scholarly journals Relación lluvia de polen-vetación en selvas de Quintana Roo

2017 ◽  
pp. 31 ◽  
Author(s):  
Gerald A. Islebe ◽  
Rogel Villanueva-Gutiérrez ◽  
Odilón Sánchez-Sánchez
Keyword(s):  
Zea Mays ◽  
Quintana Roo ◽  
Vegetation Types ◽  
Pollen Data ◽  
Indicator Taxa ◽  
Modern Pollen ◽  
Pollen Content ◽  
Ordination Techniques ◽  
Ordination Analysis ◽  
Pollen Rain

Modern pollen rain was studied along a 450 km long transect between Cancun-La Unión (Belizean border). Ten moss samples were collected in different vegetation types and analyzed for pollen content. The data were analyzed with classification (TWINSPAN), ordination analysis (DCA) and different association indices. Classification and ordination techniques allowed us to recognize three different pollen signals from semievergreen forest (with Maclura, Apocynaceae, Moraceae, Sapotaceae, Araceae, Cecropia, Celtis, Eugenia and Bursera), acahual (with con Coccoloba, Metopium, Anacardiaceae, Urticales, Melothria, Croton, Palmae) and disturbed vegetation (with Zea mays, Mimosa and Asteraceae ) . The degree of over-representation and underrepresentation of the pollen data with respect to the modem vegetation was established, being under-represented mostly entomophilous species. We can conclude that the actual pollen signal can be used for calibrating paleosignals, if clear groups of indicator taxa can be established.

Modern pollen rain and vegetation of the St. Elias Mountains, Yukon Territory

1977 ◽  
Vol 55 (18) ◽  
pp. 2367-2382 ◽  
Author(s):  
H. J. B. Birks
Keyword(s):  
Picea Glauca ◽  
Yukon Territory ◽  
Sample Type ◽  
Vegetation Types ◽  
Populus Balsamifera ◽  
Modern Pollen ◽  
Pollen Content ◽  
Pollen Rain ◽  
Shrub Tundra ◽  
Community Types

The vegetation of the area east of the Klutlan Glacier in the St. Elias Mountains is described with the methods of European phytosociology. Four major vegetation types are recognized: Picea glauca forests, Populus balsamifera forests, Betula glandulosa shrub–tundra, and Dryas integrifolia tundra.The modern pollen assemblages deposited in these vegetation types are determined by pollen analysis of surface moss polsters, lake muds, and moss samples from sedge swamps. Numerical analyses of the surface spectra indicate that spectra from the Dryas tundra and from the Populus forests are distinctive in their pollen composition. The variation in the percentage pollen content of samples from the Picea forests and the shrub–tundra is so great, even when spectra from a single sample type are considered, that no reliable distinctions can be made in modern pollen spectra from these two community types.

Application and limitations of the Artemisia/Chenopodiaceae pollen ratio in arid and semi-arid China

The Holocene ◽  
2012 ◽  
Vol 22 (12) ◽  
pp. 1385-1392 ◽  
Author(s):  
Yan Zhao ◽  
Hongyan Liu ◽  
Furong Li ◽  
Xiaozhong Huang ◽  
Jinghui Sun ◽  
...  
Keyword(s):  
Arid Regions ◽  
Positive Relationship ◽  
Vegetation Types ◽  
Pollen Data ◽  
Data Synthesis ◽  
Modern Pollen ◽  
Vegetation Zones ◽  
Desert Areas ◽  
Vegetation And Climate ◽  
Semi Arid

The Artemisia/Chenopodiaceae (A/C) ratio is assumed to be a useful index for reconstructing moisture changes in arid and semi-arid regions. Thorough modern pollen studies are still lacking to understand the reliability and limitation of A/C ratio as a moisture indicator, however. Here we review how well this ratio can be applied in arid and semi-arid China on the basis of new surface pollen data, previous data synthesis and other publications. Results indicate that variance in the A/C ratio can permit identification of modern vegetation types and that the A/C ratio generally has a positive relationship with annual precipitation. However, soil salinity, vegetation community composition, human activity and sample provenance (e.g. soil and lake sediments) will affect the values of the A/C ratio in different vegetation zones and therefore the A/C ratio is not comparable in different regions. We argue that the A/C ratio can only be used to reconstruct vegetation types and climate change in regions with precipitation <450–500 mm, and in steppe, steppe desert and desert areas. Careful studies should be undertaken to understand the modern pollen–vegetation–climate relationships in various regions before using the A/C ratio to interpret vegetation and climate.

