High Rainfall Research Articles

Scheduling irrigation events in corn using three soil water potential strategies

AbstractScheduling irrigation events is important for high corn (Zea mays L.) yield, water use efficiency, economic returns, and water conservation. The use of shallow subsurface drip irrigation (S3DI) is cost effective for small irregular shaped field areas. Currently there are no irrigation scheduling recommendations for S3DI systems for corn production. The objective was to evaluate three water potential value strategies for scheduling irrigation events and the effect on corn yield, test weight, irrigation water use efficiency (IWUE), and value water use efficiency (VWUE). Corn was grown multiple years (2012–2013; 2019–2023) at two locations (Dawson and Shellman, GA) using soil water potential sensors to schedule irrigation events. Sensors were installed at 10 and 20 inches (25 and 50 cm) soil depth. Irrigation events were scheduled when the average water potential was between 40 to 60 cbar (I1), 60 to 80 cbar (I2), 80 to 100 cbar (I3), and compared to a dryland control (I0). There was no difference in corn yield, IWUE, or VWUE between irrigation treatments, but all irrigation treatments had greater yield than I0, except in high rainfall years. At the Shellman location, total water applied for I3 was 46% less than for I1. At Dawson, I2 applied 17% more water than either I1 or I3. Across both sites, I1 and I2 applied 1.5 and 1.3 times more water than I3, respectively. Therefore, irrigation events scheduled at 80 to 100 cbar can be a viable technique for irrigating corn using S3DI without yield reductions while promoting water conservation.

Population dynamics, feeding strategies, and coccinellid predators of the larch woolly adelgid exules on the European larch

The larch woolly adelgid Adelges laricis Vallot (Hemiptera: Adelgidae) infests spruce Picea spp. and larch Larix spp. in the Northern Hemisphere. The present field and laboratory research embraced the hitherto unknown aspects of the biology and ecology of A. laricis on its secondary host, the European larch Larix decidua Mill. in Poland. The study showed that the A. laricis population on L. decidua was represented by exulis sistens females at dwarf stem bases, exulis progrediens mobile 1st instar nymphs (crawlers) on needles, exulis progrediens sessile “woolly” nymphs and “woolly” adults on needles, and winged sexupara females. The maximum abundance of the A. laricis population occurred from the end of April until mid-May, which coincided with the predomination of crawlers in the age structure of the population. The most important limiting weather component was high rainfall, affecting mainly the crawlers. Eight species of Coccinellidae were recorded on adelgid-infested larch trees and Exochomus quadripustulatus (L.) was the dominant species. The main differences in food consumption strategies among adelgid developmental stages were related to the duration of phloem sap ingestion. While the total duration of sap consumption at a given time was similar in all adelgid instars studied, the individual bouts of sap ingestion were much shorter in crawlers than in the sessile forms. The specific probing behavior of the mobile nymphs probably reflects the crawlers’ strategy to evaluate plant sap quality in different phloem vessels. It is likely that such strategy is a behavioral preadaptation for finding abundant food sources for permanent settling before crawlers develop into sessile nymphs and adult females. The feeding strategy of crawlers promotes the rapid dispersal of the population. Therefore, the control of A. laricis on L. decidua should focus on the early stages of the population development, which would most effectively reduce the final damage.

Lutetian–Bartonian (Middle Eocene) micropalaeontology, biostratigraphy and palaeoecology of the Mengen Coal Basin, Northwest Türkiye (Turkey)

This study focuses on the upper Lutetian–lower Bartonian Tokmaklar Formation in the Mengen Basin of Northwest Türkiye (Turkey), examining various aspects such as biostratigraphy, palaeoecology, and isotope data (δ18O and δ13C), providing insights into the geological history and environmental conditions during this interval. Moreover, the study incorporates coal petrography on four samples to explore a potential correlation between the coalification process and the preservation of palynomorphs. The formation is informally divided into two distinct categories: a coal-bearing sequence positioned at the base of the formation and a coal-free sequence above it. However due to dense vegetation and soil cover in the area, the availability of suitable outcrops for measured sections and obtaining samples is severely limited. Therefore, we relied on drilling data from Turkish Coal Enterprises (TCE) for the purpose of coal exploration, as well as two partial sections (Ender and Çorak) from underground mining. Microapalaeontological evidences involving benthic foraminiferans, ostracods, and palynomorphs, along with isotope data (δ18O and δ13C), suggest that the Tokmaklar Formation was deposited as a result of a local transgressive process during the late Lutetian–early Bartonian. Furthermore, palynological data, particularly the existence of mangroves such as Nypa, lepidocaryoid palm and Acrostichum aureum, coupled with quantitative palaeoclimate analysis, the negative δ18O values, and the lower δ13C values indicate a warm, probably tropical climate under high rainfall.

