Arboreal Cover Research Articles

Diverse Methods for Diverse Systems: A Large-Scale Comparison of Reptile Sampling Methods

Abstract Reptiles play a crucial role in maintaining biodiversity and ecosystem health, yet many species face increasing threats due to various anthropogenic factors. Enhancing our understanding of reptile diversity and habitat use worldwide necessitates evaluating the effectiveness of diverse survey techniques. The relative efficacy of different methods may vary significantly across regions or communities, highlighting the need for a comprehensive approach using multiple survey methods over extensive spatial and temporal scales. In this study, we compared the effectiveness of seven survey methods – pitfall traps, funnel traps, spotlighting, arboreal cover boards, incidental encounters, camera traps, and passive acoustic monitoring (PAM) – for assessing reptile biodiversity over several years across an extensive spatial range in open eucalypt woodlands throughout eastern Australia. Pitfall and funnel traps were the most effective methods for detecting reptiles across all sites and latitudes. A combination of pitfall and funnel traps accumulated species the quickest, had high detection probabilities, and accounted for nearly 90% of all different reptile species detected in this study. However, with a decrease in latitude reptile diversity increased and other survey methods became necessary to document the full extent of the reptile communities. Reptile assemblages captured by different survey methods varied significantly, except for the communities captured by pitfall and funnel traps. No single method captured all species, and no species was detected by every method. Passive acoustic monitoring failed to detect any reptiles and may not be viable for assessing reptile biodiversity in Australia. Pitfall and funnel traps proved highly effective for detecting terrestrial reptiles within open eucalypt woodlands in Australia, however, the selection of methods for evaluating reptile biodiversity depends on the objectives and target fauna, and when possible, to maximize species richness, survey designs should incorporate an array of concurrently deployed methods, particularly in regions with higher overall species richness. Nevertheless, if resources and time are limited, pitfall and funnel traps, combined with incidental encounters, should capture the majority of species.

Millennial-scale variability of water supply, vegetation and fire activity on a tropical wetland in central Brazil

The Pandeiros wetland is a tropical wetland located in the ecotone between the Cerrado and the Caatinga, in central Brazil. It has a key ecological importance for vegetation biodiversity, hydrological cycles, fauna reproduction and feeding, and for local human populations. Here, we investigate millennial-scale variability of water supply, vegetation structure and fire activity in the Pandeiros wetland during the Late Holocene and discuss forcing mechanisms that affected flooding, vegetation cover and fire regime within this fragile ecosystem. Our study is based on the previously studied pollen record of the Pandeiros palm swamp and on new charcoal analyses of two sediment cores that cover the last 4500 cal years, and their comparison to modern pollen and to available paleoclimatic data. Our results show that both local rainfall at the Pandeiros River basin and southern rainfall at the upper São Francisco River were important in maintaining water supply for the Pandeiros wetland during the last millennia. Our data also suggest that during Late Holocene the arboreal cover declined in the Cerrado of the Pandeiros Basin, an opposite trend to that observed in the wetter Cerrado-Atlantic Forest ecotone. We propose that increasing summer insolation in Southern Hemisphere was an important factor in maintaining low arboreal cover and open savanna vegetation on the drier areas around the Pandeiros wetland. Regarding fire activity, we suggest that until around 2600 cal yr BP, climate conditions were the most important driver of fire activity, in which drier conditions favored the intensification of fire, whereas subsequently, anthropic activities appear to have become an important fire inducer. Our findings highlight the multiple environmental aspects that have influenced the Pandeiros wetland history during the last four thousand years, including monsoon variability, insolation variation and human occupation.

