Field Plots Research Articles

Effects of Different Intertillage Practices on Soil Biochemical Properties and Soybean Yield in Soybean Fields

Heilongjiang Province, China, is a major soybean-producing area where low temperatures in early spring and poor soil moisture retention are the main limiting factors leading to low soybean yields. To improve land productivity, this study was conducted in Heilongjiang Province, China, from 2020–2021 via a field plot trial method, where four different intertillage treatments were set up in 2020: conventional intertillage (T1), early intertillage (T2), conventional subsoiling (T3), and early subsoiling (T4). In 2021, the effects of intertillage on soil biochemical characteristics and soybean yield formation were systematically analyzed under the T5 treatment (subsoiling at the stage of full development from the fourth to the fifth compound leaf) and the T6 treatment (soil culture at the stage of full development from the fourth to the fifth compound leaf). The results of the experiment revealed that deep loosening in advance improved the chemical properties of the soil. Compared with those of the T1 treatment, the contents of the organic carbon, total nitrogen, and available phosphorus and potassium in the early subsoiling treatments (T4, T5, and T6) were significantly increased. Intertillage time and depth had a strong influence on the soil microbial characteristics. Early medium intertillage could significantly increase the species abundance of bacteria and fungi in the soil, whereas subsoiling could increase the relative abundance ratio and uniformity of the dominant species. Compared with that in the T1 treatment, the yield of soybean in the T4 treatment was significantly greater, with yield increases ranging from 18.71% to 19.36%. In summary, the intertillage measures of one deep loosening and one medium soil cultivation at the stage of full development from the fourth to the fifth compound leaf and one large soil cultivation at the stage of full development from the sixth to the seventh compound leaf can be adopted on the basis of early deep loosening 4–5 d after soybean sowing to achieve high soybean yields. The results provide a theoretical basis for increasing the yield and efficiency of soybean fields under corn–soybean rotation, as well as innovation and development of cultivation systems

Study of the mechanism by which Bacillus subtilis improves the soil bacterial community environment in severely saline-alkali cotton fields.

Soil salinization severely damages the soil bacterial community environment. Bacillus subtilis can improve bacterial communities and enhance crop nutrient absorption. However, the mechanism by which B. subtilis improves the bacterial community environment in heavily saline-alkali-treated cotton fields is currently unclear. Therefore, this study adopted a field plot experiment and established four bacterial treatments (0, 9, 12, and 15kg·ha-1) to investigate the environmental improvement mechanism of B. subtilis on soil bacterial communities in severely saline alkali cotton fields was studied. Compared with the CK treatment, the application of B. subtilis significantly increased the available nitrogen (25.34%), available phosphorus (50.894%), available potassium (86.87%), and urease (112.961%) contents but significantly reduced the soil pH (1.07%) and salt content (39.73%) and significantly increased the proline (245.116%) and superoxide dismutase (237.46%) contents in the leaves and significantly reduced the malondialdehyde content (47.30%). This is mainly because B. subtilis enhances the diversity of bacterial communities and affects catalase, urease, phosphatase, and protease activities, thereby promoting nutrient release in the soil and improving soil fertility; specifically, B. subtilis promotes the secretion of oxalic acid, formic acid, malic acid, and soluble total sugars in cotton roots. The organic acids in root exudates lower the soil pH and chelate with salt ions in the soil, reducing the concentration of soluble salts and providing a suitable environment for B. subtilis. Soluble total sugars can provide energy and carbon sources for bacteria, maintaining the health and diversity of rhizosphere bacterial communities. The results of the principal component analysis revealed that the application rate of B. subtilis was 12kg·ha-1, which had the greatest effect on improving the soil bacterial community in severely saline-alkali cotton fields. The research results provide a theoretical basis and practical reference for microbial improvement in severely saline-alkali land in arid areas.

Rare earth benzene tetraanion-bridged amidinate complexes.

