Long-term deforestation in NW Spain: linking the Holocene fire history to vegetation change and human activities

2011 ◽  
Vol 30 (1-2) ◽  
pp. 161-175 ◽  
Author(s):  
Joeri Kaal ◽  
Yolanda Carrión Marco ◽  
Eleni Asouti ◽  
Maria Martín Seijo ◽  
Antonio Martínez Cortizas ◽  
...  
Keyword(s):  
Human Activities ◽  
Vegetation Change ◽  
Fire History ◽  
Nw Spain ◽  
The Holocene

A quantitative synthesis of Holocene vegetation change in Nigeria (Western Africa)

The Holocene ◽  
2021 ◽  
pp. 095968362110331
Author(s):  
Matthew Adesanya Adeleye ◽  
Simon Edward Connor ◽  
Simon Graeme Haberle
Keyword(s):  
Vegetation Change ◽  
Climatic Changes ◽  
The Holocene ◽  
Continental Scale ◽  
Western Africa ◽  
Chord Distance ◽  
Quantitative Synthesis ◽  
Climatic Regime ◽  
Pollen Records

Understanding long-term (centennial–millennial scale) ecosystem stability and dynamics are key to sustainable management and conservation of ecosystem processes under the currently changing climate. Fossil pollen records offer the possibility to investigate long-term changes in vegetation composition and diversity on regional and continental scales. Such studies have been conducted in temperate systems, but are underrepresented in the tropics, especially in Africa. This study attempts to synthesize pollen records from Nigeria (tropical western Africa) and nearby regions to quantitatively assess Holocene regional vegetation changes (turnover) and stability under different climatic regimes for the first time. We use the squared chord distance metric (SCD) to assess centennial-scale vegetation turnover in pollen records. Results suggest vegetation in most parts of Nigeria experienced low turnover under a wetter climatic regime (African Humid Period), especially between ~8000 and 5000 cal year BP. In contrast, vegetation turnover increased significantly under the drier climatic regime of the late-Holocene (between ~5000 cal year BP and present), reflecting the imp role of moisture changes in tropical west African vegetation dynamics during the Holocene. Our results are consistent with records of vegetation and climatic changes in other parts of Africa, suggesting the Holocene pattern of vegetation change in Nigeria is a reflection of continental-scale climatic changes.

scholarly journals Nesting Effects of Climate and Local Drivers on Long-Term Subalpine Fires in the Alps

2021 ◽  
Author(s):  
Christopher Carcaillet ◽  
Benjamin Boulley ◽  
Frédérique Carcaillet
Keyword(s):  
Biomass Burning ◽  
Large Scale ◽  
Fire History ◽  
Fire Regime ◽  
Western Alps ◽  
Biomass Combustion ◽  
Human Society ◽  
The Holocene ◽  
Soil Charcoal

Abstract Background: The present article questions the relative importance of local- and large-scale processes on the long-term dynamics of fire in the subalpine belt in the western Alps. The study is based on soil charcoal dating and identification, several study sites in contrasting environmental conditions, and sampling of soil charcoal along the elevation gradient of each site. Based on local differences in biomass combustion, we hypothesize that local-scale processes have driven the fire history, while combustion homogeneity supports the hypothesis of the importance of large-scale processes, especially the climate. Results: The results show that biomass burning during the Holocene resulted from the nesting effects of climate, land use, and altitude, but was little influenced by topography (slope exposure: north versus south), soil (dryness, pH, depth), and vegetation. The mid-Holocene (6500–2700 cal BP) was an important period for climatic biomass burning in the subalpine ecosystems of the western Alps, while fires from about 2500 years ago appear much more episodic, prompting us to speculate that human society has played a vital role in their occurrence. Conclusion: Our working hypothesis assuming that the strength of mountain natural and local drivers should offset the effects of regional climate is not validated. The homogeneity of the fire regime between sites thus underscore that climate was the main driver during the Holocene of the western Alps. Long-term subalpine fires are controlled by climate at millennial scale. Local conditions count for little in determining variability at the century scale. The mid-Holocene was a chief period for climatic biomass burning in the subalpine zone, while fires during the late Holocene appear much more episodic, prompting the assumption that societal drivers has exercised key roles on their control.

