Patch Density Research Articles

Identifying the effects of landscape pattern on soil conservation services on the Qinghai-Tibet Plateau

Land use patterns affect soil erosion processes and soil conservation services. Identifying key landscape pattern affecting soil conservation services is critical for improving soil conservation services and optimizing land use patterns. In this study, the Qinghai-Tibet Plateau (QTP), where ecosystem services are important, was selected as research area. Based on land use, meteorological, soil and vegetation data, the RUSLE model was used to estimate soil conservation quantitatively from 2000 to 2020. The temporal changes in landscape metrics were analyzed using Fragstats, and the response of soil conservation services to landscape metrics was analyzed by correlation analysis. The landscape pattern showed an obvious temporal change trend. In general, the overall landscape of the QTP became more diversified and fragmented, and the landscape shape tended to become more complicated. Patch density (PD), edge density (ED), landscape shape index (LSI), splitting index (SPLIT), Shannon's diversity index (SHDI), and Shannon's evenness index (SHEI) showed increasing trends, while largest patch index (LPI), mean patch area (AREA_MN), aggregation index (AI), and contagion index (CONTAG) showed decreasing trends. At the class level, the variations of landscape pattern metrics of different land use types were big difference. In the 20-year period, soil conservation services were generally on the rise. The spatial heterogeneity of soil conservation services decreased from the south-east to the north-west. PD and ED were positively correlated with soil conservation function, while AREA_MN and AI had a negative correlation with soil conservation function. The effect of landscape pattern metric variation on soil conservation capacity significantly differed among different land use types. Results of the research offer reasonable evidence for landscape management, water and soil retention function improvement and regional ecological protection on the QTP.

Assessing dependence between land use/land cover and water quality

Changes in land use/land cover (LULC) directly or indirectly affect water quality in watercourses and impoundments. Sustainable management strategies aimed to enhance ecosystem health and community well-being require an accurate water-quality evaluation. This study looks into the correlation between temporal changes in LULC, represented by selected landscape variables (land cover area and proportion, patch density, Euclidean nearest-neighbor distance, mean shape index, and Shannon index), and water quality variables (nitrate, total phosphorus, and total suspended solids) at catchment scale. To compare the watershed-size influence, this analysis was performed at two different spatial scales represented by two Uruguayan basins of different sizes, San Salvador (3,118 km2) and Del Tala (160 km2). Partial Least Squares and Random Forest unsupervised machine-learning models were employed for this analysis. By exploiting a non-model-biased method based on game theory (SHAP), the LULC characteristics were quantified and ranked based on their level of importance in the water-quality evaluation. The main outcomes of this study proved that patch density is one of the most influencing metrics in both watersheds and for both models. Agricultural land use is the most critical one at both catchments and agricultural with a forage crop land uses are the most important ones for both algorithms. Furthermore, it is possible to state that the adopted techniques are valuable tools that can provide an adequate overview of the water‐quality behavior in space and time and the correlations between water-quality variables and LULC.

Diverse Patterns of Understory Plant Species across Different Types of Plantations in a Mountainous Ecosystem

Artificial afforestation is considered as one of the key ecological restoration measures. The early large-scale, single-species afforestation method is considered detrimental to the environment. However, there is still a lack of empirical research on the differences in understory biodiversity between monoculture and mixed forests, as well as the response mechanisms of understory plants to environmental factors. We compared the differences in understory plant diversity in different types of plantations and analyzed the differences in understory species composition and the impact of understory plants on local scales (soil organic matter, soil-available phosphorus, and distance from the road) and landscape scales (patch density, landscape fragmentation, and patch diversity) and environmental variable response mechanisms in a mountainous area. Our findings revealed that there was no significant difference in overall understory plant diversity between monoculture and mixed forests, but the perennial species and native species in the mixed forest were significantly higher than those in the monoculture. In monoculture plots, the disparity in species composition was more pronounced compared to that observed in mixed plots. Soil organic matter had a positive effect on understory plant diversity, and soil available phosphorus and distance from the road significantly affected plant diversity in monoculture forests but had no effect in mixed forests. Landscape-scale environmental factors have no effect on understory species diversity. The findings of the current study emphasize the disparities in the plant species composition between mixed and monoculture forest plantations, as well as their respective reactions to environmental factors.

