Pattern Of Patches Research Articles

Relationship Between Intestinal Slow-waves, Spike-bursts, and Motility, as Defined Through High-resolution Electrical and Video Mapping

Background/AimsHigh-resolution extracellular mapping has improved our understanding of bioelectric slow-wave and spike-burst activity in the small intestine. The spatiotemporal correlation of electrophysiology and motility patterns is of critical interest to intestinal function but remains incompletely defined.MethodsIntestinal jejunum segments from in vivo pigs and rabbits were exteriorized, and simultaneous high-resolution extracellular recordings and video recordings were performed. Contractions were quantified with strain fields, and the frequencies and velocities of motility patterns were calculated. The amplitudes, frequencies, and velocities of slow-wave propagation patterns and spike-bursts were quantified and visualized. In addition, the duration, size and energy of spike-burst patches were quantified.ResultsSlow-wave associated spike-bursts activated periodically at 10.8 ± 4.0 cycles per minute (cpm) in pigs and 10.2 ± 3.2 cpm in rabbits, while independent spike-bursts activated at a frequency of 3.2 ± 1.8 cpm. Independent spike-bursts had higher amplitude and longer duration than slow-wave associated spike-bursts (1.4 ± 0.8 mV vs 0.1 ± 0.1 mV, P < 0.001; 1.8 ± 1.4 seconds vs 0.8 ± 0.3 seconds, P < 0.001 in pigs). Spike-bursts that activated as longitudinal or circumferential patches were associated with contractions in the respective directions. Spontaneous peristaltic contractions were elicited by independent spike-bursts and travelled slower than slow-wave velocity (3.7 ± 0.5 mm/sec vs 10.1 ± 4.7 mm/sec, P = 0.007). Cyclic peristaltic contractions were driven by slow-wave associated spike-bursts and were coupled to slow-wave velocity and frequency in rabbit (14.2 ± 2.3 mm/sec vs 11.5 ± 4.6 mm/sec, P = 0.162; 11.0 ± 0.6 cpm vs 10.8 ± 0.6 cpm, P = 0.970).ConclusionsMotility patterns were dictated by patterns of spike-burst patches. When spike-bursts were coupled to slow-waves, periodic motility patterns were observed, while when spike-bursts were not coupled to slow-waves, spontaneous aperiodic motility patterns were captured.

Wetting Pattern of Cow Urine Patch in an Andisol Assessed through Bromide Concentration Distribution: A Pilot Study

Cow urine is a rich source of mobile nutrients such as nitrate (NO3−) and potassium (K+). The aim of this experiment was to evaluate the wetting pattern distribution through soil profile of cow urine patch in an andisol. Two field experiments across two consecutive years were carried out to compare cow urine patches in relation to initial wetting pattern and volume of soil affected. Bromide (Br−) has successfully been used as an inert hydrologic tracer to indicate the movement of NO3− and K+ in soil–water systems. The distribution of Br− (used as a urine tracer) on the soil surface and down the profile was irregular in all the patches. Cow urine patches covered a surface area of 0.27 and 0.35 m2, respectively, and penetrated to a depth of 70 cm. The rapid downward movement of urine occurred through macropore flow but even so, between 27% and 40% of the applied Br− was detected in the 0–5 cm soil layer. Br− showed concentrations greater than 1500 mg kg−1 and up to 3000 mg kg−1, and as the concentration of Br− decreases, the frequency and depth of affected layers increases. Despite the differences in moisture and in the distribution of the Br− concentration in both years, the concentration frequency of 500 to 1500 mg kg−1 represented around 37% of the affected volume of soil (bulb of urine) in both years. Up to 40% of the bulb represented N equivalent rates between 187 and 975 kg N ha−1. These values can potentially be emitted in gases such as NH3, N2O, and N2. It is suggested that the presence of N in the volume of affected soil could vary due to the moisture content of the soil, and that in andisols of southern Chile under permanent grasslands there are a large number of macropores that would induce preferential flows.

Short-term responses of small mammal diversity to varying stand-scale patterns of retention tree patches.