Variable soil moisture responses to rainfall events in fields under different management practices

AbstractSoil moisture response to rainfall is a key factor that dictates how well a landscape can support crop growth as well as its susceptibility to water runoff and leaching, however, few studies have investigated how agricultural management impacts this important soil function. This study compares two common agricultural soil treatments (cover crops and soil compaction) and their soil moisture response to rainfall in comparison to a control. In a humid temperate climate during March to November, individual rainfall events were delineated over two growing seasons and corresponding soil moisture responses were identified using in situ soil moisture sensors at four soil depths (20, 30, 40, and 60 cm). Results suggest that hydrological responses differed with both event type and management treatment. Not all rainfall events triggered a response: those that triggered responses at shallower soil depths were typically characterized by higher total event rainfall, and higher maximum and average rainfall intensity. In contrast, rainfall events triggering responses at deeper soil depths were characterized by longer event duration as well as higher 10‐day antecedent rainfall (AR). Soil moisture responses for the cover crop treatment were characterized by relatively lower initial and peak soil moisture at shallower depths but higher values at 60 cm depth, whereas soil moisture responses for the control and compacted soil treatments demonstrated the opposite. Matrix flow was most often generated for rainfall events with high magnitude and was not preferentially associated with any particular soil treatment. However, specific conditions were needed to generate vertical preferential flow, namely high total event rainfall for both horizons, or high AR for preferential flow in the Ap horizon, or high rainfall intensity for preferential flow in the Bt horizon. Our findings demonstrate the potential for detailed event‐based soil water process analysis using high‐frequency, multi‐depth soil moisture data.

OS MINERAIS PESADOS E IDADES DE ZIRCÕES DOS SEDIMENTOS DE PRAIAS (BARRAS EM PONTAL) DOS RIOS PURUS E ACRE NO ESTADO DO ACRE (BRASIL)

The Purus River and its largest tributary, the Acre River, originate in Peru and constitute the main drainage system for the northeast and southeast portions of the State of Acre. These rivers and their smaller tributaries develop their beds over the Solimões Formation (Miocene to Pliocene-Late) and form a broad dendritic drainage pattern. During the rainy season, due to the high rainfall in the region and the low resistance of the drained rocks, these rivers mobilize a large volume of sediment, which is deposited mainly during the dry season, forming beaches (pointed bars), predominantly composed of fine sand, silt and clay. To investigate the probable primary sources of these sediments and their possible geographic locations, a mineralogical and morphological study of their heavy minerals and a geochronological analysis of their detrital zircons were used. Heavy minerals were extracted from fractions between 0.062-0.125 and 0.125-0.250. The transparent ones were investigated using a petrographic microscope and the opaque non-magnetic ones, together with the lithic fragments using a Scanning Electron Microscope (SEM/SED). In descending order, the main transparent heavy minerals of the Purus River are epidote (19%), kyanite (17%), zircon (14.5%), andalusite (8%), tourmaline (7.4%) and sillimanite (5 .5%), in addition to these, in amounts less than 5%, staurolite, garnet, apatite, amphibole, chlorite, muscovite, biotite, anatase, pyroxene and cassiterite occur. With similar content and different proportions, the assemblage of heavy minerals from the Acre River consists of andalusite (22.5%), kyanite (22.5%), zircon (12%), epidote (8%), sillimanite (5%) and tourmaline (5%), its accessories are: garnet muscovite, chlorite, apatite, amphibole, biotite, staurolite, titanite, anatase, serpentine and rutile. The non-magnetic opaque minerals of both rivers were shown to be predominantly formed by ilmenite, and the ages obtained in the zircons varied from 180 Ma to 3000 Ma, with great frequency in the intervals between 200-400 Ma and 900-1200 Ma.