Gamma diversity: derived from and a determinant of alpha diversity and beta diversity. An analysis of three tropical landscapes

Using three taxonomic groups of beetles we examine how alpha and beta diversity influence the species richness of a landscape (gamma diversity), and vice versa. That is, how the species richness of a landscape – which is a historical and biogeographical phenomenon – contributes to the values of alpha diversity (1) at a given site, (2) in a community, (3) in terms of cumulative species richness by community, and also contributes to (4) the intensity of species exchange between communities. To explore this question, we used two subfamilies of Scarabaeoidea: Scarabaeinae and Geotrupinae, and the family Silphidae. In all analyses these three taxonomic groups are considered as a single indicator group: the copronecrophagous beetles. Information is also included on the subfamily Aphodiinae (Scarabaeoidea), coprophagous beetles not included in the indicator group. Several types of vegetation located in three landscapes (tropical, transition and mountain) were studied, and these are located along an altitudinal gradient in the central part of the state of Veracruz, Mexico. We base this study on the following concepts. The alpha diversity of an indicator group reflects the number of species that use a given environment or resource in a given place or community. Spacial beta diversityis related to the response of organisms to spatial heterogeneity. Gamma diversity depends primarily on the historical and geographic processes that operate on the mesoscale level and is also affected by alpha and beta diversity. It is on this scale of landscape that human actions, such as the modification and fragmentation of vegetation, have their most important effects. These are, however, often beyond the scope of ecological analyses carried out on a local scale. In the three landscapes, sampling was carried out regularly at 67 sites, with complementary sampling at another 69 sites. Twenty-six types of vegetation communities were studied. A total of 16,152 specimens representing 60 species were captured (52 species of Scarabaeinae, 4 Geotrupinae and 4 Silphidae). In the tropical landscape the community richest in species was low deciduous forest. In the transition landscape, cloud forest was the richest. Each of these communities is the most representative of their respective altitudinal bands. In contrast, the greatest species richness in the mountain landscape occurred in the mountain grasslands and pastures; types of community favoured by or even created by human intervention. This is explained by the expansion of heliophilous species from the Mexican High Plateau into these areas. In the tropical landscape the species richness of the pastures is similar to that of its forests, but with a partially different composition which is characterized by the dominance of heliophilous and coprophagous species; the latter, in addition to the more ubiquitous species that are shared with the tropical forest. In the transition landscape the cloud forest and the coffee plantations with polyspecific shade are important in the context of conserving the fauna. This type of community offers arboreal cover and occupies the majority of this landscape, allowing the groups of insects studied to move between remnant fragments of cloud forest. On the landscape scale but not locally, the fragmentation of natural communities does not appear to have reduced the number of species for the beetles of the indicator group. In each landscape disturbance by human activity appears to have been overcome for distinct reasons. In the tropical landscape we find the heliophilous beetle fauna characteristic of pastures, and this has increased by two species of recent invaders. In the transition landscape, the coffee plantations with polyspecific shade create a communication matrix, while in the mountain landscape the expansion of the mountain pastures has made conditions more favourable for heliophilous species. These results are not necessarily expected for other groups of organisms.

Lowstand lake conditions in NW Anatolia during the Little Ice Age: Multi-proxy evidence from Lake Sünnet

Despite global and local evidence of significant precipitation changes since the Little Ice Age (LIA), their impact upon lake hydrology and surrounding vegetation has yet to be investigated in NW Anatolia. Moreover, the LIA, as a trigger to the social/political recession of the Ottoman Empire in the 17th century is expected to have these impacts. To address this important gap, we studied three cores from Lake Sünnet, a landslide-dammed high altitude lake with extreme sedimentation rates, by using a wide range of proxies including lithology, stable isotopes of O and C, diatoms, pollen, and ostracods. The LIA timespan of AD 1510–1750 is represented by poorly preserved diatom flora and scarce ostracod fauna that collectively suggest very shallow aquatic conditions. The period AD 1640–1710 within the LIA is standing out with higher Abies and total herb pollen percentages that denotes considerably cooler conditions. During and soon after this cold and dry period precisely overlapping the Maunder Minimum, the currently deep Lake Sülüklü in close vicinity was a dry lowland where tall trees were growing. Progressive warming/lake level rise in Lake Sünnet after the AD 1750s is suggested based on a continuous diatom record with increasing planktonic share, increase in diverse and warm demanding arboreal cover, and a positive shift in δ18O of the lake muds. Following the relatively dry/cold period of AD 1800–1850 (Dalton Minimum) when the lake level was stationary and Artemisia cover became the most expanded of the whole record, a relatively warmer climate has dominated the area until the end of the 20th century.

What a few hairs can tell us about the resource use of giant armadillos.

