High Levels Of Precipitation Research Articles

Edaphic entomofauna associated with coconut crops in the eastern Amazon

In the Eastern Amazon is the largest continuous coconut crop area in the world. This region is known for its high precipitation levels and an ecosystem of extensive insect biodiversity. It is important to know the local entomofauna and to know whether there is a balance between the different insect groups. This study aimed to understand the influence of seasonality on the dynamics of edaphic insect families, comparing the environment as a whole and in different commercial coconut crop areas and riparian forests in the Eastern Amazon. Forty pitfall traps were installed in the ground at an average distance of 1 m from the coconut stipe. They were filled with 200 ml of an aqueous solution of liquid neutral soap and 70% alcohol. Traps were installed in eight areas: an area of riparian forest (A1) and seven in commercial coconut crop areas (A2 to A8), in the Amazon dry and rainy season. The similarity between the insects was measured using Euclidean distance. The abundance of families in each collection area used qualitative similarity. For family dominance, quantitative similarity was used. Diversity analyses were performed to justify the similarities of the clusters through the Shannon and Simpson Indices. In total, 252,313 individuals, 118 families, and 9 orders were collected. There were many Formicidae in both climatic periods because it is a social insect and has edaphic habits. The families with the most individuals in the collections were Drosophilidae, Staphylinidae, Bostrichidae, Phoridae, Nitidulidae, Scolytidae, Tenebrionidae, Scarabaeidae, Ceratopogomidae, and Platyogastridae. The riparian forest area (A1) showed the greatest diversity and least dominance. The oldest cultivated areas A2 and A3 (7 years) showed the greatest diversity in the dry season. In the rainy season, the most diversified areas were those with the highest land slope (A6 and A7). The most dominant areas were A5 and A8, where the largest number of Solenopsis spp. were found. This study showed the importance of obtaining basic information about coconut entomofauna and conducting research on insect dynamics in agricultural crops in the Amazon region.

The Driving Forces Underlying Spatiotemporal Lake Extent Changes in the Inner Tibetan Plateau During the Holocene

The Inner Tibetan Plateau (ITP), the central and western part of the Tibetan Plateau (TP), covers about one-fourth of the entire TP and contains more than 800 endorheic lakes larger than 1 km2. These lakes are important water reservoirs and sensitive to TP climate changes. They regulate regional water circulations, and further influence local ecosystems. Many lakes in ITP are surrounded by conspicuous paleoshorelines indicating much higher past lake levels. Previous studies found that lakes in the western ITP (west of ∼86°E) apparently expanded to higher levels than those to the east during the Holocene high lake level stage, however, there is no in-depth study on the reasons for the spatial differences of high lake levels within the ITP. In this study, we first identify Holocene lake level (or lake extent) changes over the ITP by combining published lake level variation data with our reconstruction of Dagze Co lake level variations. We then investigate spatial differences in the magnitude of lake expansions and explore the underlying forces driving these differences using the transient climate evolution of the last 21 ka (TraCE-21ka) and Kiel Climate Model (KCM) simulation results. We find that lakes in the ITP expanded to their highest levels during the early Holocene when the Indian summer monsoon (ISM) greatly intensified. After the mid-Holocene, lake levels fell as a result of the weakening of the ISM. The early Holocene northward shift of the westerly jet and a positive phase of the Atlantic multidecadal oscillation (AMO) resulted in the intensification of southwesterly winds on the southwest TP flank. Concurrently, westerly winds over the TP weakened, causing a differential increase in water vapor transport to the ITP with higher precipitation levels in the southwestern ITP and lower levels to the northeast. These wind-driven differential precipitation levels caused lakes in the southwestern ITP to expand to higher levels than those in the central, northern and northeastern ITP. During the early Holocene, expansion of lakes in the northwestern ITP was enhanced by an increase in glacier melt water besides the increased summer rainfall associated with the intensified ISM.

