scholarly journals The effects of rainfall and arthropod abundance on breeding season of insectivorous birds, in a semi-arid neotropical environment

2020 ◽  
Vol 37 ◽  
pp. 1-7
Author(s):  
Leonardo Fernandes França ◽  
Victória Helen Figueiredo-Paixão ◽  
Thales Afonso Duarte-Silva ◽  
Kamila Barbosa dos Santos
Keyword(s):  
Temporal Distribution ◽  
Time Lags ◽  
Insectivorous Birds ◽  
Seasonally Dry ◽  
Insectivorous Bird ◽  
Reproductive Response ◽  
Daily Precipitation Data ◽  
Set Up ◽  
Semi Arid ◽  
Arthropod Abundance

Rainfall in tropical semi-arid areas may act as a reliable cue for timing bird reproduction, since it precedes future food supply. With this in mind, we set-up a study to test the reproductive response of insectivorous bird to arthropod abundance and rainfall patterns. Sampling occurred in a seasonally dry Neotropical forest, in north-eastern Brazil, between October, 2015 and October 2016, at 14-day intervals. We used brood patch to assess reproductive periodicity of insectivorous birds (eight species, 475 captures, 121 patch records). We sampled arthropods to quantify abundance, using biomass and number of individuals (1755 individuals, 15 Orders). Rainfall temporal distribution was analyzed using daily precipitation data. We used a cross-correlation function to test for correlation and time-lags between the covariates under study. Both the number of reproductively-active birds and arthropod abundance were higher in time periods close to the rainy season. Increase in arthropod biomass in the aerial stratum preceded the period of greatest rainfall by one (14 days, r = 0.44) to three sampling periods (0.47). In contrast, the highest proportion of individuals with brood patches occurred after the main rainfall peak, with the strongest relationship occurring after two (0.52) to four (0.50) time lags. Finally, the proportion of individuals with brood patches was positively correlated with aerial stratum arthropod biomass when five time lags were considered (0.55). Our results support the hypothesis of a temporal process involving rainfall, arthropods and reproduction of insectivorous birds in the wet/dry tropics. However, rainfall did not appear to act as a cue for the timing of reproduction, since records indicated higher arthropod biomass before the main rainfall peak. At least occasionally in the study area, insectivorous bird reproduction peaks after food abundance.

Agriculture expansion and deforestation in seasonally dry forests of north-west Argentina

2005 ◽  
Vol 32 (2) ◽  
pp. 140-148 ◽  
Author(s):  
H. RICARDO GRAU ◽  
N. IGNACIO GASPARRI ◽  
T. MITCHELL AIDE
Keyword(s):  
Global Trends ◽  
North West ◽  
Conservation Policies ◽  
Seasonally Dry ◽  
The North ◽  
Agriculture Expansion ◽  
Soybean Price ◽  
Different Levels ◽  
Semi Arid ◽  
Arid Chaco

In Argentina, deforestation due to agriculture expansion is threatening the Semi-arid Chaco, one of the largest forested biomes of South America. This study focuses on the north-west boundary of the Argentine Semi-arid Chaco, where soybean is the most important crop. Deforestation was estimated for areas with different levels of soil and rainfall limitation for agriculture between 1972 and 2001, with a finer analysis in three periods starting in 1984, which are characterized by differences in rainfall, soybean price, production cost, technology-driven yield and national gross domestic product. Between 1972 and 2001, 588 900 ha (c. 20% of the forests) were deforested. Deforestation has been accelerating, reaching >28 000 ha yr−1 after 1997. The initial deforestation was associated with black bean cultivation following an increase in rainfall during the 1970s. In the 1980s, high soybean prices stimulated further deforestation. Finally, the introduction of soybean transgenic cultivars in 1997 reduced plantation costs and stimulated a further increase in deforestation. The domestic economy had little association with deforestation. Although deforestation was more intense in the moister (rainfall >600 mm yr−1) areas, more than 300 000 ha have already been deforested in the drier areas, suggesting that climatic limitations are being overcome by technological and genetic improvement. Furthermore, more than 300 000 ha of forest occur in sectors without major soil and rainfall limitations. If global trends of technology, soybean markets and climate continue, and no active conservation policies are applied, vast areas of the Chaco will be deforested in the coming decades.

scholarly journals Distribution and density of the mollusk Donax striatus (Linnaeus, 1767) in a tropical estuarine region in the brazilian semi-arid

2015 ◽  
Vol 75 (4) ◽  
pp. 914-922 ◽  
Author(s):  
E. L. Medeiros ◽  
G. V. Fernandes ◽  
G. G. Henry-Silva
Keyword(s):  
Intertidal Zone ◽  
Significant Positive Correlation ◽  
River Estuary ◽  
Temporal Distribution ◽  
Average Density ◽  
Spatial And Temporal Distribution ◽  
Tropical Estuarine ◽  
Sampling Points ◽  
Estuarine Region ◽  
Semi Arid

Abstract This study evaluated the spatial and temporal distribution and density of the bivalve Donax striatus, at beaches close to the Apodi/Mossoró River estuary, through, six semiannual sampling campaigns were performed between April/2009 and October/2011. The sampled area was delimited by 20 transects that were laid perpendicular to the beach line and extended over 300 m in the intertidal zone. Seven sampling points were established in each transect, organisms and sediment were collected, and water temperature and salinity were recorded. The highest D. striatus average density (103 individuals.m–2) was observed in April/2009 and the lowest (18 individuals.m–2) in October/2010. The highest D. striatus densities occurred in beaches further from the estuarine region as demonstrated by a significant positive correlation (r2 = 0.67 and p = 0.0007). The D. striatus densities presented significant negative correlations with the percentages of organic matter in the water. This species demonstrated an aggregated distribution in the studied area.

