Tropical glaciers are rapidly disappearing, particularly in isolated mountain peaks below 5,000 m elevation. These glaciers are fundamental substrates for unique cryogenic ecosystems in high tropical environments where the ice, melting water and rocky substrate sustain microbiological communities and other meso- and macro-biota. This study uses the Red List of Ecosystems guidelines to diagnose the collapse of the tropical glacier ecosystem of the Cordillera de Mérida, Venezuela. We undertook the assessment with existing estimates of glacier ice extent, indirect historical estimates of ice mass balance and global mechanistic models of future ice mass balance. We complemented these with additional statistical analysis of trends and bioclimatic suitability modelling to calculate and predict rates of decline and relative severity of degradation in selected ecosystem indicators. The evidence suggests an extreme risk of collapse (Critically Endangered) because of a prolonged and acute reduction in ice extent and changes in climatic conditions that are leading to the complete loss of ice mass. The ice substrate has declined 90% in the last 20 years, and observed acceleration of the rate of decline suggests it will probably disappear within the next 5 years. Loss of ice substrate will trigger an immediate loss of supraglacial, englacial and subglacial biotic compartments and initiate a decades-long succession of forefield vegetation. However, ongoing inventories of native biota and monitoring of ecosystem transitions can provide valuable insights and lessons for other ecosystems facing similar risks. The Red List of Ecosystems assessment protocol provides a useful framework for comparative analysis of cryogenic ecosystems.

The wetlands of the jalca ecoregion in the Andes of northern Peru form peat and play a major role in the hydrological ecosystem services of the ecoregion. Although peat is globally valued for carbon sequestration and storage, peatlands have not yet been mapped in the jalca. In this region, the Gocta waterfall, one of the 20 highest waterfalls in the world, depends on the jalca’s wetlands ecosystem. The local population depends on tourism to the waterfall and is concerned about preserving its drainage area. To inform conservation planning, in this study we delimited the drainage area of the Gocta waterfall and identified land tenure by applying Geographic Information System (GIS), remote sensing and participatory mapping techniques. Then, by classifying optical, radar and digital elevation models data, we mapped peatland in the jalca of the Gocta drainage area with an overall accuracy of 97.1%. Our results will inform conservation strategy in this complex area of communal, private and informal land tenure systems. At a regional level, this appears to be the first attempt at mapping peatlands using remote sensing imagery in the jalca ecoregion, and it represents a milestone for future efforts to map and conserve peatlands in other tropical mountain areas of the world.

Although protected areas (PAs) play an important role in ecosystem conservation and climate change adaptation, no systematic information is available on PA protection of high-elevation freshwater ecosystems (e.g., lakes and watersheds with glaciers), their biodiversity and their ecosystem services in the tropical Andes. We therefore combined a literature review and map analysis of PAs of International Union for Conservation of Nature (IUCN) and national systems of PAs and freshwater ecosystems. We found that seven national parks were created for water resources protection but were not designed for freshwater conservation (i.e., larger watersheds). High-value biodiversity sites have not been protected, and new local PAs were created due to water resource needs. We quantified 31 Ramsar sites and observed that PAs cover 12% of lakes, 31% of glacial lakes and 12% of the total stream length in the tropical Andes. Additionally, 120 watersheds (average area 631 km2) with glaciers and 40% of the total glacier surface area were covered by PAs. Future research into the role of PAs in ecosystem services provision and more detailed freshwater inventories within and around PAs, especially for those dependent on glacier runoff, will fill key knowledge gaps for freshwater conservation and climate change adaptation in the tropical Andes.