A lake sediment–based paleoecological reconstruction of late Holocene fire history and vegetation change in Great Basin National Park, Nevada, USA

2021 ◽  
pp. 1-15
Author(s):  
Christopher S. Cooper ◽  
David F. Porinchu ◽  
Scott A. Reinemann ◽  
Bryan G. Mark ◽  
James Q. DeGrand
Keyword(s):  
Great Basin ◽  
Relative Abundance ◽  
Vegetation Change ◽  
Fire History ◽  
Ice Age ◽  
Sediment Geochemistry ◽  
Catchment Scale ◽  
Composition And Structure ◽  
Hydroclimate Variability ◽  
Late Fifteenth

Abstract Analyses of macroscopic charcoal, sediment geochemistry (%C, %N, C/N, δ13C, δ15N), and fossil pollen were conducted on a sediment core recovered from Stella Lake, Nevada, establishing a 2000 year record of fire history and vegetation change for the Great Basin. Charcoal accumulation rates (CHAR) indicate that fire activity, which was minimal from the beginning of the first millennium to AD 750, increased slightly at the onset of the Medieval Climate Anomaly (MCA). Observed changes in catchment vegetation were driven by hydroclimate variability during the early MCA. Two notable increases in CHAR, which occurred during the Little Ice Age (LIA), were identified as major fire events within the catchment. Increased C/N, enriched δ15N, and depleted δ13C values correspond with these events, providing additional evidence for the occurrence of catchment-scale fire events during the late fifteenth and late sixteenth centuries. Shifts in the vegetation community composition and structure accompanied these fires, with Pinus and Picea decreasing in relative abundance and Poaceae increasing in relative abundance following the fire events. During the LIA, the vegetation change and lacustrine geochemical response was most directly influenced by the occurrence of catchment-scale fires, not regional hydroclimate.

Impacts of human activities on coral reef ecosystems of southern Taiwan: A long-term study

2012 ◽  
Vol 64 (6) ◽  
pp. 1129-1135 ◽  
Author(s):  
Pi-Jen Liu ◽  
Pei-Jie Meng ◽  
Li-Lian Liu ◽  
Jih-Terng Wang ◽  
Ming-Yih Leu
Keyword(s):  
Coral Reef ◽  
Human Activities ◽  
Term Study ◽  
Long Term Study ◽  
Coral Reef Ecosystems ◽  
Southern Taiwan

Long-term summer warming trend during the Holocene in central Asia indicated by alpine peat α-cellulose δ13C record

2019 ◽  
Vol 203 ◽  
pp. 56-67 ◽  
Author(s):  
Zhiguo Rao ◽  
Chao Huang ◽  
Luhua Xie ◽  
Fuxi Shi ◽  
Yan Zhao ◽  
...  
Keyword(s):  
Central Asia ◽  
Warming Trend ◽  
The Holocene ◽  
Summer Warming

scholarly journals Three distinct Holocene intervals of stalagmite deposition and nondeposition revealed in NW Madagascar, and their paleoclimate implications

2017 ◽  
Vol 13 (12) ◽  
pp. 1771-1790 ◽  
Author(s):  
Ny Riavo Gilbertinie Voarintsoa ◽  
Loren Bruce Railsback ◽  
George Albert Brook ◽  
Lixin Wang ◽  
Gayatri Kathayat ◽  
...  
Keyword(s):  
Stable Isotopes ◽  
High Resolution ◽  
Late Holocene ◽  
Intertropical Convergence Zone ◽  
Convergence Zone ◽  
High Resolution Data ◽  
The Holocene ◽  
Middle Holocene ◽  
Resolution Data