The benzene tetraanion-bridged rare earth inverse arene amidinate complexes [{Ln(κ1:η6-Piso)}2(μ-η6:η6-C6H6)] (2-Ln, Ln = Gd, Tb, Dy, Y; Piso = {(NDipp)2C t Bu}, Dipp = C6H3 iPr2-2,6) were prepared by the reduction of parent Ln(iii) bis-amidinate halide precursors [Ln(Piso)2X] (Ln = Tb, Dy; X = Cl, I) or [Ln(Piso)2I] (Ln = Gd, Y) with 3 eq. KC8 in benzene, or by the reaction of the homoleptic Ln(ii) complexes [Ln(Piso)2] (Ln = Tb, Dy) with 2 eq. KC8 in benzene. The arene exchange reaction of 2-Tb with toluene gave crystals of [{Tb(κ1:η6-Piso)}2(μ-η6:η6-C7H8)] (3-Tb), while no reactions were observed when C6D6 solutions of 2-Y were separately treated with biphenyl, naphthalene or anthracene. The reactivity study shows that 2-Y can behave as a four-electron reductant to reduce 1,3,5,7-cyclooctatetraene (COT). Complexes 2-Ln were characterized by single crystal X-ray diffraction, elemental analysis, SQUID magnetometry, UV-vis-NIR, ATR-IR, NMR, density functional theory (DFT) and ab initio calculations. These data consistently show that 2-Ln formally contain Ln(iii) centres with arene-capped inverse-sandwich Dipp-Ln(iii)-(C6H6)4--Ln(iii)-Dipp configurations, and DFT calculations on a model of 2-Y revealed strong Y-(C6H6)4- δ-bonding interactions between the filled π-orbitals of the benzene tetraanion and vacant 4d orbitals of the Y(iii) ions. A strong intermolecular coupling interaction between the two Tb(iii) centres in 2-Tb (J tot = -6.84 cm-1) was evidenced by a step in a magnetization vs. field plot of 2-Tb at ca. 3.4 T at 2 K, which we attribute to an anti-ferromagnetic transition of the magnetic moment; we also determined an exchange coupling constant J ex = -0.25(1) cm-1 for 2-Gd.

Development and establishment of the laboratory for plant immunity of the FSBSI “ARC “Donskoy”

The current paper has presented the stages of the development on plant protection study over 115 years and the history of the establishing and functioning of the laboratory for plant immunity since 1974 (50 years) at the Federal State Budgetary Scientific Institution “ARC “Donskoy”. There has been presented the papers of such specialists in plant protection and immunity as Cheskis F. N., Deyanov I.G., Shchegolev V. N., Makarova V. A., Pronicheva L. L., Chala V. A. and others, who began their research from the beginning of the last century till its second half. Taking into account the immunological characteristics in conditions of infectious disease backgrounds of varieties and parental forms, there have been developed new grain varieties, combining high productivity with resistance to a complex of local populations of the main diseases and strong immunity to pests. The heads of the laboratory for plant immunity and protection set up in 1974 were Georgievskaya N. A., Derov A. I., Derova T. G., Shishkin N. V. (who is a current head). In the field plot there were formed infectious disease backgrounds and backgrounds with high pest numbers using both generally accepted methods and new ones developed by the laboratory staff, where there were studied up to 25–30 thousand samples of various crops annually. The staff developed methods for forming backgrounds with high pest numbers, there were improved and proposed simpler and more accurate methods for insect counts. In order to estimate the number of corn bug larvae, there was developed and proposed a convenient productive screencollector, as well as methods for accounting for corn thrips using test tubes and plastic bags and methods for identifying wheat and barley grain damaged by pests. In different years, there were studied such crops as maize, perennial grasses, peas, soybeans, and rice for resistance to diseases and pests. The identified resistant varieties and samples were given to breeders for using them in breeding programs for immunity. Many employees are co-authors of the developed varieties of various crops.

Soil Burn Severity Assessment Using Sentinel-2 and Radiometric Measurements

The objective of this article is to create soil burn severity maps to serve as field support for erosion tasks after forest fire occurrence in Spain (2017–2022). The Analytical Spectral Device (ASD) FieldSpec and the CIMEL CE-312 radiometers (optical and thermal, respectively) were used as input data to establish relationships between soil burn severity and reflectance or emissivity, respectively. Spectral indices related to popular forest fire studies and soil assessment were calculated by Sentinel-2 convolved reflectance. All the spectral indices that achieve the separability index algorithm (SI) were validated using specificity, sensitivity, accuracy (ACC), balanced accuracy (BACC), F1-score (F1), and Cohen’s kappa index (k), with 503 field plots. The results displayed the highest overall accuracy results using the Iron Oxide ratio (IOR) index: ACC = 0.71, BACC = 0.76, F1 = 0.63 and k = 0.50, respectively. In addition, IOR was the only spectral index with an acceptable k value (k = 0.50). It is demonstrated that, together with NIR and SWIR spectral bands, the use of blue spectral band reduces atmospheric interferences and improves the accuracy of soil burn severity mapping. The maps obtained in this study could be highly valuable to forest agents for soil erosion restoration tasks.

