scholarly journals Variación temporal y espacial en la estructura de la comunidad de pequeños mamíferos en un bosque tropical seco

2011 ◽  
Vol 1 (1) ◽  
pp. 19
Author(s):  
Yolanda Domínguez-Castellanos ◽  
Gerardo J. Ceballos González
Keyword(s):  
Tropical Forest ◽  
Small Mammals ◽  
Dry Forest ◽  
La Selva ◽  
Temporal And Spatial Variability ◽  
Palabras Clave ◽  
Spatial Changes ◽  
Temporal And Spatial ◽  
Precipitation Records

Resumen: La estructura de una comunidad biológica está conformada por atributos como la composición, la riqueza y la abundancia de las especies, e influenciada por los cambios temporales y espaciales, que a su vez, se refleja en la composición y abundancia de especies de dicha comunidad. El objetivo fue evaluar la variabilidad temporal y espacial de la comunidad de pequeños mamíferos en la selva seca de Chamela, Jalisco, considerando los dos tipos de vegetación predominantes (selva baja y selva mediana). El muestreo abarcó 18 años y la información generada se compiló en una base de datos, en la que se incluyen los registros de precipitación de los mismos periodos. Con los datos obtenidos se concluye que la abundancia anual de especies varió año con año, registrándose 13 especies de pequeños mamíferos en el área (Tlacuatzin canescens,Megasorex gigas, Spilogale pygmaea, Liomys pictus, Oryzomys melanotis, O. couesi,Nyctomys sumichrasti, Reithrodontomys fulvescens, Osgoodomys banderanus, Peromyscus perfulvus, Baiomys musculus, Sigmodon mascotensis y Xenomys nelsoni). A pesar de que la estructura y cambios temporales de la vegetación modificaron de forma distinta a cada tipo de selva, la composición fue igual para ambas, no obstante la selva mediana es más rica y diversa en especies que la selva baja. Esta estructura de la comunidad de pequeños mamíferos mostró una variación a largo plazo tanto en composición como en riqueza. Por lo que las características de la región de Chamela, permiten la coexistencia de las especies haciendo un uso diferencial del hábitat. Palabras clave: Pequeños mamíferos, comunidad, selvas secas, Jalisco, México. Abstract: The structure of a biological community consists of attributes such as composition, richness and abundance of species, and influenced by the temporal and spatial changes, which in turn is reflected in the composition and abundance of species of that community. The objective was to evaluate the temporal and spatial variability of the community of small mammals in the dry forest of Chamela, Jalisco, considering the two predominant types of vegetation (lowland and tropical forest). The sample comprised 18 and the information generated is compiled in a database, which includes the precipitation records the same periods. The data obtained showed that the annual abundance of species varied from year to year, recorded 13 species of small mammals in the area (Tlacuatzin canescens, Megasorex gigas, Spilogale pygmaea, Liomys pictus, Oryzomys melanotis, O. couesi, Nyctomys sumichrasti, Reithrodontomys fulvescens, Osgoodomys banderanus,Peromyscus perfulvus, Baiomys musculus, Xenomys nelsoni and Sigmodon mascotensis). Although the structure and temporal changes of vegetation changed differently for each type of forest, the composition was the same for both, despite the tropical forest is richer and more diverse in the lowland species. The community structure of small mammals showed a long-term variation in composition and in wealth. So that the characteristics of the region of Chamela allow coexistence of species making a differential use habitat. Key words: small mammals, community, dry forest, Jalisco, Mexico.

scholarly journals Temporal and spatial changes of rainfall and streamflow in the Upper Tekezē–Atbara river basin, Ethiopia

2017 ◽  
Vol 21 (4) ◽  
pp. 2127-2142 ◽  
Author(s):  
Tesfay G. Gebremicael ◽  
Yasir A. Mohamed ◽  
Pieter v. Zaag ◽  
Eyasu Y. Hagos
Keyword(s):  
Change Point ◽  
Statistical Tests ◽  
Catchment Management ◽  
Trend Analyses ◽  
Temporal And Spatial Variability ◽  
Spatial Changes ◽  
Changing Patterns ◽  
Temporal And Spatial ◽  
Using Data ◽  
Streamflow Trends