PENANGANAN BANJIR DAERAH ALIRAN SUNGAI BABON KOTA SEMARANG

Floods are natural disasters that we often encounter during the rainy season. Apart from there are also tidal floods which are caused by global warming, this problem occurs in the city of Semarang, especially North Semarang, specifically the north coast of the Java Sea. Floods that occurred in 2021 in the city of Semarang include Starting from Genuk, Kaligawe, Satsiun Tawang, Tanjungmas, Karangayu, the flood disaster was caused by high rainfall, while tidal floods caused high tides and inundated roads and houses of residents on the north coast of Semarang city. To handle this problem, the government Currently we have made embankments, namely making embankments including the Sringin River which is equipped with a ponpa, Tenggang River, Babon River, Semarang River, Banger River, and others. These embankments are equipped with pumps so that when the water from upstream to downstream is high, the water is pumped. to the sea, the aim is to find out one of the annual discharges of the river, namely the Babon, and to find out the tamping capacity of the Babon River Longstorage. Apart from that, there is a method for handling tidal floods, namely using the Babon River Longstorage which is equipped with a pump, if there is high tide which inundates roads and houses. residents then the pump is turned on, whereas if the water recedes and does not inundate residential areas then the pump is turned off. Flood control analysis is calculated using the HEC-RAS program simulation using a return period of 50 years. Based on calculations using the HEC-HMS program. The flood discharge is 2,529 m3/sec. The high tide elevation is + 1.67 m, while the normal water level is -0.5 m.

Evaluating rainfall erosivity on the Tibetan Plateau by integrating high spatiotemporal resolution gridded precipitation and gauge data

High-precision rainfall erosivity mapping is crucial for accurately evaluating regional soil erosion on the Tibetan Plateau (TP) under the backdrop of climate warming and humidification. Although high spatiotemporal resolution gridded precipitation data provides the foundation for rainfall erosivity mapping, the increasing spatial heterogeneity of rainfall with decreasing temporal granularity can lead to greater errors when directly computing rainfall erosivity from gridded precipitation data. In this study, a site-scale conversion coefficient was established so that rainfall erosivity calculated using hourly data can be converted to rainfall erosivity calculated using per-minute data. A revised model was established for calculating the rainfall erosivity based on high-resolution hourly precipitation data from the Third Pole gridded precipitation dataset (TPHiPr). The results revealed a notable underestimation in the original calculation results obtained using the TPHiPr, but strong correlation was observed between the two sets of results. There was a significant improvement in the Nash–Sutcliffe coefficient of efficiency (from −0.39 to 0.80) and the Percent Bias (from −63.95 % to 0.37 %) after model revision. The TPHiPr effectively depict the spatial characteristics of rainfall erosivity on the TP. It accurately reflected the rain shadow area on the northern flank of the Himalayas and the dry-hot valley in the Hengduan Mountains. It also showed high rainfall erosivity values in the tropical rainforest area on the southern flank of the eastern Himalayas. The overall trend of rainfall erosivity has increased on the TP during the period 1981 to 2020, with 65.91 % of the regions exhibiting an increasing trend and 22.25 % showing significant increases, indicating an intensified risk of water erosion. These findings suggest that the 40-year-high spatial resolution rainfall erosivity dataset can provide accurate data support for a quantitative understanding of soil erosion on the TP.

Soil Instability and Building Damage in the Urban District, Morocco: Chefchaouen City as Case Study

Ground instability is one of the most significant issues that affect the social, economic, and environmental levels in the northern Rif area and many other parts of Morocco. To understand and analyze this natural hazard of terrain instability, Chefchaouen City is chosen as a case study. based on the inventory of ground movements carried out by the Geotechmed Laboratory to identify and characterize cases of instability in this city and their relationship with the geological structure and soil characteristics is the aim of this research. As well as, the inventory of constructions damaged by instability in all municipality districts. The results indicated that the soils in the administrative district were reliable. Several factors contributed to the 2016 landslide in the Ain Haouzi District, including high rainfall, water resurgence, and human activity. The damage inventory of 83 houses showed how the geographical distribution of the severely damaged homes was placed on top of the distribution of landslides in the surrounding areas. The management plan needs to adapt to the geomorphological characteristics and behavior of the subsoil. That will help to avoid any future material damage and provide better guidance for the planning and the city's expansion development, with its remarkable urban sprawl.