Comparative study and effects of urban green scape on the land surface temperature of a large metropolis and green city

Previous studies have provided valuable insights into the impact of green space (GS) on land surface temperature (LST). However, there is a need for in-depth comparative research on changing landscape patterns in cities and their effects on the urban thermal environment. This study investigates the spatial arrangement of GS and the influence of impervious surfaces on LST in urban areas, examining their cooling and warming effects in the urban landscapes of Beijing and Islamabad. The study aims to assess the impact of the spatial arrangement of GS on LST using a moving window of 1 km2 to analyze the overall effect of landscape patterns on the urban environment. Using Gaofen (GF–2) and Landsat–8 satellite data, we examined the biophysical surface properties of core urban areas. The results indicate a significant difference in the mean LST of 5.44 °C and 3.31 °C between impervious surfaces and GS in Beijing and Islamabad, respectively. The barren land and GS in Islamabad experience a higher LST of 3.39 °C compared to Beijing, which accounts for 1.39 °C. In Beijing, configuration metrics show no significant effect on urban LST, while edge density (ED) exhibits a slightly negative trend. In contrast, in the city of Islamabad, the landscape shape index (LSI), patch density (PD), and number of patches (NP) metrics have a significant influence on LST. The cooling effect of GS patches (0.1–0.5 ha) is more pronounced, while that of GS patches of 15–20 ha shows no significant effect on LST. The temperature difference (TD) of 5.01 °C was observed from the edge of GS in Beijing and 3.3 °C in Islamabad. Considering Islamabad's lush green scape compared to Beijing, this study suggests that Islamabad may experience an increase in LST in the future due to urbanization. This study's findings may assist urban policy-makers in designing sustainable green city layouts that effectively address future planning considerations.

Impacts of spatial explanatory variables on surface urban heat island intensity between urban and suburban regions in China

ABSTRACT The intensified thermal environment in suburban areas is raising wide concerns for human society and public health due to rapid urbanization. Although the satellite-derived surface urban heat island intensity (SUHII) is a commonly used indicator, it still needs to be determined the SUHII between urban and suburban areas due to the challenges in delineating their boundaries with changes. Thus, a comprehensive analysis of the spatial explanatory variables (SEVs) and SUHII among urban and suburban areas is highly needed. Here, using the long-term satellite observations, we analyzed the spatiotemporal patterns of SUHII in different temporal intervals (i.e. seasonal and diurnal) and the contribution of SEVs in urban and suburban areas. Our results indicate that SUHII shows predominantly increasing trend from 2012–2021 in cities of China. Despite the trends of SEVs (i.e. increasing/decreasing) being relatively consistent in both urban and suburban, the latter shows a higher proportion regarding the trends in various SEVs. Besides, the partial least squares regression (PLSR) model shows that the major contributors to SUHII in urban areas are landscape shape index (LSI), patch density (PD), and the digital elevation model (DEM), while in suburban areas, those critical SEVs are LSI, normalized difference built-up index (NDBI), and DEM. These findings can facilitate the sustainable design of urban planning in a nature-based solution.