Analysis of the Fickle Fires in Global Regions

Forest fires occur in a wide range with distinctive fire elements, including fire size, expansion, speed and duration. To investigate when and where fire occurs in recent years and how the four factors differ in various regions, we here to analyse the chronological and terrestrial distribution of these fires, seeing the tendency to change four main fire elements. We focus on fourteen regions, including BONA (Boreal North America), TENA (Temperate North America), CEAM (Central America), NHSA (Northern Hemisphere South America), SHSA (Southern Hemisphere South America), EURO (Europe), MIDE (Middle East), NHAF (Northern Hemisphere Africa), SHAF (Southern Hemisphere Africa), CEAS (Central Asia), SEAS (Southeast Asia), EQAS (Equatorial Asia), AUST (Australia and New Zealand), BOAS (Boreal Asia. We finally conclude that the high level of precipitation, decrease in vegetation coverage and human intervention account for the decreasing fires in NHAF, SHAF, CEAS, NHSA. We also confirm that the increasing fires in BONA, TENA and MIDE are because of the rising temperature globally or more specifically, in these areas.

Assessment of current climate conditions changes in the territory of Ciscaucasia for the purposes of forecasting winter wheat yield

Аim. Assessment of current climate changes in the territory of Ciscaucasia in order to predict the yield of winter wheat.Methods .Integral indicators of climatic conditions for agricultural production were employed. For the investigations, we selected five‐year periods for which the meteorological parameters were averaged, and to identify trends the data of specific five‐year periods were compared with the average value for the entireseries of observations (1960‐2020).Results. The deviation of precipitation in April was highest in 2011‐2015, when it increased by 22 mm, and in 1986‐1990 and 1991‐1995, when it decreased by 15 and 10 mm respectively. In Eastern Ciscaucasia,where conditions are more arid than in the Western and Central regions, in both the rise in air temperature and the amount of precipitation, especially in April and May, increased in the 21stcentury for the entire period of active vegetation.Conclusion.It was established that the value of the hydrothermal coefficient practically did not change during the 1960‐2020 period. In the late 1990s and early 2000s, there was an increase in productivity against the background of a relatively high level of annual precipitation and this stability is confirmed at the present time. There is a very close relationship between natural and climatic factors and the level of winter wheat yield.

Effects of egg mass and local climate on morphology of East Pacific leatherback turtle Dermochelys coriacea hatchlings in Costa Rica

Global climate patterns are shifting due to anthropogenic causes, putting pressure on many species that are unable to adapt to such rapid changes. Sea turtle clutches, for example, normally develop between 26 and 33°C, but tolerate higher temperatures at the end of development. High temperatures, protracted rainfall, and droughts have been linked to fewer hatchlings. Likewise, climatic conditions can affect the size of sea turtle hatchlings, which could affect their probability of survival. We analyzed the effects of a biotic factor (egg mass) and environmental factors (precipitation and incubation temperature) on East Pacific leatherback turtle Dermochelys coriacea hatchling sizes in Costa Rica. Hatchling size (mass, straight carapace length, straight carapace width, and head width) was affected by both biotic and environmental factors. While egg mass was the strongest predictor for hatchling mass, temperature was the strongest for carapace length and head width. Carapace width was most strongly predicted by precipitation. Hatchling carapace length and width decreased with increases in temperature and increased with higher levels of precipitation. Hatchling mass also decreased with increasing temperature, although the relationship was not statistically significant. Head width decreased with greater precipitation during development. These findings suggest that increases in temperature and decreases in precipitation may not only decrease the number of hatchlings produced, but may also produce smaller leatherback hatchlings in Pacific Costa Rica, which may impair hatchling survival in the first hours after emergence.

Silphium perfoliatum—A Herbaceous Crop with Increased Interest in Recent Years for Multi-Purpose Use

Silphium perfoliatum is a perennial crop native to North America that has been the subject of increased scientific interest in recent years, especially in Europe. It is drought- and frost-resistant, which makes it suitable for cultivation in Europe on marginal lands that are not used for growing other crops. This review analyzed the distribution and purposes of the cultivation of Silphium perfoliatum worldwide, as well as its biomass yields and characteristics as a feedstock for biogas production and other purposes. A total of 121 scientific publications on Silphium perfoliatum were identified, with the highest number (20 papers) published in 2019. It was found that higher biomass yields can be obtained at higher precipitation levels, with the use of fertilizers and an adequate type of plantation. The mean dry matter yield of Silphium perfoliatum was 13.3 Mg ha−1 DM (dry matter), and it ranged from 2 to over 32 Mg ha−1 DM. In some countries, Silphium is used as a forage crop mainly due to its high crude protein content (from 4.9% to 15% DM), depending on the vegetation phase. Silphium perfoliatum is a promising perennial crop in terms of energy and other benefits for biodiversity, soil quality and applications in medicine and pharmacology.