Understanding of resource requirements of vulnerable species is key for conservation planning. Here, we used stable carbon (δ13 C) and nitrogen isotopes (δ15 N) of hair from giant armadillos (Priodontes maximus) to understand individual resource use. We collected hair from 19 giant armadillos analyzing 34 samples from the Brazilian Pantanal and compared the resource use between sexes and age classes. We also assessed the relationship of isotopic values with individuals' body mass and the habitat type used. We observed a wide variation in resource use by giant armadillos, showing that individuals consume prey that feeds on distinct resources and occupies different habitat types, indicating that there is individual variation in foraging behavior. Most giant armadillos presented a mixed diet (C3 /C4 resources, forests/open areas), but a quarter of individuals had strictly C4 diets (open areas). Males are more prone to forage on C4 resources, presenting an isotopic niche 2.6-times larger than that of females. Subadults presented diets more associated with habitats with high arboreal cover (C3 resources, forests), while adults foraged more in open areas (C4 resources). This result is mirrored by the positive relationship between δ13 C values and body mass, suggesting that larger giant armadillos tend to feed more in open areas. We observed that δ13 C values decreased as individuals increased the use of habitats with high arboreal cover. We stress the importance of conserving the natural mosaic in the Pantanal landscape for the species persistence, given that giant armadillos require all habitat types to fulfill their dietary, spatial, and developmental needs.

Loss of Natural Habitats: High-Altitude Vegetation, Pantanal

The objective of this study is to quantify the spatiotemporal variation of high-altitude grassland (Campos de Altitude) in two different study areas between 1985 and 2020. First, the types of vegetation present in both areas were classified using a false-color (Red, Green, Blue) composition, with the channels replaced by mid-infrared, near-infrared, red, respectively. Following the definition of vegetation classes and the creation of polygons over them, they were superimposed on the NDVI product (1985 and 2020) to obtain the maximum and minimum values of the index and to identify which value ranges each class would be in. Next, a multitemporal false-color composition was carried out with the modification of the Red channel by the NDVI 1985 product, the Green channel by the NDVI 2020 product and the Blue channel without any changes. The results show that the total area of Campos de Altitude decreased between 1985 and 2020 in both study areas, with area 1 losing 31.93% and area 2 losing 35.12%, whereas the vegetation of denser strata (arboreal) increased in its spatial distribution in both study areas, with area 2 gaining the most (230%). There was a noticeable increase in arboreal vegetation in the two study areas during the years analyzed. The tendency for the fraction of arboreal vegetation cover to increase is in line with the decrease in Campos de Altitude vegetation, and this phenomenon may be related to environmental factors such as temperature variations, amount of rainfall, solar radiation, and soil composition.

Environmental Dynamics of the Ribbon-Like Pine Forests in the Parklands of North Kazakhstan

The ribbon-like pine forests of North Kazakhstan represent the principal territorial intrazonal and azonal biotopes. Integrated bio-geographic studies of the pine forests’ status were performed in the Beskaragai and Chaldai Nature Reserves in the Pri-Irtysh River basin within, at present, the climate–change most susceptible transitional parkland-steppe zone of Central Asia, adjoining the West Siberian Lowland. The investigations followed the regional topographic gradient with a series of mapped sites characterizing the spatial relief patterns of the pristine forest distribution and the associated phytocenoses. The results revealed marked natural arboreal cover restoration differences between the geographically close upland and lowland forest ecosystems. The regional tree growth dynamics show the varying intensity of the pine seedlings’ succession, the tree stands’ biomass productivity and the environmental stability, weakened by the extreme continentality and progressing aridification along with adverse anthropogenic ecological impacts. The specific geomorphic, soil and hydrological conditions are the principal determining factors. The more vital plain and lowland pine forests host the floristically richer fescue-dominated communities compared to the more fragile and precipitation-poorer upland pine settings. The latter forest ecosystems display a higher vulnerability to the current climate change, generating tree drying, forest fires, and to modern human activities such as logging, herding and recreation. The research conclusions provide new insights on the natural ribbon-like pine forests’ sustainability and adaptation to the ongoing continental warming triggering fundamental environmental transformations in Central Asia’s parklands.