Evaluation of Newly-transplanted Blackberry Tolerance to a Selection of Preemergence Herbicides

Abstract This trial assessed the effect of preemergence herbicides on newly transplanted blackberries. A two-year field trial was initiated in 2021 and conducted at two locations: Fayetteville, AR and Clarksville, AR. Seven treatments consisted of six preemergence herbicides (flumioxazin, mesotrione, napropamide, oryzalin, pendimethalin, and S-metolachlor) and one nontreated check. Preemergence herbicide treatments were applied to field plots of newly-transplanted blackberry plugs (var. ‘Ouachita’), using a CO2 backpack sprayer at 187 L ha-1 covering a 1 m swath, ensuring spray pattern overlap over newly planted blackberries in 2021 and reapplied in the same manner to established blackberries of the same plots in 2022. Data were collected on crop injury and plant height of blackberry plants in each plot. Yield data was collected in the second year, and fruit were analyzed for soluble solids content, pH, and average berry weight. In the first year mesotrione and flumioxazin treatments caused injury to newly transplanted blackberries, and mesotrione-treated blackberries (58% - Fayetteville, 29% - Clarksville) did not fully recover by 84 days after treatment (DAT). Napropamide, S-metolachlor, oryzalin, and pendimethalin did not cause crop injury over 6% throughout the 2021 season. In the second year (2022), no crop injury was caused by any herbicide treatments. Results from these trials verify that flumioxazin, napropamide, oryzalin, and pendimethalin at the tested rates would be appropriate options for weed control in newly planted blackberries. These results corroborate regional recommendations against the use of mesotrione in first year blackberry plantings. The findings from this trial indicate S-metolachlor would be safe for registration for use in blackberries, regarding crop injury and blackberry yield.

Effect of fast and slow-acting bait toxicants on tawny crazy ant (Hymenoptera: Formicidae) foraging and nesting in the field.

Tawny crazy ants (TCAs), Nylanderia fulva (Mayr) are an invasive species that develops extremely large populations that overrun landscapes. Control measures frequently rely on spraying contact insecticides, which often are inadequate. To provide insights for utilizing baits for their control, TCA foraging behavior was examined on liquid ant bait formulations that contained either fast-acting dinotefuran or slow-acting disodium octaborate tetrahydrate (DOT), and the impacts of these baits were assessed. Bayesian modeling of counts from time-lapse photography of TCA feeding on the baits and a control of sucrose solution in the field revealed strong evidence of similar foraging intensities between the control and the DOT bait and less foraging intensity on the dinotefuran bait. TCA abundance on the dinotefuran bait peaked within 8h, then diminished to smaller feeding bouts over the 3-day study. In contrast, foraging on the DOT and control remained consistently high before bait depletion. The impact of the fast and slow-acting baits in field plots were based on TCA nest sizes and TCA abundance on sausage lures. Bayesian modeling predictions revealed nest sizes declined over the 2 months with bait present while the control had large nests. Abundance on the lures in the dinotefuran plots declined from the start of the study, while with the slow-acting DOT bait, declines in abundance were not lower than the control plot until 30 days after baiting was initiated. Further refinements in baiting with liquid baits containing fast and slow acting active ingredients may provide fast and sustained control of TCA.

Comparison of Visual and Normalized Difference Vegetation Index (NDVI) Assessments to Predict the Yield Tolerance of Wheat Genotypes to Root-Lesion Nematode Pratylenchus thornei

Wheat breeding programs have selected genotypes that are tolerant to the root-lesion nematode Pratylenchus thornei by measuring grain yield in field plots on infested sites. However, quicker methods are desirable to increase the capacity to assess more breeding lines for tolerance without harvesting grain. Two field experiments, time of sowing 1 (TOS1) and time of sowing 2 (TOS2), were conducted in the subtropical grain region of eastern Australia each year for eight years (sixteen experiments total) to characterize 396 wheat genotypes for tolerance when grown on high population densities of P. thornei. For each experiment, up to two visual tolerance ratings (TRs) and two normalized difference vegetation index (NDVI) readings were recorded using a Greenseeker™ during crop growth, and grain yield was obtained at crop maturity. The results showed that both TR and NDVI were predictive of tolerance based on the grain yield of the wheat genotypes. Generally, higher genetic correlations between grain yield and each vegetative assessment method were obtained with TOS2 than with TOS1 each year. The vegetative methods for assessing P. thornei tolerance proved to be valuable surrogates when grain yield was unreliable for germplasms that were agronomically unadapted to the regional environment. Our study established that at high population densities of P. thornei only, NDVI is a high-throughput phenotypic measurement of tolerance that can be used to screen a range of genetically diverse genotypes.