Analysis of Perceived Effects of Rainfall Variability on Rice Yield in Lokoja, Kogi State, Nigeria

This study analyzes the perceived effects of rainfall variability on rice production in Lokoja using data on rainfall and rice production from 2013 to 2022, and data on demographic and socio-economic characteristics of farmers as well as their perception on the effects of rainfall variability. The study was done using well-structured questionnaire administered in the study area to the 140 selected respondents, and the Statistical Package for the Social Sciences (SPSS) version 24 was utilized to analyze the data. Results showed that rainfall have significant effects on rice production with varied yield based on rainfall fluctuations in the amount of rainfall with as much rice production of about 4269 tonha-1 when precipitation was suitable between about 1250 - 1350mm, but when less than normal precipitation (<1250mm), it reduces the production yield to about 2361 tonha-1. Similarly, the results revealed that when the rainfall amount was highest, the total rice production was reduced, with cultivated areas having heavy rainfall resulting in flooding. Results further showed that on average 1282mm of rainfall produced 2693 tons of rice in the study years. About 44% of the respondents refuted early rainfall onset affecting rice production with months such as June, July, and September in some of the years with high rainfall intensity having adverse effects on rice farming, with 43% of the respondent noting that it limited the amount of land available for cultivation, while 26% noted that it reduces rice yield while the remaining 31% noted that it destroys rice stands.

Optimization of Biopori and Construction of Absorption Wells in Blawi Village to Overcome Annual Flood Disasters

This activity was carried out in Blawi Village - Lamongan Regency. Floods often hit this village due to overflowing rivers and waterways due to high rainfall. In practice, infiltration wells for rainwater have never been implemented in Blawi Village, while biopores were only added at several points because this activity continued the previous year's activities. This community service activity made several rainwater infiltration wells and added biopores to accommodate the surface runoff water component from rainfall. This Student Organization Capacity Strengthening Program (PPK ORMAWA) activity was carried out by the Civil Student Association (HMS) of Lamongan Islamic University in collaboration with Blawi Village officials and residents for conservation-based waterlogging mitigation. Infiltration wells and biopores use a method that is very easy to implement, this activity is also useful for maintaining groundwater and utilizing biopore leaves for compost. This program can reduce the problem of inundation in Blawi Village during the rainy season.

Analisis Pengaruh Curah Hujan terhadap Frekuensi Kejadian Banjir di Kabupaten Kotabaru, Kalimantan Selatan

The accumulation of water on the ground is what causes flooding, whereas rainfall is the amount of rainwater collected in a flat area Rainfall and flooding are two related but distinct concepts. While rainfall refers to the amount of precipitation that falls in a particular area, flooding is the result of excessive water accumulation on the ground. Indonesia can be classified as a country with high rainfall due to its average annual rainfall ranging from 2000 to 3000 millimeters. In cases of heavy rainfall, excessive water discharge can occur. This can result in flooding when the land, rivers, or water reservoirs cannot manage the overflow effectively. Flooding is a common occurrence in Kotabaru Regency located in South Kalimantan, as it is a combination of mountainous regions, coastal areas, land areas, and small islands. The objective of the study is to examine whether flooding is always caused by high rainfall in Kotabaru Regency from January 2018 to December 2022. The correlation analysis is part of the research design, which utilizes secondary data collected and analyzed in Microsoft Excel. The findings suggest that moderate intensity rainfall is responsible for 73.3% of floods that occurred between 2018-2022. Moreover, 26.7% of floods occurred when rainfall is less than 20 mm/day. However, other factors such as monsoons, tropical cyclones, and El-Nino Southern Oscillation (ENSO) can affect the variability of rainfall and inffluence the occurrence of flood in the area.

