Paleovegetation Simulations of Lowland Amazonia and Implications for Neotropical Allopatry and Speciation

2001 ◽  
Vol 55 (2) ◽  
pp. 140-149 ◽  
Author(s):  
Sharon A. Cowling ◽  
Mark A. Maslin ◽  
Martin T. Sykes
Keyword(s):  
Amazon Basin ◽  
Forest Cover ◽  
Vegetation Type ◽  
Relative Importance ◽  
Physiological Mechanisms ◽  
Area Index ◽  
Canopy Density ◽  
Last Glaciation ◽  
Highly Sensitive ◽  
Ecosystem Level

AbstractPaleovegetation modeling simulations of the lowland Amazon basin were made to assess the relative importance of glacial climate and atmospheric CO2 for altering vegetation type and structure, as well as to explore the potential physiological mechanisms underlying these ecosystem-level responses. Modeling results support the view that widespread invasion of grasslands into the Amazon lowlands during the last glaciation was not likely. Glacial cooling was probably responsible for maintaining glacial forest cover via its effects in reducing photorespiration and decreasing evapotranspiration, which collectively improve plant carbon and water relations. Modeling results confirm that leaf area index (LAI), a common proxy for canopy density, is highly sensitive to independent and interactive changes in climate and low concentration of atmospheric CO2, and the results show considerable region-to-region variation during the last glaciation. Heterogeneous variations in glacial vegetation LAI may have promoted allopatric speciation by geographically isolating species (called vicariance) in the forest (sub)canopy. The proposed vicariance hypothesis incorporating spatial variations in canopy density conforms to many of the essential tenets addressed by previous neotropical speciation models, but also helps to overcome some of their inconsistencies.

scholarly journals Estimating Canopy Density Parameters Time-Series for Winter Wheat Using UAS Mounted LiDAR

2021 ◽  
Vol 13 (4) ◽  
pp. 710
Author(s):  
Jordan Steven Bates ◽  
Carsten Montzka ◽  
Marius Schmidt ◽  
François Jonard
Keyword(s):  
Winter Wheat ◽  
Optical Sensors ◽  
Forest Cover ◽  
Growing Season ◽  
Unmanned Aircraft ◽  
Airborne Lidar ◽  
Potential Yield ◽  
Area Index ◽  
Canopy Density ◽  
Plant Area Index

Monitoring of canopy density with related metrics such as leaf area index (LAI) makes a significant contribution to understanding and predicting processes in the soil–plant–atmosphere system and to indicating crop health and potential yield for farm management. Remote sensing methods using optical sensors that rely on spectral reflectance to calculate LAI have become more mainstream due to easy entry and availability. Methods with vegetation indices (VI) based on multispectral reflectance data essentially measure the green area index (GAI) or response to chlorophyll content of the canopy surface and not the entire aboveground biomass that may be present from non-green elements that are key to fully assessing the carbon budget. Methods with light detection and ranging (LiDAR) have started to emerge using gap fraction (GF) to estimate the plant area index (PAI) based on canopy density. These LiDAR methods have the main advantage of being sensitive to both green and non-green plant elements. They have primarily been applied to forest cover with manned airborne LiDAR systems (ALS) and have yet to be used extensively with crops such as winter wheat using LiDAR on unmanned aircraft systems (UAS). This study contributes to a better understanding of the potential of LiDAR as a tool to estimate canopy structure in precision farming. The LiDAR method proved to have a high to moderate correlation in spatial variation to the multispectral method. The LiDAR-derived PAI values closely resemble the SunScan Ceptometer GAI ground measurements taken early in the growing season before major stages of senescence. Later in the growing season, when the canopy density was at its highest, a possible overestimation may have occurred. This was most likely due to the chosen flight parameters not providing the best depictions of canopy density with consideration of the LiDAR’s perspective, as the ground-based destructive measurements provided lower values of PAI. Additionally, a distinction between total LiDAR-derived PAI, multispectral-derived GAI, and brown area index (BAI) is made to show how the active and passive optical sensor methods used in this study can complement each other throughout the growing season.