Childhood visceral leishmaniasis in Tunisia: A cross-sectional study in local spatial analysis

This paper describes spatial distribution of Visceral Leishmaniasis (VL) and determines its correlation with climatic factors in an endemic focus in northern and central Tunisia. Data on VL cases in children under five years of age were obtained by consulting medical reports from all Tunisian Pediatric Departments (TPD) during 2006–2016. Three key climatic factors, namely precipitation, continentality index and pluviometric coefficient of Emberger were used as predictor variables to model the VL geographical distribution. Data handling and statistical analysis were performed using R and Arcview GIS software systems. Bayesian local spatial model was employed to analyse the data. The results show a progressive increase in the VL incidence rates in regions with high levels of precipitation, but with low values of both continentality index and pluviometric coefficient of Emberger. A likely explanation of these findings arises from the opposite local effects of climatic factors which tend to cancel each other out in the calculation of the mean parameter estimate over the whole study area. We conclude that using non-local spatial analysis approach leads to misleading epidemiological interpretations, which in turn are of relevance for more efficient and cost-effective resource allocation for control and well manage the spread of VL in the study region and elsewhere in Tunisia.

Demand Side Management System Characterization for Residential Users in Manizales City

This paper presents the characterization of Demand Side Management System with three constitutive subsystems: i) graphic operation and control interface, ii) communications network through narrow-band power lines (NB-PLC) according to G3-PLC standard, and iii) an array of six photovoltaic solar panels. The LabView graphical interface simulates the system operator and contains the management system control program. The photovoltaic solar generation system was implemented in Manizales city, allowing energy contribution analysis of photovoltaic array with centralized inverter or with microinverters over an 11 months period. Communications system quality tests are presented reaching a Data Transfer Rate of 0.2702 KB/s for a 20.44 meters distance between nodes. Additionally, it is observed that, despite the high levels of precipitation and cloudiness of Manizales city, photovoltaic array with microinverters got a 16.5% gain of generated energy over the energy generated by photovoltaic array with centralized inverter.

Investigations on yellowing of chestnut crowns in Trentino (Alps, Northern Italy)

Yellowing of part or the whole canopy of chestnut trees was observed during the summer of 2014 in the areas of Tenno, Pranzo and Drena in Trentino, where chestnut cultivation is traditional on the lateral moraine deposit in a context of a prevalent limestone lithological substrate. Symptoms were observed on chestnut trees of different ages, either grafted or not, scattered or in stripes along the maximum slope. Investigations were carried out in the form of field surveys, chemical and molecular analyses of soil and leaves and greenhouse trials, to assess the damage evolution and its causes. No known pathogens emerged during the field surveys, and laboratory tests excluded the presence of phytoplasma infections. A comparison of yellow and asymptomatic leaves evidenced significant deficiencies of manganese (Mn) and iron (Fe) in the yellow leaves, though the level of the two nutrients was the same in the soil below green and yellowed trees. Experimental run-off trials in the greenhouse reproduced the foliage damage with a continuous basic water regime; open-field fertilizations with Mn and Fe led to a slightly recovery on the part of some treated leaves, thus confirming the hypothesis of a probable, sudden deficiency of the mentioned microelements. A possible explanation of this phenomenon could be, on one side, the high precipitation level of 2014, and, on the other side, the previous outbreaks of the Asian chestnut gall wasp, that had reduced foliage volume and thus the organic substance in the soil. The natural recovery from symptoms was clearly visible in trees after four years in a context of normal rainfall regime and increasing organic acid in the soil, after effective biological control of wasp. Even if related to a particular and rare geological condition, this is the first description of Mn deficiency in Castanea sativa.