Soil infectivity and arbuscular mycorrhizal fungi communities in four urban green sites in central Argentina

Many cities around the globe strive for create and maintain urban forests to improve human health, welfare and more positive interactions towards nature. Frequently, the only available land has compacted and degraded soils with an altered soil biota. Studies are needed to address soilborne fungi biodiversity especially that of arbuscular mycorrhizal fungi (AMF), essential for plant development. Our aim was to evaluate the AMF community composition and soil infectivity in four urban sites with different disturbance levels and management histories (Córdoba, Argentina). In two urban forests (reference and restored) and two parklands (forested and control), indigenous AMF morphospecies, soil compaction and dominant plant cover were determined together with the soil infectivity in a greenhouse experiment. Results indicated that AMF communities were dominated by Funneliformis geosporum, Glomus brohultii and Rhizophagus intraradices which are considered generalists and resilient to harsh environmental conditions. AMF community composition varied greatly between the undisturbed reference site and the more disturbed parklands. The richness, diversity and soil infectivity were higher in both urban forests compared to parklands and was partially related with the greater variety of plant physiognomies (in restored site), the dominance of arboreal cover (in reference site) and the lowest soil compaction compared to parklands. In the restored forest, AMF richness and diversity were higher compared to the parklands and to the control parkland, respectively. The greater subsoil compaction and the higher percentage of herbaceous cover (mainly monospecific lawn) represented the most disturbed conditions as a consequence of trampling and subsequent soil erosion. We concluded that differences existed between urban forests and parklands sites with variable disturbance intensities and management histories, however, the parameters analysed here do not fully describe the effects of local urban conditions in the composition and infectivity status of AMF in the soil, and hence future research approaches are discussed.

Feasibility of satellite image and GIS sampling for population representative surveys: a case study from rural Guatemala

BackgroundPopulation-representative household survey methods require up-to-date sampling frames and sample designs that minimize time and cost of fieldwork especially in low- and middle-income countries. Traditional methods such as multi-stage cluster sampling, random-walk, or spatial sampling can be cumbersome, costly or inaccurate, leading to well-known biases. However, a new tool, Epicentre’s Geo-Sampler program, allows simple random sampling of structures, which can eliminate some of these biases. We describe the study design process, experiences and lessons learned using Geo-Sampler for selection of a population representative sample for a kidney disease survey in two sites in Guatemala.ResultsWe successfully used Epicentre’s Geo-sampler tool to sample 650 structures in two semi-urban Guatemalan communities. Overall, 82% of sampled structures were residential and could be approached for recruitment. Sample selection could be conducted by one person after 30 min of training. The process from sample selection to creating field maps took approximately 40 h.ConclusionIn combination with our design protocols, the Epicentre Geo-Sampler tool provided a feasible, rapid and lower-cost alternative to select a representative population sample for a prevalence survey in our semi-urban Guatemalan setting. The tool may work less well in settings with heavy arboreal cover or densely populated urban settings with multiple living units per structure. Similarly, while the method is an efficient step forward for including non-traditional living arrangements (people residing permanently or temporarily in businesses, religious institutions or other structures), it does not account for some of the most marginalized and vulnerable people in a population–the unhoused, street dwellers or people living in vehicles.

Vegetation and fire variability in the central Cerrados (Brazil) during the Pleistocene-Holocene transition was influenced by oscillations in the SASM boundary belt

This study investigates historical fire regimes and arboreal cover variability in the Brazilian Cerrados, a large Neotropical savanna ecosystem, during the Pleistocene-Holocene transition and early Holocene, and then tests whether the observed variation is linked to South American Summer Monsoon (SASM) variability. We present high-resolution pollen, XRF and charcoal records from Lagoa Feia, located in central Cerrados, and assess how they compare with other pollen records from the surrounding region to investigate regional trends of vegetation and fire regime variability. Our results show that the Pleistocene-Holocene transition was marked by a wet episode, which included moist forest expansion and rising lake levels, that correlates well with increased monsoon activity in a large area of central South America during the same period. This wet episode chronologically coincides with the Younger Dryas cold episode in the northern hemisphere. Our data revealed moisture declines in central Cerrados after 11.2 kyr BP, along with centennial-scale fluctuations from dry to wet conditions throughout the early Holocene period until around 6 kyr BP. These dry/wet oscillations are associated with weakened SASM activity and repeated shifts of its belt position during this time range. Fire activity increased in central Cerrados just after the onset of drier conditions during the early Holocene, and likely contributed to decreased arboreal cover at that time. A trend of increasing moisture in the region was observed after 6 kyr BP. Our study reveals how centennial and millennial-scale changes in monsoon activity influenced arboreal cover, diversity and fire regimes in the central Cerrados.

