scholarly journals The influence of water table depth on evapotranspiration in the Amazon arc of deforestation

2019 ◽  
Vol 23 (9) ◽  
pp. 3917-3931 ◽  
Author(s):  
John O'Connor ◽  
Maria J. Santos ◽  
Karin T. Rebel ◽  
Stefan C. Dekker
Keyword(s):  
Soil Moisture ◽  
Water Stress ◽  
Growing Season ◽  
Dry Season ◽  
Rooting Depth ◽  
Recycling System ◽  
Moisture Recycling ◽  
Arc Of Deforestation ◽  
Dry Seasons ◽  
Wet And Dry Seasons

Abstract. The Amazon rainforest evapotranspiration (ET) flux provides climate-regulating and moisture-provisioning ecosystem services through a moisture recycling system. The dense complex canopy and deep root system creates an optimum structure to provide large ET fluxes to the atmosphere, forming the source of precipitation. Extensive land use and land cover change (LULCC) from forest to agriculture in the arc of deforestation breaks this moisture recycling system. Crops such as soybean are planted in large homogeneous monocultures and the maximum rooting depth of these crops is far shallower than forest. This difference in rooting depth is key as forests can access deep soil moisture and show no signs of water stress during the dry season, while in contrast crops are highly seasonal with a growing season dependent on rainfall. As access to soil moisture is a limiting factor in vegetation growth, we hypothesised that if crops could access soil moisture, they would undergo less water stress and therefore would have higher evapotranspiration rates than crops which could not access soil moisture. We combined remote-sensing data with modelled groundwater table depth (WTD) to assess whether vegetation in areas with a shallow WTD had higher ET than vegetation in deep WTD areas. We randomly selected areas of forest, savanna, and crop with deep and shallow WTD and examined whether they differ on MODIS Evapotranspiration (ET), Land Surface Temperature (LST), and Enhanced Vegetation Index (EVI), from 2001 to 2012, annually and during transition periods between the wet and dry seasons. As expected, we found no differences in ET, LST, and EVI for forest vegetation between deep and shallow WTD, which because of their deep roots could access water and maintain evapotranspiration for moisture recycling during the entire year. We found significantly higher ET and lower LST in shallow WTD crop areas than in deep WTD during the dry season transition, suggesting that crops in deep WTD undergo higher water stress than crops in shallow WTD areas. The differences found between crop in deep and shallow WTD, however, are of low significance with regards to the moisture recycling system, as the difference resulting from conversion of forest to crop has an overwhelming influence (ET in forest is ≈2 mm d−1 higher than that in crops) and has the strongest impact on energy balance and ET. However, access to water during the transition between wet and dry seasons may positively influence growing season length in crop areas.

scholarly journals The influence of water table depth on evapotranspiration in the Amazon arc of deforestation

2019 ◽  
Author(s):  
John O'Connor ◽  
Maria J. Santos ◽  
Karin T. Rebel ◽  
Stefan C. Dekker
Keyword(s):  
Soil Moisture ◽  
Water Stress ◽  
Growing Season ◽  
Dry Season ◽  
Rooting Depth ◽  
Limiting Factor ◽  
Recycling System ◽  
Moisture Recycling ◽  
Growing Season Length ◽  
Arc Of Deforestation