Abstract. The Upper Tekezē–Atbara river sub-basin, part of the Nile Basin, is characterized by high temporal and spatial variability of rainfall and streamflow. In spite of its importance for sustainable water use and food security, the changing patterns of streamflow and its association with climate change is not well understood. This study aims to improve the understanding of the linkages between rainfall and streamflow trends and identify possible drivers of streamflow variabilities in the basin. Trend analyses and change-point detections of rainfall and streamflow were analysed using Mann–Kendall and Pettitt tests, respectively, using data records for 21 rainfall and 9 streamflow stations. The nature of changes and linkages between rainfall and streamflow were carefully examined for monthly, seasonal and annual flows, as well as indicators of hydrologic alteration (IHA). The trend and change-point analyses found that 19 of the tested 21 rainfall stations did not show statistically significant changes. In contrast, trend analyses on the streamflow showed both significant increasing and decreasing patterns. A decreasing trend in the dry season (October to February), short season (March to May), main rainy season (June to September) and annual totals is dominant in six out of the nine stations. Only one out of nine gauging stations experienced significant increasing flow in the dry and short rainy seasons, attributed to the construction of Tekezē hydropower dam upstream this station in 2009. Overall, streamflow trends and change-point timings were found to be inconsistent among the stations. Changes in streamflow without significant change in rainfall suggests factors other than rainfall drive the change. Most likely the observed changes in streamflow regimes could be due to changes in catchment characteristics of the basin. Further studies are needed to verify and quantify the hydrological changes shown in statistical tests by identifying the physical mechanisms behind those changes. The findings from this study are useful as a prerequisite for studying the effects of catchment management dynamics on the hydrological variabilities in the basin.

Temporal and Spatial Variability and Trend Investigation of Total Ozone Column over Iraq Employing Remote Sensing Data: 1979-2012

2015 ◽  
Vol 53 ◽  
pp. 1-18
Author(s):  
Ali M. Al-Salihi ◽  
Zehraa M. Hassan
Keyword(s):  
Remote Sensing ◽  
Spatial Variability ◽  
Total Ozone ◽  
Positive Trend ◽  
Climate Change Research ◽  
Total Ozone Column ◽  
Temporal And Spatial Variability ◽  
Temporal And Spatial ◽  
Ozone Column

The objective of this paper is to analyze the temporal and spatial variability of the total ozone column (TOC) distributions and trends over Iraq, during the last 30 years (1979–2012) using remote sensing-derived TOC data. Due to shortage of ground-based TOC measurements. TOC data derived from the Total Ozone Mapping Spectrometer (TOMS) for the period 1979–2004 and Ozone Monitoring Instrument (OMI) for the period 2005–2012 with spatial resolution (1o×1o) were used in present study. The spatial, long-term, monthly variations of TOC over Iraq were analysed. For the spatial variability, the latitudinal variability has a large range between (45 to 55) DU in winter and spring whereas during summer and autumn months ranged between (6 to 10) DU. Also represents an annual cycle with maximum in March and minimum in October. In contrast, the longitudinal variability is not significant. The long-term variability represented a notable decline for the period 1979–2012. The ozone negative trend was observed significantly during 1979–2004, for all months with trend ranged between (− 0.3 to 2) DU/year whereas the ozone positive trend was appear clearly during 2005–2007, for all months (0.1 to 2.3) DU/year ,except February and September which presented negative trends. The results can provide comprehensive descriptions of the TOC variations in Iraq and benefit climate change research in this region.