Catastrophic disturbance in the presettlement forests of the Upper Peninsula of Michigan

1999 ◽  
Vol 29 (1) ◽  
pp. 106-114 ◽  
Author(s):  
Quanfa Zhang ◽  
Kurt S Pregitzer ◽  
David D Reed
Keyword(s):  
Forest Cover ◽  
Vegetation Type ◽  
Natural Disturbance ◽  
Growth Stages ◽  
Mosaic Landscape ◽  
Upper Peninsula ◽  
Rotation Periods ◽  
General Land Office ◽  
Ecological Unit ◽  
Upper Peninsula Of Michigan

The General Land Office (GLO) survey notes (1840-1856) were used to examine the interaction among natural disturbance, vegetation type, and topography in the presettlement forests of the Luce District, an ecological unit of approximately 902 000 ha in the Upper Peninsula of Michigan, U.S.A. The surveyors recorded 104 fire and 126 windthrow incidences covering 3.1 and 2.8% of the total length of the surveyed lines, respectively. The rotation periods over the entire landscape were 480 years for fire and 541 years for windthrow, but these varied with vegetation type and topographic position. Fire occurred more frequently on southerly aspects and at elevations where pinelands were concentrated. The density of windthrow events increased with elevation and slope, with the highest occurrence on westerly aspects. Based on the estimated rotation periods, we calculated that 7.5, 24.4, and 68.1% of the presettlement forest were in the stand initiation, stem exclusion, and old forest (including both understory reinitiation and old growth) stages, respectively. Pinelands and mixed conifers were the major components in both the stand initiation (34.5 and 31.1%) and the stem exclusion stage (20.9 and 39.8%), while mixed conifers (39.3%) and northern hardwoods (34.7%) were the major old-forest cover types. The diverse mosaic of various successional stages generated by natural disturbance suggests a "shifting-mosaic" landscape in this region.

Flesh flies (Diptera: Sarcophagidae) from a white-sand habitat in the Brazilian Amazon, with the description of four new species

Zootaxa ◽  
2018 ◽  
Vol 4504 (3) ◽  
pp. 401
Author(s):  
FERNANDO DA SILVA CARVALHO-FILHO ◽  
INOCÊNCIO DE SOUSA GORAYEB ◽  
JÉSSICA MARIA MENEZES SOARES ◽  
MATHEUS TAVARES DE SOUZA
Keyword(s):  
New Species ◽  
Tropical Forest ◽  
Amazon Basin ◽  
Vegetation Type ◽  
Brazilian Amazon ◽  
Insect Fauna ◽  
Flesh Fly ◽  
Small Areas ◽  
White Sand ◽  
Flesh Flies

The white-sand enclaves in the Amazon Basin are small areas scattered through the tropical forest, with sandy and nutrient-poor soils and an unusual vegetation type. The insect fauna of this ecosystem is poorly known, especially in the eastern Amazon. The flesh fly fauna of an area of open herbaceous white-sand vegetation known as “Campo Redondo” in the municipality of Cametá, state of Pará, was surveyed, resulting in the discovery of 43 species in 11 genera representing the subfamilies Sarcophaginae and Miltogramminae. Four new species are described: Dexosarcophaga (Dexosarcophaga) campina sp. nov., Helicobia cametaensis sp. nov., Helicobia domquixote sp. nov., and Metopia fofo sp. nov. Lepidodexia (Lepidodexia) grisea Lopes and Lepidodexia (Notochaeta) setifrons (Lopes) are newly recorded from Brazil. Dexosarcophaga (Bezzisca) ampullula (Engel), D. (Dexosarcophaga) transita Townsend and Titanogrypa (Cucullomyia) larvicida (Lopes) are newly recorded from the Brazilian Amazon. 

Movement of small mammals across divided highways with vegetated medians

2011 ◽  
Vol 89 (12) ◽  
pp. 1214-1222 ◽  
Author(s):  
Ashley A.D. McLaren ◽  
Lenore Fahrig ◽  
Nigel Waltho
Keyword(s):  
Small Mammals ◽  
Small Mammal ◽  
Vegetation Cover ◽  
Forest Cover ◽  
Vegetation Type ◽  
Barrier Effect ◽  
Cover Type ◽  
Study Sites ◽  
Median Width ◽  
Initial Capture

Previous studies suggest the gap in forest cover generated by roads contributes to the barrier effect of roads on movement of forest-dwelling small mammals. However, it is not known if vegetated medians of divided highways affect movement of small mammals by reducing the effective highway width. The purpose of our study was to determine whether the type of vegetation cover in the median (treed or grassy) or median width affects small-mammal crossings of divided highways. At 11 study sites varying in median cover type and width, we live-trapped small mammals next to one side of the highway and translocated them to the opposite side of the highway using a standardized translocation distance. In total, 24% of translocated individuals were recaptured on the side of the highway of initial capture, i.e., they had moved across the entire highway. This was significantly lower than what would have been expected in the absence of the highway (58%). The overall probability of recapturing a translocated individual was not significantly related to median cover type or width. Our results suggest that efforts to mitigate the barrier effect of highways on small mammals cannot be accomplished by altering median vegetation type and width.

