Assessing the effects of climate change and land use on northern Labrador forest stands based on paleoecological data

2016 ◽  
Vol 86 (3) ◽  
pp. 260-270 ◽  
Author(s):  
Isabel Lemus-Lauzon ◽  
Najat Bhiry ◽  
James Woollett

AbstractWe reconstructed the late Holocene vegetation of the Nain region (northern Labrador, northeastern Canada) in order to assess the influence of climate and historic land use on past shifts in forest composition. Chronostratigraphy was used in combination with macrofossil and pollen data from monoliths sampled from four peatlands. Paleoecological reconstructions produced a vegetation history spanning 4900 years for the Nain region that is largely concordant with other studies in Labrador. An initial open forest tundra phase was followed by an increase in tree cover at around 2800 cal yr BP. Paludification began ∼200 cal yr BP. A decline in Picea and its subsequent disappearance from most of the sites occurred ∼170 cal yr BP (AD 1780) in a period of relatively mild conditions during the Little Ice Age. This event was followed by the establishment of Larix laricina in the region. Local anthropogenic factors are likely responsible for these later developments, as they were not observed in other regional studies. The period around AD 1780 corresponds to the establishment of the Moravian missionaries on the Labrador coast, which increased the need for fuel and lumber. We conclude that changes in land use are reflected in the patterns of vegetation and hydrological change at the study sites.

Forests ◽  
2022 ◽  
Vol 13 (1) ◽  
pp. 102
Author(s):  
Fabrizio Michelangeli ◽  
Federico Di Di Rita ◽  
Alessandra Celant ◽  
Nadine Tisnérat-Laborde ◽  
Fabrizio Lirer ◽  
...  

This study presents the first Late Holocene marine pollen record (core ND2) from SE Sicily. It encompasses the last 3000 years and is one of the most detailed records of the south-central Mediterranean region in terms of time resolution. The combined approach of marine palynology and historical ecology, supported by independent palaeoclimate proxies, provides an integrated regional reconstruction of past vegetational dynamics in relation to rapid climatic fluctuations, historical socio-economic processes, and past land-use practices, offering new insights into the vegetation history of SE Sicily. Short-term variations of sparse tree cover in persistently open landscapes reflect rapid hydroclimatic changes and historical land-use practices. Four main phases of forest reduction are found in relation to the 2.8 ka BP event, including the Late Antique Little Ice Age, the Medieval Climate Anomaly, and the Little Ice Age, respectively. Forest recovery is recorded during the Hellenistic and Roman Republican Periods, the Early Middle Ages, and the last century. Agricultural and silvicultural practices, as well as stock-breeding activities, had a primary role in shaping the current vegetational landscape of SE Sicily.


2018 ◽  
Vol 169 (2) ◽  
pp. 60-68 ◽  
Author(s):  
Willy Tinner ◽  
W.O. (Pim) van der Knaap ◽  
Marco Conedera ◽  
Brigitta Ammann

Invasions and collapses of tree species after the Ice Age Pollen and macrofossils are used to reconstruct mechanisms and processes of past invasions and collapses of tree species. They are also providing bottom lines for future invasions and collapses. The Swiss forest communities were always shifting to adjust to climate and land use changes. Some invasions occurred surprisingly synchronous in space. Ecosystem adjustment processes started rapidly after climate change or disturbance, but usually lasted several centuries, given that they involved several tree generations. The available climate and vegetation history evidence suggests that the today's rather homogenous sweet chestnut, oak, beech and spruce forests are particularly prone to be invaded, because the communities were created by millennial-long land use and also because the realized climatic niche of the dominant species is strongly anthropogenically widened. On the other hand, the realized climatic niche of silver fir is strongly narrowed by human impact. This implies that silver fir is far more resilient to climate change than its today's range would suggest. Thus new plant species may have considerable difficulties to enter quasi-natural mixed silver fir forest communities. A similar finding, although less pronounced, was obtained for linden, elm, ash and maple species. Evergreen broadleaved species from the Mediterranean region, which are native to Switzerland since millennia but were not able to expand due to climatic reasons (e.g. Quercus ilex), will presumably spread spontaneously within a few decades under changing climate. Such future invasions can be considered as a natural process from an ecological point of view, if the invading species involved originate from the neighboring subtropics.


2004 ◽  
Vol 12 (3) ◽  
pp. 239-251 ◽  
Author(s):  
Tanja Pless-Mulloli ◽  
Vivienne Air ◽  
Catherine Vizard ◽  
Ian Singleton ◽  
David Rimmer ◽  
...  

Author(s):  
Tiziana Pedrotta ◽  
Erika Gobet ◽  
Christoph Schwörer ◽  
Giorgia Beffa ◽  
Christoph Butz ◽  
...  

