Summer Rainy Season Research Articles

Spatiotemporal variations on infrared temperature as a thermal comfort indicator for cattle under agroforestry systems.

With the expanding use of thermal assessment techniques in beef cattle, infrared thermography has become a promising tool for assessing the environment for animal thermal comfort. Goals of this study were: (1) to evaluate cattle thermal comfort in agroforestry systems with different shade availability (2) to verify the spatiotemporal variations of infrared temperature inside agroforestry systems, and; (3) to test infrared thermography as a potential tool to assess animal thermal comfort indices in agroforestry systems. A trial was carried out between June 2015 and February 2016, covering Central-Brazil's dry winter and rainy summer seasons, respectively. The experimental area of Embrapa Beef Cattle is located in Campo Grande (Mato Grosso do Sul), coordinates 20°24'53″ S, 54°42'26″ W and 558m altitude. The 12ha plot has two agroforestry systems varying shade availability. Traditional Black Globe Temperature and Humidity Index, Heat Load Index and Radiation Thermal Load were determined, from measurements using digital thermo-hygrometers, with datalogger. Surface temperature and humidity of tree canopies and pasture were determined using an infrared thermographic camera. Results show spatiotemporal variations in infrared temperature. This means that the environment inside agroforestry systems is not homogeneously comfortable for cattle, and the system with the lowest shade availability has the greatest heat accumulation area. Weak to strong associations were identified between infrared variables and thermal comfort indices (0.08=r≤0.75). Positive relationships were also obtained and equally well explained by the Black Globe Temperature and Humidity Index and Heat Load Index (0.55=R2≤0.94). We conclude that infrared thermography can be used as a tool to assess thermal comfort indices in agroforestry systems and to determine onset of animal thermal stress from environment and heat body accumulation.

A July-August relative humidity record in North China since 1765 AD reconstructed from tree-ring cellulose δ18O.

Since the late 1970s, East Asian summer monsoon (EASM) has shown a significant weakening trend, and sustained drought has occurred across North China. Placing recent climate changes in the paleoclimatic context can better understand the EASM variations. Four δ18O sequences based on tree-ring cellulose of Chinese pine were developed from Mt. Beiwudang, North China, covering a period from 1700 to 2013. Based on a climatic response analysis, a transfer function was designed to reconstruct the relative humidity from July to August (RHJA hereafter). The RHJA spans from 1765 to 2013 and explains 49% (R2adj = 48%) of the instrumental variance during the calibration period (1961-2013, r = - 0.70, p < 0.0001). The RHJA is mainly influenced by precipitation in the summer rainy season and reflect EASM variations. Spatial representation analysis indicates that RHJA represents the dry/wet variations across North China. At the interannual scale, RHJA records many extreme dry/wet events, among which the events in 1876-1878, 1900, and the 1920s are extensive droughts. Those events correspond well to ENSO events, plus further correlation and periodicity analysis indicate that RHJA contains ENSO signals. At the interdecadal scale, RHJA shows a decreasing trend and unprecedented low values from 1981 to 2013, suggesting that the weakening of EASM since the late 1970s is unprecedented in the past 249 years. Similarly, the significantly correlating region in the spatial correlation analysis, covering the Meiyu/Baiu/Changma rainfall belt and India, have also undergone a climatic shift since the late 1970s according to previous papers.

Phenological tracking of a seasonal climate window in a recovering tropical island bird species

Constraints on evolutionary adaptation and range shifts mean that phenotypic plasticity, which includes physiological, developmental or behavioural responses to environmental conditions, could be an important mode of adaptation to a changing climate for many species with small insular populations. While there is evidence to suggest adaptive plasticity to climate in some island populations, little is known about this capacity in species that have experienced a severe population bottleneck. In a changing climate, plasticity in the timing of life-history events, such as in breeding phenology, is adaptive if timing is optimised in seasonal environments, although these processes are poorly understood for tropical species. Here, we quantify the effects of climate on the breeding phenology and success of the Mauritius kestrel (Falco punctatus), a tropical raptor whose extinction has been averted by conservation management. We show that the timing of egg-laying is advancing in response to warming, at rates similar to temperate bird populations. Individual females show plasticity to temperature, although there is limited variation among individual responses. We show that advances in breeding phenology are likely to be adaptive, as they track changes in a seasonal climate window of favourable conditions, defined by late winter-early spring temperatures and the onset of the summer rainy season. Our results provide a rare example of a small and bottlenecked insular population that has adjusted to recent climate change through phenotypic plasticity. Furthermore, seasonal climate windows and their dynamics may be widespread mechanisms through which tropical species are impacted by and respond to climate change.