Terrestrial arthropod abundance and phenology in the Canadian Arctic: modelling resource availability for Arctic-nesting insectivorous birds

2013 ◽  
Vol 145 (2) ◽  
pp. 155-170 ◽  
Author(s):  
Elise Bolduc ◽  
Nicolas Casajus ◽  
Pierre Legagneux ◽  
Laura McKinnon ◽  
H. Grant Gilchrist ◽  
...  
Keyword(s):  
Seasonal Changes ◽  
Canadian Arctic ◽  
Insectivorous Birds ◽  
Weather Variables ◽  
Degree Day ◽  
Terrestrial Arthropods ◽  
Bird Breeding ◽  
Using Data ◽  
The Relationship ◽  
Arthropod Abundance

AbstractArctic arthropods are essential prey for many vertebrates, including birds, but arthropod populations and phenology are susceptible to climate change. The objective of this research was to model the relationship between seasonal changes in arthropod abundance and weather variables using data from a collaborative pan-Canadian (Southampton, Herschel, Bylot, and Ellesmere Islands) study on terrestrial arthropods. Arthropods were captured with passive traps that provided a combined measure of abundance and activity (a proxy for arthropod availability to foraging birds). We found that 70% of the deviance in daily arthropod availability was explained by three temperature covariates: mean daily temperature, thaw degree-day, and thaw degree-day2. Models had an adjusted R2 of 0.29–0.95 with an average among sites and arthropod families of 0.67. This indicates a moderate to strong fit to the raw data. The models for arthropod families with synchronous emergence, such as Tipulidae (Diptera), had a better fit (average adjusted R2 of 0.80) than less synchronous taxa, such as Araneae (R2 = 0.60). Arthropod abundance was typically higher in wet than in mesic habitats. Our models will serve as tools for researchers who want to correlate insectivorous bird breeding data to arthropod availability in the Canadian Arctic.

Carbon cycle response to Dansgaard-Oeschger events in a freely oscillating LGM setup of the Community Earth System Model.

2021 ◽  
Author(s):  
Markus Jochum ◽  
Zanna Chase ◽  
Roman Nutermn ◽  
Joel Pedro ◽  
Sune Rasmussen ◽  
...  
Keyword(s):  
North Atlantic ◽  
Deep Convection ◽  
Time Lags ◽  
Biological Productivity ◽  
The North ◽  
Community Earth System Model ◽  
Free Running ◽  
The North Atlantic ◽  
Set Up ◽  
The North Pacific

<p>We use a LGM setup of the CESM with marine and terrestrial biogeochemistry. This free-running  set-up (i.e., no freshwater hosing) exhibts Dansgaard-Oeschger events and Antarctic Isotope Maxima with time-lags and amplitudes that are consistent with paleo reconstructions. The CO2 signal associated DO events is also consistent with reconstructions: a 10 ppm/kyr increase during stadials, with the increase continuing some 400 years after Antarctica has started to cool again. An analysis of the modelled air-sea/land carbon fluxes reveals that some 3ppm of the stadial increase are due to shifting rain and temperature patterns that reduce growth of land vegetation. This adjustment is largely concluded after 3 centuries. The remainder of the signal is due to reduced ocean uptake. It turns out that reduced subduction of carbon in the Southern Ocean is mostly compensated by reduced upwelling in the equatorial oceans. Thus, as found in previous studies, much of the extra carbon is due to reduced uptake in the North Atlantic, partly directly due to reduced deep convection, and partly due to a reduced biological productivity because much of the North Atlantic nutrients are supplied by the AMOC. A big surprise is the emergence of the North Pacific as a major contributor to the changes in the air-fluxes of carbon. It is the reorganization of its wind-driven circulation that explains why global net-outgassing of carbon continues long after the interstadial has begun.</p>

Seasonal water use patterns of semi-arid plants in China

2013 ◽  
Vol 89 (02) ◽  
pp. 169-177 ◽  
Author(s):  
Guodong Jia ◽  
Xinxiao Yu ◽  
Wenping Deng
Keyword(s):  
Water Use ◽  
Seasonal Changes ◽  
Water Sources ◽  
Plant Water ◽  
Seasonally Dry ◽  
Use Patterns ◽  
Different Seasons ◽  
Water Use Patterns ◽  
Plant Water Sources ◽  
Semi Arid

Water sources of woody plants in semi-arid or seasonally dry areas of China are little known. This study investigated the differences in water sources for plants due to seasonal changes (wet/transitional and dry seasons) in semi-arid areas. Stable isotope techniques were applied to determine plant water sources in different seasons. The results show that there is generally a switch of water sources from shallow depths in the rainy season to lower depths in the dry season. This study highlights how seasonal changes in climate in semi-arid China affect plant water uptake and suggests that further study with replicated systematic experiments are needed to better understand the responses in water use patterns to changes in environmental conditions in drought-prone areas.