Effects of the insecticide imidacloprid on aquatic invertebrate communities of the Ecuadorian Amazon

Imidacloprid is a neonicotinoid insecticide that has received particular attention due to its widespread use and potential adverse effects for aquatic and terrestrial ecosystems. Its toxicity to aquatic organisms has been evaluated in central and southern Europe as well as in (sub-)tropical regions of Africa and Asia, showing high toxic potential for some aquatic insects and zooplankton taxa. However, its toxicity to aquatic organisms representative of tropical regions of Latin America has never been evaluated. To fill this knowledge gap, we carried out a mesocosm experiment to assess the short- and long-term effects of imidacloprid on freshwater invertebrate communities representative of the Ecuadorian Amazon. A mesocosm experiment was conducted with five weekly applications of imidacloprid at four nominal concentrations (0.01 μg/L, 0.1 μg/L, 1 μg/L and 10 μg/L). Toxic effects were evaluated on zooplankton and macroinvertebrate populations and communities, as well as on water quality parameters for 70 days. Given the climatic conditions prevailing in the study area, characterized by a high solar radiation and abundant rainfall that resulted in mesocosm overflow, there was a rapid dissipation of the test compound from the water column (half-life: 4 days). The macroinvertebrate taxa Callibaetis pictus (Ephemeroptera), Chironomus sp. (Diptera), and the zooplankton taxon Macrocyclops sp., showed population declines caused by the imidacloprid treatment, with a 21-d Time Weighted Average No Observed Effect Concentrations (21-d TWA NOEC) of 0.46 μg/L, except for C. pictus which presented a 21-d TWA NOEC of 0.05 μg/L. In general terms, the sensitivity of these taxa to imidacloprid was greater than that reported for surrogate taxa in temperate zones and similar to that reported in other (sub-)tropical regions. These results confirm the high sensitivity of tropical aquatic invertebrates to this compound and suggest the need to establish regulations for the control of imidacloprid contamination in Amazonian freshwater ecosystems.

Dampak Alih Fungsi Lahan Sawah ke Kolam Ikan Air Tawar terhadap Pendapatan Petani di Kecamatan Padang Gelugur, Kabupaten Pasaman

This research aims to investigate two main aspects in Padang Gelugur Subdistrict, Pasaman Regency: first, the change in paddy field area into fish ponds from 2017 to 2022; second, to analyze the factors influencing this land conversion. The research method used is a mixed methods approach, which integrates quantitative and qualitative data to answer research questions related to behavior, social, and health aspects. The research results indicate that during the period from 2017 to 2022, approximately 144 hectares of paddy fields were converted into fish ponds. The main factors driving the community to undertake this land conversion include the significant income difference between paddy harvests and fish ponds, with income from fish ponds tending to be higher. Additionally, educational factors and weather conditions also play a significant role, particularly as Padang Gelugur Subdistrict frequently experiences high rainfall intensity, which can lead to flooding and crop failure.

Flood Susceptibility Mapping for Kedah State, Malaysia: Geographics Information System-Based Machine Learning Approach

ABSTRACT Background: The world economy is significantly impacted by floods. Identifying flood risk is essential to flood mitigation techniques. Aim: The primary goal of this study is to create a geographic information system (GIS)-based flood susceptibility map for the study area. Methods: Ten flood-influencing factors from a geospatial database were taken into account when mapping the flood-prone areas. Every element demonstrated a robust relationship with the probability of flooding. Results: The highest contributing elements for the flood disaster in the study region were drainage density, distance, and the curvature. Flood susceptibility models’ performance was validated using standard statistical measures and AUC. The ROC curves demonstrated that all ensemble models had good performance on the validation data sets (AUC = >0.97) with high accuracy scores of 0.80. Based on the flood susceptibility maps, most of the northwest regions of the study area are more likely to flood because of low land areas, areas with a lower gradient slope, linear and concave shape curvature, high drainage density with high rainfall, more “water bodies,” “crops land,” and “built areas,” abundance on sea and surface water, and Quaternary types of soil feature and so on. The very high flood susceptibility class accounts for 18.2% of the study area, according to the RF-embedding model, whereas the high, moderate, low, and very low susceptibility classes were found at about 20.0%, 24.6%, 24.3%, and 12.9%, respectively. Conclusion: In comparison with other commonly used applied approaches, this research presents a novel modeling approach for flood susceptibility that integrates machine learning and geospatial data. It has been found to be stronger and more efficient, highly accurate, has good prediction performance, and is less biased. Overall, our research into machine learning-based solutions points in a positive path technologically and can serve as a reference manual for future research and applications for academic specialists and decision-makers.

