Search Results (361)

Substantial tracts of fallow farmland remain unutilized across southwestern China throughout winter and spring. To explore a high-yield planting pattern for utilizing such fallow land, a cereal–legume intercropping experiment was conducted in Chengdu in 2021–2022 and in 2022–2023. This involved five different intercropping ratios of oat (Avena sativa) and common vetch (Vicia sativa) including 100:0, 75:25, 50:50, 25:75, and 0:100 based on seed number per unit area. The relative density, LER (land equivalent ratio), hay yield, nutritional composition and in vitro fermentation characteristics were assessed. The study revealed that the combination of oat and common vetch led to a significant enhancement in the production performance over the monocultures. At the flowering stage, the most balanced interspecific competition was observed at a ratio of 50:50. The ratio of 50:50 had the higher LER in the mixture—from 1.018 to 1.873—, which was significantly higher than the other two intercropping ratios in 2021–2022. At the flowing development stage in 2021–2022, the harvesting of mixed crops at the 50:50 ratio resulted in a significant higher crude protein yield, 1454.7 kg/hm², than the other intercropping ratios. As the growth stage continued, the mixture hay neutral detergent fiber and acid detergent fiber contents increased, while the relative feed value and crude fat content decreased. The soluble sugar content increased with the prolongation of the growth stage and peaked at the jointing stage, and decreased with the decrease in the proportion of oat in the mixture. Additionally, the gas production showed an overall decreasing trend with the increase in the proportion of common vetch. The dry matter degradation rate in the mixture hay was overall higher than that of the monocultures, and the NH₃-N content showed an overall trend of increasing with the decrease with the intercropping ratio of oat. Consequently, the 50:50 ratio may be recommended as an oat-common vetch intercropping ratio suitable for utilizing fallow fields in southwestern China from October to April to produce high-quality forage. Full article

Habitat destruction is a major driver of biodiversity decline, yet how it reshapes multispecies coexistence by altering interaction structure remains unclear. We adopt a spatially explicit metacommunity model framework under a homogeneity assumption and introduce a tunable parameter controlling intransitive competition. Within this framework, we represent the system using a generalized Lotka–Volterra model to examine how coexistence mechanisms respond to habitat destruction. Our findings demonstrate that (1) coexistence is not driven by a single mechanism: under transitive competition, it highly relies on niche differentiation, whereas in intransitive structures, coexistence can be maintained even with low niche differentiation. (2) Habitat destruction compresses the feasible coexistence space, but regions dominated by different mechanisms respond asymmetrically, with niche-difference-driven coexistence shrinking and intransitive-dominated coexistence expanding under certain conditions. (3) The difference stems from habitat destruction, altering the relative proportions of intraspecific and interspecific competition, driving the community beyond the coexistence threshold. This reduces the probability of coexistence and reshapes the relative importance of several coexistence mechanisms. This finding provides a new theoretical perspective for biodiversity in fragmented landscapes. Full article

Riparian vegetation plays an important role in the morphological evolution of rivers; here, an alternative numerical methodology for modeling river morphodynamics influenced by vegetation is presented. The approach integrates a vegetation growth and flow-resistance submodule coupled with the TELEMAC–MASCARET system. Vegetation is represented at the patch scale, and its hydraulic effect is incorporated through an additional drag force in the momentum equation, while stem obstruction is accounted for using the porosity formulation in TELEMAC-2D. Vegetation dynamics consider water depth variability, interspecific competition, and nutrient availability. The model is applied to a braided river reach in southeastern Mexico. The results indicate that riparian vegetation promotes more organized flow paths, enhances bar development, and plays a significant role in modulating bar stability. These findings highlight the importance of explicitly representing flow–sediment–vegetation feedback in river hydro-morphological modeling. Full article