Microbiome Structures and Beneficial Bacteria in Soybean Roots Under Field Conditions of Prolonged High Temperatures and Drought Stress.

Drought stress has a significant impact on agricultural productivity, affecting key crops such as soybeans, the second most widely cultivated crop in the United States. Endophytic and rhizospheric microbial diversity analyses were conducted with soybean plants cultivated during the 2023 growing season amid extreme weather conditions of prolonged high temperatures and drought in Louisiana. Specifically, surviving and non-surviving soybean plants were collected from two plots of a Louisiana soybean field severely damaged by extreme heat and drought conditions in 2023. Although no significant difference was observed between surviving and non-surviving plants in microbial diversity of the rhizosphere, obvious differences were found in the structure of the endophytic microbial community in root tissues between the two plant conditions. In particular, the bacterial genera belonging to Proteobacteria, Pseudomonas and Pantoea, were predominant in the surviving root tissues, while the bacterial genus Streptomyces was conspicuously dominant in the non-surviving (dead) root tissues. Co-occurrence patterns and network centrality analyses enabled us to discern the intricate characteristics of operational taxonomic units (OTUs) within endophytic and rhizospheric networks. Additionally, we isolated and identified bacterial strains that enhanced soybean tolerance to drought stresses, which were sourced from soybean plants under a drought field condition. The 16S rDNA sequence analysis revealed that the beneficial bacterial strains belong to the genera Acinetobacter, Pseudomonas, Enterobacter, and Stenotrophomonas. Specific bacterial strains, particularly those identified as Acinetobacter pittii and Pseudomonas sp., significantly enhanced plant growth metrics and reduced drought stress indices in soybean plants through seed treatment. Overall, this study advances our understanding of the soybean-associated microbiome structure under drought stress, paving the way for future research to develop innovative strategies and biological tools for enhancing soybean resilience to drought.

Estimating tree aboveground biomass in an Atlantic Forest remnant using different modelling methods

The Atlantic Forest stores vast amounts of aboveground biomass (AGB), yet it is still a challenge to estimate these stocks. We aimed to predict the AGB stock of the largest biodiversity remnant of Serra da Tiririca State Park (Rio de Janeiro, Brazil) by comparing the accuracy of generalized linear models (GLM) and random forest (RF) models, using data from field plots, remote sensing, and environmental variables. The plots showed an AGB of 371.12 Mg/ha. The comparison between the modelling methods revealed that the GLM is more accurate, still the RF is also fit to estimate the AGB of the remnant. The most accurate GLM predicted an AGB of 405.31 Mg/ha. We observed that the accuracy of the models improved when all predictor variables were combined. This study allowed us to improve the AGB estimates, and produce an AGB map useful for the management and conservation of the remnant

STRUKTUR POPULASI, KOMPOSISI PROKSIMAT DAN MINERAL KEONG GONDANG (Pila scutata) PADA EKOSISTEM PERSAWAHAN DI WILAYAH KABUPATEN GIANYAR

The Pila scutata is a species of Mollusca Phylum that is also known as the kakul in Bali and the gondang snail in Indonesia. The environment of rice fields is one of the snail's habitats. Snails are utilized in religious ceremonies in Bali as a ceremonial component and as an alternate source of protein. The purpose of this study was to ascertain the snail population structure, including density, frequency of presence, and dispersion patterns in Gianyar Regency's rice field ecosystem. The snail sample's mineral and proximate compositions were also examined. Samples were collected from three plots of rice fields with rice plants that were less than a month old at each of the several rice field locations. Sampling using a 1m × 1m square positioned in every rice field corner. Environmental factor measurements are made for every sample. Samples of snails collected from every site were brought to the laboratory for morphological analysis and counting. According to research result, there were 0,83–2,0 ind/m2 of snails, 58,33–91,67% of the frequency of present, and their distribution pattern was regular. There was more than 50% protein. Iron 18,987–38,70; potassium 162,886-216,121, 407,082–567,960 mg/100g; copper and lead not found. Calcium content ranges 90,347–122,97 mg/100g. Keywords: Freshwater snail; native species; nutrition; rice field

Long-Term Conservation Agriculture Improves Soil Quality in Sloped Farmland Planting Systems.