Fatores associados a casos de Dengue na área industrial brasileira: um estudo ecológico

Introdução: A dengue é uma doença infecciosa viral sistêmica aguda, estabelecida mundialmente em ciclos de transmissão epidêmica e endêmica. Altos níveis de precipitação, temperaturas adequadas, proximidade entre centros urbanos e peri-urbanos, movimento humano entre centros populacionais e produção de resíduos sólidos urbanos (RSU) podem facilitar a transmissão e a disseminação da dengue.
 Objetivo: Identificar a relação entre casos diagnosticados de dengue e fatores socioeconômicos, geração de massa de RSU e índice pluviométrico.
 
 Método: Estudo ecológico, com coleta secundária de dados de 2010 a 2016 para cada município da Região do Grande do ABC, em São Paulo, Brasil. Foram investigados a população total, o produto interno bruto (PIB) per capita, RSU, número de casos de dengue e índice pluviométrico. Os dados foram coletados nos sites do Instituto Brasileiro de Geografia e Estatística (IBGE), os municípios da Região do Grande ABC, o Consórcio Intermunicipal do Grande ABC, a Agência de Desenvolvimento Econômico do Grande ABC, o Sistema Nacional de Informação sobre Saneamento, Centro de Vigilância Epidemiológica do Estado de São Paulo e o Departamento de Água e Energia Elétrica do Estado de São Paulo. As relações entre variáveis foram testadas pela correlação de Spearman.
 
 Resultados: A análise dos dados de todos os municípios mostrou correlação positiva entre casos de dengue com população total (r = 0,675, p <0,01), produto interno bruto per capita (r = 0,539, p <0,01) e RSU por habitante por ano (r = 0,492, p <0,01). Também foram observadas correlações positivas entre população total e produto interno bruto per capita (r = 0,583, p <0,01), RSU / dia (r = 0,302, p <0,05) e RSU / ano (r = 0,961, p <0,01); produto interno bruto per capita e RSU / dia (r = 0,849, p <0,01), RSU / ano (r = 0,410, p <0,05) e índice de precipitação (IR) (r = 0,416, p <0,05); RSU / dia e RSU /ano (r = 0,389, p <0,01) e IR (r = 0,388, p <0,05).
 Conclusão: Quanto maior a população total, poder de compra ou condição socioeconômica (PIB per capita) e a geração de RSU, maior o número de casos de dengue. O descarte adequada dos RSU parece ser uma maneira de ajudar no controle dos casos de dengue.

Avaliação de Macroinvertebrados Bentônicos em Viveiros Escavados em Londrina-PR.

Biomonitoring with the use of benthic macroinvertebrates has been an effective tool used to evaluate water quality in several water bodies. In this context, there are several factors that can act on the structure of macroinvertebrate commuinities, with indications of the influence of aquaculture. Therefore, the present study evaluated the composition of macroinvertebrate populations in two earthen ponds of a fish farm in Londrina-PR. Three collections were carried out: in October of 2015 and February and July of 2016, with the use of artificial biocolectors. The macroinvertebrates were quantified and identified, and diversity indexes were calculated with the data obtained. Higher number of taxa, higher number of individuals and greater diversity and uniformity in macroinvertebrate communities were found in pond 1 (water entrance), due mainly to the presence of taxa tolerant or resistant to organic pollution, which may be related to the higher concentration of nutrients and organic matter in this pond. However, in pond 2 (water outlet), individuals of Polycentropodidae (Trichoptera) were found in all collections, in addition to a low abundance of taxa that would indicate organic enrichment, demonstrating better water quality. Furthermore, greater abundance and diversity were observed in the months with higher level of precipitation. From the perspective of aquaculture, the results found in pond 1 can be used as indicative of greater productive potential, however, the low frequency of taxa typical of clean environments may indicate low oxygen levels.These results demonstrate that the position of the pond relative to the water source in a fish farm can influence the water quality, which can be verified through the structure of the benthic macroinvertebrates communities.