Retention forestry is a common practice for biodiversity conservation in forests managed for wood production. Retention forestry often leaves unharvested patches of trees that vary in size and spatial pattern but experiments evaluating the effects of different retention patch configurations at a constant level of retention are lacking for many regions and taxonomic groups. We implemented an experimental study in clearcut conifer stands with retention across the U.S. Pacific Northwest region. The study consisted of five stand-level (11–55 ha) experimental treatments each replicated 10 times within a randomized complete block design, resulting in 50 treated stands. Retained tree density was comparable across treatments but size, number, and location (upland or riparian) of patches within stands varied among the five treatments. Within experimental treatments, we measured small mammal (<1kg) species and functional trait (i.e., body size, diet, activity stratum) richness in retention patches, surrounding harvested portions of stands, and nearby unharvested stands. We evaluated species and functional trait richness by treatment using generalized linear mixed-effects models and species-specific responses to retention placement using a community occupancy model. We obtained repeat captures of 21 species of small mammals but found limited evidence of a treatment effect on species richness, and no differences in functional trait richness. Species richness was highest where all retained trees were aggregated into one patch placed adjacent to a forested riparian buffer (mean = 6.6 species, 95% CI = 5.7–7.5), and lowest in the treatment containing one retention patch in the upland portion of a harvested stand (mean = 4.7 species, 95% CI = 3.8–5.6). Furthermore, estimates of species richness within retention patches of harvested stands (i.e., not considering species in harvested areas) did not differ among treatments, indicating that the slightly elevated species richness in riparian-associated retention results from 1–2 species in these patches that do not occur in adjacent harvested portions of each treated stand. Patch occupancy of several species was higher in riparian patches than harvested portions of the treated stands, and fewer species had higher occupancy in upland patches compared to harvested portions of treated stands. Our results indicated that at retention densities currently required in Oregon and Washington, the location of retention patches had a small influence on stand-scale measures of small mammal diversity, but local increases in species richness may be obtained by retaining trees adjacent to riparian buffers.

The Spatial Pattern Strategy of Urban Ecological Patches Based on the Mesoscale WRF-UCM Model: Taking Wuhan City as an Example

In the context of rapid urbanization, the reduction of urban ecological land area, space chaos, and fragmentation have led to a series of climate and environmental problems. This paper takes the ecological patches of the urban climate environment compensation space as the research object and establishes several urban canopy models of several cases based on geographic information data. Then, we input them into the mesoscale WRF-UCM model and simulate after loading the meteorological data to derive the meteorological indicators of each case, quantitatively analyze the meteorological conditions in the ecological patch boundaries with different surface attributes, and conduct research on the “quality-efficiency” correspondence of the physical characteristics of the ecological patches and the spillover effects of climate regulation. Studies have shown that the highest surface temperature difference between water patches and patches with other attributes ∆ Tsk is up to 6.5°C in winter and 11.5°C in summer. The highest temperature difference at a somatosensory height of 2 meters ∆ T 2 is up to 2.0°C in winter and 3.0°C in summer, which can improve the surrounding environment. Under light wind conditions, water patches will have a positive spillover effect within 5.5 km of the downwind direction. Based on the data, an optimization strategy for the spatial pattern of urban ecological patches is proposed: the best distribution of water patches that are beneficial to the climate adjustment of Wuhan in winter and summer is in the north or northeast of the city, followed by the south or southwest. The north and northeast of the city should keep the woodland patches and reduce the setting of vegetation/arable land and wetland patches. This research is an interdisciplinary study of urban spatial planning that adapts to climate change, to supplement the deficiencies of urban planning theory, and to provide guidance for the promotion of green and ecological city construction.