scholarly journals MODELING PRECIPITATION DEPENDENT FOREST RESILIENCE IN INDIA

2018 ◽  
Vol XLII-3 ◽  
pp. 263-266 ◽  
Author(s):  
P. Das ◽  
M. D. Behera ◽  
P. S. Roy
Keyword(s):  
Forest Cover ◽  
Vegetation Type ◽  
Annual Precipitation ◽  
Mean Annual Precipitation ◽  
High Tendency ◽  
North East India ◽  
North East ◽  
Forest Resilience ◽  
The Impact

The impact of long term climate change that imparts stress on forest could be perceived by studying the regime shift of forest ecosystem. With the change of significant precipitation, forest may go through density change around globe at different spatial and temporal scale. The 100 class high resolution (60 meter spatial resolution) Indian vegetation type map was used in this study recoded into four broad categories depending on phrenology as (i) forest, (ii) scrubland, (iii) grassland and (iv) treeless area. The percentage occupancy of forest, scrub, grass and treeless were observed as 19.9&amp;thinsp;%, 5.05&amp;thinsp;%, 1.89&amp;thinsp;% and 7.79&amp;thinsp;% respectively. Rest of the 65.37&amp;thinsp;% land area was occupied by the cropland, built-up, water body and snow covers. The majority forest cover were appended into a 5&amp;thinsp;km&amp;thinsp;&amp;times;&amp;thinsp;5&amp;thinsp;km grid, along with the mean annual precipitation taken from Bioclim data. The binary presence and absence of different vegetation categories in relates to the annual precipitation was analyzed to calculate their resilience expressed in probability values ranging from 0 to 1. Forest cover observed having resilience probability (Pr) &amp;lt;&amp;thinsp;0.3 in only 0.3&amp;thinsp;% (200&amp;thinsp;km<sup>2</sup>) of total forest cover in India, which was 4.3&amp;thinsp;% &amp;lt;&amp;thinsp;0.5&amp;thinsp;Pr. Majority of the scrubs and grass (64.92&amp;thinsp;% Pr&amp;thinsp;&amp;lt;&amp;thinsp;0.5) from North East India which were the shifting cultivation lands showing low resilience, having their high tendency to be transform to forest. These results have spatial explicitness to highlight the resilient and non-resilient distribution of forest, scrub and grass, and treeless areas in India.

Response of tropical rainfall to reduced evapotranspiration depends on continental extent

2021 ◽  
pp. 1-50
Author(s):  
Marianne Pietschnig ◽  
Abigail L. S. Swann ◽  
F. Hugo Lambert ◽  
Geoffrey K. Vallis
Keyword(s):  
Stomatal Conductance ◽  
General Circulation ◽  
Amazon Basin ◽  
Circulation Model ◽  
Complex Model ◽  
Earth System ◽  
Area Index ◽  
Tropical Rainfall ◽  
System Models ◽  
Earth System Models

AbstractFuture projections of precipitation change over tropical land are often enhanced by vegetation responses to CO2 forcing in Earth System Models. Projected decreases in rainfall over the Amazon basin and increases over the Maritime Continent are both stronger when plant physiological changes are modelled than if these changes are neglected, but the reasons for this amplification remain unclear. The responses of vegetation to increasing CO2 levels are complex and uncertain, including possible decreases in stomatal conductance and increases in leaf area index due to CO2-fertilisation. Our results from an idealised Atmospheric General Circulation Model show that the amplification of rainfall changes occurs even when we use a simplified vegetation parameterisation based solely on CO2-driven decreases in stomatal conductance, indicating that this mechanism plays a key role in complex model projections. Based on simulations with rectangular continentswe find that reducing terrestrial evaporation to zero with increasing CO2 notably leads to enhanced rainfall over a narrow island. Strong heating and ascent over the island trigger moisture advection from the surrounding ocean. In contrast, over larger continents rainfall depends on continental evaporation. Simulations with two rectangular continents representing South America and Africa reveal that the stronger decrease in rainfall over the Amazon basin seen in Earth System Models is due to a combination of local and remote effects, which are fundamentally connected to South America’s size and its location with respect to Africa. The response of tropical rainfall to changes in evapotranspiration is thus connected to size and configuration of the continents.

scholarly journals Phytogeographic support tor the theory of Pleistocene forest refuges in the Amazon Basin, based on evidence from distribution patterns in Caryocaraceae, Chrysobalanaceae, Dichapetalaceae and Lecythidaceae