Crop Productivity and Climatic Conditions: Evidence from Hungary

Hungarian agriculture is expected to experience greater risks due to more variability in crop productivity due to increasing yearly average temperatures and extreme precipitation patterns. This study investigates the effect of changing climatic conditions on productivity, using a Hungarian sample of crop producers for a 12-year time period. Our empirical analysis employs True Fixed Effects frontier models of Farm Accountancy Data Network data that are merged with specific meteorological data representatively maintained for seeding, vegetative, and generative periods for cereals, oil seed and protein crops, along with soil quality and usage-related data. Estimations indicate that climate variables have significant impacts on technical efficiency. In addition, calculation suggest that an increase in temperature during seeding and vegetative periods, combined with higher precipitation levels in May and June, will reduce crop farmers’ production frontier. Estimations explain the variance, while the technical efficiency (TE) scores emphasize the impact of the difference in soil quality and its water absorption capacity.

Avaliação de pontos de alagamento no Setor Profissional da Cidade Universitária Professor José da Silveira Netto

Estudos sobre poluição hídrica e inundações urbanas são cada vez mais frequentes, já que podem estar relacionados com a expansão e o crescimento populacional urbano das grandes cidades ou com as mudanças climáticas que podem estar proporcionando o aumento do nível do mar e, consequentemente, a intensificação do potencial de inundações em áreas de regiões litorâneas, principalmente aquelas que estejam localizadas abaixo do nível do mar. Assim, essas questões precisam cada vez mais serem estudadas para uma gestão sustentável das bacias urbanas. A pesquisa tem como objetivo avaliar pontos de alagamento do Setor Profissional da Cidade Universitária Professor José da Silveira Netto. Para isto, foi inicialmente levantado o Modelo Digital de Terreno-MDT da área de estudo e em seguida foram avaliadas algumas cotas altimétricas que sofrem influência direta das maiores marés de preamar. Os dados de maré foram extraídos do Centro de Previsão de Tempo e Estudos Climáticos do Instituto Nacional de Pesquisas Espaciais-CPTEC/INPE (2020), na cidade de Belém-PA. Foram então correlacionadas a altura máxima de preamar, a precipitação e as cotas altimétricas, e verificou-se que em algumas áreas do Setor Profissional com cotas altimétricas inferiores ao nível de elevação máxima da maré, independentes de precipitação, ocorrem alagamentos e que estes se intensificam quando coincidem a maré máxima de preamar e a precipitação. Os alagamentos geralmente ocorrem com maior intensidade no primeiro trimestre do ano, que coincide com a maior precipitação e as maiores alturas de maré. Algumas ações devem ser tomadas pela prefeitura do Campus de modo a minimizar os impactos desses alagamentos.

Flowering and fruiting phenology of Acer laurinum (Sapindaceae) at ex-situ conservation site

Acer laurinum (Sapindaceae) is a threatened tree plant species with least concern (LC) status. There is only limited information regarding the phenology of flowering and fruiting of this species. Along with the increasing damage to its natural habitat, not surprisingly, in the future, this status will be more threatened. Therefore, it is necessary to study the phenology cycle of this species for the purposes of further development. In order to achieve a continuous and sequenced observation, the study was conducted in a built environment, one of an ex-situ plant conservation site. Furthermore, the study also conducted to analyze the effect of the microclimate on this cycle. The study conducted with A. laurinum tree specimen planted in 1986 at Cibodas Botanic Gardens, Cianjur, West Java. The study used descriptive quantitative analysis based on the exploratory-inventory observation of flowering and fruiting phase data, and the microclimate conditions assessed from 2014 to 2015. The results showed that the flowering and fruiting occurred from early January to April, and at the end of the year, from September to December, along with the high level of precipitation of the periods. Even the other microclimate units also dynamically changed, but there were no significantly affected the flowering and fruiting phenology. The results suggested that these periods can be conducted seeds harvesting and (re)stock in order to achieve maximum results.