Ascochyta blight remains a major constraint for field pea (Pisum sativum L.) production and a priority for breeding programmes. So far, only moderate levels of incomplete resistance have been identified in pea germplasm and accumulated in pea cultivars by breeding. Resistance identified so far appears to be of complex inheritance, with phenotypic expression strongly affected by plant phenology and morphology and by environ-mental factors. This has slowed down the development and release of resistant elite cultivars. In this work, we describe the development of novel resistant breeding lines derived from targeted intra- and interspecific crosses combined with cycles of selection under high disease pressure at seedling and adult plant stages. The performance of thirteen breeding lines selected for improved resistance and good agronomic traits was further validated in a comparative field trial. Results confirmed the successful combination of competitive yield and good standing ability with good levels of resistance exceeding those of the resistant check. These advanced breeding lines are available on request for research and breeding use. Full article

This study was conducted in the Xinjiang region, China, along the Sino-Kazakh border, an area recognized as high-risk for locust outbreaks and characterized by ongoing shifts in dominant pest species. This study systematically examined the structural characteristics of locust communities across different grassland types and identified the underlying environmental driving mechanisms. Field surveys were conducted to assess the diversity characteristics, density variations, and niche width of the locust communities across the different grassland types. The locust community in the mountain meadows had a significantly lower Shannon diversity index compared with the other grassland types (p < 0.05). Although the Simpson dominance index and Pielou evenness index were also the lowest in the mountain meadows, these differences were not statistically significant (p > 0.05). Permutational multivariate analysis of variance (PermANOVA) revealed highly significant differences in locust density among the grassland types (p = 0.001). Ecological niche analysis revealed stronger interspecific competition in the lowland meadow, and weaker competition in the temperate steppe-enriched deserts and temperate desert grasslands. Structural equation modeling and random forest analysis identified soil organic, plant total potassium, and soil pH as the key factors driving locust community structure across grassland types. This study clarifies the diversity patterns of locust communities in the Xinjiang region along the Sino-Kazakh border and provides empirical data to better understand locust community structure and distribution. It also offers a scientific basis for developing sustainable locust management strategies. Full article

Ground-dwelling pheasants are vital indicators of forest ecosystem health. Understanding their distribution and response to climate change is crucial for regional biodiversity conservation. Based on 97,000 camera-days of infrared monitoring from 2019 to 2022 in Huzhou, China, we analyzed the spatial patterns and niche overlap of five pheasant species, including the first class national protected animal Elliot’s Pheasant (Syrmaticus ellioti), using MaxEnt modeling and Schoener’s D index. Results showed the following: (1) Pheasants in Huzhou exhibited distinct vertical gradients, with Elliot’s Pheasant restricted primarily to mid-mountain forests (200–600 m) in western Anji. (2) Iso-thermality and winter thermal limits were the primary drivers of its distribution. (3) Niche analysis revealed intense competitive pressure; Elliot’s Pheasant habitat was largely encompassed by dominant species like the Silver Pheasant (Lophura nycthemera), showing a high overlap (D = 0.642) with the Koklass Pheasant (Pucrasia macrolopha). (4) By 2050, its suitable habitat is projected to shrink by 84.6% (from 1085.7 to 118.8 km²) and shift eastward. These findings highlight the high climate sensitivity and competitive vulnerability of Elliot’s Pheasant. We recommend prioritizing micro-habitat maintenance in mid-mountain zones and proactively establishing ecological corridors between Anji and Deqing to mitigate habitat loss and displacement. Full article

Climate change-driven range expansions are creating novel interspecific interactions that may significantly impact the breeding success of established resident species. This study examines the ecological consequences of competition between Mute Swans (Cygnus olor) and expanding Whooper Swans (Cygnus cygnus) in central and eastern Poland. We monitored 80 Mute Swan breeding pairs across fishpond complexes using UAV-based surveys to assess habitat selection and reproductive output in sites with and without Whooper Swan presence. Mute Swans breeding alongside Whooper Swans selected nest sites deeper within reed vegetation and showed altered habitat preferences compared to pairs breeding without competition from a related species. Significantly, reproductive output was reduced in competitive environments, with pairs breeding in areas without Whooper Swans producing considerably more offspring than those coexisting with the expanding species. These results demonstrate that the expansion of a given species’ range can cause immediate costs to local species, both via direct confrontations and through the impact on the quality of the occupied habitat. The substantial reduction in breeding success suggests that interspecific competition may have population-level consequences for established waterbird communities. Full article