Stability Analysis of Submerged Vegetation Patterns in Rivers

AbstractAquatic vegetation in fluvial systems is often characterized by spatial patterning of the plant patches. To investigate the conditions for the formation of vegetation patches, we explore the stability of a uniform flow over a non‐erodible bed with a uniform vegetation cover of submerged plants. The flow model consists of the two‐dimensional shallow water and continuity equations. The hydrodynamic equations are coupled firstly to the classic formulation for vegetation dynamics, and secondly to a modified version of the equation. The revised relationship for vegetation dynamics accounts for the influence of removal, transport, and resettlement of propagules on the growth rate of aquatic vegetation. Linear stability analysis of the eco‐hydrodynamic problem is performed by enforcing the quasi‐steady approximation. We obtain a dispersion relation disclosing the growth rate and the migration rate of the perturbations of vegetation density as a function of the wavenumber and the relevant flow and vegetation parameters. The present theory predicts the onset of vegetation patterns and includes an adequate wavelength selection mechanism. While uprooting initially reduces plant density, the analysis demonstrates that resettled propagules after removal are fundamental for further plant population increases and the development of vegetation patterns. The proposed framework is then validated against data available in the literature. Additionally, the presence of an upper threshold in terms of vegetation density, above which uniform vegetation cover is stable, might explain the absence of any spatial pattern and thus the extremely dense vegetation cover induced by climate change and invasive species in altered ecosystems.

Exploring patterns and consequences of land consumption in a coastal city-region

BackgroundThe rapid expansion of built-up areas and land consumption with unsustainable spatial patterns in coastal urban areas has become a global major concern due to its far-reaching consequences for human daily life, environmental sustainability, and living organisms. However, the research on this phenomenon in these areas has received less attention. To fill this gap, we conducted a study to explore the spatial patterns of land consumption at both micro- and macro-levels and to evaluate its consequences in terms of sustainable development in a coastal city-region of Mazandaran Province in northern Iran. To achieve these two goals, we combined two methods of urban land density function and landscape expansion index (LEI) to explore spatial patterns of land consumption and also evaluated the sustainability of the region with two methods of the hierarchical analytical process (AHP) and urban sustainability index (USI).ResultsThe spatial patterns of land consumption in the city-region of Mazandaran from 1996 to 2016 at the macro-level changed from a decentralized-sprawl to a centralized-sprawl pattern. At the micro-level, the dominant spatial pattern of land consumption in the city-region changed gradually from the outlying pattern towards the edge expansion and infilling patterns. Also, the spatial pattern of the built-up patches in the majority of the urban areas had conformity with the dominant pattern of the region. Besides, the spatial patterns of land consumption in the region were in an unsustainable state and were changing towards more unsustainability. The absence of urban containment policies and plans could lead to further destruction of the natural environment and increase its unsustainability.ConclusionsOur results indicate that the urban areas of the coastal Mazandaran have the same behavior in the spatial pattern of land consumption at the macro- and micro-levels and all are in the same direction and follow the dominant pattern of the region.

Stochastic Model for Quasi-One-Dimensional Transitional Turbulence with Streamwise Shear Interactions.

The transition to turbulence in wall-bounded shear flows is typically subcritical, with a poorly understood interplay between spatial fluctuations, pattern formation, and stochasticity near the critical Reynolds number. Here, we present a spatially extended stochastic minimal model for the energy budget in transitional pipe flow, which successfully recapitulates the way localized patches of turbulence (puffs) decay, split, and grow, respectively, as the Reynolds number increases through the laminar-turbulent transition. Our approach takes into account the flow geometry, as we demonstrate by extending the model to quasi-one-dimensional Taylor-Couette flow, reproducing the observed directed percolation pattern of turbulent patches in space and time.

Spatial Vegetation Patch Patterns and Their Relation to Environmental Factors in the Alpine Grasslands of the Qilian Mountains

Globally, grasslands are affected by climate change and unsustainable management practices which usually leads to transitions from stable, degraded and then to desertification. Spatial vegetation patch configurations are regarded as key indicators of such transitions. Understanding the relationships between this grass-land vegetation and its environment is key to vegetation restoration projects. Spatial vegetation patch patterns were chosen across different soil and topographic conditions. Patch numbers, perimeter, and cover of each patch were measured along transects of each patch type. Using field surveys and multivariate statistical analysis, we investigated the differences in vegetation biomass and distribution and soil properties of four typical alpine plant species patches along with a range of environmental and topographic conditions. It was found that topographic conditions and soil properties, particularly soil moisture explained most of the variation in spatial patch vegetation characteristics and thus control vegetation restoration in the alpine grassland. The Kobresia humilis, Blysmus sinocompressus and Iris lactea patches under the drylands recorded small patch sizes, large patch numbers, low connectivity, and large total perimeter per unit area. Generally, species within the high moisture sites recorded small patch numbers, a large fraction of vegetation cover and a small total perimeter per m2. Patches in limited soil moisture areas recorded patch configurations indicating they are unstable and undergoing degradation and therefore need urgent restoration attention to forestall their further degradation and its resultant effect of desertification. These results would provide quantitative easy-to-use indicators for vegetation degradation and help in vegetation restoration projects.