Abstract. The Amazon rainforest evapotranspiration (ET) flux provides climate regulating and moisture provisioning ecosystem services through a moisture recycling system. The dense complex canopy and deep root system creates an optimum structure to provide large ET fluxes to the atmosphere forming the source for precipitation. Extensive land use and land cover change (LULCC) from forest to agriculture in the arc of deforestation breaks this moisture recycling system. Crops such as soybean are planted in large homogeneous monocultures and the maximum rooting depth of these crops is far shallower than forest. This difference in rooting depth is key as forests can access deep soil moisture and show no signs of water stress during the dry season while in contrast crops are highly seasonal with a growing season dependant on rainfall. As access to soil moisture is a limiting factor in vegetation growth, we hypothesised that if crops could access soil moisture they would undergo less water stress and therefore would have higher evapotranspiration rates than crops which could not access soil moisture. We combined remote sensing data with modelled groundwater table depth (WTD) to assess whether vegetation in areas with a shallow WTD had higher ET than vegetation in deep WTD areas. We randomly selected areas of forest, savanna and crop with deep and shallow WTD and examined whether they differ on MODIS Evapotranspiration (ET), Land Surface Temperature (LST) and Enhanced Vegetation Index (EVI), from 2001 to 2012, annually and during transition periods between the wet and dry season. As expected, we found no differences in ET, LST, and EVI for forest vegetation between deep and shallow WTD, which because of their deep roots could access water and maintain evapotranspiration for moisture recycling during the entire year. We found significantly higher ET and lower LST in shallow WTD crop areas than in deep WTD during the dry season transition, suggesting that crops in deep WTD undergo higher water stress than crops in shallow WTD areas. The differences found between crop in deep and shallow WTD, however, are of low significance with regards the moisture recycling system as the difference resulting from conversion of forest to crop has an overwhelming influence (ET in forest is ≈ 2 mm day−1 higher than that in crops) and has the strongest impact on energy balance and ET. However, access to water during the transition between wet and dry seasons may positively influence growing season length in crop areas.

scholarly journals Fruiting phenology and consumption by birds in Ficus calyptroceras (Miq.) Miq. (Moraceae)

2002 ◽  
Vol 62 (2) ◽  
pp. 339-346 ◽  
Author(s):  
J. RAGUSA-NETTO
Keyword(s):  
Food Resource ◽  
Bird Species ◽  
Dry Season ◽  
Dry Forest ◽  
Wet Season ◽  
Frugivorous Birds ◽  
Fruiting Phenology ◽  
Dry Seasons ◽  
Seed Dispersers ◽  
Wet And Dry Seasons

Figs are a remarkable food resource to frugivores, mainly in periods of general fruit scarcity. Ficus calyptroceras Miq. (Moraceae) is the only fig species in a type of dry forest in western Brazil. In this study I examined the fruiting pattern as well as fig consumption by birds in F. calyptroceras. Although rainfall was highly seasonal, fruiting was aseasonal, since the monthly proportion of fruiting trees ranged from 4% to 14% (N = 50 trees). I recorded 22 bird species feeding on figs. In the wet season 20 bird species ate figs, while in the dry season 13 did. Parrots were the most important consumers. This group removed 72% and 40% of the figs consumed in the wet and dry seasons, respectively. No bird species increases fig consumption from dry to wet season. However, a group of bird species assumed as seed dispersers largely increases fig consumption from wet to dry season, suggesting the importance of this resource in the period of fruit scarcity. The results of this study points out the remarkable role that F. calyptroceras plays to frugivorous birds, in such a dry forest, since its fruits were widely consumed and were available all year round.

scholarly journals Difference in Canopy and Air Temperature as an Indicator of Grassland Water Stress

2013 ◽  
Vol 1 (No. 4) ◽  
pp. 127-138 ◽  
Author(s):  
Duffková Renata
Keyword(s):  
Soil Moisture ◽  
Water Stress ◽  
Moisture Content ◽  
Air Temperature ◽  
Temperature Difference ◽  
Soil Moisture Content ◽  
Growing Season ◽  
Plant Residues ◽  
Dead Plant ◽  
Linear Correlations

In 2003–2005 in conditions of the moderately warm region of the Třeboň Basin (Czech Republic) the difference between canopy temperature (Tc) and air temperature at 2 m (Ta) was tested as an indicator of grass­land water stress. To evaluate water stress ten-minute averages of temperature difference Tc–Ta were chosen recorded on days without rainfall with intensive solar radiation from 11.00 to 14.00 CET. Water stress in the zone of the major portion of root biomass (0–0.2 m) in the peak growing season (minimum presence of dead plant residues) documented by a sudden increase in temperature difference, its value 5–12°C and unfavourable canopy temperatures due to overheating (> 30°C) was indicated after high values of suction pressure approach­ing the wilting point (1300 kPa) were reached. High variability of temperature difference in the conditions of sufficient supply of water to plants was explained by the amount of dead plant residues in canopy, value of va­pour pressure deficit (VPD), actual evapotranspiration rate (ETA) and soil moisture content. At the beginning of the growing season (presence of dead plant residues and voids) we proved moderately strong negative linear correlations of Tc–Ta with VPD and Tc–Ta with ETA rate and moderately strong positive linear correlations of ETA rate with VPD. In the period of intensive growth (the coverage of dead plant residues and voids lower than 10%) moderately strong linear correlations of Tc–Ta with VPD and multiple linear correlations of Tc–Ta with VPD and soil moisture content at a depth of 0.10–0.40 m were demonstrated.