scholarly journals Isopoll Maps and an Analysis of the Distribution of the Modern Pollen Rain, Eastern and Central Northern Canada

2007 ◽  
Vol 36 (1-2) ◽  
pp. 91-108 ◽  
Author(s):  
D. L. Elliot-Fisk ◽  
J. T. Andrews ◽  
S. K. Short ◽  
W. N. Mode
Keyword(s):  
Principal Component ◽  
Eastern Canada ◽  
Northern Canada ◽  
Modern Pollen ◽  
Pollen Content ◽  
Pollen Types ◽  
Pollen Rain ◽  
Multiple Samples ◽  
Percentage Data ◽  
Component Scores

ABSTRACT At 39 sites in eastern and central northern Canada, multiple samples of surface moss and lichens have been analyzed for their pollen content. Although pollen from 20 to 30 taxa were identified in the samples from each site, 8 pollen types (Alnus, Betula, Picea. Pinus, Salix, Gramineae, Cyperaceae and Ericaceae) usually comprise 90 to 100% of the pollen rain. We present isopoll maps of these taxa based on mean percentages of multiple samples from the 39 sites. The data are further analyzed by a number of statistical methods to determine whether there are specific pollen assemblages within this region and to what extent present day climatic parameters and floristic/vegetation zones correlate with pollen counts. Cluster analysis on raw data and on principal component scores yields six distinct pollen assemblages which are further examined by discriminant analysis. Pollen concentration maps for eastern Canada are also presented here and used as an aid in interpreting the percentage data.

Stomate and pollen content of lake surface sediments from across the tree line on the Taimyr Peninsula, Siberia

1996 ◽  
Vol 74 (7) ◽  
pp. 1009-1015 ◽  
Author(s):  
S. L. Clayden ◽  
L. C. Cwynar ◽  
G. M. MacDonald
Keyword(s):  
Taimyr Peninsula ◽  
Data Set ◽  
Picea Obovata ◽  
Forest Tundra ◽  
Modern Pollen ◽  
Vegetation Zones ◽  
Forest Sites ◽  
Pollen Content ◽  
Pollen Rain ◽  
Components Analysis

Surface-sediment samples from 23 lakes on the Taimyr Peninsula were collected along a transect from tundra to forest and analyzed for their pollen and coniferous stomate content. Larix sibirica, the dominant tree in forest–tundra and forest vegetation zones, is poorly represented in the pollen spectra, never exceeding 8%. To examine the correspondence between the modern pollen rain and the vegetation zones of tundra, forest–tundra, and forest, a principal components analysis was applied to the pollen percentages. Betula and Alnus account for the greatest variance in the data set, and the set of tundra sites farthest north is distinct from the forest sites farthest south. Stomates of L. sibirica are present in all samples from sites where Larix trees are present, and some samples contained higher concentrations of stomates than pollen of Larix. Picea obovata stomates are found less consistently and less abundantly than Larix stomates.

scholarly journals Phytosociological and ecological discrimination of Mediterranean cypress ('Cupressus sempervirens') communities in Crete (Greece) by means of pollen analysis

2019 ◽  
Vol 40 (2) ◽  
pp. 145-163 ◽  
Author(s):  
José Antonio López-Sáez ◽  
Arthur Glais ◽  
Ioannis Tsiripidis ◽  
Spyros Tsiftsis ◽  
Daniel Sánchez-Mata ◽  
...  
Keyword(s):  
Cluster Analysis ◽  
Hierarchical Cluster ◽  
Cupressus Sempervirens ◽  
New Associations ◽  
Modern Pollen ◽  
Surface Samples ◽  
Aegean Islands ◽  
Temperature Regimes ◽  
Pollen Content ◽  
Pollen Rain

Sixty modern surface samples collected from mosses in different cypress forest communities (Cupressus sempervirens L.) on the island of Crete (Greece) were analysed for their pollen content. The samples were taken from six different cypress phytosociological associations between 23 and 1600 m asl, and fall within distinct rainfall and temperature regimes. The aims of this paper are to provide new data on the modern pollen rain from the Aegean islands, and to perform these data using multivariate statistics (hierarchical cluster analysis and canonical correspondence analysis) and pollen percentages. The discrimination of pollen assemblages corresponds to a large extent to the floristic differentiation of Cupressus sempervirens forest vegetation and indicates the existence of three new associations.