Positive effects of intercrop yields in farms from across Europe depend on rainfall, crop composition, and management

Modern “intensive” agriculture drives the biodiversity-climate crisis but is also central to global food security. Future farming needs management approaches that maintain (or even enhance) food production while reducing negative climate and biodiversity impacts. Intercrops could provide part of the solution, increasing biodiversity and boosting production with fewer inputs. However, barriers remain to their wide-scale uptake, in particular tailoring intercrops to local equipment, management practice, and environment. We analyze data from multiple trials of cereal-legume intercrops conducted on farms across Europe between 2018 and 2021. Our study is the first attempt, to our knowledge, to quantify the yield benefits of cereal-legume intercropping undertaken at commercially relevant scales for farms across Europe. We used crop performance ratio (CPR)—the ratio of the observed intercrop yield compared to the expected yield based on monoculture yields—as our metric of intercrop performance. Using CPR, we found a roughly 30% yield gain across all sites. However, CPR was modulated by a number of factors. CPR was not strongly affected by management except for the negative effects of direct drilling and the positive effects of organic fertilizer addition. CPR also depended on intercrop composition (number and identity of components), background yields (being highest where yields were lower), and rainfall (being higher with higher rainfall). Our findings allow us to reduce uncertainty about how intercrops will perform in realistic local farm conditions, give guidance for tailoring intercrops to local farming conditions, and provide key goals for further work to integrate intercrops into sustainable farming systems.

Vulnerability to climate change of coastal mangrove-dependent communities in the Tana Delta, Kenya: a local perspective

Coastal mangrove-dependent communities face various risks due to climate change, thus rendering them vulnerable. This study explored the vulnerability of these communities in the Tana Delta in Kenya using an indicator-based vulnerability assessment framework to better understand their exposure, sensitivity and adaptive capacity. Data was collected through household surveys (n = 377), focus group discussions (FGDs), and key informant interviews (KIIs). The analysis revealed mean vulnerability indices at the sub-location level ranged from 0.850 for Kipini to − 0.913 for Kilelengwani and − 2.702 for Ozi. The statistically significant indicators of vulnerability were (i) exposure—high temperatures and rainfall changes; (ii) sensitivity—household numbers, head of household’s age, dependents’ education, and dependents’ employment; and (iii) adaptive capacity—ownership of assets, access to community infrastructure and services, condition/quality of houses, total income, and alternative sources of income. The findings highlight the need for adaptation strategies that ensure greater financial assets supported by education and skills enhancement to utilize existing opportunities. Attention to community infrastructure and services is crucial. Policy should focus on financial, physical, and human assets to reduce community vulnerability alongside the continued conservation and management of mangrove resources. The results will help policymakers in addressing the impacts of climate change and benefit households in the study area. These insights can be applied to regions with similar climate conditions and livelihood systems.

Investigated Signal-to-Noise Ratio for Terrestrial Free Space Optical based on Libya Cities Data

Free Space Optical (FSO) communication links offer high-speed data transmission but can be affected by weather conditions like rain, haze, fog, and snow. This study investigates the impact of rain on FSO link availability in the Libyan cities of Garian, Elkhoms, and Tripoli. An empirical model based on the ITU Carb. (France) Model is proposed to predict FSO link availability for ranges up to 5 km. Rain data shows that Garian has the highest rainfall, followed by Elkhoms and Tripoli. The study examines the effects of rainfall on FSO link performance for these three cities over a 5 km link distance. The results show that signal-to-noise ratio (SNR) and received power at the FSO link are influenced by both rainfall and path length. For a 2 km link distance, the SNR ranges from 16 dB in Tripoli to 10 dB in Garian. Under the influence of rain, the SNR varies from 45 dB to 5 dB over a link distance of 1 km to 5 km.