Diversity, distribution and relative abundance of avifauna at Ansas Dam and surrounding farmland site Debre Berhan Town, Ethiopia

2020 ◽  
pp. 175815592096320
Author(s):  
Alemayehu Shiferaw ◽  
Dereje Yazezew
Keyword(s):  
Relative Abundance ◽  
Bird Species ◽  
Dry Season ◽  
Avian Species ◽  
Ordinal Scale ◽  
Line Transect ◽  
Wet Season ◽  
Debre Berhan ◽  
Dry Seasons ◽  
Wet And Dry Seasons

The diversity, distribution, and relative abundance of avifauna were studied at and Around Ansas Dam, Debre Berhan Town, Ethiopia, from early September 2018 to early February 2019, covering both wet and dry seasons. Line transect technique was employed to study the diversity, abundance and distribution of birds species in the farmland site while total count employed on the dam. Data were collected in both wet and dry seasons from 6:30 to10:00 early morning and 15:30 to 18.00 late afternoon, when birds are more active. The data were analyzed with Shannon-Weiner Index, Simpson Index, Evenness Index, and relative abundance. A total of 45 bird species (35 in the dam and 22 in the farmland) belonging to nine orders and 21 families were recorded during the study period. Order Passeriformes (37.8%) followed by order Charadriformes (24.4%) were represented highest number. From all identified species at Ansas Dam and surrounding farmland, Abyssinian longclaw, Black-headed siskins, White-tailed swallow, Blue-winged goose, and Spot-breasted lapwing were endemic birds to Ethiopia. The highest Shannon diversity (H′ = 2.1) was recorded in dam during the dry season while the lowest (H′ = 1.78) was recorded during wet season in farmland. However, the Simpson diversity Index of avian species indicated relatively higher avian species diversity during the dry season in dam (D = 0.80) than farmland (D = 0.71) habitat. Evenness was highest in the dam (E = 0.65) and lowest in the farmland (E = 0.58) habitat. More avian species similarity (SI = 0.42) at farmland and dam habitat during the wet season but least similarity (SI = 0.2) was observed during the dry season. Most birds had scored rare in the ordinal scale while few species with abundant and uncommon ranks in both habitats and seasons. Conservation of the different charismatic bird species should be taken as an important component of wildlife management plan in the area.

A survey of insect populations in Capsicum chinense L. plantings in Georgetown, St. Vincent, using modified CC traps.

1969 ◽  
Vol 93 (3-4) ◽  
pp. 207-221
Author(s):  
Matthew Ciomperlik ◽  
Chang Chi Chu ◽  
Jason Carlson ◽  
Marcus Richards ◽  
Thomas J. Henneberry
Keyword(s):  
Propylene Glycol ◽  
Dry Season ◽  
Hot Pepper ◽  
Capsicum Chinense ◽  
Wet Season ◽  
Insect Populations ◽  
Dry Seasons ◽  
Wet And Dry Seasons

The insect populations in hot pepper, Capsicum chinense L. (Solanaceae), were surveyed in Georgetown, St. Vincent, during the 2004 wet and 2005 dry seasons. Modified white, blue, and yellow CC traps were used to capture insects in the plantings. Overall, 69 insect families were captured, 41 of which were captured during both the wet and dry seasons. During the wet season, the greatest numbers of individuals captured were from the Cecidomyiidae, Chironomidae, Chloropidae, Chrysomelidae, Cicadellidae, and Drosophilidae families. During the dry season, the greatest numbers of individuals captured were from Chrysomelidae and Cicadellidae families. The addition of dichlorvos as a killing agent and propylene glycol as an insect preservative to the CC traps increased the number and diversity of insects caught. Additionally, propylene glycol helped to preserve the specimens for taxonomic and genetic determinations. CC traps with yellow bases attracted more insect families than traps with white or blue bases. However, CC traps with blue bases caught more Lonchaeidae during both the wet and dry seasons, and more Tachinidae during the dry season. CC traps with white or yellow trap bases were equally attractive to insects in the families Aleyrodidae, Drosophilidae, Lauxaniidae, and Otitidae.