The characterization of modern pollen rain assemblages along environmental gradients is an essential prerequisite for reliable interpretations of fossil pollen records. In this study, we identify pollen-vegetation relationships using modern pollen rain assemblages in moss polsters (n = 13) and lake sediment surface samples (n = 11) along a steep temperature gradient of 7°C (3100–4200 m above sea level) on the western Andean Cordillera, Ecuador. The pollen rain is correlated to vascular plant abundance data recorded in vegetation relevées (n = 13). Results show that pollen spectra from both moss polsters and sediment surface samples reflect changes in species composition along the temperature gradient, despite overrepresentation of upper montane forest taxa in the latter. Estimated pollen transport distance for a lake (Laguna Llaviucu) situated in a steep upper montane forest valley is 1–2 km, while a lake (Laguna Pallcacocha) in the páramo captures pollen input from a distance of up to 10–40 km. Weinmannia spp., Podocarpus spp., and Hedyosmum sp. are indicators of local upper montane forest vegetation, while Phlegmariurus spp. and Plantago spp. are indicators for local páramo vegetation.

A multidecadal-scale lake-level reconstruction for Lago Wiñaymarca, the southern basin of Lake Titicaca, has been generated from diatom species abundance data. These data suggest that ~6500 cal yr BP Lago Wiñaymarca was dry, as indicated by a sediment unconformity. At ~4400 cal yr BP, the basin began to fill, as indicated by the dominance of shallow epiphytic species. It remained somewhat saline with extensive wetlands and abundant aquatic plants until ~3800 cal yr BP, when epiphytic species were replaced by planktic saline-indifferent species, suggesting a saline shallow lake. Wiñaymarca remained a relatively shallow lake that fluctuated on a multidecadal scale until ~1250 cal yr BP, when freshwater planktic species increased, suggesting a rise in lake level with a concomitant decrease in salinity. The lake became gradually fresher, dominated by deep, freshwater species from ~850 cal yr BP. By ~80 cal yr BP, saline-tolerant species were rare, and the lake was dominated by freshwater planktic diatoms, resembling the fresh and deep lake of today. These results reveal a more dynamic and chronologically specific record of lake-level fluctuations and associated ecological conditions that provide important new data for paleoclimatologists and archaeologists, to better understand human-environmental dynamics during the mid- to late Holocene.

Dating moraines by lichenometry enabled us to reconstruct glacier recession in the Bolivian Andes since the Little Ice Age maximum. On the 15 proglacial margins studied, we identified a system of ten principal moraines that marks the successive positions of glaciers over the last four centuries. Moraines were dated by performing statistical analysis of lichen measurements based on the extreme values theory. Like glaciers in many mid-latitude mountain areas, Bolivian glaciers reached their maximal extent during the second half of the 17th century. This glacier maximum coincides with the Maunder minimum of solar irradiance. By reconstructing the equilibrium-line altitude and changes in mass-balance, we think the glacier maximum may be due to a 20 to 30% increase in precipitation and a 1.1 to 1.2 °C decrease in temperature compared with present conditions. In the early 18th century, glaciers started to retreat at varying rates until the late 19th to early 20th century; this trend was generally associated with decreasing accumulation rates. By contrast, glacier recession in the 20th century was mainly the consequence of an increase in temperature and humidity. These results are consistent with observations made in the study region based on other proxies.

Radiocarbon dated lacustrine sequences in Perú show that the chronology of glaciation during the late glacial in the tropical Andes was significantly out-of-phase with the record of climate change in the North Atlantic region. Fluvial incision of glacial-lake deposits in the Cordillera Blanca, central Perú, has exposed a glacial outwash gravel; radiocarbon dates from peat stratigraphically bounding the gravel imply that a glacier advance culminated between ∼11,280 and 10,990 14C yr B.P.; rapid ice recession followed. Similarly, in southern Perú, ice readvanced between ∼11,500 and 10,900 14C yr B.P. as shown by a basal radiocarbon date of ∼10,870 14C yr B.P. from a lake within 1 km of the Quelccaya Ice Cap. By 10,900 14C yr B.P. the ice front had retreated to nearly within its modern limits. Thus, glaciers in central and southern Perú advanced and retreated in near lockstep with one another. The Younger Dryas in the Peruvian Andes was apparently marked by retreating ice fronts in spite of the cool conditions that are inferred from the ∂18O record of Sajama ice. This retreat was apparently driven by reduced precipitation, which is consistent with interpretations of other paleoclimatic indicators from the region and which may have been a nonlinear response to steadily decreasing summer insolation.