Understanding woody plant encroachment: A plant functional trait approach

AbstractThe increasing density of woody plants threatens the integrity of grassy ecosystems. It remains unclear if such encroachment can be explained mostly by direct effects of resources on woody plant growth or by indirect effects of disturbances imposing tree recruitment limitation. Here, we investigate whether woody plant functional traits provide a mechanistic understanding of the complex relationships between these resource and disturbance effects. We first assess the role of rainfall, soil fertility, texture, and geomorphology to explain variation in woody plant encroachment (WPE) following livestock grazing and consequent fire suppression across the Serengeti ecosystem. Second, we explore trait‐environment relationships and how these mediate vegetation response to fire suppression. We find that WPE is strongest in areas with high soil fertility, high rainfall, and intermediate catena positions. These conditions also promote woody plant communities characterized by small stature and seed sizes smaller relative to a comparative baseline within the Serengeti ecosystem, alongside high recruit densities (linked to a recruitment‐stature trade‐off). The positioning of species along this “recruitment‐stature axis” predicted woody stem density increase in livestock sites. Structural equation modeling suggested a causal pathway where environmental factors shape the community trait composition, subsequently influencing woody recruit numbers. These numbers, in turn, predicted an area's vulnerability to WPE. Our study underscores the importance of trait‐environment relationships in predicting the impact of human alterations on local vegetation change. Understanding how environmental factors directly (resources) and indirectly (legacy effects and plant traits) determine WPE supports the development of process‐based ecosystem structure and function models.

Total and Extractable Micronutrients in Tropical Acid Soils of Lampung, Indonesia

ABSTRACT The study aimed to determine the total and available amounts of iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu) in the humid tropical acid soils of Lampung, Indonesia, and to identify the key factors affecting them. Topsoil samples were taken from 10 agricultural fields and 6 natural fields in 16 sub-districts of Lampung, Indonesia. The average total contents of Fe (26.36 g kg−1), Cu (8.97 mg kg−1), and Zn (53.24 mg kg−1) are generally below the world-soil average contents and those in other acid soils, which may be due to eluviation of Fe, Cu, and Zn into subsoil induced by high rainfall and the low natural contents of especially Cu and Zn in the parent rocks (acid volcanic rocks and sandstone). In contrast, the average total Mn content (1.20 g kg−1) is 2 to 8 times higher than that commonly found in acid soils and the world-soil average content, indicating that the parent materials may contain high Mn-bearing minerals. The total Fe, Mn, and Zn are positively correlated to the clay content, exchangeable-Ca and -Mg, and exchangeable-Mg, respectively, whereas the total Cu has no correlation to any soil properties. The amounts of available Fe, Mn, Cu, and Zn account for on average 0.38%, 6.20%, 21.50%, and 4.40% of the total contents, respectively. Around 6%, 12.5%, and 56% of the soil samples exhibit Mn, Cu, and Zn deficiency, respectively, and 25% face Fe toxicity. Total Fe and Mn are the main factors determining available Fe and Mn, respectively, whereas exchangeable-Mg and organic-C content mainly control available Cu and Zn, respectively.

Seasonal and Circadian Variation of Non-Volatile Metabolites in Lippia alba Leaves.

The present study describes the seasonal and circadian variations of the major compounds from Lippia alba leaves. SPSS was used to identify, quantify, and associate the variations in the secondary metabolites of this species through HPLC/DAD analysis of the leaves hydroethanolic extracts of six selected L. alba specimens. For the circadian study, the samples were collected at four different daily hours in each year's season. For the seasonal study, the samples were collected monthly from the same individuals for two consecutive years (2018 and 2019). These samples were analyzed and quantified using a validated HPLC method for flavonoids, iridoids, and phenyl ethanoid glycoside. Mussaenoside, acteoside, and tricin-7-O-diglucuronide showed a moderate positive correlation between their biosynthesis and the precipitation index, while epi-loganin had a moderate negative correlation. Acteoside showed a moderate positive correlation between the minimum registered temperature and its production. Compared with previous studies, a drastic reduction (about 95 %) in the production of tricin-7-O-diglucuronide compared with previous study and this difference could be attributed to the plant's aging. Thus, the data demonstrated that lower temperatures and high rainfall could favor the production of the major L. alba active compounds (acteoside and tricin-7-O-diglucuronide) and that older plants harm their production.