Effects of Vegetation Patch Patterns on Channel Morphology: A Numerical Study

AbstractThis study investigates the effects of vegetation patch patterns on the morphological evolution of alluvial river channels at the reach‐scale. For this, a new two‐dimensional numerical biomorphodynamic model has been developed using the Telemac‐Mascaret system. Considering the newest development in the topic, the effects of vegetation on bedload transport are included by extending Einstein's parameters for the sediment transport formula. The model was subsequently validated by published laboratory experiments reproducing alternate bar dynamics with different vegetation establishment scenarios. The validated model was then used to study the influence of vegetation patch patterns on the channel morphological evolution considering the two most observed ones: (a) the filled pattern with plants well distributed within the patch, and (b) the stripe pattern with plants established only along the patch edges. 14 scenarios were simulated in total, including sensitivity analyses on the coefficients of vegetation characteristics. The results indicate that the morphological responses of an alternate bar system to the stripe pattern consist of channel widening, steeper slope and reduced water depth, with increased sediment transport rates. The effects of the filled pattern are similar but weaker. The results also show that with the stripe pattern, the alternate bars tend to migrate toward the centerline forming center bars. Besides, the scroll bars forming downstream are shorter, corresponding to less visible chute channels, compared to the filled pattern. Despite much less vegetation coverage, the stripe pattern decreases the bar elongation rates in a way similar to the filled pattern.

Measuring the Paradigm Shift in Ecological Services in the Mountainous Urban and Peri-Urban Systems of the Himalaya

In the present study, an attempt has been made to understand the dynamics in ecological demand and supply in the mountainous urban systems of Himalayas using spatial approach during the three decades. The study discusses the spatio-temporal dynamics of urban ecological services (UES) by investigating the pattern of demand and supply patches in the major mountainous urban systems of the Himalayas during the period of 1991-2018. The demand patch (135 %) in the mountainous urban systems of the Himalayas has increased significantly in contrast to a serious decline in the supply patch (-24 %) over the last three decades (1991-2018). The city-scale comparative study indicated Srinagar (80.37 km 2 ) and Kathmandu (51.82) exhibited higher growth in the demand patch in contrast to Gangtok (3.52 km 2 ), which observed comparatively lower growth for the same. On the contrary, the supply patches observed higher depletion in Srinagar (-68.03 km 2 ) and Kathmandu (-54.66 km 2 ) while lower in Gangtok (3.52 km 2 ). However, the intensity of rate of change of demand patch was higher in Srinagar (181.69 %), Shimla (163.04 %) and Itanagar (153.75 %), and comparatively lower in Gangtok (71.84 %) whereas the intensity of the same for supply patch was in higher in Kathmandu (-57.48 %), and lower in Shimla (-12.26 %) and Gangtok (-7.66 %). Significant changes in ecological services, particularly in cities such as Srinagar and Kathmandu, lead to a loss of heterogeneity and wellbeing in urban ecosystems. The cities in Himalayan valleys (Srinagar, Dehradun and Kathmandu) exhibited severe decline in the supply patch and significant rise of demand patch in especially the peri-urban areas followed by the saturation of urban regions. Also, the city on ridges (Shimla, Gangtok and Thimphu) showed moderate growth of demand patch in the urban regions and insignificant growth in the peri-urban regions. As a result, the supply patch exhibited lower depletion in both urban and peri-urban regions. For a robust and sustainable urban system in the Himalayas, the study highlights the implementation of contingent policies combined with resilience methods, particularly in urban and peri-urban areas.