Influence of Holocene permafrost aggradation and thaw on the paleoecology and carbon storage of a peatland complex in northwestern Canada

The Holocene ◽  
2017 ◽  
Vol 27 (9) ◽  
pp. 1391-1405 ◽  
Author(s):  
Nicolas Pelletier ◽  
Julie Talbot ◽  
David Olefeldt ◽  
Merritt Turetsky ◽  
Christian Blodau ◽  
...  
Keyword(s):  
Testate Amoebae ◽  
Carbon Accumulation ◽  
Peat Core ◽  
Creek Watershed ◽  
Temporal And Spatial Variability ◽  
C Stocks ◽  
Temporal And Spatial ◽  
Thawing Permafrost ◽  
Carbon Accumulation Rates

Permafrost in peatlands strongly influences ecosystem characteristics, including vegetation composition, hydrological functions, and carbon cycling. Large amounts of organic carbon are stored in permafrost peatlands in northwestern Canada. Their possible degradation into permafrost-free wetlands including thermokarst bogs may affect carbon (C) stocks, but the direction and magnitude of change are uncertain. Using peat core reconstructions, we characterized the temporal and spatial variability in vegetation macrofossil, testate amoebae, C content, and peat decomposition along a permafrost thaw chronosequence in the southern portion of the Scotty Creek watershed near Fort Simpson, Northwest Territories. The accumulation of limnic and minerotrophic peat prevailed at the site until permafrost formed around 5000 cal. yr BP. Three distinct permafrost periods were identified in the permafrost peat plateau profile, while permafrost only aggraded once in the thermokarst bog profile. Permafrost thawed at ~550 and ~90 cal. yr BP in the thermokarst bog center and edge, respectively. Both allogenic (climatic shifts and wildfire) and autogenic (peat accumulation, Sphagnum growth) processes likely exerted control on permafrost aggradation and thaw. While apparent carbon accumulation rates (ACARs) were lower during present and past permafrost periods than during non-permafrost periods, long-term C accumulation remained similar between cores with different permafrost period lengths. Deep peat was less decomposed in the permafrost plateau compared with the thermokarst bog, which we speculate is due more to differences in peat type rather than differences in decomposition environment between these two ecosystem states. Our study highlights the importance of considering potential deep peat C losses to project the fate of thawing permafrost peat C stores.

scholarly journals Diversidad y abundancia de murciélagos en selvas secas de estacionalidad contrastante en el oeste de México.

2001 ◽  
Vol 5 (1) ◽  
pp. 27 ◽  
Author(s):  
Cuauhtémoc Chávez ◽  
Gerardo Ceballos González
Keyword(s):  
Diversity Index ◽  
Biosphere Reserve ◽  
Dry Forest ◽  
La Selva ◽  
Leptonycteris Curasoae ◽  
Western Mexico ◽  
Artibeus Jamaicensis ◽  
Palabras Clave ◽  
Glossophaga Soricina ◽  
And Function

Resumen: Las selvas bajas y medianas tropicales del oeste de México presentan características estructurales y fenológicas contrastantes, que se traducen en diferencias notables en la diversidad de especies de muchos grupos de plantas y animales. A pesar de que los murciélagos juegan un papel muy importante en la estructura y función de esas selvas se desconoce como varía su diversidad en tales ecosistemas. En este estudio examinamos los patrones de riqueza y abundancia de los murciélagos en una selva baja y una selva mediana en la Reserva de la Biosfera Chamela - Cuixmala, Jalisco, México. En el periodo de febrero de 1992 a enero de 1994 muestreamos 18 meses, 36 noches y 180 horas, en un esfuerzo equivalente a 16,416 m² de red para cada ambiente. En total capturamos a 338 ejemplares de 15 especies. Nuestra predicción de encontrar diferencias importantes en la estructura y diversidad de la comunidad de murciélagos en ambos ambientes fue apoyada por la información recabada. El hábitat con mayor riqueza específica fue la selva baja con 13 especies; en la selva mediana registramos solo 10 especies. El índice de diversidad fue de H’= 1.99 y H’= 1.40 para la selva baja y la selva mediana, respectivamente. El mayor número de individuos capturados fue en la selva baja. Las especies que capturamos únicamente en la selva baja fueron Carollia subrufa, Leptonycteris curasoae, Musonycteris harrisoni, Pteronotus davyi y P. parnelli, mientras que, en la selva mediana fue Rhogeessa parvula. Las especies más abundantes en los la selva baja fueron Artibeus jamaicensis, A. intermedius, Glossophaga soricina y Dermanuraphaeotis mientras que en la selva mediana sólo A. jamicensis y A. intermedius fueron abundantes. Palabras clave: Diversidad, abundancia, murciélagos, temporalidad, selvas secas, selva baja, selva mediana, Jalisco, México.Abstract:Tropical dry and semi-dry forests of western Mexico show contrasting structural and phenologic characteristics that result in important differences in the species diversity of many groups of plants and animals. Despite the importance of bats in the structure and function of these forests, the variation in diversity in these ecosystems is not known. This study examines the patterns of richness and abundance of bats in a tropical dry and tropical semi-dry forest in the Biosphere Reserve of Chamela - Cuixmala, Jalisco, Mexico. Between Februray 1992 and January 1994 we sampled 18 months, 36 nights and 180 hours, in an equivalent effort of 16,416 m² of mist-nets for each environment. In total, we captured 338 individuals of 15 species. Our prediction of finding important differences in the structure and diversity of the bat community in both environments was supported by our findings. The habitat with highest specific richness was the dry forest, with 13 species; in the semi-dry forest we only recorded 10 species. The diversity index was respectively H’=1.99 and H’=1.40 for the dry and semi-dry forest. The greatest number of individuals was captured in the dry forest. The species captured solely in the dry forest were Carollia subrufa, Leptonycteris curasoae, Musonycteris harrisoni, Pteronotus davyi and P.parnelli while in the semi-dry forest was Rhogeessa parvula. The species more abundant in the dry forest were  Artibeus jamaicensis A. intermedius, Glossophaga soricina and Dermanura phaeotis, while in the semi- dry forest only A. jamaicensis and A. intermeius were abundant.