Long-term enrichment with the camedor palm (Chamaedorea elegans Mart.) improved forest cover in an anthropogenic tropical landscape

The use of non-timber forest products forms part of the strategy contributing to the well-being of populations near forest areas. Chamaedorea is one of the most important palm genera that is globally commercialized profitably for its attractive foliage used in floral decorations. In our study area located in the central region of Veracruz, Mexico we identified changes in tree cover between 1973 and 2017 using the normalized difference vegetation index (NDVI). We conducted plant surveys to identify tree species richness associated with the cultivation of C. elegans. We conducted semi-structured interviews with local palm producers to understand their perceptions regarding changes in tree cover in the study area and its association with the presence of the camedor palm. Soil cover patterns and vegetation index signatures indicated an increase in the forested area from 1973 to 2017 (after more than 43 years), with a 69% gain in secondary vegetation coverage with low NDVI values. This increase is associated with the cultivation of palm, since arboreal cover had previously been dominated by species traditionally used as shade for camedor cultivation. Tree diameters at breast height (DBH) were low, indicating young secondary forests with low recruitment and diversity in the understory suggestive of simplified species assemblages; most of the associated species were long-living pioneers and typical of the secondary forest favored by the palm producers. Producers mentioned they did not remove coffee because it is their main means of subsistence, and in combination with the palm, there is greater economic benefit. They also confirmed an increase in forest cover owing to the introduction of palm cultivars in the areas north and south of the study area. This was confirmed with the NDVI results, which detected the same spatial pattern. These changes resulted in the interruption of the processes of succession without the transition of secondary to old-growth forests. However, the canopy of the study area provides better environmental services than did the previously existing vegetation cover. This study showed the need for the assessment of non-timber forest products as key indicators of land use change and alterations in associated plant cover.

Response of riparian ecosystem to dike construction on the Middle Reaches of the Tarim River, Northwest China

AbstractStudies have demonstrated that water management engineering may bring ecological degradation to the riparian ecosystems. However, most such works focus on dams, and the impact of dikes has been less studied. We investigated how dikes interfere with the desert riparian ecosystem on the middle reaches of the Tarim River, Xinjiang, China. We collected data of vegetation species and coverage, groundwater depth, total dissolved solids (TDS), and soil salinity, along eight transects crossing the river channel, from 2001 to 2010. We conducted spatio‐temporal analyses of the data from the transects and calculated correlations between the ecological indices and the groundwater measurements and between the ecological indices and the soil properties. We found that since the construction of dikes in 2001, both the depth of and TDS in groundwater had been increasing so did soil salinity; their spatial distributions changed from irregular to increasing along with the distance from the dikes, and the width of solute‐dilution belt became narrower. The overall species richness had been declining, and spatially, it had decreased as the distance to the dikes increases; meanwhile, the species evenness had been increasing. The correlation between the species diversity and the groundwater measurements was not significant before 2003 but became highly significant for 2006–2010, after the dikes were fully established. A shrinkage of arboreal cover is accompanied by expansions of shrubby and herbaceous covers. Particularly for the Populus euphratica community, the main arboreal community in the region, the ratio between seedlings and young trees had been declining; the structure of the community became simpler as the diversity decreased; and the lateral width of the community changed from 1,500 m to 800–1,000 m. This community degradation appears to be a consequence of the dike constructions, which prevented overbank floods, resulting in a shortage of water for groundwater recharging, an increase of soil salinity leaching, and a loss of proper habitats for seeds germination.