The influence of mistletoes on the litter-layer arthropod abundance and diversity in a semi-arid savanna, Southwest Zimbabwe

2014 ◽  
Vol 383 (1-2) ◽  
pp. 291-299 ◽  
Author(s):  
Hilton G. T. Ndagurwa ◽  
John S. Dube ◽  
Donald Mlambo ◽  
Mukai Mawanza
Keyword(s):  
Litter Layer ◽  
Abundance And Diversity ◽  
Semi Arid ◽  
Arthropod Abundance

scholarly journals Potential for nutrient contribution from litter in a seasonally dry forest

2017 ◽  
Vol 11 (4) ◽  
pp. 269 ◽  
Author(s):  
José Fredson Bezerra Lopes ◽  
Eunice Maia Andrade ◽  
Lindbergue Araújo Crisóstomo ◽  
Meilla Marielle Araújo Rodrigues
Keyword(s):  
Nutrient Dynamics ◽  
Tropical Dry Forest ◽  
Essential Elements ◽  
Dry Forest ◽  
Seasonally Dry ◽  
Time Variations ◽  
The Mean ◽  
Semi Arid Region ◽  
Seasonally Dry Forest ◽  
Semi Arid

Litter is the most important way of transferring essential elements from vegetation to the soil. This is due to nutrient cycling, a process by which decomposition of the litter adds nutrients to the soil. An understanding of this process goes beyond the need for knowledge of nutrient dynamics, since it is a question of understanding the way in which ecosystems function in the search for a correct use of natural resources. The aim of this study was to quantify the average concentrations of the following nutrients: Nitrogen (N), phosphorus (P), Potassium (K), and Organic Carbon (C) in litter remaining in an area of tropical dry forest - Caatinga. The work was carried out on the Elias Andrade Private Natural Heritage Reserve (PNHR) of the Irmãos Andrade Farm, located in the semi-arid region of the State of Ceará. In February 2009, 48 nylon litter bags were randomly distributed, each containing 30 g of litter collected in the area of the Reserve. Every two months, from February 2009 to January 2011, four bags were randomly collected. Over time, variations were seen in the average levels of N, P and K for the litter in the nylon bags. The nutrient with the greatest contribution to the system from the litter was Nitrogen, followed by K and P. The highest N content occurred at the beginning of the experiment. The C content decreased over the study period. The mean C to N ratio of the litter was 21, which was in the borderline range between the processes of mineralisation and immobilisation.

scholarly journals Anticipated or delayed responses to rainfall: Effects of rainfall on arthropods assemblage in an enclave of evergreen forest

2020 ◽  
Vol 9 (12) ◽  
pp. e47291210923
Author(s):  
Raul Azevedo ◽  
Raimundo Nonato Costa Ferreira ◽  
Francisco Roberto de Azevedo ◽  
Larissa da Silva Nascimento ◽  
João Roberto Pereira dos Santos ◽  
...  
Keyword(s):  
Species Richness ◽  
Evergreen Forest ◽  
Annual Rainfall ◽  
Delayed Response ◽  
Soil Arthropods ◽  
Seasonally Dry ◽  
Caatinga Vegetation ◽  
Fauna Composition ◽  
Predator Abundance ◽  
Arthropod Abundance

In northeast Brazil, the most part of vegetation is a deciduous seasonally dry tropical forest called of “Caatinga”. Despite the semi-arid areas correspond to most of the caatinga vegetation, there are some areas 500 m above sea level with an annual rainfall up to 1200 mm forming evergreen forest enclaves. Macroarthropod abundance and fauna composition differences in Caatinga are related to seasonal rainfall effects but, this difference is unclear in the enclaves of evergreen forests. Thus, the aim of this study was to measure the effects of rainfall on insect, arachnid, and centipede assemblages in an enclave of evergreen forest within the Caatinga vegetation. We tested the following hypotheses: 1) rainfall changes arthropod abundance and species richness; 2) predator abundance correlate with prey, and 3) abundance arthropod abundance and species richness exhibit a delayed or anticipated response to rainfall. No effects of rainfall on insects and arachnids abudance were observed. There was a significant correlation between prey and predator abundance with changes in dominant species between the rainy and dry seasons. The insects and arachnids can show some anticipated responses to rainfall. The abundance and richness of centipedes were influenced by rainfall whith a delayed response. Our findings indicate that, in evergreen forest enclaves within Caatinga vegetation, the soil arthropods show different responses compared to rainfall than the most common areas of the Caatinga domain and an increase in the detection of insects and arachnids just before the beginning of the rainy season.

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