Abstract. Petrographic features, mineralogy, and stable isotopes from two stalagmites, ANJB-2 and MAJ-5, respectively from Anjohibe and Anjokipoty caves, allow distinction of three intervals of the Holocene in NW Madagascar. The Malagasy early Holocene (between ca. 9.8 and 7.8 ka) and late Holocene (after ca. 1.6 ka) intervals (MEHI and MLHI, respectively) record evidence of stalagmite deposition. The Malagasy middle Holocene interval (MMHI, between ca. 7.8 and 1.6 ka) is marked by a depositional hiatus of ca. 6500 years. Deposition of these stalagmites indicates that the two caves were sufficiently supplied with water to allow stalagmite formation. This suggests that the MEHI and MLHI intervals may have been comparatively wet in NW Madagascar. In contrast, the long-term depositional hiatus during the MMHI implies it was relatively drier than the MEHI and the MLHI. The alternating wet–dry–wet conditions during the Holocene may have been linked to the long-term migrations of the Intertropical Convergence Zone (ITCZ). When the ITCZ's mean position is farther south, NW Madagascar experiences wetter conditions, such as during the MEHI and MLHI, and when it moves north, NW Madagascar climate becomes drier, such as during the MMHI. A similar wet–dry–wet succession during the Holocene has been reported in neighboring locations, such as southeastern Africa. Beyond these three subdivisions, the records also suggest wet conditions around the cold 8.2 ka event, suggesting a causal relationship. However, additional Southern Hemisphere high-resolution data will be needed to confirm this.

scholarly journals Vegetation change (1988–2010) in Camdeboo National Park (South Africa), using fixed-point photo monitoring: The role of herbivory and climate

Koedoe ◽  
2013 ◽  
Vol 55 (1) ◽  
Author(s):  
Mmoto L. Masubelele ◽  
Michael T. Hoffman ◽  
William Bond ◽  
Peter Burdett
Keyword(s):  
South Africa ◽  
Fixed Point ◽  
National Parks ◽  
Vegetation Cover ◽  
National Park ◽  
Vegetation Change ◽  
Growth Form ◽  
Annual Rainfall ◽  
Management Interventions

Fixed-point photo monitoring supplemented by animal census data and climate monitoring potential has never been explored as a long-term monitoring tool for studying vegetation change in the arid and semi-arid national parks of South Africa. The long-term (1988–2010), fixed-point monitoring dataset developed for the Camdeboo National Park, therefore, provides an important opportunity to do this. Using a quantitative estimate of the change in vegetation and growth form cover in 1152 fixed-point photographs, as well as series of step-point vegetation surveys at each photo monitoring site, this study documented the extent of vegetation change in the park in response to key climate drivers, such as rainfall, as well as land use drivers such as herbivory by indigenous ungulates. We demonstrated the varied response of vegetation cover within three main growth forms (grasses, dwarf shrubs [< 1 m] and tall shrubs [> 1 m]) in three different vegetation units and landforms (slopes, plains, rivers) within the Camdeboo National Park since 1988. Sites within Albany Thicket and Dwarf Shrublands showed the least change in vegetation cover, whilst Azonal vegetation and Grassy Dwarf Shrublands were more dynamic. Abiotic factors such as drought and flooding, total annual rainfall and rainfall seasonality appeared to have the greatest influence on growth form cover as assessed from the fixed-point photographs. Herbivory appeared not to have had a noticeable impact on the vegetation of the Camdeboo National Park as far as could be determined from the rather coarse approach used in this analysis and herbivore densities remained relatively low over the study duration.Conservation implications: We provided an historical assessment of the pattern of vegetation and climatic trends that can help evaluate many of South African National Parks’ biodiversity monitoring programmes, especially relating to habitat change. It will help arid parks in assessing the trajectories of vegetation in response to herbivory, climate and management interventions.

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