Cobertura vegetal em microbacias urbanas: análise temporal da cobertura arbórea e temperatura de Rondonópolis, Mato Grosso (Vegetation cover in urban microbasins: temporal analysis of the arboreal cover and temperature of Rondonópolis, Mato Grosso)

Os objetivos deste trabalho foram quantificar a cobertura vegetal presente nas microbacias urbanas de Rondonópolis-MT e relacionar com o número de habitantes para calcular o IVC; realizar um comparativo da quantidade de cobertura vegetal nos anos de 2013 e 2017 para saber se houve déficit ou ganho de vegetação relacionando com as variações da temperatura do ar. Foi realizado o levantamento da cobertura vegetal através do NDVI e posteriormente relacionado aos valores de vegetação em m2 de cada microbacia com o número de habitantes para se obter o ICV. Já a comparação dos anos estudados (2013 e 2017) foi realizado também pelo cálculo do NDVI e posteriormente extraído os valores de NDVI para cada imagem e comparado através da correlação de Pearson e teste t pareado. Os valores de temperatura entre os anos de 2013 a 2017 foram comparados com os resultados do levantamento da vegetação. Da área total estudada (7753 hectares), a cobertura vegetal representou 622 hectares, cerca de 8% do total. O ICV para a microbacia do Escondidinho foi de 2 m2/hab. A cobertura vegetal para o ano de 2013 foi de 2.500 hectares e em 2017 foi reduzida para 1.661 hectares. Ocorreu um déficit de cobertura vegetal de 839 hectares. Os resultados da cobertura vegetal de 2013 e 2017 relacionados com a temperatura, demonstraram que houve diferenças na temperatura em locais que houve perda de vegetação, com aumento de até 1.5°C. A cobertura vegetal exerce um importante papel na dinâmica ambiental urbana, mantendo a temperatura mais baixa, servindo como refúgio para a biodiversidade e proporcionando saúde física e mental aos habitantes. A B S T R A C TThe aims of this work were the measurement of the forest cover present on the watershed of Rondonópolis-MT and relate this with the number of inhabitants to calculate the IVC; to make a comparison of the quantity of forest cover in 2013 and 2017 in order to know if there has been deficit or gain of vegetation relating them with the air temperature. It was done the survey of the forest cover by NDVI and it was later related to the data about the vegetation in m2 of each watershed with the number of inhabitants in order to get ICV. As to the comparison of the examined years (2013 and 2017), it was done, too, by the calculation of the NDVI and later it was extracted the values of the NDVI to each image and it was compared using the Pearson's correlation and the paired t-test. The values of the temeprature between 2013 and 2017 were compared with the outcome of the survey of the vegetation. Of the total area investigated (7753 hectares), the forest cover represented 622 hectares, about 8% of the total. The ICV to the watershed of Escondidinho was 2 m2/inh. The forest cover to 2013 was 2.500 hectares and in 2017 it was reduced to 1.661 hectares. There was a deficit of 839 hectares in the forest cover. The results about the forest cover of 2013 and 2017 that were related with the temperature have shown that there were differences in the temperature in places with loss of vegetation, with a temperature rise of up to 1.5°C. The forest cover plays an important role in the urban environmental dynamics, keeping a lower temperature, serving as a refuge to the biodiversity and affording physical and mental health to the inhabitants.Keywords: ICV, Geoprocessing, Watershed, Urban microclimate.

Using landscape composition and configuration metrics as indicators of woody vegetation attributes in tropical pastures