Effects of urban wetland patch pattern on the biodiversity of aquatic birds in Nairobi, Kenya

Urban wetlands are ubiquitous landscape elements that affect the spatial pattern and functions of cities. Despite being rich and important habitats for a variety of birds, they are continually being isolated or lost. Isolation and loss negatively impact on the integrity of the urban landscape pattern and compromises on biophilic planning and development. Since urbanization is a continuous cultural process, it is important to investigate how its impacts, which are invariably in conflict with nature, would portend for aquatic bird communities in urban areas. This study sought to determine the variability and relationship between the structural patch pattern of palustrine wetlands in Nairobi and the species richness and abundance of aquatic birds in these wetlands. From a population of 300 wetlands, this study used heterogeneous sampling to identify and investigate 31 palustrine wetlands spread across the city of Nairobi. For each of these wetlands, a variety of landscape metrics were calculated and the species diversity of aquatic birds was quantified. Multiple regression analysis was performed in IBM SPSS Statistics 21 to determine the relationships between wetland patch pattern and wetland biodiversity. The study found that patch pattern significantly affects aquatic bird biodiversity, R² = .516, F (7, 23) = 3.498, p &lt; .05. It was also found that the characteristics of the wetland neighbourhood significantly affected aquatic bird biodiversity, R² = .301, F (3, 27) = 3.867, p &lt; .05. This study highlights the need to mainstream, plan, and design for the conservation and monitoring of spatial patterns and biodiversity of palustrine wetlands in urban landscapes. In doing so, biophilic cities are created, bio-systemic urban infrastructure is generated, human wellbeing is enhanced, and urban wetland ecosystem services are valued.

Optimal foraging strategies in varying nutrient heterogeneity: responses of a stoloniferous clonal plant to patch pattern, size and quality

ABSTRACT Contrast and aggregation are two components of spatial heterogeneity. To precisely determine the influence of varying nutrient heterogeneity on the foraging behavior of clonal plants, we selected Potentilla anserina L. as the material and designed different patch patterns, sizes and qualities. In Experiment 1, compared with random and uniform patch patterns, aggregation increased ramet density and biomass accumulation at the patch scale, but not at the plot scale. This implies that the adaptive responses of clonal plants to nutrient heterogeneity depend on spatial scale. We further designed three levels of patch size with the same fertilizer concentration at the patch scale in Experiment 2, and four levels of patch quality with the same total amount of fertilizer at the plot scale in Experiment 3. Increased ramet density and stolon growth rate within small patches in Experiment 2 demonstrated effects of heterogeneity on plant foraging responses at the patch scale, while no difference was found in Experiment 3. This means that the influence of patch size on ramet establishment and residence time was alleviated by patch contrast at larger spatial scales. Hence, spatial scale is a key factor determining the interactions between heterogeneous ecosystem components.

A deep Generative Artificial Intelligence system to predict species coexistence patterns

Abstract Predicting coexistence patterns is a current challenge to understand diversity maintenance, especially in rich communities where these patterns' complexity is magnified through indirect interactions that prevent their approximation with classical experimental approaches. We explore cutting‐edge Machine Learning techniques called Generative Artificial Intelligence (GenAI) to predict species coexistence patterns in vegetation patches, training generative adversarial networks (GAN) and variational AutoEncoders (VAE) that are then used to unravel some of the mechanisms behind community assemblage. The GAN accurately reproduces real patches' species composition and plant species' affinity to different soil types, and the VAE also reaches a high level of accuracy, above 99%. Using the artificially generated patches, we found that high‐order interactions tend to suppress the positive effects of low‐order interactions. Finally, by reconstructing successional trajectories, we could identify the pioneer species with larger potential to generate a high diversity of distinct patches in terms of species composition. Understanding the complexity of species coexistence patterns in diverse ecological communities requires new approaches beyond heuristic rules. Generative Artificial Intelligence can be a powerful tool to this end as it allows to overcome the inherent dimensionality of this challenge.