Conservation agriculture practices (CAs) are important under the increasingly serious soil quality degradation of sloping farmlands worldwide. However, little is known about how the long-term application of CAs influences soil quality at different slope positions. We conducted field experiments for a watershed sloping farmland's mainstream planting systems in the Three Gorges Reservoir area of China. Orchard plots were treated with a conventional citrus planting pattern (C-CK), citrus intercropped with white clover (WC), citrus orchard soil mulched with straw (SM) and citrus intercropped with Hemerocallis flava contour hedgerows (HF). Crop field plots were treated with a conventional wheat-peanut rotation (W-CK), a wheat-peanut rotation intercropped with Toona sinensis contour hedgerows (TS), a wheat-peanut rotation intercropped with alfalfa contour hedgerows (AF) and a ryegrass-sesame rotation (RS). We collected soil samples from the plots at the upper, middle and lower slope positions and measured their soil properties after a nine-year experiment. We found that (1) CAs improved the soil properties at the three slope positions; (2) the effect of the CAs on the soil properties was more significant than that on the slope position; and (3) the soil quality index at the upper, middle and lower slope positions increased by 29.9%, 45.8% and 33.3%, respectively, for WC; 48.7%, 39.5% and 27.1%, respectively, for SM; and 21.7%, 25.5% and 21.6%, respectively, for HF compared to C-CK; as well as 18.7%, 23.7% and 20.4%, respectively, for TS; 16.9%, 18.6% and 16.5%, respectively, for AF; and 16.1%, 13.0% and 13.9%, respectively, for RS compared to W-CK. These findings suggest that long-term CA application enhances the soil quality of the slope position, of which SM and TS applied to orchards and crop fields, respectively, are the most effective.

Physical and Biochemical Characteristics of Soil in a Watershed of the Valley of Oueme: A Rice-based Agroforestry System in the South of Benin

The present study aimed to assess the sustainability of rice cultivation in regard to soil physical and biochemical characteristics within the watershed of the Valley of Oueme. by promoting agroforestry in rice-growing systems. For that concern, four kinds of areas were showcased for rice cultivation: Adjido. Agondo. Dame, and Houedomey. Eighty-nine thoughts of farmers on their knowledge of involvement of trees in field production were assessed. Soil samples were collected into rice fields and near of the “under trees” at 0-20 cm alongside the village of Hetin-Houedomey from April to June 2023. It was conducted into some of pieces of plots of lowland rice field to study soil physical and chemical properties. Spores’ density of Arbuscular Mycorrhizas Fungi (AMF) in that soil and their diversity were assessed. A correlation test indicated regarding quantities of clay, silt, and sand, there is a predominance of clay at the “under trees”, and in the fields, that tends to disappear little by little as we move away from trees. The pH (water) of the soil sampled is acidic and varied from 4.37 to 5.44. For chemical analysis, the average rate of total nitrogen varied from 0.218% to 1.476%. The concentrations of available phosphorus in the Valley of Oueme varied from 2 to 7 cmol/kg that revealed weak. Soils appeared to be rich in exchangeable potassium (0.21 and 1.1 cmol/kg) with the highest proportion observed under the tree in the higher topographic altitudes from the village of Dame. The Cation Exchange Capacity (CEC) for its part varied between 11.36 and 59.68 cmol/kg, and with the highest value that is in higher topographic altitudes at the Adjido county. Sixteen Glomus species of AMF were identified and the Glomus multisubstensum was the most abundant. The community of AMF was mostly diversified in the “under trees” soil, according to the Shannon index H = 5.5.

