A 23-million-year record of morphological evolution within Neotropical grass pollen.

Grass-dominated biomes in South America comprise c. 20 million years of history, yet their evolution and underlying drivers remain poorly understood. Here we apply a novel approach that combines scanning electron microscopy imaging with computational analysis to quantify the morphometrics of grass (Poaceae) pollen micro-ornamentation from the Neotropics since the Early Miocene (23 million years ago).

Greater difference between airborne and flower pollen chemistry, than between pollen collected across a pollution gradient in the Netherlands.

The prevalence in allergic diseases has increased considerably in the past decades. An important trigger of the symptoms of allergic rhinitis (hay fever) is the pollen of wind-pollinating plants. This pollen is developed by plants and is released into the air where it gets exposed to environmental influences and air pollution.

Pre-contact and post-colonial ecological legacies shape Surinamese rainforests.

Disturbances in tropical forests can have long-lasting ecological impacts, but their manifestations (ecological legacies) in modern forests are uncertain. Many Amazonian forests bear the mark of past soil modifications, species enrichments, and fire events, but the trajectories of ecological legacies from the pre-contact or post-colonial period remain relatively unexplored. We assessed the fire and vegetation history from 15 soil cores ranging from 0 to 10 km from a post-colonial Surinamese archaeological site.

Phytolith assemblages reflect variability in human land use and the modern environment.

Unlabelled: Phytoliths preserved in soils and sediments can be used to provide unique insights into past vegetation dynamics in response to human and climate change. Phytoliths can reconstruct local vegetation in terrestrial soils where pollen grains typically decay, providing a range of markers (or lack thereof) that document past human activities. The ca.

Floristic homogenization of South Pacific islands commenced with human arrival.

The increasing similarity of plant species composition among distinct areas is leading to the homogenization of ecosystems globally. Human actions such as ecosystem modification, the introduction of non-native plant species and the extinction or extirpation of endemic and native plant species are considered the main drivers of this trend. However, little is known about when floristic homogenization began or about pre-human patterns of floristic similarity.

Warming, drought, and disturbances lead to shifts in functional composition: A millennial-scale analysis for Amazonian and Andean sites.

Tropical forests are changing in composition and productivity, probably in response to changes in climate and disturbances. The responses to these multiple environmental drivers, and the mechanisms underlying the changes, remain largely unknown. Here, we use a functional trait approach on timescales of 10,000 years to assess how climate and disturbances influence the community-mean adult height, leaf area, seed mass, and wood density for eight lowland and highland forest landscapes.

A stronger role for long-term moisture change than for CO in determining tropical woody vegetation change.

Anthropogenically elevated CO (eCO) concentrations have been suggested to increase woody cover within tropical ecosystems through fertilization. The effect of eCO is built into Earth system models, although testing the relationship over long periods remains challenging. Here, we explore the relative importance of six drivers of vegetation change in western Africa over the past ~500,000 years (moisture availability, fire activity, mammalian herbivore density, temperature, temperature seasonality, CO) by coupling past environmental change data from Lake Bosumtwi (Ghana) with global data.

Legacies of Indigenous land use and cultural burning in the Bolivian Amazon rainforest ecotone.

The southwestern Amazon Rainforest Ecotone (ARE) is the transitional landscape between the tropical forest and seasonally flooded savannahs of the Bolivian Llanos de Moxos. These heterogeneous landscapes harbour high levels of biodiversity and some of the earliest records of human occupation and plant domestication in Amazonia. While persistent Indigenous legacies have been demonstrated elsewhere in the Amazon, it is unclear how past human-environment interactions may have shaped vegetation composition and structure in the ARE.

Early to mid-Holocene human activity exerted gradual influences on Amazonian forest vegetation.

Humans have been present in Amazonia throughout the Holocene, with the earliest archaeological sites dating to 12 000 years ago. The earliest inhabitants began managing landscapes through fire and plant domestication, but the total extent of vegetation modification remains relatively unknown. Here, we compile palaeoecological records from lake sediments containing charcoal and from pollen analyses to understand how human land-use affected vegetation during the early to mid-Holocene, and place our results in the context of previous archaeological work.

Paleo-ENSO influence on African environments and early modern humans.

In this study, we synthesize terrestrial and marine proxy records, spanning the past 620 ky, to decipher pan-African climate variability and its drivers and potential linkages to hominin evolution. We find a tight correlation between moisture availability across Africa to El Niño Southern Ocean oscillation (ENSO) variability, a manifestation of the Walker Circulation, that was most likely driven by changes in Earth's eccentricity. Our results demonstrate that low-latitude insolation was a prominent driver of pan-African climate change during the Middle to Late Pleistocene.

A checklist of vascular plants of Ewe-Adakplame Relic Forest in Benin, West Africa.

Covering 560.14 hectares in the south-east of Benin, the Ewe-Adakplame Relic Forest (EARF) is a micro-refugium that shows insular characteristics within the Dahomey Gap. It is probably one of the last remnants of tropical rain forest that would have survived the late Holocene dry period.

Carbon sequestration rates indicate ecosystem recovery following human disturbance in the equatorial Andes.