Explaining multiple patches of aquatic vegetation through linear stability analysis

Aquatic vegetation is ubiquitous in lowland rivers, and it is typically present in the shape of spatial self-organized patches of biomass. In this work, we mathematically define the threshold conditions for the incipient formation of self-organized vegetated patterns in the shape of central or multiple row patches. The analysis is carried out through a linear stability analysis whereby the 2D eco-hydrodynamic model is linearized and the growth rate of small-scale perturbations is evaluated considering a basic state represented by an initially uniformly vegetated and straight channel having a certain aspect ratio and Froude number. Results illustrate that, for given vegetation properties, instability arises when both the Froude number and the aspect ratio are higher than a given threshold; in this case, self-organization occurs, and spatial patterns of patches will develop according to the wavelength associated to the maximum growth rate. Moreover, instability and self-organization take place when the undisturbed vegetation density is lower than upper bound; this suggests that densely vegetated channels, as in the case of rivers populated by invasive species, will not experience the formation of any spatial patterns.

On a consumer-resource system with asymmetric diffusion and geographic heterogeneity

A recent laboratory experiment on consumer-resource interactions showed that when the consumer moves between patches with homogeneous/heterogeneous distribution of toxicant, a homogeneous distribution leads to the lowest abundance of the consumer. Since diffusion rates in both the experiment and the corresponding model are assumed to be symmetric, an extended model with asymmetric diffusion is considered in this work. Rigorous analysis on the model shows global stability of a positive equilibrium, while further study on the equilibrium demonstrates mechanisms how toxicant distribution, asymmetric diffusion and spatial pattern of patches influence total population abundance of the consumer. Consistent with previous results, we show that when the system is in heterogeneous distribution of toxicant, consumer’s diffusion could make its total abundance higher than if non-diffusing, even higher than that when in homogeneous distribution without diffusion. Spatial pattern of patches is also proven to play a role in the increase. Different from previous results, we show that when the system is in homogeneous distribution of toxicant, asymmetric diffusion would make the consumer’s abundance lower than if non-diffusing. Our conclusion predicts that both toxicant distribution and consumer’s diffusion are important in the efficacy of toxicant, which may be helpful for both controlling pest and protecting desirable populations.

Effects of patch pattern on plant diversity and functional traits in center Hunshandak Sandland

Effects of patch pattern on plant diversity and functional traits in center Hunshandak Sandland

Generation of Novelty Ground Truth Image Using Image Classification and Semantic Segmentation for Copy-Move Forgery Detection

Since the ground truth (GT) generated by CNN has pieces of patch information of the learned class, the accurate detection of Copy-Move is ambiguous. With various CNNs for image classification and semantic segmentation, the generated GT images are different yet similar to patch patterns for detecting forgery regions. It is difficult to determine which network model-generated GT image is suitable. Therefore, an optimal GT image is essential in image forensics. The proposed scheme in this paper generates a novelty GT image to solve this problem for the correct detection of Copy-Move forgery. The novelty GT image was configured using image classification and semantic segmentation. The variety of GT images is generated by adopting the state-of-the-art four image classifications and one semantic segmentation in the deep neural network. The proposed scheme implements mainly three tasks: 1) each network model generates the GT images (GT <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">net</i> ), 2) which are convergence synthesized into one (GT <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">conv</i> ), and 3) it decomposed again into GT images (GT <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">decomp</i> ) with a threshold value of the ‘Threshold Filter.’ Here, the GTnet images involve two pieces of information about the image classification and semantic segmentation of the forgery image. The GTconv has two pieces of information as one GT image. The GTdecomp is decomposed GTconv into various GT images by the threshold value, which is a permeated degree of the information about ‘Image classification’ and ‘Semantic segmentation.’ The proposed novelty GT image is accomplished with this operational flow for Copy-Move forgery detection. The results confirmed in the experiment for comparing the performance of the existing GT <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">net</i> image, and the GT <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">decomp</i> image of the proposed scheme showed that the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Accuracy</i> and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">F1 Score</i> of the proposed scheme had the maximum improvement rate of 0.4% and 0.2%, respectively. Also, by estimating the proposed CMFD scheme, Area Under the Curve (AUC) is graded as ‘ <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Excellent</i> ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$A$ </tex-math></inline-formula> )’ with a value of 0.9 higher.