1973 ◽  
Vol 3 (3) ◽  
pp. 5-26 ◽  
Author(s):  
Ghillean T. Prance
Keyword(s):  
Species Diversity ◽  
Amazon Basin ◽  
Forest Cover ◽  
Woody Plant ◽  
Distribution Patterns ◽  
Genetic Isolation ◽  
Lowland Forest ◽  
Previous Evidence ◽  
Plant Families ◽  
Refuge Areas

Abstract In recent years it has generally been accepted that Amazonia was subject to long dry periods in the late Pleistocene and post-Pleistocene which induced forest cover to a few limited areas or refuges. It has been proposed that the subsequent genetic isolation into separate populations is a mnjor factor in the evolution of the species diversity within the lowland forest of Amazonia. Most of the previous evidence for this theory is based on studies of animals, for example: lizards, butterflies, and birds. Here data are presented to confirm the theory of forest refuges using evidence from phytogeography. Distribution patterns of the lowland species of the woody plant families Caryocaraceae, Chrysobalanaceae, Dichapetalaceae and Lecythidaceae are discussed and concur with the possibility of forest refuges. A map is given of the refuge areas that seem most likely, based on evidence from species distribution of the above plant families. The refuges proposed here correspond closely with the refuge areas proposed by Haffer and Brown rather than the extremely reduced areas proposed by Vanzolini.

scholarly journals Genotypic Variation in Biomass Produced Is Linked to Differences in Radiation Acquisition in Mungbean

Proceedings ◽  
2019 ◽  
Vol 36 (1) ◽  
pp. 21
Author(s):  
Geetika ◽  
Rachaputi ◽  
Collins ◽  
Singh ◽  
Wenham ◽  
...  
Keyword(s):  
Leaf Area ◽  
Dry Matter ◽  
Genotypic Variation ◽  
Total Biomass ◽  
Potential Productivity ◽  
Area Index ◽  
Canopy Density ◽  
Significant Difference ◽  
Plant Densities ◽  
Rotation Crop

Mungbean has become an important cash and legume rotation crop in the Australian Northern Grains region. Thus, it is necessary to narrow the gap between potential productivity and actual production by understanding the crop physiological attributes contributing to the acquisition of radiation, and it’s conversion into total biomass. A field experiment was conducted at Gatton, during 2018-19 summer season, growing two commercial varieties of mungbean; Jade-AU and Satin II under irrigated conditions. The varieties were planted at 0.5m and 1.0m row spacing and different plant densities. Weekly biomass cuts were taken from a square meter and separated into its components. The area of a green leaf sub-sample was used to compute the leaf area of the canopy. Weekly Ceptometer measurements were taken above and below the canopy at noon on clear, sunny days to obtain a measure of Fraction of radiation interception (Fi). Total shoot dry matter (TDM), pod dry mater (PDM) and leaf area index (LAI) was investigated. There was a significant effect of canopy density on Fi. There was no significant difference in total dry matter between the two varieties, however, there was a highly significant effect of canopy density on TDM. . A highly significant variation in LAI amongst the two varieties and across canopy densities, with Satin II having a higher mean LAI compared to Jade-AU. There was significant effect of canopy density on PDM. Our data indicate variation in dry matter production across canopy densities and there is a need to examine varietal differences in radiation use efficiency which may provide better understanding of hot the captured radiation is utilized in biomass production in mungbean.

scholarly journals The role of forest conversion, degradation, and disturbance in the carbon dynamics of Amazon indigenous territories and protected areas

2020 ◽  
Vol 117 (6) ◽  
pp. 3015-3025 ◽  
Author(s):  
Wayne S. Walker ◽  
Seth R. Gorelik ◽  
Alessandro Baccini ◽  
Jose Luis Aragon-Osejo ◽  
Carmen Josse ◽  
...  
Keyword(s):  
Large Scale ◽  
Amazon Basin ◽  
Forest Cover ◽  
Carbon Dynamics ◽  
Forest Degradation ◽  
Published Data ◽  
Forest Conversion ◽  
Carbon Density ◽  
Aboveground Carbon ◽  
Indigenous Territories