Grassland degradation is a critical ecological problem worldwide that threatens ecosystem integrity and functional services. Although previous studies have documented the drivers of climate change, overgrazing, and anthropogenic perturbation, research concerning the impact of invasive alien plants on grassland ecosystems remains limited. The present study, integrating pairwise field investigation of Ageratina adenophora invasion and non-invasion plots across heterogeneous grassland types (tropical grasslands [TG]; tropical shrub-grasslands [TS]; warm-temperate grasslands [WG]; and warm-temperate shrub-grasslands [WS]) and A. adenophora indigenous plants phytotoxicity bioassay, aims to assess the invasibility and resilience of heterogeneous grassland landscapes to A. adenophora invasion. The field investigation demonstrated the greater vulnerability of TG and TS to A. adenophora invasion, whereas WG and WS possessed higher resilience. In addition, regression analysis revealed significant reductions of the Shannon–Wiener index and the Pielou index as the A. adenophora’s important value reached the threshold 0.36. Bioassay showed that A. adenophora aqueous extracts inhibit seed germination and seedling growth of recipient plants, with Saccharum arundinaceum exhibiting the highest tolerance to A. adenophora stress. In summary, our findings not only highlight the flora communities’ dynamics and invasibility of diverse grasslands driven by A. adenophora invasion in subtropical regions but also verify S. arundinaceum’s potential for A. adenophora replacement management. Full article

To clarify the ecological characteristics of herbaceous plants on parabolic dunes in the Ebinur Lake Basin and to support regional ecological conservation, this study focused on herbaceous species with an importance value (IV) > 1%. Standard ecological indices and analytical approaches were used for assessment. The results showed the following. (1) A total of 12 herbaceous species were recorded, belonging to 10 genera and 7 families. The ranking of niche breadth showed no clear qualitative association with IV. (2) Niche overlap (Oik) among species was generally high. Fifty-eight species pairs had Oik > 0.60. Most herbaceous species differed only slightly in their environmental and resource requirements, indicating interspecific competition. (3) Overall species associations were significantly positive. The ratios of positive to negative associations were 12.2 based on the χ² test, the interspecific association coefficient (AC), and Spearman rank correlation. Species were strongly associated. The community was at the mid-successional stage. (4) Diversity indices followed a normal distribution. The community showed moderate richness and evenness, with pronounced dominance. For future conservation, species with similar ecological preferences and biological traits should be selected. Management should adjust and optimize species composition to improve resource use efficiency and enhance community stability. Full article

Insects use oviposition secretions containing deterrent signals to regulate intra- and interspecific competition and structure resource partitioning; certain Tephritidae display a striking reversal of this strategy. Herein, we induced female aggregation and oviposition using eggs from the three fruit fly species (B. dorsalis, Z. cucurbitae, Z. tau) and characterized the eggs’ volatile profiles by GC–MS. Within 6 h, female attraction rates to egg stimuli varied significantly by species combination. B. dorsalis females were attracted to conspecific eggs at 39.33%, to Z. cucurbitae eggs at 28.67%, and to Z. tau eggs at 0%. Z. cucurbitae females showed attraction rates of 22.67% to B. dorsalis eggs, 13.00% to conspecific eggs, and 1.33% to Z. tau eggs. Z. tau females exhibited 27.67% attraction to B. dorsalis eggs, 13.67% to Z. cucurbitae eggs, and 18.33% to conspecific eggs. Oviposition assays confirmed strong interspecific effects, with B. dorsalis eggs stimulating the greatest egg-laying. GC–MS analysis revealed distinct volatile profiles, with B. dorsalis eggs producing the highest number of unique compounds (57), potentially explaining their strong behavioral effects. In total, 79 volatiles differed significantly between Z. cucurbitae and B. dorsalis eggs, 73 between Z. tau and B. dorsalis eggs, and 91 between Z. cucurbitae and Z. tau eggs. These findings reveal a behavioral hierarchy where B. dorsalis is the most responsive to egg volatiles, Z. cucurbitae is intermediate, and Z. tau is the least responsive, a ranking that correlates with significant differences in the eggs’ volatile compositions. This study directly links a behavioral status in interspecific oviposition to species-specific egg volatile profiles. Full article