IDENTIFICACIÓN DE ÁREAS POTENCIALES EN MEXICO PARA LA INTERVENCIÓN CON MAÍZ BIOFORTIFICADO CON ZINC

2018 ◽  
Vol 41 (3) ◽  
pp. 327-337
Author(s):  
Rocío Ramírez-Jaspeado ◽  
Natalia Palacios-Rojas ◽  
José Funes ◽  
Salomón Pérez ◽  
M. Laura Donnet
Keyword(s):  
Zea Mays ◽  
Zea Mays L ◽  
Quintana Roo ◽  
Per Capita ◽  
Sobre Todo

La desnutrición es un problema que afecta el crecimiento, desarrollo y salud en general, especialmente de los niños menores de cinco años y mujeres embarazadas. En México, los indicadores de bajo peso y talla señalan una reducción de 8 y 13.3 %, respectivamente, entre 1988 y 2012. A pesar de las intervenciones de salud pública la prevalencia de baja talla continúa siendo un importante problema de salud pública (13.6 % en promedio), especialmente en zonas rurales y urbanas marginales. La biofortificación de cultivos como maíz (Zea mays L.) con zinc es una forma de contribuir a combatir la deficiencia de este micronutriente, sobre todo en estados donde se observa una importante producción y un alto consumo per capita del grano (cerca de 200 kg/año). El objetivo del presente trabajo fue identificar áreas con mayor potencial para la introducción de maíces biofortificados con zinc; para ésto, se determinó un Índice de Priorización para Biofortificación (IPB) y las Condiciones de Intervención para Biofortificación (CIB). Los dos parámetros fueron determinados mediante la estimación de tres índices: producción, consumo y deficiencia de zinc. El IPB constituye una media geométrica de los tres índices, mientras que CIB establece los parámetros de atención para la biofortificación. Los resultados tanto del IPB como CIB indican que las áreas con prioridad elevada para biofortificación son Chiapas, Oaxaca, Guerrero, Hidalgo y Puebla. Las áreas establecidas con prioridad media son Nayarit y Durango, mientras que Quintana Roo fue determinada como de prioridad baja.

Pollen Taphonomy in a Canyon Stream

1987 ◽  
Vol 28 (3) ◽  
pp. 393-406 ◽  
Author(s):  
Patricia L. Fall
Keyword(s):  
Surface Soil ◽  
Pollen Grains ◽  
Close Correlation ◽  
Soil Samples ◽  
Alluvial Deposits ◽  
Modern Pollen ◽  
Pollen Types ◽  
Pollen Rain ◽  
Arid Steppe ◽  
Turbulent Water

AbstractSurface soil samples from the forested Chuska Mountains to the arid steppe of the Chinle Valley, Northeastern Arizona, show close correlation between modern pollen rain and vegetation. In contrast, modern alluvium is dominated by Pinus pollen throughout the canyon; it reflects neither the surrounding floodplain nor plateau vegetation. Pollen in surface soils is deposited by wind; pollen grains in alluvium are deposited by a stream as sedimentary particles. Clay-size particles correlate significantly with Pinus, Quercus, and Populus pollen. These pollen types settle, as clay does, in slack water. Chenopodiaceae-Amaranthus, Artemisia, other Tubuliflorae, and indeterminate pollen types correlate with sand-size particles, and are deposited by more turbulent water. Fluctuating pollen frequencies in alluvial deposits are related to sedimentology and do not reflect the local or regional vegetation where the sediments were deposited. Alluvial pollen is unreliable for reconstruction of paleoenvironments.

MODERN POLLEN RAIN STUDIES IN EASTERN ONTARIO

1963 ◽  
Vol 41 (2) ◽  
pp. 243-252 ◽  
Author(s):  
James E. King ◽  
Ronald O. Kapp
Keyword(s):  
United States ◽  
Long Range ◽  
Southwestern United States ◽  
Pollen Trap ◽  
Modern Pollen ◽  
Pollen Rain ◽  
Moss Polsters ◽  
Eastern Ontario

Moss polsters were collected at 15 sites between Toronto and Lake Timagami, Ontario, and at 4 localities in the Lake Timagami area for the purpose of determining the regional pollen rain and its local variations. Pollen percentages of Acer, Quercus, Ambrosia, Chenopodiaceae, Compositae, and Gramineae decrease northward and Picea, Pinus, and Betula increase at the more northerly sites. From the three most northern sites a regional pollen rain was calculated by averaging the percentages from nine pollen spectra. In this area the regional pollen rain is dominated by Picea (15%), Pinus (38%), and Betula (22%). At one site a grain of Ephedra was recovered, apparently carried in by long range drift. The nearest place that it grows naturally is in the southwestern United States. Various pollen trap types were investigated and it was found that all types of moss polsters and some types of decaying stumps (depending on their moisture-holding capacity) were effective in preserving the modern pollen rain.

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