Comparing the Accuracy and Efficiency of Leaf Gas Exchange Measurements of Excised and Nonexcised Strawberry (Fragaria ×ananassa Duch. ‘Camino Real’) Leaves

Acquiring leaf gas exchange (LGE) data from field experiments is critical for numerous research endeavors. However, because of the extended time needed to perform measurements and the necessity for moving equipment, the number of leaf samples collected is often limited. To address this concern, two studies were conducted to evaluate the accuracy and efficiency of LGE measurements of excised and nonexcised strawberry leaves. Research was conducted in experimental field plots located in Lubbock, TX, USA, where ‘Camino Real’ strawberry leaves was sampled for LGE measurements, during the 2021 growing season. Using an auto program mode, two LI-6400/XT portable machines simultaneously measured the LGE of nearby selected leaves from the same plant. Measurements were recorded every 30 seconds. After 90 seconds, the petiole of one leaf was cut (excised leaf treatment), and the auto program continued for an additional 480 seconds. The results indicated that although the LGE for nonexcised leaves remained stable, excised leaf LGE changed after excision. Within 30 seconds, the postexcision stomatal conductance to water vapor (gsw) and net leaf photosynthetic rate (A) exhibited nearly 97% and 99% accuracy, respectively, of nonexcised leaf gsw and A. However, the excised LGE decrease accelerated over time, with gsw continuing to decrease by more than 5% after 43 seconds, indicating ≤95% accuracy of the gsw results. The data suggested that strawberry LGE may be measured accurately within 30 to 40 seconds after leaf excision. During a separate experiment, the mean time to complete each individual strawberry LGE measurement was 68.4 seconds (±0.9 seconds) for nonexcised leaves. Conversely, the mean time to complete each LGE measurement of excised leaves was 42.2 seconds (±0.2 seconds). Therefore, leaf excision appears to be a viable method of maintaining accuracy and increasing the sample size while collecting strawberry LGE data.

Synthesizing Field Plot and Airborne Remote Sensing Data to Enhance National Forest Inventory Mapping in the Boreal Forest of Interior Alaska

Synthesizing Field Plot and Airborne Remote Sensing Data to Enhance National Forest Inventory Mapping in the Boreal Forest of Interior Alaska

Effects of rhizobacteria producing deaminase enzymes for aminocyclopropane‐1‐carboxylate on drought tolerance and post‐stress recovery in creeping bentgrass under field conditions

AbstractSome endophytic rhizobacteria, including species producing deaminase enzymes for 1‐aminocyclopropane‐1‐carboxylic acid (ACC) suppressing ethylene production (ACCd), form symbiosis with plant roots to enhance plant growth and stress tolerance. The objectives of this study were to determine growth‐promoting effects and effective rates of inoculation with ACCd‐producing Paraburkholderia aspalathi (WSF23 and WSF14) on creeping bentgrass (Agrostis stolonifera L.) performance under deficit irrigation in field conditions and effectiveness on post‐stress recovery during re‐watering. Turf field plots established with ‘L‐93’ creeping bentgrass were inoculated with P. aspalathi strains (WSF23 and WSF14) through soil drenching either as a single strain or as a combination of both strains. After inoculation, plots were subjected to drought stress with deficit irrigation to replace 60% of the daily evapotranspiration rate, followed by re‐watering for post‐stress recovery. Three inoculant rates of 1.0, 1.5, and 2.0 × 107 colony‐forming units (CFUs) were evaluated to determine the most effective dosage to apply under field conditions. Inoculation of plants with the consortium of the two strains at 1.5 × 107 CFUs was most effective in enhancing turf quality, percent green cover, normalized difference vegetation index, and dark green color index during drought stress and recovery periods. These results suggest that creeping bentgrass tolerance to drought stress and improved post‐stress recovery could benefit from inoculation with P. aspalathi strains under field conditions and also ACC deaminase‐producing rhizobacteria could be incorporated into turf management programs to maintain creeping bentgrass during abiotic stress conditions.

First Report of the cyst nematode Heterodera koreana parasitizing bamboo (Phyllostachys reticulata) in Georgia, USA.