A climatological analysis of the monsoon break following the summer monsoon onset over Luzon Island, Philippines

AbstractThis study investigates the climatology of the monsoon break following the onset of the summer rainy season over Luzon Island (120–122.5°E, 13–22°N) in the Philippines from 1979–2017. The first post‐onset monsoon break is remarkable in stations located over the north and central Luzon Island and occurs climatologically in early June. Composite analysis of the large‐scale circulation features during the monsoon break period shows that this break is associated with the westward extension of the western North Pacific Subtropical High (WNPSH), which weakened the monsoon southwesterlies and induced enhanced low‐level divergence over Luzon Island. The westward extension of the WNPSH may be facilitated by the phase change of the boreal summer intraseasonal oscillation (BSISO). About 59% (23/39) of the monsoon break cases occurred when suppressed convection, associated with the dry phases of the BSISO, is apparent over the western North Pacific. This suppressed convection favours the westward expansion of the WNPSH.With the occurrence of the monsoon break in early summer, the seasonal march of the early summer monsoon over the Philippines can be divided into three phases: (1) the monsoon onset phase, which occurs between mid to late May under the influence of the westerly/southwesterly low‐level winds, (2) the monsoon break phase, when rainfall decreases over Luzon Island in early June, and (3) the monsoon revival phase, when rainfall increases again due to the intrusion of monsoon southwesterlies over the Philippines. This study highlights the complex features of the summer monsoon onset and the impact of the WNPSH on the local climate of the Philippines in early summer.

Intraseasonal evolution and climatic characteristics of hourly precipitation during the rainy season in the Poyang Lake Basin, China

In the key flood control area of the Poyang Lake Basin (China), over 80% of annual precipitation is concentrated in the rainy season. This study investigated the intraseasonal evolution and climatic characteristics of precipitation during the rainy season in the Poyang Lake Basin under the background of climate change. On the basis of the precipitation pattern, the rainy season was divided into three stages: the spring rainy season, Meiyu season, and summer rainy season. Generally, total precipitation and precipitation hours showed no significant trends of change, whereas precipitation intensity had an obvious trend of increase. In the spring rainy season, the trend of total precipitation was downward but not significant; however, owing to substantial reduction in precipitation duration, precipitation intensity was enhanced significantly. In the Meiyu season (summer rainy season), total precipitation increased significantly because of increased precipitation duration (precipitation intensity). The spatial distributions of total precipitation in the spring rainy season and Meiyu season were similar, i.e., precipitation occurred mostly in the east and less in the west; however, the spatial distributions of the change trends were opposite. In the summer rainy season, precipitation was concentrated primarily in the surrounding mountainous areas.

Greenhouse Gas Emissions from Subtropical Agriculture Fields Decrease Over Time

AbstractExpansion of cultivated lands and field management impacts greenhouse gas (GHG) emissions from agriculture soils. Soils naturally cycle GHGs and can be sources or sinks depending on physical and chemical properties affected by cultivation and management status. We looked at how cultivation history influences GHG emissions from subtropical soils. We measured CO2, N2O, and CH4fluxes, and soil properties from newly converted and continuously cultivated lands during the summer rainy season in calcareous soils from south Florida. Newly converted soils had more soil organic matter (OM), more moisture, higher porosity, and lower bulk density, leading to more GHG emissions compared to historically cultivated soils. Although more nutrients make newly converted lands more desirable for cultivation, conversion of new areas for agriculture was shown to release more GHGs than cultivated lands. Our data suggest that GHG emissions from agricultural soils may decrease over time with continued cultivation.