Maintaining the abundance of carbon stored aboveground in Amazon forests is central to any comprehensive climate stabilization strategy. Growing evidence points to indigenous peoples and local communities (IPLCs) as buffers against large-scale carbon emissions across a nine-nation network of indigenous territories (ITs) and protected natural areas (PNAs). Previous studies have demonstrated a link between indigenous land management and avoided deforestation, yet few have accounted for forest degradation and natural disturbances—processes that occur without forest clearing but are increasingly important drivers of biomass loss. Here we provide a comprehensive accounting of aboveground carbon dynamics inside and outside Amazon protected lands. Using published data on changes in aboveground carbon density and forest cover, we track gains and losses in carbon density from forest conversion and degradation/disturbance. We find that ITs and PNAs stored more than one-half (58%; 41,991 MtC) of the region’s carbon in 2016 but were responsible for just 10% (−130 MtC) of the net change (−1,290 MtC). Nevertheless, nearly one-half billion tons of carbon were lost from both ITs and PNAs (−434 MtC and −423 MtC, respectively), with degradation/disturbance accounting for >75% of the losses in 7 countries. With deforestation increasing, and degradation/disturbance a neglected but significant source of region-wide emissions (47%), our results suggest that sustained support for IPLC stewardship of Amazon forests is critical. IPLCs provide a global environmental service that merits increased political protection and financial support, particularly if Amazon Basin countries are to achieve their commitments under the Paris Climate Agreement.

Volatile Organic Compound fluxes in a subarctic peatland and lake

2020 ◽  
Author(s):  
Roger Seco ◽  
Thomas Holst ◽  
Andreas Westergaard-Nielsen ◽  
Tao Li ◽  
Tihomir Simin ◽  
...  
Keyword(s):  
Forest Cover ◽  
Growing Season ◽  
Mass Spectrometers ◽  
Mixing Ratios ◽  
Discontinuous Permafrost ◽  
Volatile Organic ◽  
Trace Gas Fluxes ◽  
Ecosystem Level ◽  
Carex Rostrata ◽  
High Fraction

&lt;p&gt;Arctic climate is warming twice as much as the global average, due to a number of climate system feedbacks, including albedo change due to retreating snow cover and sea ice, and the forest cover expansion across the open tundra. Northern ecosystems are known to emit trace gases (e.g., methane and volatile organic compounds, VOCs) to the atmosphere, from sources as diverse as soils, vegetation and lakes. These trace gas fluxes are likely to show a trend towards greater emissions with climate warming.&lt;/p&gt;&lt;p&gt;Here we report ecosystem-level VOC fluxes from Stordalen Mire, a subarctic peatland complex with a high fraction of open pond and lake surfaces, underlain by discontinuous permafrost and located in the Subarctic Sweden (68&amp;#186;20' N, 19&amp;#186;03' E).&lt;/p&gt;&lt;p&gt;In 2018, we deployed two online mass spectrometers (PTR-TOF-MS) to measure rapid fluctuations in VOC mixing ratios and to quantify ecosystem-level fluxes with the eddy covariance technique. One of the instruments obtained a growing-season-long dataset of biogenic emissions from palsa mire vegetation dominated by mosses (e.g., &lt;em&gt;Sphagnum&lt;/em&gt; spp.), graminoids (such as &lt;em&gt;Eriophorum&lt;/em&gt; spp. and &lt;em&gt;Carex&lt;/em&gt; spp.), dwarf shrubs (e.g. Empetrum spp. and Betula nana) surrounding the ICOS Sweden Abisko-Stordalen long-term measurement station. The second instrument measured VOC fluxes during two contrasting periods (the peak and the end of the growing season) from a subarctic lake and its adjacent fen, permafrost-free, minerotrophic wetland with vegetation dominated by tall graminoids, mainly &lt;em&gt;Carex rostrata&lt;/em&gt; and &lt;em&gt;Eriophorum angustifolium&lt;/em&gt;.&lt;/p&gt;&lt;p&gt;At both sites, isoprene was the dominant VOC emitted by vegetation, showing clear diurnal patterns along the season and especially during the peak of the growing season in July. At the ICOS Sweden station, isoprene fluxes exceeded 2 nmol m&lt;sup&gt;-2&lt;/sup&gt; s&lt;sup&gt;-1&lt;/sup&gt; on several days in July, with a July monthly average midday emission of 1 nmol m&lt;sup&gt;-2&lt;/sup&gt; s&lt;sup&gt;-1&lt;/sup&gt;. The fen site showed average midday emissions of 2 nmol m&lt;sup&gt;-2&lt;/sup&gt; s&lt;sup&gt;-1&lt;/sup&gt; during the peak growing season. Other VOCs emitted by vegetation at both sites in July were, with decreasing magnitude, methanol, acetone, acetaldehyde and monoterpenes. In contrast, acetaldehyde and acetone were not emitted but mostly deposited to the fen at the end of the season. In contrast to the wetland, the lake was a sink for acetaldehyde and acetone during all measurement periods.&lt;/p&gt;&lt;p&gt;Thermal imaging and spectral analysis of vegetation will be used to assess relationships between VOC fluxes, vegetation surface temperatures and phenology under varying environmental conditions.&lt;/p&gt;

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