宁夏东部风沙区沙化草地土壤水分和植被的空间特征

PDF HTML阅读 XML下载 导出引用 引用提醒 宁夏东部风沙区沙化草地土壤水分和植被的空间特征 DOI: 10.5846/stxb202101140146 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 宁夏自治区重点研发计划项目（2018BEG03007）；宁夏高等学校一流学科建设（草学学科）项目（NXYLXK2017A01） Spatial characteristics of soil moisture and vegetation in desertification grassland in eastern Ningxia sand-wind area, China Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:土壤水分作为土壤-植被-大气连续体的关键因子，对沙化草地的演化过程具有重要作用。为探讨宁夏东部风沙区沙化草地土壤水分、物种丰富度指数及植被盖度的空间变异及其相互关系，以哈巴湖自然保护区沙化草地为对象，采用样线法自潜在沙化草地至重度沙化草地进行植被调查和土壤取样，通过经典统计学和地统计学分析，得出以下结果：0-100 m各土层土壤水分含量、植被盖度和物种丰富度指数的分布范围分别为0.82%-28.22%、41.00%-93.00%和0.82-2.80，变异系数范围为0.20-0.48，均属于中等变异。各土层土壤水分和物种丰富度指数表现为中等的空间自相关性，植被盖度则表现为强烈的空间自相关性。Kriging插值结果表明，0-100 cm各土层土壤水分和植被盖度的空间插值图呈条带状和斑块状的梯度变化，物种丰富度呈斑块分布，自潜在沙化草地至重度沙化草地，表现为逐渐降低的趋势。相关分析表明，植被盖度与0-40 cm各土层土壤水分呈显著正相关，与40-100 cm各土层土壤水分呈极显著正相关。宁夏东部风沙区沙化草地土壤水分含量总体较低，由于结构因素和随机因素的共同作用，随草地沙化程度的加重，表现为逐渐降低的梯度变化过程中出现局部升高的斑块格局，受土壤水分的影响，草地植被呈现出类似的空间分布特征。研究结果可为草地沙化演变过程的定量化测度及干旱风沙区草地生态环境保护和建设提供理论依据。 Abstract:Soil moisture is of crucial importance for hydrological, biological and biogeochemical processes, especially in arid and semiarid regions where water is the main factor limiting vegetation survival and economic development. In order to explore the spatial variability and their relationship with soil moisture, Margalef richness index and vegetation coverage of the desertified grassland in eastern Ningxia sand-wind area, three 3.6 km parallel transects were laid out from the potential desertified grassland to the severe desertified grassland with 500 m interval between the two adjacent transects. Along each transect, quadrats were established at 200 m intervals for the vegetation investigation and soil sampling. Soil samples were collected at the following depths:0-10, 10-20, 20-30, 30-40, 40-50, 50-60, 60-70, 70-80, 80-90, and 90-100 cm. The soil moisture, Margalef richness index and vegetation coverage were measured and their spatial distributions and interrelationships were analyzed by combining of the classical and geostatistical methods. The results showed that the vegetation coverage, species richness and the contents of soil moisture at each soil layer from 0-100 cm ranged from 41.00%-93.00%, 0.82-2.80, and 0.82%-28.22%, respectively, and the variation coefficient ranged from 0.20 to 0.48, all of which belonged to moderate variability. The optimal models of the soil moisture at 0-10 cm layer and Margalef richness index were Spherical and Exponential models, respectively. The Gaussian models are applicable to the soil moisture of each layer at 10-100 cm depth. The determination coefficients ranged from 0.593 to 0.941. The nugget coefficient for the soil moisture in each layer and Margalef richness index were 26.31%-41.86%, which means the spatial heterogeneity caused by structural factors and random factors plays a major role in the soil moisture in each layer and Margalef richness index. The nugget coefficients of vegetation coverage was 2.50%. The nugget coefficients of vegetation coverage were low, which means the spatial heterogeneity caused by structural factors. The range of vegetation coverage, the Margalef richness index, and the soil moisture content of each soil layer ranged from 1453 m to 8110 m, indicating that the ecological process played a role on a large scale with good continuity. Kriging-interpolated maps showed that the soil moisture in each soil layer and vegetation coverage of the study area appeared as stripe and patchy gradient changes. With the aggravating of grassland desertification, the soil moisture of each soil layer, the Margalef richness index and the vegetation coverage decreased gradually. The Margalef richness index presented an obvious patchy pattern, with high-value areas appearing in the transitional area between the potential desertification grassland and the light desertification grassland, the light desertification grassland and the moderate desertification grassland. The values of the soil moisture in each soil layer in the west changed more gently than those in the east of the study plot. The vegetation coverage was significantly related to the soil moisture contents in each layer at 0-40 cm soil depth, and was extremely significantly related to those at the soil depth of 40-100 cm. There was a significantly positive correlation between soil moisture and Margalef richness index in each soil layer at 0-50 cm depth. It was found that the soil moisture contents of each soil layer in the 0-100 cm layer was relatively low in eastern Ningxia sand-wind area. Due to effects of structural factors and random factors, with the degree of grassland desertification increased, the soil moisture contents manifested as a locally increased patch pattern in the process of gradually decreasing gradient changes. Under the influence of soil moisture, the vegetation parameters showed similar spatial distribution pattern to the soil water content. The results of this paper can provide a theoretical basis for the quantitative measurement of the evolution process of grassland desertification and the ecological environment protection and construction of grasslands in arid and sandy areas. 参考文献 相似文献 引证文献