Few studies exist that document how high-elevation Andean ecosystems recover naturally after the cessation of human activities and this can limit the implementation of cost-effective restoration actions. We assessed Andean forest (Polylepis stands) and páramo grassland recovery along an elevation gradient (3,600-4,350 m.a.

Leaf wax alkane patterns of six tropical montane tree species show species-specific environmental response.

It remains poorly understood how the composition of leaf wax -alkanes reflects the local environment. This knowledge gap inhibits the interpretation of plant responses to the environment at the community level and, by extension, inhibits the applicability of alkane patterns as a proxy for past environments. Here, we studied the alkane patterns of five species and one species, in the Ecuadorian Andes (653-3,507 m a.

A 7000-year history of changing plant trait composition in an Amazonian landscape; the role of humans and climate.

Tropical forests are shifting in species and trait composition, but the main underlying causes remain unclear because of the short temporal scales of most studies. Here, we develop a novel approach by linking functional trait data with 7000 years of forest dynamics from a fossil pollen record of Lake Sauce in the Peruvian Amazon. We evaluate how climate and human disturbances affect community trait composition.

Columbus' environmental impact in the New World: Land use change in the Yaque River valley, Dominican Republic.

Columbus' arrival in the New World in AD 1492 on the northern coast of Hispaniola was followed by a suite of changes in land-use. We reconstruct environmental change from a 225-cm-long sediment core from site Los Indios from an abandoned and sediment-filled meander of the Yaque River, Cibao Valley, northeastern Dominican Republic. The sediment record starts ca.

Past and future global transformation of terrestrial ecosystems under climate change.

Impacts of global climate change on terrestrial ecosystems are imperfectly constrained by ecosystem models and direct observations. Pervasive ecosystem transformations occurred in response to warming and associated climatic changes during the last glacial-to-interglacial transition, which was comparable in magnitude to warming projected for the next century under high-emission scenarios. We reviewed 594 published paleoecological records to examine compositional and structural changes in terrestrial vegetation since the last glacial period and to project the magnitudes of ecosystem transformations under alternative future emission scenarios.

A novel approach to study the morphology and chemistry of pollen in a phylogenetic context, applied to the halophytic taxon L.(Nitrariaceae).

is a halophytic taxon (i.e., adapted to saline environments) that belongs to the plant family Nitrariaceae and is distributed from the Mediterranean, across Asia into the south-eastern tip of Australia.

Modeling the ecology and evolution of biodiversity: Biogeographical cradles, museums, and graves.

Individual processes shaping geographical patterns of biodiversity are increasingly understood, but their complex interactions on broad spatial and temporal scales remain beyond the reach of analytical models and traditional experiments. To meet this challenge, we built a spatially explicit, mechanistic simulation model implementing adaptation, range shifts, fragmentation, speciation, dispersal, competition, and extinction, driven by modeled climates of the past 800,000 years in South America. Experimental topographic smoothing confirmed the impact of climate heterogeneity on diversification.

Ecological consequences of post-Columbian indigenous depopulation in the Andean-Amazonian corridor.

European colonization of South America instigated a continental-scale depopulation of its indigenous peoples. The impact of depopulation on the tropical forests of South America varied across the continent. Furthermore, the role that indigenous peoples played in transforming the biodiverse tropical forests of the Andean-Amazonian corridor before AD 1492 remains unknown.

Long-Term Vegetation Dynamics in a Megadiverse Hotspot: The Ice-Age Record of a Pre-montane Forest of Central Ecuador.

Tropical ecosystems play a key role in many aspects of Earth system dynamics currently of global concern, including carbon sequestration and biodiversity. To accurately understand complex tropical systems it is necessary to parameterise key ecological aspects, such as rates of change (RoC), species turnover, dynamism, resilience, or stability. To obtain a long-term (>50 years) perspective on these ecological aspects we must turn to the fossil record.

Pollen-vegetation richness and diversity relationships in the tropics.

Tracking changes in biodiversity through time requires an understanding of the relationship between modern diversity and how this diversity is preserved in the fossil record. Fossil pollen is one way in which past vegetation diversity can be reconstructed. However, there is limited understanding of modern pollen-vegetation diversity relationships from biodiverse tropical ecosystems.

Aquatic community response to volcanic eruptions on the Ecuadorian Andean flank: evidence from the palaeoecological record.

Aquatic ecosystems in the tropical Andes are under increasing pressure from human modification of the landscape (deforestation and dams) and climatic change (increase of extreme events and 1.5 °C on average temperatures are projected for AD 2100). However, the resilience of these ecosystems to perturbations is poorly understood.

Pollen and spores as biological recorders of past ultraviolet irradiance.

Solar ultraviolet (UV) irradiance is a key driver of climatic and biotic change. Ultraviolet irradiance modulates stratospheric warming and ozone production, and influences the biosphere from ecosystem-level processes through to the largest scale patterns of diversification and extinction. Yet our understanding of ultraviolet irradiance is limited because no method has been validated to reconstruct its flux over timescales relevant to climatic or biotic processes.