Soil and root samples were collected from two plots (5.5 x 6 m) cultivated with bamboo Phyllostachys reticulata (syn. P. bambusoides) at the USDA Southeastern Fruit and Tree Nut Research Station in Byron, Georgia, USA, in November 2021, December 2022, and December 2023. Each soil sample consisted of five randomly collected subsamples, which were analyzed for the presence of plant-parasitic nematodes as part of regular monitoring. No aboveground symptoms were seen in the field plots, but roots showed discoloration and stunted growth (Fig. 1A). An average population density of 160, 36, and 188 second-stage juveniles (J2) of cyst nematodes (Heterodera spp.) per 100 cm3 of soil was detected in 2021, 2022, and 2023, respectively. To confirm the cyst nematode parasitism, three healthy P. reticulata plants were transplanted into 10 cm diameter pots filled with nematode-infested soil and grown in a greenhouse at 25-28°C. After three months, young cysts containing eggs protruding from the bamboo roots were seen, confirming nematode parasitism (Fig. 1B and C). Morphological and molecular analyses were conducted to identify the nematode species. The J2 body shape was cylindrical with three incisures in lateral field and well-developed rounded stylet knobs. Measurements of J2 (n = 10) included the length (range = 406.0-518.1 μm, mean = 458.2 ± 16.1 μm) and width (16.0-17.2 μm, 16.6 ± 0.5 μm) of body, labial region height (3.0-3.6 μm, 3.2 ± 0.2 μm), stylet (17.2-18.9 μm, 18.02 ± 0.6 μm), tail (61.1-65.9 μm, 63.1 ± 5.8 μm), body width at anus (9.7-12.4 μm, 10.8 ± 0.3 μm), and hyaline tail terminus (35.4-53.0 μm, 44.0 ± 3.8 μm). The cysts (n = 5) were relatively lemon-shaped, light to dark brown in color with projected neck and vulval cone that lacked fenestration, bullae, and underbridge. Morphometrics were body length including neck (420.5-745.0 μm, 550.4 ± 72 μm), body width (345.0-544.1 μm, 430.1 ± 59 μm), and L/W ratio (1.0-1.4 μm, 1.1 ± 0.1 μm). The morphometric of vulval cone included fenestral length (48 to 69 µm, 60.2 ± 4.0 µm), fenestral width (43 to 51 µm, 48.9 ± 4.0 µm) and vulval slit (47 to 58 µm, 49.1 ± 2.6 µm). Morphology and morphometric measurements of the cysts and J2 (Fig. 2A-C) were comparable to previous reports of Korean cyst nematode, H. koreana from other Asian countries (Mundo-Ocampo et al., 2008; Wang et al., 2012; Tanha Maafi and Taheri, 2015; Sekimoto et al., 2017). For molecular diagnosis, DNA was extracted from single cysts (n= 3) using DNeasy Blood and Tissue Kit, and 28S rRNA and partial cytochrome oxidase I (COI) gene fragments were amplified using D2A/D3B and Het-coxiF/Het-coxiR primer sets, respectively according to Subbotin et al. (2015) and Hajihassani et al. (2018). PCR products were then purified by a DNA Clean & Concentrator kit (Zymo Research, CA, USA) and sequenced at Genewiz (South Plainfield, NJ, USA). The resulting sequences were deposited into the GenBank database and subjected to BLASTn searches. Sequence analysis of the 28S rRNA gene (GenBank accession number OL812726) showed that the H. koreana isolate from Georgia was 100% identical (692/692 bp) with H. koreana populations from Japan and South Korea. Analysis of the H. koreana isolate from Georgia based on the COI sequence (OL813218 and OL813219) revealed 100% similarity (421/422 bp) with a population of H. koreana from Japan and 98% similarity (409/409 bp) with a population from South Korea. To our knowledge, this is the first report of H. koreana parasitizing P. reticulata in Georgia as the second state in the USA. This nematode was first reported in Florida infecting fish pole bamboo (P. aurea) propagated from plant material from the Far East (Inserra et al. 1999). This report expands the information on the geographical distribution of H. koreana. Given the significant potential for damage to bamboo, precautions should be taken to prevent the nematode's spread to unaffected regions.

Detection of snow disturbances in boreal forests using unitemporal airborne lidar data and aerial images