Seasonally dry tropical forests in the Neotropics are typically transformed into pasture-dominated landscapes that represent a major threat to habitat biodiversity. Developing alternative management strategies that minimize the loss of native biota in agricultural landscapes is crucial. In a fragmented landscape in Veracruz, Mexico, we analyzed the community attributes of woody vegetation present in pastures in which different types of arboreal elements are common. We hypothesized that different landscape patterns, distinguishable using GIS land-cover maps, would be linked to woody plant diversity and its spatial variation. We created a detailed map of our study area distinguishing six forest cover types. We sampled the woody vegetation within 16 circular plots (100 m radius) each centered on an isolated fig tree and that varied in the amount of arboreal cover and proximity to remnant forest. We used a multimodel-inference approach to assess the relationship between different landscape metrics and woody vegetation response variables. Forest cover within each plot ranged from 3% to 44%. A total of 1777 woody plants (density = 35.4 plants ha−1), belonging to 88 species were recorded. Landscape composition and configuration metrics, particularly the type and amount of arboreal cover, were strong indicators of woody plant richness and abundance, while landscape structural heterogeneity was strongly related to floristic composition. In contrast proximity metrics were weak explanatory variables. Tall canopy forest fragments and isolated trees explained most of the variation in richness and abundance. Results suggest that maintaining 20–40% woody cover within pastures and maximizing the heterogeneity of arboreal elements promotes the conservation of biodiversity in rural landscapes dedicated to livestock. Further, easily obtained landscape metrics can be used as a tool to enhance vegetation assessment and help in the development of more convenient management practices that seek to increase native species richness, while improving landscape connectivity and resilience.

Reconstructing past arboreal cover based on modern and fossil pollen data: A statistical approach for the Gredos Range (Central Spain)

Quantifying and reconstructing past vegetation changes is an important step to fully understand human-environment interactions in the past. In this study we present a reconstruction of arboreal cover of six study sites in the Gredos Range (central Spain) over the last 3000 yr based on multivariate statistical analysis (cluster analysis and non-metric multidimensional scaling, NMDS) of 186 modern pollen samples, modern vegetation data and six detailed fossil pollen records. The integrated approach allows distinguishing eight modern vegetation communities and linking the fossil pollen records with these vegetation communities as modern analogues. The information of the arboreal cover of the modern pollen sites was used to estimate the past arboreal cover of the fossil pollen sites in the Gredos Range. This estimated arboreal cover shows a higher level of landscape openness than suggested by the original pollen percentages data. Our results show that the evolution of the arboreal cover through time differs along an altitudinal gradient, with a decrease in arboreal cover during the Roman and Visigoth periods (2000–1240 cal BP) at low altitudes and only during the Christian/Feudal period (850–500 cal BP) at high altitudes. The applied methodology, integrating fossil pollen data with modern pollen and vegetation data in one NMDS, allows reconstructing past arboreal cover in a quantitative way.

Early evidence of Prunus and Prunus cf. amygdalus from Palaeolithic sites in the Khorramabad Valley, western Iran

Along with the early age obtained for the cultural remains attributed to anatomically modern humans from Kaldar Cave, the archaeological assemblages recovered from both Kaldar and Gilvaran Cave located in the Khorramabad Valley (Iran), have yielded charcoal remains that allow the identification of Prunus spp. These remains correspond to the Middle and Upper Palaeolithic, which are the earliest finds attesting to the presence of this taxa in the area. Our anatomical observation of the samples revealed the presence of Prunus spp. (plums) and Prunus cf. amygdalus (cf. almond). This also reflects specific plant communities in the area, characteristic of open forest growing in cool, dry conditions. These results provide new insights into the arboreal cover in this area during an Upper Pleistocene period. Furthermore, anthracological evidence together with other contextual materials provides new clues to assess how Neanderthals and early modern humans adapted to their surrounding landscape, and their relationship with their environment in this region and beyond.

Natural Regeneration Potential of the Black Saxaul Shrubforests in Semi-Deserts of Central Asia - the Ili River Delta Area, SE Kazakhstan

ABSTRACT Two saxaul species - black saxaul (Haloxylon aphyllum Minkw.) and white saxaul (Haloxylon persicum Bunge) - constitute the principal arboreal cover of the cold continental deserts of Central Asia. While the latter is a rain-fed shrub distributed on sand dunes, the former is a ground-water phreatophyte mainly found on alluvial terraces. Saxaul has played an important role as a fodder plant also used as firewood by local herders. Due to over-grazing and over-exploitation for fuel during the past fifty years, the oncedominant saxaul vegetation has considerably degraded. Important growth characteristics at the present plantations (such as height, and basal trunk and crown diameters) show a direct quantitative relationship between the plants' age up to the 25-year lifetime and the total tree biomass reduced by natural degradation. Annual productivity largely depends on the overall vegetation density that reflects specific environmental conditions at particular locations. The recommended harvest rate, ...