AbstractKnowledge about the vegetation history of Sardinia, the second largest island of the Mediterranean, is scanty. Here, we present a new sedimentary record covering the past ~ 8,000 years from Lago di Baratz, north-west Sardinia. Vegetation and fire history are reconstructed by pollen, spores, macrofossils and charcoal analyses and environmental dynamics by high-resolution element geochemistry together with pigment analyses. During the period 8,100–7,500 cal bp, when seasonality was high and fire and erosion were frequent, Erica arborea and E. scoparia woodlands dominated the coastal landscape. Subsequently, between 7,500 and 5,500 cal bp, seasonality gradually declined and thermo-mediterranean woodlands with Pistacia and Quercus ilex partially replaced Erica communities under diminished incidence of fire. After 5,500 cal bp, evergreen oak forests expanded markedly, erosion declined and lake levels increased, likely in response to increasing (summer) moisture availability. Increased anthropogenic fire disturbance triggered shrubland expansions (e.g. Tamarix and Pistacia) around 5,000–4,500 cal bp. Subsequently around 4,000–3,500 cal bp evergreen oak-olive forests expanded massively when fire activity declined and lake productivity and anoxia reached Holocene maxima. Land-use activities during the past 4,000 years (since the Bronze Age) gradually disrupted coastal forests, but relict stands persisted under rather stable environmental conditions until ca. 200 cal bp, when agricultural activities intensified and Pinus and Eucalyptus were planted to stabilize the sand dunes. Pervasive prehistoric land-use activities since at least the Bronze Age Nuraghi period included the cultivation of Prunus, Olea europaea and Juglans regia after 3,500–3,300 cal bp, and Quercus suber after 2,500 cal bp. We conclude that restoring less flammable native Q. ilex and O. europaea forest communities would markedly reduce fire risk and erodibility compared to recent forest plantations with flammable non-native trees (e.g. Pinus, Eucalyptus) and xerophytic shrubland (e.g. Cistus, Erica).


Water ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 1636
Author(s):  
Thanh N. Le ◽  
Duy X. Tran ◽  
Thuong V. Tran ◽  
Sangay Gyeltshen ◽  
Tan V. Lam ◽  
...  

Saltwater intrusion risk assessment is a foundational step for preventing and controlling salinization in coastal regions. The Vietnamese Mekong Delta (VMD) is highly affected by drought and salinization threats, especially severe under the impacts of global climate change and the rapid development of an upstream hydropower dam system. This study aimed to apply a modified DRASTIC model, which combines the generic DRASTIC model with hydrological and anthropogenic factors (i.e., river catchment and land use), to examine seawater intrusion vulnerability in the soil-water-bearing layer in the Ben Tre province, located in the VMD. One hundred and fifty hand-auger samples for total dissolved solids (TDS) measurements, one of the reflected salinity parameters, were used to validate the results obtained with both the DRASTIC and modified DRASTIC models. The spatial analysis tools in the ArcGIS software (i.e., Kriging and data classification tools) were used to interpolate, classify, and map the input factors and salinization susceptibility in the study area. The results show that the vulnerability index values obtained from the DRASTIC and modified DRASTIC models were 36–128 and 55–163, respectively. The vulnerable indices increased from inland districts to coastal areas. The Ba Tri and Binh Dai districts were recorded as having very high vulnerability to salinization, while the Chau Thanh and Cho Lach districts were at a low vulnerability level. From the comparative analysis of the two models, it is obvious that the modified DRASTIC model with the inclusion of a river or canal network and agricultural practices factors enables better performance than the generic DRASTIC model. This enhancement is explained by the significant impact of anthropogenic activities on the salinization of soil water content. This study’s results can be used as scientific implications for planners and decision-makers in river catchment and land-use management practices.


2021 ◽  
Vol 67 (4) ◽  
Author(s):  
Gianpasquale Chiatante ◽  
Marta Giordano ◽  
Anna Vidus Rosin ◽  
Oreste Sacchi ◽  
Alberto Meriggi

AbstractMore than half of the European population of the Barbary Partridge is in Sardinia; nonetheless, the researches concerning this species are very scarce, and its conservation status is not defined because of a deficiency of data. This research aimed to analyse the habitat selection and the factors affecting the abundance and the density of the Barbary Partridge in Sardinia. We used the data collected over 8 years (between 2004 and 2013) by spring call counts in 67 study sites spread on the whole island. We used GLMM to define the relationships between the environment (topography, land use, climate) both the occurrence and the abundance of the species. Moreover, we estimated population densities by distance sampling. The Barbary Partridge occurred in areas at low altitude with garrigue and pastures, avoiding woodlands and sparsely vegetated areas. We found a strong relationship between the occurrence probability and the climate, in particular, a positive relation with temperature and a negative effect of precipitation, especially in April–May, during brood rearing. Furthermore, dry crops positively affected the abundance of the species. We estimated a density of 14.1 partridges per km2, similar to other known estimates. Our findings are important both because they increase the knowledge concerning this species, which is considered data deficient in Italy, and because they are useful to plan management actions aimed to maintain viable populations if necessary.


2019 ◽  
Vol 16 (19) ◽  
pp. 3883-3910 ◽  
Author(s):  
Lina Teckentrup ◽  
Sandy P. Harrison ◽  
Stijn Hantson ◽  
Angelika Heil ◽  
Joe R. Melton ◽  
...  

