbon dates. The record indicates that during the late Pleistocene (ca. 19 750–12 500 cal yr BP) the Upper Mountain Rainforest (UMF), with some smaller areas of páramo and subpáramo were the main vegetation type in the study area. Additionally, there is evidence for Polylepis woodland in the region during this period, which does not exist in the area today. During the transition from the late Pleistocene to the early and mid-Holocene between ca. 12 500 to 3600 cal yr BP, there is a significant presence of mountain rainforest and stable proportions of subpáramo and páramo taxa. The early Holocene from ca. 11 500 to 7800 cal yr BP is characterized by UMF vegetation at the study site. Polylepis became more frequent and reached its maximum. During the mid-Holocene between 7800 to 3600 cal yr BP, the composition of the UMF changed. Polylepis decreased after ca. 4000 cal yr BP, probably due to higher fire frequency. During the mid- to late Holocene, human landscape dis- turbance is evident, especially between ca. 2000 and 1380 cal yr BP, with Asteraceae, Muehlenbeckia/Rumex, Osmunda and Huperzia all increasing in abundance. The late Holocene, from ca. 1380 cal yr BP, was characterized by an increased abundance of páramo taxa and a decrease in mountain rainforest taxa. The expansion of grassland during the late Holocene is interpreted as a result of an increase in human activity, which limited forest vegetation to isolated patches. However, between ca. 1200 and 900 cal yr BP the UMF expanded, probably due to forest recovery after the high frequency of fire. Between ca. 90

Abstract:

Late Holocene human impact and environmental changes were reconstructed from a sediment core of the Laguna Daniel Alvarez (2200 m asl) located on the outskirts of the city of Loja, southeastern Ecuador. Palaeoenvironmental changes were investigated by pollen, spore, algae and charcoal analysis in com- bination with X-Ray Fluorescence (XRF) scanning and element analysis of d13C, Total Organic Carbon (TOC), Total Nitrogen (TN) and radiocarbon dating. This multi-proxy study provides in detail the set- tlement history in the inner-Andean dry valley in southern Ecuador over the last ca. 1400 years. Between 630 and 1470 AD, Zea mays was intensively cultivated around the studied lake by the native Palta culture in the Loja region. After ca. 1470 AD, Z. mays cultivation collapsed, accompanied by an increase in fallow vegetation, such as Mimosa and Poaceae, probably as a result of the Inca invasion and occupation from 1463 to 1531 AD in southern Ecuador. After ca. 1570 AD, Amaranthaceae/Chenopo- diaceae markedly increased, re?ecting the beginning of the Spanish Conquest. In 1531 AD, Loja became Spanish and, during the ?rst ca. 100 years of the Spanish regime, Loja developed into the forti?ed capital of the province. In the 17th century, crop growing strongly declined due to the diminished indigenous population that probably suffered from new diseases introduced by the Spanish invaders. Pinus and Eucalyptus as well as Plantago lanceolata were introduced in the Loja region about 220 years ago.

Abstract:

We reconstructed the palaeoenvironmental conditions of the last ca. 8000 years in the Tres Lagunas region of the Quimsacocha volcanic basin (ca. 3800 m a.s.l.) in the southwestern Ecuadorian Andes by means of a pollen and charcoal record. Sediment deposits and pollen taxa reflect warm and possibly drier conditions in the early to mid-Holocene. The late Holocene undergoes several warm and cold-phases of which the most prominent one was the Little Ice-Age which is characterised by a marked increase of taxa that correspond to cold and moist conditions. As charcoal can be recorded since the early to mid-Holocene and Polylepis underwent several phases of degradation and re-establishment in the region, the presence of human influence might be dated back to this time.

Abstract:

We reconstructed the palaeoenvironmental conditions of the last ca. 8000 years in the Tres Lagunas region of the Quimsacocha volcanic basin (ca. 3800 m a.s.l.) in the southwestern Ecuadorian Andes. By means of a pollen and charcoal record, we analysed vegetation, fire, and climate history of this area, which is sensitive to climatic changes of both the Pacific as well as of the eastern Andes and Amazon region. Sediment deposits, pronounced increase of pollen and charcoal concentrations, and pollen taxa reflect warmer and drier conditions in the early to mid-Holocene (~8000 to 3900 cal B.P.). During the late Holocene (2250 to -57 cal B.P.), 5 warm and cold-phases occurred at Quimsacocha. The most prominent cold phase possibly corresponds to the globally recognized Little Ice-Age (LIA; ~600 to 100 cal B.P.). The cold phase signal at Quimsacocha was characterized by a higher abundance of Poaceae, Isoëtes and Gentianella, which favour cold and moist conditions. Frequent charcoal particles can be recorded since the early to mid-Holocene (~7600 B.P.). The high Andean tree species Polylepis underwent several phases of degradation and re-establishment in the basin, which can indicate the use of fire by pre-Columbian settlers to enhance the growth of preferred herb species. The Tres Lagunas record suggests that human populations have been influencing the environment around Quimsacocha since the last ca. 8,000 years.