Pharmacokinetic Evaluation of a Novel Donepezil-Loaded Dissolving Microneedle Patch in Rats.

Research on the development of dissolving microneedles (DMNs) has focused on bolus drug delivery, with little attention on sustained release. Here, we evaluated the sustained release, absorption pattern, and effective drug permeation of a novel donepezil-loaded DMN patch through an in vivo investigation on rats. The applications of DMN patches to the shaved skin of rats for 1 week and 1 h were compared with oral donepezil administration to assess their sustained release capabilities. We used a validated liquid chromatography–tandem mass spectrometry method to quantify donepezil in the plasma. We found that the microneedle arrays effectively delivered donepezil across the skin, with dissolution observed within 1 h of application. Furthermore, skin irritation test showed that the patches produced no irritation response. The DMN arrays also effectively increased drug permeation and demonstrated sustained release and absorption of donepezil from DMN patches. These patches allow extended dosing intervals, reduced gastrointestinal adverse effects, and convenient self-administration to mitigate poor drug compliance, making them beneficial for the treatment of elderly patients with Alzheimer’s disease.

Capsule-like DNA Hydrogels with Patterns Formed by Lateral Phase Separation of DNA Nanostructures.

Phase separation is a key phenomenon in artificial cell construction. Recent studies have shown that the liquid–liquid phase separation of designed-DNA nanostructures induces the formation of liquid-like condensates that eventually become hydrogels by lowering the solution temperature. As a compartmental capsule is an essential artificial cell structure, many studies have focused on the lateral phase separation of artificial lipid vesicles. However, controlling phase separation using a molecular design approach remains challenging. Here, we present the lateral liquid–liquid phase separation of DNA nanostructures that leads to the formation of phase-separated capsule-like hydrogels. We designed three types of DNA nanostructures (two orthogonal and a linker nanostructure) that were adsorbed onto an interface of water-in-oil (W/O) droplets via electrostatic interactions. The phase separation of DNA nanostructures led to the formation of hydrogels with bicontinuous, patch, and mix patterns, due to the immiscibility of liquid-like DNA during the self-assembly process. The frequency of appearance of these patterns was altered by designing DNA sequences and altering the mixing ratio of the nanostructures. We constructed a phase diagram for the capsule-like DNA hydrogels by investigating pattern formation under various conditions. The phase-separated DNA hydrogels did not only form on the W/O droplet interface but also on the inner leaflet of lipid vesicles. Notably, the capsule-like hydrogels were extracted into an aqueous solution, maintaining the patterns formed by the lateral phase separation. In addition, the extracted hydrogels were successfully combined with enzymatic reactions, which induced their degradation. Our results provide a method for the design and control of phase-separated hydrogel capsules using sequence-designed DNAs. We envision that by incorporating various DNA nanodevices into DNA hydrogel capsules, the capsules will gain molecular sensing, chemical-information processing, and mechanochemical actuating functions, allowing the construction of functional molecular systems.