Differences in soil water content and movement drivers of runoff under climate variations in a high-altitude catchment

The interconnected soil water content and movement processes are ill constrained for changing climates, making estimates of surface runoff relatively unpredictable. Particularly for high-altitude areas, which are characterized by vertical climate variance, changing climatic conditions raise many challenges to runoff estimates and ecosystem management. To address these challenges, soil property investigation, hydrological modelling, and multivariate statistical analysis were integrated to quantify the driving forces of surface runoff in three typical sub-basins (headwater, highland, and subtropical valley) in the Tibetan Plateau under climate variations. The results showed that soil water processes in the subtropical areas with high precipitation levels and in the headwaters with deep freeze-thaw processes were very sensitive to climate variations. For the headwater sub-basin, the soil water content was the highest (≤90 mm), but the percolation and lateral flow were the lowest (≥14.3 mm and ≥173.9 mm, respectively) among the sub-basins. During the period 1972–2017, the annual surface runoff of the sub-basins decreased as follows: headwater > highland > subtropical valley, which corresponded to the increase in precipitation and temperature during this time period. Furthermore, the redundancy analysis showed that percolation was the most powerful governing process in the subtropical areas and the headwaters. Although the soil water content contributed less than percolation, it was a substantial driver of surface runoff in the headwater and highland sub-basins due to the freeze-thaw process. Our results suggest that it is critical to prioritize soil water content in freeze-thaw areas and subsurface flow in warmer valley areas to improve soil and water resource regulation. These findings provide vital information from a systematic perspective for hydrological, environmental and ecological management in high-altitude areas.

Spatial and temporal characteristics of the daily precipitation concentration index over China from 1979 to 2015

Abstract Irregular precipitation has a nontrivial influence on hydrological processes and regional agriculture. The precipitation concentration index provides convenient quantitative characterizations of precipitation variability. To explore the spatial and temporal distribution of the precipitation concentration index, the long-term concentration index (LCI) and the annual concentration index (ACI) during 1979–2015 were calculated based on the China Meteorological Forcing Dataset. The results are as follows: (1) The LCI in China ranged from 0.4571 to 0.9197, and the values between 0.6 and 0.7 accounted for 61.61% of the dataset. The highest and lowest LCI values were both recorded in Northwest China, which features low precipitation levels. Additionally, there are high LCI values (greater than 0.6) in Southeast China, which features high precipitation levels. (2) Application of the Mann-Kendall test (M-K test) and Sen's slope revealed that more than 88% of the grids exhibited nonsignificant positive or negative ACI trends and that more than 10% of the grid ACI values exhibited positive trends, with approximately 2.8% showing significant changes at the 0.1 significance level. (3) Application of the Pettitt test revealed that approximately 11.9% of the grid ACI values exhibited an abrupt change at the 0.5 significance level, with abrupt changes occurring in 1991, 1992 and 1993, together accounting for 45.89% of all grids with abrupt changes.

Influence of the El Niño Phenomenon on Shoreline Evolution. Case Study: Callao Bay, Perú

Analyzing the long-term behavior of the coastlines in the vicinity of river mouths and estuaries usually relies on the mean (predicted) values of the sediment discharge from the river. However, this approach does not consider low frequency, severe events, such as El Niño (EN), that can have a large effect on coastlines. While the effects of an EN on flooding and droughts are well studied, little information exists about its effects on coastal zones, and especially on the evolution of coastlines. In early 2017, an EN occurred in the equatorial Pacific Ocean, and the country of Peru was affected with high precipitation levels, and extreme river discharges and flooding. During this event, in the district of Lima, the Rimac River discharged a huge amount of sediment into the Callao Bay, and the shoreline accreted approximately 1 km, demonstrating the significant effects that an EN can have on coastal zones. To explore these effects, this paper studies the influence of an EN on shoreline evolution in the Callao Bay by analyzing Landsat images from 1985–2019 to understand the shoreline evolution and identify changes to the coastline. Results show that when an extraordinary EN occurs (e.g., 1982–1983, 1997–1998, and 2017), the shoreline experiences high accretion compared to when a smaller, or no EN occurs. During these events, a significant delta forms at the south end of the bay, and the redistribution of the accumulated sediment by wave action causes the accretion of the adjacent coastlines for as far as 7 km north of the river mouth. This shows the importance of these events for the wellbeing of coastlines adjacent to river mouths affected by EN.