Phytoliths indicate significant arboreal cover at Sahelanthropus type locality TM266 in northern Chad and a decrease in later sites

We analyzed phytolith and diatom remains preserved at 45 Miocene and Pliocene localities dated between 8 and 1 Ma in northern Chad (16–17°N). Some of these localities yielded cranial remains, lower jaws, and teeth of the hominin species Australopithecus bahrelghazali (∼3.6 Ma) and Sahelanthropus tchadensis (∼7 Ma). Of the 111 sediment samples analyzed, 41 yielded phytoliths, 20 yielded diatoms, and seven yielded both phytoliths and diatoms. Freshwater planktonic and tychoplanktonic diatom species, indicative of lacustrine conditions, are dominant (>91%) in the samples. The phytolith assemblages indicate an opening of the vegetation and a general trend toward an expansion of grass-dominated environments during the time spanning the two hominin occurrences in Chad. The phytoliths suggest the presence of a mosaic environment, including closed forest patches, palm groves, and mixed/grassland formations, between 7.5 and 7 Ma, the replacement by palm grove-like vegetation at approximately 6.5–5 Ma, and the presence of exclusive grass-dominated formations after 4.5 Ma. The type-locality of S. tchadensis (TM266) was likely similar to modern palm grove formations with an arboreal cover percentage ≥40%. The type locality of A. bahrelghazali (KT12) was a grass-dominated ecosystem (likely savanna) with an unrated percentage of arboreal cover. Furthermore, the grass phytolith data support the existence of a (recurrent) Sahelian-like dry climate in northern Chad since at least 8 Ma. Therefore the local closed vegetation formations in the Djurab region at 7.5–7 Ma were sustained by aquatic systems (such as lakes or related rivers, marshes) rather than by extensive annual precipitation.

Landscape transformations at the dawn of agriculture in southern Syria (10.7–9.9 ka cal. BP): Plant-specific responses to the impact of human activities and climate change

In southwest Asia, the accelerated impact of human activities on the landscape has often been linked to the development of fully agricultural societies during the middle and late Pre-Pottery Neolithic B (PPNB) period (around 10.2–7.9 ka cal. BP). This work contributes to the debate on the environmental impact of the so-called Neolitisation process by identifying the climatic and anthropogenic factors that contributed to change local and regional vegetation at the time when domesticated plants appeared and developed in southern Syria (around 10.7–9.9 ka cal. BP). In this work a multidisciplinary analysis of plant microremains (pollen and phytoliths) and macroremains (wood charcoal) is carried out along with stable carbon isotope discrimination of wood charcoals in an early PPNB site (Tell Qarassa North, west of the Jabal al-Arab area). Prior to 10.5 ka cal. BP, the results indicate a dynamic equilibrium in the local and regional vegetation, which comprised woodland-steppe, Mediterranean evergreen oak-woodlands, wetland vegetation and coniferous forests. Around 10.5–9.9 ka cal. BP, the elements that regulated the vegetation system changed, resulting in reduced proportions of arboreal cover and the spread of cold-tolerant and wetlands species. Our data show that reinforcing interaction between the elements of the anthropogenic (e.g. herding, fire-related activities) and climatic systems (e.g. temperature, rainfall) contributed to the transformation of early Holocene vegetation during the emergence of fully agricultural societies in southern Syria.

The relationship between vegetation and modern pollen assemblages on Mount Paggeo (NE Greece)

In this study, we investigated the relationship between vegetation and modern-pollen rain along the elevational gradient of Mount Paggeo. We apply multivariate data analysis to assess the relationship between vegetation and modern-pollen rain and quantify the representativeness of forest zones. This study represents the first statistical analysis of pollen-vegetation relationship along an elevational gradient in Greece. Hence, this paper improves confidence in interpretation of palynological records from north-eastern Greece and may refine past climate reconstructions for a more accurate comparison of data and modelling. Numerical classification and ordination were performed on pollen data to assess differences among plant communities that beech (Fagus sylvatica) dominates or co-dominates. The results show a strong relationship between altitude, arboreal cover, human impact and variations in pollen and nonpollen palynomorph taxa percentages.