scholarly journals Temporal and spatial changes of rainfall and streamflow in the Upper Tekeze–Atbara River Basin, Ethiopia

2016 ◽  
Author(s):  
Tesfay Gebretsadkan Gebremicael ◽  
Yasir Abbas Mohamed ◽  
Pieter van der Zaag ◽  
Eyasu Yazew Hagos
Keyword(s):  
River Basin ◽  
Change Point ◽  
Statistical Tests ◽  
Catchment Management ◽  
Temporal And Spatial Variability ◽  
Spatial Changes ◽  
Changing Patterns ◽  
Temporal And Spatial ◽  
Using Data ◽  
Streamflow Trends

Abstract. The Upper Tekeze–Atbara river basin–part of the Nile basin, is characterized by high temporal and spatial variability of rainfall and streamflow. In spite of its importance for sustainable water use and food security, the changing patterns of streamflow and its association with climate change is not well understood in the basin. This study aims at improving the understanding of the linkages between rainfall and streamflow trends and identifying the drivers of streamflow variabilities in the basin. Trend and change point detections of rainfall and streamflow were analysed using Mann–Kendall and Pettitt tests, respectively, using data records for 21 rainfall and 9 streamflow stations. The nature of changes and linkages between rainfall and streamflow were carefully examined for monthly, seasonal, annual flows as well as Indicators of Hydrological Alterations (IHA). The trend and change point analyses found that 20 of the tested 21 rainfall stations did not show statistically significant changes. In contrast, trend analyses on the streamflow showed a significant increasing/decreasing patterns. A decreasing trend in the dry (October to February), short (March to May), main rainy seasons (June to September) and annual totals is dominant in 6 out of the 9 stations. Only one out of nine gauging stations experienced increasing flow significantly in the dry and short rainy seasons. This increasing trend is attributed to the construction of Tekeze hydropower dam above the station in 2009. Overall, streamflow trends and change point timings were found to be inconsistent among the stations. Changes in streamflow without significant change in rainfall suggests other factors than rainfall to drive the change. Weak linkages between rainfall and streamflow trends indicate that the observed changes in streamflow regimes could be due to changes in catchment characteristics of the basin. Further studies are needed to verify and quantify the hydrological changes shown in statistical tests by identifying the physical mechanisms behind those changes. The findings from this study are useful as a pre-requisite for studying the effects of catchment management dynamics on the hydrological variabilities in the basin.

Sign in / Sign up

Export Citation Format

Share Document