Can providing safe cycling infrastructure encourage people to cycle more when it rains? The use of crowdsourced cycling data (Strava)

Abstract Many local authorities in the UK and other developed countries have spent a substantial amount of time and money providing safe cycling infrastructure to improve cycling environments. However, it is not clear whether these expensive physical investments are an effective strategy to encourage people to cycle more in cities where there is a high level of precipitation. The evidence is limited, partly due to data limitations. We used crowdsourced cycling data (taken from the Strava activity-tracking app) and fixed-effects panel regression models to investigate whether providing safe cycling infrastructure could be an effective way to overcome adverse weather conditions. We selected the city centre of Glasgow, Scotland because of the current size and scope of investments. We found that providing safe cycle paths could encourage people to cycle more, especially on dry days. However, findings suggested that rainy cities like Glasgow may not have realised the full benefits of safe cycling infrastructure because there are larger reductions in the volume of cycling on rainy days on these routes. Planners, especially from cities with a high level of precipitation, should consider how to improve cycle paths to overcome adverse weather and other policies (e.g., providing shower facilities at workplaces, incentives to cycle, etc.) to increase cyclists’ resilience to bad weather.

Whether climatic factors influence the frequency of punctual on-demand deliveries of groundwater for irrigation? Empirical study in the North China Plain

Using household level and plot level survey data spanning over 10 years, this study examines the effects of climatic factors on the frequency of punctual on-demand deliveries of groundwater for irrigation at the farm level in the North China Plain. Data show that for the past few decades, farmers have experienced a decline in the frequency of punctual on-demand deliveries of groundwater for irrigation, which is measured by the proportion of the number of groundwater irrigations whose delivery timing matched the requests of farmers. Econometric estimation results show that both long-term climate conditions (mean temperature and total precipitation) and short-term weather conditions during the growing seasons have statistically significant effects on the frequency of punctual on-demand deliveries of groundwater for irrigation. However, these effects can show opposite results. The frequency of punctual on-demand deliveries of groundwater for irrigation is negatively associated with an increase in the long-term average temperature but is positively associated with a short-term temperature rise. The effects, moreover, may also differ in magnitude. Although the frequency of punctual on-demand deliveries of groundwater for irrigation is positively associated with higher precipitation levels in both the short-term and the long-term, the latter exerts a larger influence.

Photodegradation influences litter decomposition rate in a humid tropical ecosystem, Brazil

Solar radiation in general and UV radiation in particular have been recognized to stimulate plant litter decomposition through photochemical mineralization of organic molecules such as lignin and through facilitation of microbial decomposition in dryland ecosystems. However, little is known about how photodegradation may influence decomposition in other ecosystems not subject to moisture limitations and under what conditions photodegradation may be favored. Decomposition in humid tropical ecosystems is a complex process, and it can be influenced by a number of environmental factors that are distinct from arid and semi-arid ecosystems. To assess the mechanisms underlying photodegradation by ultraviolet B (UV-B) radiation in a humid tropical ecosystem, we designed a 300-day field experiment in a tropical site in Brazil with high levels of annual precipitation, compared to arid ecosystems, and exposed litter to three levels of radiation (full sun, UV-B removed, and shade) combined with a biocide treatment. Results show that after nearly one year of exposure, the microbial biomass was not affected by UV-B incidence, and this effect has not yet been fully understood for tropical ecosystems. Modeled using an exponential deceleration equation, the removal of UV-B radiation decelerated the plant litter decomposition rate for the control conditions by 21% compared to litter exposed to full sun. Interestingly, shaded litter exhibited similar mass loss compared to litter exposed to full sun. Furthermore, differences in the decay constant among radiation treatments due to the UV-B effect were independent of lignin loss. Overall, our study suggests that UV-B radiation contributed to plant litter decomposition through carbon losses but had no discernible effect on nitrogen, lignin, or cellulose loss specifically. Importantly, our results demonstrate that photodegradation occurs under humid tropical conditions, and further studies are necessary to examine the mechanisms of carbon loss.