scholarly journals Effect of Irrigation and Soil Water Stress on Densities of Macrophomina phaseolina in Soil and Roots of Two Soybean Cultivars

Plant Disease ◽  
2000 ◽  
Vol 84 (8) ◽  
pp. 895-900 ◽  
Author(s):  
S. R. Kendig ◽  
J. C. Rupe ◽  
H. D. Scott
Keyword(s):  
Soil Moisture ◽  
Water Stress ◽  
Soil Water ◽  
Growth Stage ◽  
Root Colonization ◽  
Growing Season ◽  
Moisture Stress ◽  
Macrophomina Phaseolina ◽  
Soil Moisture Stress ◽  
Soil Water Stress

The effects of irrigation and soil water stress on Macrophomina phaseolina microsclerotial (MS) densities in the soil and roots of soybean were studied in 1988, 1989, and 1990. Soybean cvs. Davis and Lloyd received irrigation until flowering (TAR2), after flowering (IAR2), full season (FSI), or not at all (NI). Soil water matric potentials at 15- and 30-cm depths were recorded throughout the growing season and used to schedule irrigation. Soil MS densities were determined at the beginning of each season. Root MS densities were determined periodically throughout the growing season. Microsclerotia were present in the roots of irrigated as well as nonirrigated soybean within 6 weeks after planting. By vegetative growth stage V13, these densities reached relatively stable levels in the NI and FSI treatments (2.23 to 2.35 and 1.35 to 1.63 log [microsclerotia per gram of dry root], respectively) through reproductive growth stage R6. After R6, irrigation was discontinued and root densities of microsclerotia increased in all treatments. Initiation (IAR2) or termination (TAR2) of irrigation at R2 resulted in significant changes in root MS densities, with densities reaching levels intermediate between those of FSI and NI treatments. Year to year differences in root colonization reflected differences in soil moisture due to rainfall. The rate of root colonization in response to soil moisture stress decreased with plant age. Root colonization was significantly greater in Davis than Lloyd at R5 and R8. This was reflected in a trend toward higher soil densities of M. phaseolina at planting in plots planted with Davis than in plots planted with Lloyd. Although no charcoal rot symptoms in the plant were observed in this study, these results indicated that water management can limit, but not prevent, colonization of soybean by M. phaseolina, that cultivars differ in colonization, and that these differences may affect soil densities of the fungus.

scholarly journals Overview: Precipitation characteristics and sensitivities to environmental conditions during GoAmazon2014/5 and ACRIDICON-CHUVA

2018 ◽  
Vol 18 (9) ◽  
pp. 6461-6482 ◽  
Author(s):  
Luiz A. T. Machado ◽  
Alan J. P. Calheiros ◽  
Thiago Biscaro ◽  
Scott Giangrande ◽  
Maria A. F. Silva Dias ◽  
...  
Keyword(s):  
Environmental Conditions ◽  
Land Surface ◽  
Rain Rate ◽  
Vertical Motion ◽  
Cloud Droplet ◽  
Dry Season ◽  
Wet Season ◽  
Aerosol Loading ◽  
Dry Seasons ◽  
Wet And Dry Seasons