Studies on genetic variability, heritability and genetic advance in turmeric [Curcuma longa L.] under low hills of Himachal Pradesh

The present investigation “Studies on genetic variability, heritability and genetic advance in turmeric [Curcuma longa L.]” under low hills of Himachal Pradesh was carried out at Vegetable Research Farm, Department of Vegetable Science, College of Horticulture and Forestry, Neri, Hamirpur (HP) during summer-rainy season, 2019. Twenty-one genotypes were evaluated in Randomized Complete Block Design with three replications to ascertain extent of variability, heritability and genetic advance for yield and other horticultural traits among the genotypes. Analysis of variance showed significant differences among all the genotypes for all the characters under study. Three genotypes namely LC-T-20-18, LC-T-9-18 and LC-T-12-18 were found to be high yielding as well as better from consumer’s point of view. They could be the promising parents for utilization in further breeding programmes. Moderate PCV and GCV were observed for weight of mother rhizome, length of mother rhizome, girth of mother rhizome, number of primary fingers per plant, number of secondary fingers per plant, number of leaves per plant, curcumin content, dry matter content and yield per plot. High heritability estimates were observed for curcumin content, plant height, weight of mother rhizome, leaf length, dry matter content, leaf breadth, length of mother rhizome, number of primary fingers per plant and girth of mother rhizome while, high estimates of genetic gain were observed for weight of mother rhizome, length of mother rhizome, number of primary fingers per plant and girth of mother rhizome.

Depositional and environmental controlling factors on the genesis of Quaternary tufa deposits from Bonito region, Central-West Brazil

The Pleistocene and Holocene tufas of the Serra da Bodoquena (Bonito region, Brazilian Midwest) consist of several deposits related to a karstic system developed in the carbonatic rocks of Corumbá Group. Tufas currently forming in the Serra da Bodoquena area (Mimoso and Formoso rivers) were investigated for a better understanding of which environmental changes control the deposition of different types of tufa facies. The Mimoso River displays waterfalls, cascades, barriers and large pools as morphological elements. The topographic breaks on the bedrock of this river control the distribution of these main morphological elements. Five facies were identified: (i) stromatolitic boundstones, characterized by an alternation of dense and porous laminae; (ii) phytohermal boundstones, corresponding to bryophyte cushions; (iii) phytoclastic rudstones, formed by the accumulation of leaves and plant fragments; (iv) oncoidal rudstones, composed by coated grains with concentric laminae (oncoids); and (v) unconsolidated detrital sediment, formed by bioclasts and tufa fragments. SEM images indicated the presence of microorganisms such as Oocardium stratum Nägeli 1849 and Phormidium incrustatum Gomont ex Gomont 1892, as well as diatoms and fungi filaments colonizing tufa samples. On the other hand, the Formoso River is more sinuous, lacking significative topographic breaks and presents flooded sub-environments, such as inactive barriers and other shallow fluvial areas, containing unconsolidated detrital sediment, lime mud and oncoidal rudstones. No microbial remains have been observed. The Bonito region has a humid warm climate with a rainy summer season and a dry winter season, and temperatures barely varying through year. The seasonality of rainy and dry seasons influences both the physicochemical changes of water and, indirectly, the microbial communities of tufa. However, the very different facies displayed by each river, Mimoso and Formoso, are not directly linked to climate. The stepped profile of the Mimoso River allows fast flowing waters producing fast CO2 outgassing that leads to high calcite precipitation rates. The gentle slope of the Formoso River and its slow flowing waters leads to slow passive CO2 outgassing and photosynthesis controlling calcite precipitation at lower rates than in the Mimoso River.