Abstract. Understanding how fire regimes change over time is of major importance for understanding their future impact on the Earth system, including society. Large differences in simulated burned area between fire models show that there is substantial uncertainty associated with modelling global change impacts on fire regimes. We draw here on sensitivity simulations made by seven global dynamic vegetation models participating in the Fire Model Intercomparison Project (FireMIP) to understand how differences in models translate into differences in fire regime projections. The sensitivity experiments isolate the impact of the individual drivers on simulated burned area, which are prescribed in the simulations. Specifically these drivers are atmospheric CO2 concentration, population density, land-use change, lightning and climate. The seven models capture spatial patterns in burned area. However, they show considerable differences in the burned area trends since 1921. We analyse the trajectories of differences between the sensitivity and reference simulation to improve our understanding of what drives the global trends in burned area. Where it is possible, we link the inter-model differences to model assumptions. Overall, these analyses reveal that the largest uncertainties in simulating global historical burned area are related to the representation of anthropogenic ignitions and suppression and effects of land use on vegetation and fire. In line with previous studies this highlights the need to improve our understanding and model representation of the relationship between human activities and fire to improve our abilities to model fire within Earth system model applications. Only two models show a strong response to atmospheric CO2 concentration. The effects of changes in atmospheric CO2 concentration on fire are complex and quantitative information of how fuel loads and how flammability changes due to this factor is missing. The response to lightning on global scale is low. The response of burned area to climate is spatially heterogeneous and has a strong inter-annual variation. Climate is therefore likely more important than the other factors for short-term variations and extremes in burned area. This study provides a basis to understand the uncertainties in global fire modelling. Both improvements in process understanding and observational constraints reduce uncertainties in modelling burned area trends.


The Holocene ◽  
2021 ◽  
pp. 095968362098805
Author(s):  
Asmae Baqloul ◽  
Enno Schefuß ◽  
Martin Kölling ◽  
Lydie Dupont ◽  
Jeroen Groeneveld ◽  
...  

The southwest of Morocco is considered to be an area of refuge within the Mediterranean region, hosting the endemic tropical Argan tree. This region is presently subject to severe droughts, desertification and land degradation, and likely facing increased climate variability and socio-economic stress in the future. Here, we use the stable hydrogen and carbon isotope composition (δD and δ13C) of plant-waxes in a high-resolution marine sediment core (GeoB8601-3) collected off Cape Ghir in southwestern Morocco, in combination with published data on pollen and XRF element ratios from the same archive. We aim to reconstruct the hydroclimate and vegetation history during the last 3000 years. Stable carbon isotope compositions of leaf waxes (δ13Cwax) show that natural vegetation in southwestern Morocco consists of C3 plants. Minor variations in δ13Cwax were positively correlated to changes in stable hydrogen isotope compositions of leaf waxes (δDwax) before 700 CE. Changes in rainfall amounts and water use efficiency indicate a clear vegetation response to precipitation changes and thus to climate forcing. After 700 CE, δDwax and δ13Cwax became de-coupled suggesting that the plant wax discharge and their isotope signals were no longer solely controlled by climate; the waxes likely mainly originate from the lowlands and carry an enriched (dry) δD signal but a depleted 13C signature. The depletion of δ13Cwax correlates with the increase of Argan pollen concentration in the record. The period between ~700 and 900 CE coincides with the Arabization of Morocco which had an impact on the demographic composition of the country leading to new agricultural habits and, as a result, on the land-use triggering a higher erosion of lowland material by the Souss River.


Author(s):  
Sigrún Dögg Eddudóttir ◽  
Eva Svensson ◽  
Stefan Nilsson ◽  
Anneli Ekblom ◽  
Karl-Johan Lindholm ◽  
...  

AbstractShielings are the historically known form of transhumance in Scandinavia, where livestock were moved from the farmstead to sites in the outlands for summer grazing. Pollen analysis has provided a valuable insight into the history of shielings. This paper presents a vegetation reconstruction and archaeological survey from the shieling Kårebolssätern in northern Värmland, western Sweden, a renovated shieling that is still operating today. The first evidence of human activities in the area near Kårebolssätern are Hordeum- and Cannabis-type pollen grains occurring from ca. 100 bc. Further signs of human impact are charcoal and sporadic occurrences of apophyte pollen from ca. ad 250 and pollen indicating opening of the canopy ca. ad 570, probably a result of modification of the forest for grazing. A decrease in land use is seen between ad 1000 and 1250, possibly in response to a shift in emphasis towards large scale commodity production in the outlands. Emphasis on bloomery iron production and pitfall hunting may have caused a shift from agrarian shieling activity. The clearest changes in the pollen assemblage indicating grazing and cultivation occur from the mid-thirteenth century, coinciding with wetter climate at the beginning of the Little Ice Age. The earliest occurrences of anthropochores in the record predate those of other shieling sites in Sweden. The pollen analysis reveals evidence of land use that predates the results of the archaeological survey. The study highlights how pollen analysis can reveal vegetation changes where early archaeological remains are obscure.


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