Abstract. This study provides an overview of precipitation processes and their sensitivities to environmental conditions in the Central Amazon Basin near Manaus during the GoAmazon2014/5 and ACRIDICON-CHUVA experiments. This study takes advantage of the numerous measurement platforms and instrument systems operating during both campaigns to sample cloud structure and environmental conditions during 2014 and 2015; the rainfall variability among seasons, aerosol loading, land surface type, and topography has been carefully characterized using these data. Differences between the wet and dry seasons were examined from a variety of perspectives. The rainfall rates distribution, total amount of rainfall, and raindrop size distribution (the mass-weighted mean diameter) were quantified over both seasons. The dry season generally exhibited higher rainfall rates than the wet season and included more intense rainfall periods. However, the cumulative rainfall during the wet season was 4 times greater than that during the total dry season rainfall, as shown in the total rainfall accumulation data. The typical size and life cycle of Amazon cloud clusters (observed by satellite) and rain cells (observed by radar) were examined, as were differences in these systems between the seasons. Moreover, monthly mean thermodynamic and dynamic variables were analysed using radiosondes to elucidate the differences in rainfall characteristics during the wet and dry seasons. The sensitivity of rainfall to atmospheric aerosol loading was discussed with regard to mass-weighted mean diameter and rain rate. This topic was evaluated only during the wet season due to the insignificant statistics of rainfall events for different aerosol loading ranges and the low frequency of precipitation events during the dry season. The impacts of aerosols on cloud droplet diameter varied based on droplet size. For the wet season, we observed no dependence between land surface type and rain rate. However, during the dry season, urban areas exhibited the largest rainfall rate tail distribution, and deforested regions exhibited the lowest mean rainfall rate. Airplane measurements were taken to characterize and contrast cloud microphysical properties and processes over forested and deforested regions. Vertical motion was not correlated with cloud droplet sizes, but cloud droplet concentration correlated linearly with vertical motion. Clouds over forested areas contained larger droplets than clouds over pastures at all altitudes. Finally, the connections between topography and rain rate were evaluated, with higher rainfall rates identified at higher elevations during the dry season.

scholarly journals Current Population Status and Activity Pattern of Lesser Flamingos (Phoeniconaias minor) and Greater Flamingo (Phoenicopterus roseus) in Abijata-Shalla Lakes National Park (ASLNP), Ethiopia

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Tewodros Kumssa ◽  
Afework Bekele
Keyword(s):  
Population Size ◽  
Activity Pattern ◽  
Habitat Preference ◽  
Time Of Day ◽  
Dry Season ◽  
Population Status ◽  
Wet Season ◽  
Current Population ◽  
Dry Seasons ◽  
Wet And Dry Seasons

A study of the population status, habitat preference, and activity pattern of nonbreeding flamingos was carried out in Lakes Abijata, Shalla, and Chitu, part of the Great Rift Valley, Ethiopia, from 2011 to 2013. The current population status and habitat preference of flamingos in the area are still poorly known. Likewise, data on diurnal and seasonal activity pattern of the species are scarce and this leads to the misunderstanding of how Flamingos use local wetlands throughout the different seasons. Data regarding population size and activity pattern were gathered during the wet and dry seasons. Point-count method was used to estimate the population size. Behaviors were recorded using scan sampling techniques. A total of 53671 individuals representing two species of flamingo were counted during both wet and dry seasons from the three lakes. There were more flamingos during the dry season than the wet season in Lake Abijata contrary to Lakes Shalla and Chitu during the wet season. Lesser flamingos (Phoeniconaias minor) were the most abundant species comprising 95.39%, while Greater Flamingos (Phoenicopterus roseus) accounted for 4.61% of the total population. Lake Abijata is the major stronghold of Lesser Flamingos in the area. There was significant variation in the mean number of both species during the wet and dry season in the different study sites of the lake, respectively. The species were known to use varied habitats within the lakes. The Lesser Flamingo mainly preferred the shoreline and mudflat areas of the lakes. However, Greater Flamingo on several occasions showed preference to offshore area of the lakes. Seasonal average flock sizes were not similar between the species. There was a strong relationship between time allocated to each activity and time of day. Feeding activity varied among daylight hours and was higher in the evening (76.5%) and late morning (74.56%) and least during midday (54%). Some variations in activity breakdown were observed between time blocks and season. Conservation efforts in the park should include the wild flora and fauna not only of the land but also of the aquatic systems. The information in this study will be very useful for the future management of the species in the area.

scholarly journals SEDIMENT TRAPPING BY TERRACED PADDY FIELD ON SLOPPING AGRICULTURAL LAND

2013 ◽  
Vol 11 (2) ◽  
pp. 57 ◽  
Author(s):  
Sukristiyonubowo Sukristiyonubowo ◽  
D. Gabriels ◽  
M. Verlooc
Keyword(s):  
Paddy Field ◽  
Agricultural Land ◽  
Dry Season ◽  
Movement Behavior ◽  
Wet Season ◽  
Sediment Trapping ◽  
Before And After ◽  
Dry Seasons ◽  
Terraced Paddy Field ◽  
Wet And Dry Seasons