Research on the Application of the Concept of Sponge Cities in Urban Landscape Planning

&lt;p&gt;Landscape architecture has developed rapidly since a long time ago. Green space in cities has been slowly designed as parks and greenways, with greenery decoration becoming systematic and integrated. Emerging late in China, the concept of landscape and public space design was not put forward until the first five-year plan after the founding of the People’s Republic of China. After entering the 21st century, with the development of landscape architecture, China gradually attached importance to and developed landscape and public space design. As people deepen their understanding of the world and the earth, the awareness of environmental protection has been enhanced. The urban construction and development have brought about a negative impact on the environment. On the other hand, because people selectively ignored sustainable development, it has in turn caused a passive influence and restricted the development direction of cities. Especially in the rainy season in summer, cities often fail to make effective use of rainwater resources and are damaged.&lt;/p&gt;

Tracing source and transformation of carbon in an epikarst spring-pond system by dual carbon isotopes (13C[sbnd]14C): Evidence of dissolved CO2 uptake as a carbon sink

δ13C and D14C measurements on dissolved inorganic carbon (DIC), particulate organic carbon (POC) and aquatic plants from a karst spring and two spring-fed ponds in Laqiao, Maolan Township, Libo County, southeastern Guizhou of China in January, July and October of 2013 have been carried out to understand the roles of aquatic photosynthesis through DIC uptake in surface karst waters. The mean D14C and δ13C values of DIC for the spring, midstream pond (MP) and downstream pond (DP) are −26 ± 36‰ and −13 ± 2‰, 6 ± 56‰ and −12 ± 3‰, and 0 ± 64‰ and −9 ± 2‰, respectively. The carbon source for the DIC is mainly from biogenic CO2 rather than the dissolution of limestone rock as the D14C and δ13C of limestone are about −1000‰ and 2‰, respectively. The enrichment trend of D14CDIC and δ13CDIC from the spring to the DP indicates CO2 exchange between atmospheric CO2 and DIC, because D14C and δ13C values of atmospheric CO2 are ca. 50‰ and −8‰, respectively. The average D14CPOC values in the spring, MP and DP were −325‰, −123‰ and −158‰, respectively, which are all lower than these of the DIC in each reservoir. The lower D14C values of the POC may be caused by older soil carbon from surface runoff and dust fall. More aquatic algae were formed through photosynthesis in the stream ponds, especially in summer, shown by strongly increased D14CPOC and evidence of growth in EDS/SEM analyses. Furthermore, the D14C values of the submerged aquatic plants range from −153‰ to −26‰, reflecting that the aquatic plants used DIC for photosynthesis. The D14C value of an emergent plant which uses atmospheric CO2 during photosynthesis is 52.5 ± 0.3‰, equivalent to the atmospheric D14C. Seasonal variations of D14CDIC and δ13CDIC are influenced by soil CO2 input, primary productivity in the ponds, and CO2 exchange; hydrochemical condition show lower D14C values but higher δ13C values in cold/dry season, and vice versa in summer rainy season. A simple mass balance calculation indicates ~90% of carbon for the spring DIC is from biogenic CO2, with higher contribution in summer due to higher productivity. Although this simple calculation may overestimate the biogenic CO2, it indicates that organic decomposition is a major carbon source for DIC in the karst hydrological system. The results of the present study have implications for 14C dating on aquatic plant remains, regional and perhaps global carbon budgets, and the different behaviors of 13C and 14C in karst systems.

Assessment of Aerosol optical depth under background and polluted conditions using AERONET and VIIRS datasets

We investigated aerosol optical depth (AOD) under background and polluted conditions using Aerosol Robotic Network (AERONET) and Visible Infrared Imaging Radiometer Suite (VIIRS) observations. The AOD data were separated into background, high, and median AOD (BAOD, HAOD, and MAOD, respectively) based on the cumulative AOD distribution at each point and then their spatiotemporal variations were analyzed. Persistent pollutant emissions from industrial activity in South Asia (SUA) and Northeast Asia (NEA) produced the highest BAOD values. Gridded-BAODs obtained from VIIRS Deep Blue AOD products showed widespread high-level BAOD over the oceans associated with transport from dust and biomass burning events. The temporal variations in BAOD and HAOD were generally consistent with that of MAOD, but differences were found in seasonal variation as well as in long-term trends in some regions. Southeast Asia (SEA) and South America/South Africa (SAM/SAF) showed similar HAOD levels owing to biomass burning, but BAODs were higher in SEA than in SAM/SAF. In NEA, BAOD was lowest during the summer rainy season, as opposed to the peaks in MAOD and HAOD. Long-term trends of the AODs show clear regional characteristics. The AODs have decreasing trends in NEA, Europe/Mediterranean basin, and Northeast America but increasing trends in SUA, North Africa, and the Middle East. The trend of HAOD in Northwest America and Australia was opposite to that of BAOD. The spatiotemporal patterns of the HAOD and BAOD provide detailed information on changes in aerosol loading compared to using only MAOD.

