Department of Palynology and Climate Dynamics

Research

Doctoral Thesis
Niemann, Holger, 2008. Late Quaternary vegetation, climate and fire dynamics in the Podocarpus National Park region, southeastern Ecuadorian Andes



Goals and results

The three years lasting (2005-2008) research activities are embedded in the interdisciplinary research unit "Tropical Mountain Ecosystems" (FG 402) of the "Deutsche Forschungsgemeinschaft" (DFG). The study area is the Podocarpus National park, located in the Mountain forest and Paramo zone.


Map PNP 2


Pollen analytical methods have been combined with XRF-Scanning and Multivariate data analysis (Behling et al. 2004), to reconstruct late Pleistocene vegetation, climate and fire dynamics. The studies are focused on the scientific understanding of the tropical mountain ecosystem and the potential of this ecosystem for sustainable use by humans. The main topics of the interdisciplinary research unit "Tropical Mountain Ecosystems" (FG 402) are published in the book "Gradients in a Tropical Mountain Ecosystem of Ecuador", including preliminary results of the studies from this subunit:


  • Niemann H, Behling H, 2008. Past vegetation and fire dynamics. In: Beck E, Bendix J, Kottke I, Makeschin F, Mosandl R (Eds) Gradients in a Tropical Mountain Ecosystem of Ecuador. Ecological Studies 198, Springer Verlag, Berlin, Heidelberg, pp 101-112



In order to study the stability and dynamics of highly biodiverse mountain rain forest and paramo ecosystems, the late Pleistocene and Holocene climate and fire variability as well as human impact in the Podocarpus National Park region, the first comprehensive palaeoenviremental study from the southeastern Ecuadorian Andes will be presented.
An initial study of recent vegetation/modern pollen rain relationship on an altitudinal transects between 1800 and 3200 m elevation in the mountain forest and (sub)-paramo vegetation of the ECSF (Estacion Cientifica San Francisco) research area provide important background information in the interpretation of late Quaternary pollen records. Cluster analysis on the pollen rain data by CONISS, clearly reflects the zonation of the different vegetation units, lower mountain forest (LMF), upper mountain forest (UMF) and (sub)-paramo. A relatively high number of pollen taxa correspond to the altitudinal distribution of genera and families of modern vegetation. The modern tree line in the research area is at ca. 2790 m, which is pointed out by an increase of (sub)-paramo taxa and a decrease of mountain forest taxa in the pollen rain data:


  • Niemann H, Behling H, 2008. Recent vegetation/modern pollen rain relationship studies on an altitudinal transect of mountain forest and paramo in the southeastern Ecuadorian Andes. Review of Palaeobotany and Palynology (in review)



Palaeoenvironmental changes, inferred from 9 lake, peat bog and soil deposits, collected at different elevations between ca. 2000 and 3300 m, were investigated by pollen, spores and charcoal analysis, in combination with XRF- and magnetic susceptibility-scanning on the lake sediment cores.
During the late Pleistocene from ca. 21,000 to 11,200 cal yr BP, grass-paramo vegetation occurred at the Tiro-Pass (2810 m), reflecting cold and moist climatic conditions as well as a shift of vegetation zones into lower elevation during this period. During the transition from late Pleistocene to early Holocene from ca. 14,500 to 9700 cal yr BP, arboreal taxa, mainly Weinmannia strongly increase at Laguna Cocha Caranga (2710 m), reflecting a raise in temperature. The early Holocene from ca. 11,200 to 8900 cal yr BP (El Tiro-Pass) is characterised by an increase of temperature and moisture, as well as a shift of vegetation zones into higher elevation. During the mid Holocene period, from ca. 8900 to 3300 cal yr BP, upper mountain forest vegetation developed at the El Tiro-Pass, where subparamo vegetation occurred in recent times, suggesting a warmer climate than present day at this elevation. XRF-scanning data from Laguna Rabadilla de Vaca (3310 m) reflects a drier period from ca. 8990 to 6380 cal yr BP and a wetter period from ca. 6380 to 3680 cal yr BP. The green algae Botryococcus braunii, Isoetes and Cyperaceae were used to reconstruct Holocene wet/dry phases at Laguna Cocha Caranga. Drier climatic conditions occurred from ca. 9700 to 6900 cal yr BP and from ca. 4200 to 1300 cal yr BP. From ca. 6900 to 4200 cal yr BP and from ca. 1300 cal yr BP to modern time's wetter climatic conditions occurred.
During the late Holocene, modern climatic conditions, as well as recent vegetation established since ca. 3680 cal yr BP at Laguna Rabadilla de Vaca and since ca. 3300 cal yr BP at the El Tiro-Pass:


  • Niemann H, Behling H, 2008. Late Quaternary vegetation, climate and fire dynamics inferred from the El Tiro record in the southeastern Ecuadorian Andes. Journal of Quaternary Science: 23(3): 203-212
  • Niemann H, Haberzettl T, Behling H, 2009. Holocene climate variability and vegetation dynamics inferred from the (11,700 cal yr BP) Laguna Rabadilla de Vaca sediment record in the southeastern Ecuadorian Andes. The Holocene 19 (2): 000-000



An increase of fire intensity during the early to mid Holocene period after ca. 9700 cal yr BP at Laguna Cocha Caranga and after about 7500 cal yr BP at the El Tiro-Pass reflects beginning human impact on the ecosystem in the Podocarpus National Park region. High occurrence of grasses document, that past fires have markedly influenced the floristic composition of the mountain rain forest and paramo ecosystems during the mid to late Holocene period. The reduction of fire intensity coupled with a decrease of grasses after ca. 1300 cal yr BP (Laguna Cocha Caranga) and between ca. 970 to 400 cal yr BP (Upper Rio San Francisco valley), coupled with a missing of Zea mais pollen, suggests a reduction and/or absence of human activities, may be as a result of political unrest. After the reduction and/or absence of human influence the mountain forest vegetation starts to recover.


  • Niemann H, Behling H, 2008. Late Holocene environmental change and human impact inferred from three soil monoliths and the Laguna Zurita multi-proxi record in the southeastern Ecuadorian Andes. Vegetation History and Archaeobotany (in review)
  • Niemann H, Behling H, 2008. Late Pleistocene and Holocene vegetation development, climate variability and human impact inferred from the Cocha Caranga multi-proxy records in the southeastern Ecuadorian Andes. Palaeogeography, Palaeoclimatology, Palaeoecology (in review)



Special thanks to the "Deutsche Forschungsgemeinschaft (DFG)" for the financial support of this successful project.