Understanding the ecological behavior of invasive species is essential for assessing their impacts on native biodiversity. This study examines the basking dynamics of the invasive freshwater turtle Trachemys scripta in a Mediterranean wetland within Mesir Nature Park, Türkiye. Data were collected between March and October 2024 using camera traps, yielding 72,456 cumulative basking observations. Principal Component Analysis (PCA) revealed a high degree of environmental synchronization (PC1 = 97.24%), indicating that basking activity is strictly governed by ambient thermal availability. Furthermore, Negative Binomial Regression (NBR) was employed to evaluate temporal shifts and behavioral plasticity. The basking intensity exhibited distinct seasonal transitions, characterized by afternoon peaks during the spring and autumn and an opportunistic shift toward early morning activity during the summer to mitigate thermal constraints. The peak basking duration recorded in May (696.00 ± 10.25 min) and the bimodal activity observed in summer reflect a significant adaptive capacity. These patterns suggest that Mediterranean wetlands provide optimal conditions for the persistence of Trachemys scripta. The species’ ability to effectively track environmental cues and monopolize thermal resources implies a high potential for the ecological displacement of native turtles, particularly Mauremys rivulata. This study provides critical quantitative baseline data in order to inform evidence-based management and control strategies in the Mediterranean region. Full article

Exploring how nitrogen deposition alters the competitive interactions between invasive plants and native plants is critical for predicting the invasion trends of invasive plants and for formulating their control strategies. In this study, the invasive plant Solanum rostratum and its native congener S. nigrum were selected as research subjects, and three different nitrogen (N) concentration treatments (N1: 50 mg·kg⁻¹, N2: 100 mg·kg⁻¹, N3: 150 mg·kg⁻¹) were set up to compare the two species in terms of growth and development, leaf nutrient utilization strategies, stress tolerance, and rhizosphere microbial community differences under competitive conditions. The results showed that the biomass of S. rostratum was 1.4 to 2.3 times that of S. nigrum; the former had a lower root–shoot ratio and a larger crown width, enabling it to seize more living space and light resources. Across all nitrogen treatments, the net photosynthetic rate of S. rostratum leaves was significantly higher than that of S. nigrum, reflecting a stronger carbon sequestration capacity. With the increase in soil nitrogen concentration, the malondialdehyde content in S. rostratum leaves showed a decreasing trend; meanwhile, its leaf soluble sugar and catalase contents were 3.5 to 4.3 times and 1.5 to 2.5 times those of S. nigrum, respectively, indicating a lower oxidative stress level and higher stress tolerance in S. rostratum. The leaf C/P and C/N ratios of S. rostratum increased with the rise in soil N, demonstrating a higher nutrient use efficiency, while the decrease in leaf phosphorus (P) content might be attributed to the element dilution effect caused by the rapid plant growth. In addition, the diversity and stability of the rhizosphere microbial community of S. rostratum gradually increased with increasing soil N and were significantly higher than those of S. nigrum. The rhizosphere-recruited microbes of the genera Comamonas and Chryseobacterium may help promote its root nutrient absorption and thus enhance its competitive ability. Collectively, our findings reveal that under exogenous N application, S. rostratum gains a significant growth advantage over S. nigrum, which is attributed to its stronger capacities for carbon assimilation and spatial resource acquisition, a nutrient strategy characterized by low acquisition and high utilization, as well as a stable and diverse rhizosphere microbial community. Full article