Water and Soil Nutrient Dynamics of Huanglongbing-Affected Citrus Trees as Impacted by Ground-Applied Nutrients

The decrease in the rate of inflow and outflow of water—and thereby the uptake of plant nutrients as the result of Huanglongbing (HLB or citrus greening)—leads to a decline in overall tree growth and the development of nutrient deficiencies in HLB-affected citrus trees. This study was conducted at the University of Florida, Southwest Florida Research and Education Center (SWFREC) near Immokalee, FL from January 2017 through December 2019. The objective of the study was to determine the effect of rootstocks, nutrient type, rate, and frequency of applications on leaf area index (LAI), water relations (stomatal conductance [gs], stem water potential [Ψw], and sap flow), soil nutrient accumulation, and dynamics under HLB-affected citrus trees. The experiment was arranged in a split-split plot design that consisted of two types of rootstocks, three nitrogen (N) rates, three soil-applied secondary macronutrients, and an untreated control replicated four times. LAI significantly increased in response to the secondary macronutrients compared with uncontrolled trees. A significantly greater gs, and thus a decline in Ψw, was a manifestation of higher sap flow per unit LA (leaf area) and moisture stress for trees budded on Swingle (Swc) than Cleopatra (Cleo) rootstocks, respectively. The hourly sap flow showed significantly less water consumption per unit LA for trees that received a full dose of Ca or Mg nutrition than Ca + Mg treated and untreated control trees. The soil nutrient concentrations were consistently higher in the topmost soil depth (0–15 cm) than the two lower soil depths (15–30 cm, 30–45 cm). Mobile nutrients: soil nitrate–nitrogen (NO3-N) and Mg2+ Mg2+, Mn2+, Zn2+, and B leached to the lower soil (15–30 cm) depth during the summer season. However, the multiple split applications of N as Best Management Practices (BMPs) and optimum irrigation scheduling based on reference evapotranspiration (ETo) maintained soil available N (ammonium nitrogen [NH4-N] and NO3-N) below 4.0 mg kg−1, which was a magnitude 2.0–4.0× less than the conventional N applications. Soil NH4-N and NO3-N leached to the two lower soil depths during the rainy summer season only when trees received the highest N rate (280 kg ha−1), suggesting a lower citrus N requirement. Therefore, 224 kg ha−1 N coupled with a full Ca or Mg dose could be the recommended rate for HLB-affected citrus trees.

Feeding Ecology of Pachypterus atherinoides (Actinopterygii; Siluriformes; Schilbeidae): A Small Freshwater Fish from Floodplain Wetlands of Northeast India

Abstract The feeding ecology of Pachypterus atherinoides was investigated for two consecutive years (2013-2015) from floodplain wetlands in the Subansiri river basin of Assam, North East India. The analysis of its gut content revealed the presence of 62 genera of planktonic life forms along with other animal matters. The organization of the alimentary tract and maximum Relative Mean Length of Gut (0.511±0.029 mm) indicated its carnivorous food habit. The peak gastro-somatic index (GSI) in winter-spring seasons and summer-rainy seasons indicated alteration of its feeding intensity. Furthermore, higher diet breadth on resource use (Levins’ and Hurlbert’s) with zooplankton compared to phytoplankton and total plankton confirmed its zooplanktivore habit. The feeding strategy plots also suggested greater preference to zooplankton compared to phytoplankton. The organization of its gill rakers specified a secondary modification of gut towards either carnivory or specialized zooplanktivory. So, the fish may be a carni-omnivore with preference to zooplankton.