10Be terrestrial cosmogenic nuclide surface exposure ages from moraines on Nevado Illimani, Cordillera Real, Bolivia suggest that glaciers retreated from moraines during the periods 15.5–13.0 ka, 10.0–8.5 ka, and 3.5–2.0 ka. Late glacial moraines at Illimani are associated with an ELA depression of 400–600 m, which is consistent with other local reconstructions of late glacial ELAs in the Eastern Cordillera of the central Andes. A comparison of late glacial ELAs between the Eastern Cordillera and Western Cordillera indicates a marked change toward flattening of the east-to-west regional ELA gradient. This flattening is consistent with increased precipitation from the Pacific during the late glacial period.

Hypseocharis is a genus endemic to the high Andes and sister to all other Geraniaceae genera. Regarding its basal position in Geraniaceae evolution, its germination ecology can provide important insights into the early evolution of physical dormancy. Imbibition tests performed on seeds of two Hypseocharis populations from Bolivia indicate that their seeds indeed have physical dormancy like all other Geraniaceae. These results indicate that physical dormancy in Geraniaceae evolved during the Eocene before the uplift of the Andes mountains and before the events that led to the cross-Atlantic disjunct distribution of Geraniacae.

Ecuador harbours a diverse assemblage of tropical mammals, yet the natural history and local-scale distributions of many species remain poorly understood. We conducted the first systematic camera-trap survey of terrestrial mammalian carnivores at Wildsumaco Wildlife Sanctuary, a mid-elevation (1,250–1,450 m), montane rainforest site on the slopes of Sumaco Volcano, in the heart of the Tropical Andes biodiversity hotspot. We quantified trap success, latency to detection and temporal activity patterns for each species detected. We recorded nine carnivore species (four felids, two procyonids and three mustelids), including the first verified record of the jaguarundi Puma yagouaroundi in the region. These species comprise one-third of all terrestrial carnivore species known to occur in Ecuador and 82% of those thought to occur at mid-elevation. All except one of the carnivores we detected have reported elevational ranges ≤ 1,500 m; the one exception, the puma Puma concolor, occurs throughout mainland Ecuador at 0–4,500 m. No cloud forest or highland species (i.e. those with a reported lower elevational limit of ≥ 1,500 m) were detected. Trap success was highest, and latency to detection smallest, for the margay Leopardis wiedii, and temporal activity patterns for all species were consistent with those reported previously in the literature. Our results demonstrate that the mid-elevation montane rainforests of Sumaco Volcano support an exceptionally high diversity of co-existing mammalian carnivores, many of which appear to be near their upper elevational limits, and emphasize the conservation value of this area.

Arrested succession is conspicuous in the abandoned pastures of the Andean piedmont that have encroached upon the tropical montane forests toward higher limits and steeper slopes. Habitat 'shredding' is analysed to depict the current spatial configuration of tropical Andean landscapes, based on fragmentation patterns prompted by seed dispersal ecology and pasture encroachment.

Seed dispersal was studied to address the hypo-thesis that seed input constrains the recruitment of montane forest seedlings, thus impeding pasture conversion to forest. It turns out that a better competitor, the tussock grass Setaria sphacelata, is limiting dispersal success due to its bioarchitecture and planting patterns. Because of the variegation of fragments, the area is in danger of landscape homogeneity within a matrix of degraded pasture. Currently, protection of fragmented remnants and restoration of original landscape structure and function are urgent needs for land-use planning toward sustainable development in the region.

Restoration ecology is plausible as a means of conservation for degraded Tropandean forests, since human impacts have shredded landscapes entirely. Dispersal ecology may be used to facilitate pasture conversion to forest in equatorial landscapes, but the proactive approach of pasture removal or planting strategy should differ from that for lowland Amazonia, where abandoned pastures are different from those of montane environs. However, the region may be proactively managed only if political decisions include conservation as a goal of development.