Strip intercropping of maize and soybean is a key practice for improving land productivity and ensuring food and oil security in the hilly regions of the Loess Plateau. However, complex interspecific interactions generate highly heterogeneous canopy structures, making it difficult for traditional linear models to capture yield variability within mixed pixels. Based on a single-season (2025) field experiment, this study developed a UAV multispectral imagery-based yield estimation framework integrating multiple machine-learning algorithms. Shapley additive explanations (SHAP) and partial dependence plots (PDP) were used to interpret the spectral–yield relationships under different spatial configurations. The predictive performance of linear regression and eight nonlinear algorithms was compared using 20 spectral features. Ensemble learning outperformed linear approaches in all intercropping scenarios. In the maize–soybean 3:2 pattern, the GBDT model delivered the highest accuracy (R² = 0.849; NRMSE = 9.28%), whereas in the 4:2 pattern with stronger shading stress on soybean, the random forest model showed the greatest robustness (R² = 0.724). Interpretation results indicated that yield in monoculture systems was mainly driven by physiological traits characterized by visible-band indices, while yield in intercropping systems was dominated by structural and stress-response traits represented by near-infrared and soil-adjusted vegetation indices. The generated centimeter-scale yield maps revealed clear strip-like spatial variability driven by interspecific competition. Overall, explainable machine learning combined with UAV multispectral data shows promise for within-season yield estimation in intercropping systems and can support spatially differentiated precision management under the sampled conditions. Full article

Background/Objectives: Arctic foxes (Vulpes lagopus) exemplify the vulnerability of Arctic species to global warming and anthropogenic impacts, including habitat loss, interspecific competition with temperate species, pollution (chemical and biological), and declining prey abundance. Despite their ecological importance, the evolutionary and demographic history of the species is still incompletely understood, and the colonization history of isolated island populations, such as the one on Iceland, remains unresolved. Methods: We analyzed 80 mitochondrial genomes from across the Holarctic, including 22 Icelandic individuals. We combined phylogenetic reconstruction, coalescence-dating, haplotype network analysis, and diversity metrics to infer matrilineal relationships and colonization history. Results: Seven distinct haplogroups (Hg.1–Hg.7) were identified, which diverged ≥65 thousand years ago (kya). Two haplogroups were broadly distributed across Fennoscandia, Russia, Iceland, and Canada, while others were region-specific: two in eastern Russia (respectively diverging ~171 kya and ~89 kya), one in central Russia (~66 kya), and two in Iceland (~95 kya and ~66 kya). Three haplogroups were detected in Iceland, and at least four unrelated founding females are required to explain the current matrilineal diversity. One haplogroup contained sufficient representatives for molecular dating, yielding a minimum colonization age of ~5600 years, assuming in situ diversification. Observed matrilineal diversity in Iceland does not uniquely identify a single geographic source. Conclusions: Arctic foxes’ distribution and diversity reflect repeated cycles of isolation and expansion as circumpolar environments shifted. Broader sampling across the Nearctic is critical to clarify the timing, sources, and routes of Iceland’s colonization, as Nearctic sampling was limited to a single Canadian mitogenome. Full article

Cavity limitations and interspecific competition render large macaws valuable models for elucidating the integration of parental care, pair-bond maintenance, and nest defense across reproductive stages. Through continuous video monitoring of a single artificial polyvinyl chloride nest box in the Tambopata National Reserve, Peru, we quantified the complete breeding cycle of a resident green-winged macaw (Ara chloropterus) pair and the visitation behavior of a sympatric scarlet macaw (Ara macao) pair within the same cavity. We constructed daily time budgets for 17 behaviors, categorized into seven functional groups, from motion-triggered video clips; employed multivariate tests; and generalized additive models with beta error distribution to describe the temporal changes across the five reproductive stages. The resident A. chloropterus exhibited a significant reorganization of parental investment, with early courtship behaviors transitioning to peak nest attendance and sentinel vigilance during incubation and early brooding. In later stages, locomotion increased significantly, associated with chick provisioning, whereas the frequency of allopreening remained relatively constant throughout the cycle. The visiting A. macao displayed a brief, behaviorally rich prospecting phase, characterized by nest inspection and locomotion, followed by a sharp decline in minimal activity. These divergent strategies align with owner–intruder asymmetries and floater dynamics, indicating that artificial cavities can support A. chloropterus breeding, while suggesting that additional cavities may redistribute breeding opportunities among competing macaws, a hypothesis necessitating multi-nest and multi-year evaluation. Full article