Terraced paddy field is not only important for rural food security, but also for trapping sediment in the slopping land. The aims of this research were to quantify the amount of incoming and outgoing sediments and to study sediment movement behavior during harrowing and fertilizing under traditional irrigation of terraced paddy field system. This study was carried out at Keji Village, Semarang District, Central Java during two cropping seasons, a wet season 2003/04 and a dry season 2004. A paddy field with eight terraces was selected. The terraces were flat, different in size and descending to the river. Sediment samples were taken at harrowing and fertilizing activities. The results indicated that at harrowing, outgoing sediment was higher than incoming both during the wet and the dry seasons. About 0.53 and 0.27 t ha-1 day-1 of soil were eroded during harrowing in the wet and the dry seasons, respectively. However, a week before and after fertilizing, both in the wet and the dry seasons, the amounts of incoming sediment were higher than the outgoing one. In the wet season, the amounts of incoming sediments were three to four times higher than the outgoing one, both a week before and after fertilizing. During the wet season, about 0.31 and 0.34 t ha-1 day-1 of sediment was yielded a week before and after fertilizing, respectively. During the dry season, the incoming sediments were ten times higher than the outgoing one. On an average the sediment yields were about 0.07 and 0.08 t ha-1 day-1 a week before and after fertilizing, respectively. Terraces having greater areas deposited more sediment than those with smaller sizes. During a week before and after first fertilizing, the total amounts of incoming sediments were 6.44 and 1.19 t ha-1 for the wet and dry seasons, while that of outgoing sediments were 1.89 and 0.14 t ha-1 for the wet and dry seasons, respectively. This indicates that terraced paddy fields are not only producing rice, but also providing environmental service in term of sediment trapping. This external service minimizes sedimentation in the downstream.<p> </p>

scholarly journals Long-Term historical and Projected Herbivore Population Dynamics in Ngorongoro Crater, Tanzania

2019 ◽  
Author(s):  
Joseph O. Ogutu ◽  
Patricia D Moehlman ◽  
Hans-Peter Piepho ◽  
Victor A Runyoro ◽  
Michael B Coughenour ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Population Size ◽  
Dry Season ◽  
Climate Change Scenarios ◽  
Wet Season ◽  
Large Herbivore ◽  
Herbivore Species ◽  
Dry Seasons ◽  
Wet And Dry Seasons

The Ngorongoro Crater is an intact caldera with an area of approximately 310 km2. Long term records on herbivore populations, vegetation and rainfall made it possible to analyze historic and project future herbivore population dynamics. In 1974 there was a perturbation in that resident Maasai and their livestock were removed from the Crater. Vegetation structure changed in 1967 from predominately short grassland to mid and tall grasses dominating in 1995. Even with a change in grassland structure, total herbivore biomass remained relatively stable from 1963 to 2012, implying that the crater has a stable multi-herbivore community. However, in 1974, Maasai pastoralists were removed from the Ngorongoro Crater and there were significant changes in population trends for some herbivore species. Buffalo, elephant and ostrich numbers increased significantly during 1974-2012. The zebra population was stable from 1963 to 2012 whereas numbers of other eight species declined substantially between 1974 and 2012 relative to their peak numbers during 1974-1976. Numbers of Grant’s and Thomson’s gazelles, eland, kongoni, waterbuck (wet season only) declined significantly in the Crater in both seasons after 1974. Wildebeest numbers decreased in the Crater between 1974 and 2012 but this decrease was not statistically significant. In addition, some herbivore species were consistently more abundant inside the Crater during the wet than the dry season. This pattern was most evident for the large herbivore species requiring bulk forage, comprising buffalo, eland, and elephant. Analyses of rainfall indicated that there was a persistent annual cycle of 4.83 years. Herbivore population size was correlated with rainfall in both the wet and dry seasons. The relationships established between the time series of historic animal counts in the wet and dry seasons and lagged wet and dry season rainfall series were used to forecast the likely future trajectories of the wet and dry season population size for each species under three alternative climate change scenarios.

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