Abstract Snow is among the most significant natural disturbance agents in Finland. In silviculture, maps of snow disturbance are needed to recognize severely disturbed forests where the risk of subsequential disturbances, such as insect outbreaks, is high. We investigated the potential of unitemporal airborne lidar (light detection and ranging) data and aerial images to detect snow disturbance at the tree level. We used 81 healthy and 128 snow-disturbed field plots established in a 63 800 ha study area in Eastern Finland. A subset of trees (n = 675) was accurately positioned in the field plots. We carried out individual tree detection (ITD) using airborne lidar data (5 p/m2), and a random forest classifier was used to classify healthy and broken trees. Tree features were extracted from a terrain elevation model, lidar data, and aerial imagery. We compared canopy height model–based (ITDCHM) and point cloud–based (ITDPC) ITD approaches. We explored random forest variable importance scores and evaluated the classification performance by an F1-score and its components (precision and recall). Performance was also evaluated at the plot level to investigate errors associated with the predicted number of broken trees. We achieved F1-scores of 0.66 and 0.85 for the tree- and plot-level classifications, respectively. The variable importance scores showed that elevation above sea level was the most important predictor variable followed by ITD-based features characterizing the neighborhood of trees. The ITDCHM slightly outperformed the ITDPC at the tree level, while they both underestimated the number of broken trees at the plot level. The proposed approach can be carried out alongside lidar-assisted operational forest management inventories provided that a set of positioned broken and healthy trees are available for model training. Since airborne lidar data often have a temporal resolution of several years for the same areas, future research should consider the utilization of other remotely sensed data sources to improve the temporal resolution.

Incorporating Forest Mapping-Related Uncertainty into the Error Propagation of Wall-to-Wall Biomass Maps: A General Approach for Large and Small Areas

The sources of uncertainty in wall-to-wall AGB maps propagate from the tree to pixel, but uncertainty due to forest cover mapping is rarely incorporated into the error propagation process. This study aimed to (1) elaborate an analytical procedure to incorporate forest-mapping-related uncertainty into the error propagation from plot and pixel predictions; (2) develop a stratified estimator with a model-assisted estimator for small and large areas; and (3) estimate the effect of ignoring the mapping uncertainty on the confidence intervals (CIs) for totals. Data consist of a subset of the Brazilian national forest inventory (NFI) database, comprising 75 counties that, once aggregated, served as strata for the stratified estimator. On-ground data were gathered from 152 clusters (plots) and remotely sensed data from Landsat-8 scenes. Four major contributions are highlighted. First, we describe how to incorporate forest-mapping-related uncertainty into the CIs of any forest attribute and spatial resolution. Second, stratified estimators perform better than non-stratified estimators for forest area estimation when the response variable is forest/non-forest. Comparing our stratified estimators, this study indicated greater precision for the stratified estimator than for the regression estimator. Third, using the ratio estimator, we found evidence that the simple field plot information provided by the NFI clusters is sufficient to estimate the proportion forest for large regions as accurately as remote-sensing-based methods, albeit with less precision. Fourth, ignoring forest-mapping-related uncertainty erroneously narrows the CI width as the estimate of proportion forest area decreases. At the small-area level, forest-mapping-related uncertainty led to CIs for total AGB as much as 63% wider in extreme cases. At the large-area level, the CI was 5–7% wider.

Evaluating forest aboveground biomass estimation model using simulated ALS point cloud from an individual-based forest model and 3D radiative transfer model across continents

Area-based approach (ABA) has been widely employed for estimating forest aboveground biomass (AGB) using airborne laser scanning (ALS) data. However, its scalability is limited due to challenges in model generalization across different forest types and regions. The selection of sensitive variables from ALS data is crucial for constructing robust forest AGB estimation models, yet this selection varies significantly among forest types and regions. Traditionally, assessing the influence of variable selection is hindered by the lack of accurate reference forest AGB values. Computer simulation-based method provides a perspective for exploring these challenges. This study employs an individual-based forest growth process model, FORMIND, coupled with a 3D radiative transfer model (RTM), LESS, to evaluate the transferability of ABA-based forest AGB estimation models and the generalization of ALS-derived variables. We used six virtual 3D forest scenes and two real-world forest sites, representing a range of global forest types, along with their simulated ALS data, to develop a forest AGB estimation model using the random forest algorithm, which allowed us to analyze the importance of various variables. We assessed model transferability through cross-comparison. Additionally, we validated the model using field plots and ALS data collected from two distinct regions. The results showed that the canopy surface area and volume extracted using the α-shape algorithm and parameters fitted from the Weibull distribution are vital variables when using ALS for forest AGB estimation across forest types and regions. Incorporating these variables into the model significantly improves the accuracy of forest AGB estimation. The optimized model achieved a R2 of 0.945, a RMSE of 34.22 t/ha, and a MAE of 20.53 t/ha. Our study not only deepens the understanding of the relationship between forest vertical structural metrics and AGB but also highlights the potential of computer simulation as a tool for refining the estimation of forest structural parameters.