Characteristics of Water and Sediment Qualities in the Oncheon Stream, Busan during Summer Rainy Season

Characteristics of Water and Sediment Qualities in the Oncheon Stream, Busan during Summer Rainy Season

Performance evaluation of different genotypes of brinjal (Solanum melongena L.) under mid hill conditions of Himachal Pradesh

The field experiment was conducted to study the performance of fifty genotypes of brinjal (Solanum melongena L.) under mid-hill conditions at the Research Farm, Department of Vegetable Science, Dr YS Parmar University of Horticulture and Forestry, Nauni, Solan, (HP) during the summer rainy season of 2017. All these fifty brinjal genotypes showed significant variation in growth and yield attributing characters. Maximum fruit yield per plant was observed in PBH-3 (1.180 kg) closely followed by another 5 genotypes namely PBHR-42 (1.120 kg), SR-312 (1.063), Punjab Barsati (1.000 kg), UHF BRL-4 (0.997 kg) and SR-333 (0.997 kg).

Sentinel-3 OLCI observations of water clarity in large lakes in eastern China: Implications for SDG 6.3.2 evaluation

The Sustainable Development Goal (SDG) 6.3.2 of the United Nations (UN) focuses on ambient water quality, while water clarity simplistically and visually reflect water quality and can potentially support SDG 6.3.2 reporting. In this study, based on extensive field data and Sentinel-3 Ocean and Land Color Instrument (OLCI) imagery, a random forest regression (RFR) Secchi depth (Zsd) model suitable for turbid and eutrophic waters was established. With this model, the Zsd of 86 large (> 30 km2) lakes in Eastern China was obtained from May 2016 to April 2018. Additionally, the potential for applying OLCI-derived Zsd data in the SDG 6.3.2 evaluation was assessed. Of six common atmospheric correction (AC) processors (i.e., BAC, C2RCC, POLYMER, BP, MUMM, and 6SV), 6SV often exhibited the best performance except for at 754 nm (root mean square error (RMSE) ≤ 0.0094 sr−1, mean absolute percentage error (MAPE) ≤ 36.27%, and mean normalized bias (MNB) ≤ 15.89%). The RFR model had higher accuracy (R2 = 0.70, RMSE = 0.13 m, MAPE = 33.43%, and MNB = 14.55%) and was more suitable for eutrophic and turbid inland lakes across Eastern China than the other available Zsd algorithms. The average OLCI-derived Zsd of the lakes in Eastern China was 0.44 ± 0.13 m, suggesting that these lakes are extremely turbid. The average Zsd of lakes in the Eastern Plain Lake (EPL) zone (0.45 ± 0.12 m) was higher than that of the lakes in the Northeastern Plain and Mountain Lake (NPML) zone (0.40 ± 0.17 m). The majority of lakes showed higher Zsd values in summer (rainy season) than in fall and winter (dry season). A simple SDG 6.3.2 evaluation scheme was developed based on the Zsd product, and only 54.65% of the lakes (N = 47) reached the “good” level during the monitoring period as a result of the eutrophication of the lakes in Eastern China. This study provides water clarity information for large lakes in Eastern China and facilitates the understanding of ambient water quality under the 2030 UN SDG framework as well as data and technical support for future SDG 6.3.2 evaluations.

Deciphering interwoven drivers of environment-related migration – A multisite case study from the Ethiopian highlands

Global environmental change is increasing livelihood pressure for many communities, and agricultural households in the Global South are particularly vulnerable. Extant research has debated whether and to what degree this amplifies migration flows while also acknowledging that migration can be an adaptive strategy. However, little is known about which contextual factors are most relevant and how they interact in shaping environment-related migration. We shed light on this issue by conducting an in-depth qualitative, yet multisite and medium-N study of farming households in the northern Ethiopian highlands. We utilized qualitative comparative analysis (QCA) – a novel approach in the research field – to overcome the existing methodological challenges. We found that the migration experience within the household in combination with either the usage of the longer summer rainy season (Kiremt) or non-farm in situ diversification are sufficient causes for migration. Non-farm income activities and favorable environmental conditions during the Kiremt season increases economic household resources and as such migration ability. However, only together with migrant networks, which can reduce the costs and risks of migration and shape migration aspirations, can these drivers explain why households engage in migration. Our findings reveal that capabilities and networks, rather than commonly cited push factors, are far more important drivers of environment-related migration at the household level. Additionally, we illustrate that while migration is an important adaptation strategy, it cannot be adopted equally among households and as a result often reinforces existing inequalities.

