Four centuries of vegetation change in the mid-elevation Andean forests of Ecuador

Abstract

Mid-elevation Andean ecosystems have immense species richness and endemism. Taxonomic composition is known to change through time on the eastern slopes of the Andes as a result of climatic change and disturbance events, both natural and by human actions. Fossil phytoliths can capture local scale vegetation changes, especially among monocotyledonous plants. Phytolith production is high in grasses and palms, plant groups that are particularly sensitive to climatic changes and disturbance events in Andean ecosystems. Here, we reconstruct four centuries of local-scale vegetation change and the corresponding fire history from lake sediment records retrieved from Lagunas Cormorán and Chimerella, located at ca. 1,700 m a.s.l. in the mid-elevation Andean forests of eastern Ecuador. The charcoal analysis of the lake sediments showed no sign of past fires, and no evidence of cultivation was found at either lake. The phytolith assemblages indicated changes in the relative abundances of palms, grasses and trees over the last few centuries, suggesting that mid-elevation Andean phytolith assemblages are sensitive to local scale vegetation dynamics. The largest change in vegetation occurred at the end of the Little Ice Age, at which point the diversity of palm phytoliths decreases. These phytolith assemblages are probably responding to changes in the cloud base position through time, which strongly influences the distributions of many plants and animals.

Forest Transformation in the Wake of Colonization: The Quijos Andean Amazonian Flank, Past and Present

“…The same structures seem to exist further north towards the "La Bonita" area in the headwaters of the Putumayu River. If all this evidence gets confirmed, then the area has to be incorporated within a new model of biocultural heritage of this ecological legacy, indicating that the cloud forest is actual a "feral" community that has settled again, with the ecological legacy of about four centuries of abandonment [28,42,49].…”

“…A discursive analysis of population dynamics in this wide region showed that, despite the number of inhabitants (ca. 16,500-24,500) by the year 1577 [72] was from 2.4 to almost 3.6 times below the census figures for the year 2000, it is comparable to the present number of 17,268 people [28,58]. Therefore, it is important to observe current ethnographic data to understand the process of historical and ongoing cultural transformation.…”

“…The confluence of atmospheric rivers that come from Amazonia towards the steep slopes, where the easterly winds approach the cordillera, make the Upper Quijos River one of the wettest zones of the country, harboring a mossy forest shrouded in cloud almost all year long, and the plethora of wetlands, including lakes, lagoons, bogs, fens, and other The Andean Amazon flank has been studied for decades by biologists, yet the scientific knowledge is just now being compelled to integrate paleoecological insight, landscape archaeology, and current thinking [24][25][26][27]. The explosive richness of biodiversity there called the attention of early explorers and naturalists, who, reportedly, were impressed by the growing attention to neotropical diversity that could not be readily explained [26,27], such as the diversity found by the Antisana volcano and the eastern slopes in gradient to the Amazon [28][29][30]. There was such an impressive accumulation of tropical life that Humboldt's profile of Chimborazo in the Western cordillera-his famous Tableau physique or Naturgemälde-included species that are found on Mount Antisana in the Eastern cordillera [31,32] and perpetuated the Humboldtian paradigm for altitudinal zonation [32][33][34].…”

Characterising Dutch forests, wetlands and cultivated lands on the basis of phytolith assemblages

“…All soil surface samples (n = 42) were processed for phytoliths at the Palaeoecology Laboratory at the University of Amsterdam (UvA), using a subsample containing 1 cm 3 of soil. At the onset of laboratory processing, 56,000 microspheres (Microparticles GmbH, Lot: SiO2-R-L3519-3, ø 15.29 μm, SD 0.49 μm) were added to each sample to calculate phytolith concentrations (Huisman et al, 2019;Witteveen et al, 2022). A series of chemical treatments, with 33% hydrogen peroxide (H 2 O 2 ), 10% hydrochloric acid (HCl) and potassium manganate (KMnO 4 ), were performed on each sample.…”