Seasonal germination responses of seeds in fruits of the cold desert shrub Zygophyllum xanthoxylon buried in the field

We hypothesized that seeds of the central Asian cold desert shrub Zygophyllum xanthoxylon exhibit dormancy cycling in nature, which would help ensure that germination occurs at a favorable time for seedling survival. Fresh mature fruits of Z. xanthoxylon were placed on the soil surface and buried at a depth of 3–5 cm in soil in a natural habitat in August 2015. At regular intervals until July 2017, fruits/seeds were taken to the laboratory and evaluated for viability and germination. Fresh seeds in fruits germinated to 22–62% over a range of temperatures. After 6 weeks in the field, seeds on the surface germinated to 72–99% and those in soil to 70–100%. From 12 to 98 weeks, seeds on and in soil germinated to 72–100% at low (15/5 and 20/10 °C) temperatures, but germination at high (25/25 and 30/15 °C) temperatures was higher in summer than in spring. Seeds in fruits on the soil surface had higher germination percentages than those in the soil, especially at high temperatures. Although about half the seeds were dormant at maturity, they became nondormant in the field during summer. There was a decrease in ability to germinate at high temperatures in spring, especially for seeds in buried fruits, which indicates conditional dormancy/nondormancy cycling. Lack of germination at high temperatures in spring would help delay germination until the onset of the summer rainy season in the desert. Burial of fruits in the soil enhances the formation of a short-lived persistent seed bank.

Future Changes of Summer Monsoon Characteristics and Evaporative Demand Over Asia in CMIP6 Simulations

AbstractFuture greenhouse warming is expected to influence the characteristics of global monsoon systems. However, large regional uncertainties still remain. Here we use 16 Coupled Model Intercomparison Project Phase 6 (CMIP6) models to determine how the length of the summer rainy season and precipitation extremes over the Asian summer monsoon domain will change in response to greenhouse warming. Over East Asia the models simulate on average on the earlier onset and later retreat; whereas over India, the retreat will occur later. The model simulations also show an intensification of extreme rainfall events, as well as an increase of seasonal drought conditions. These results demonstrate the high volatility of the Asian summer monsoon systems and further highlight the need for improved water management strategies in this densely populated part of the world.

Effect of stand density, canopy leaf area index and growth variables on Dendrocalamus brandisii (Munro) Kurz litter production at Simao District of Yunnan Province, southwestern China

Litterfall is the primary interface between the forest canopy and forest floor for efficient carbon and nutrient cycling. However, there is limited knowledge on factors that influence D. brandisii litter production and its seasonal dynamics. In this study, we investigated the relationship between stand density, canopy leaf area index (LAI) and growth variables in relation to litter production and its seasonal dynamics. In the 5-year-old D. brandisii plantation, three blocks were established and 72 litter traps were installed in the forest floor. Litter collection was conducted at the end of every season from June 2018 to May 2019. The relationship between litter production with climate variables further analyzed using 12 months weather data. On average, 207.23 ± 6.89 g m−2 y−1D. brandisii annual litter production was recorded in the forest floor. Of this, the highest amount of litterfall (97.39 ± 4.62 g m−2 y−1) was obtained during warm and rainy summer season, followed by autumn (52.42 ± 2.43 g m−2 y−1). Higher stand density with larger canopy leaf area attributed to enhanced canopy LAI. Dense stands associated with closed canopy closure, by contrast, reduced culms diameter at breast height (DBH) size. This results in lower canopy LAI and hence reduced litter production in the forest floor. Alternatively, lower canopy leaf area compared to higher canopy spread area resulted in reduced canopy LAI (0.74 ± 0.09 m2 m−2). As a whole, the generalized linear mixed model (GLMM) confirmed that litter production was directly proportional to stand density or canopy LAI across almost all culm DBH classes. Litter production also had a positive relation with stand density in relation to canopy LAI or the vice versa. In conclusion, managing the canopy structure in a dense stands and closed canopy through thinning practices enhances canopy LAI and culms DBH and hence maximize D. brandisii litter production in the forest floor.