Impact of landscape patterns on ecosystem services in China: a case study of the central plains urban agglomeration

Urban agglomeration is the highest stage of urban development, which reasonable planning will be conducive to the rapid and healthy development of the regional economy. However, in recent years, unreasonable urban agglomeration planning has changed landscape patterns and brought huge challenges to ecosystem services. Moreover, there is currently a lack of understanding of the relationship between landscape patterns and ecosystem services, especially in the process of urban agglomeration construction. In this study, we attempt to reveal the impact of landscape patterns on ecosystem services value (ESV) based on many years of remote sensing data in the Central Plains Urban Agglomeration (CPUA). The results show that landscape patterns have significant spatiotemporal evolution characteristics, and there are significant differences between different landscape patterns in the CPUA. Moreover, most of landscape patterns show significant east-west differences. Total ESV has decreased from USD 838.53 million in 2000 to USD 792.32 million in 2018. From a spatial perspective, the areas with high ESV are mostly distributed in the western mountainous and southern hilly areas, but low ESV area are mainly concentrated in the central and northern plains. In addition, the results of model analysis reveal that there is a remarkable positive correlation between ESV and patch density, interspersion juxtaposition index, cohesion index, and splitting index, but a remarkable negative correlation between ESV and total edge. These results provide critical guidance and suggestions for the improvement of future urban agglomeration construction.

Effects of floral display size, local open raceme density, patch size, and distance between patches on pollinator behaviour in Salvia nipponica

Flowers cluster at various spatial scales, so pollinators use information from multiple scales when foraging in natural plant populations. Little is known about the effects of interactions between scales or their relative strength. We examined bumblebee foraging behaviour in a natural population of Salvia nipponica in 10 and 7 patches in 2019 and 2020, respectively. We recorded within-patch factors (display size of racemes and local open raceme densities) and patch-level factors (patch size and distance from the nearest patch) and analysed their relationships with pollinator behaviour. The numbers of visits per raceme and flower were mainly affected by the interaction of patch size and raceme density; they were higher in locations with lower raceme density in larger patches. The ratio of flowers visited to all open flowers in a raceme during a raceme visit, which relates to a bumblebee’s choice to leave a raceme, was mainly affected by the interaction of display size and local open raceme density; in 2019 it was higher in racemes with smaller display sizes, while in 2020 the strength and direction of the relationship depended on the open raceme density. These results suggest that pollinators relied on the sizes of flower clusters at different spatial scales when visiting and leaving racemes and adjusted their responses to the sizes of flower clusters depending on the distances between clusters. Therefore, it is important to evaluate factors at various spatial scales and their interactions to fully understand pollinator behaviour in natural plant populations.

Evaluating the Impact of Environmental Performance and Socioeconomic and Demographic Factors on Land Use and Land Cover Changes in Kibira National Park, Burundi

In Kibira National Park, Burundi, socioeconomic and demographic factors lead to environmental performance challenges that impede biodiversity; thus, understanding the impact of these determinants on land use and land cover change is important to address these challenges. In this study, a multivariate analysis of variance (MANOVA) model was used to quantify the impact of socioeconomic and demographic factors on land cover/land use (LCLU) changes using Landsat images captured between 1990 and 2021. In addition, the impact of the environmental performance index (EPI), particularly ecosystem vitality (ECO), on landscape fragmentation was examined using a Spearman correlation analysis. A Pearson correlation analysis and a principal component analysis (PCA) were used to investigate the connections between the indicators of relevance in this study. The results reveal a decrease in forestland from 86.1% to 81.32%, a decrease in water bodies from 0.352% to 0.178%, and a decrease in open land from 2.124% to 1.134%, whereas grassland increased from 11.43% to 17.37% between 1990 and 2021. The landscape fragmentation in the edge density, contagion (CONTAG), largest patch index (LPI), number of patches (NP), and patch density (PD) was reduced in 2011 but increased again from 2016 to 2021, when only the ED fragmentation continued to decrease. The MANOVA results show that the rural population had a significant impact on LCLU changes at the 5% level of significance. Demographic factors significantly contributed to changes in grassland and forestland at a probability of 5%. In addition, moderately significant connections were observed between population growth per year and water and between gross domestic product (GDP) and grassland at the 10% level. ECO issues in ecosystem services (ECSs) were statistically significant for the increased fragmentation metrics, while biodiversity and habitat (BDH) were important for reducing the edge density (ED) at a 5% level of significance. The Pearson correlations showed a substantial positive relationship between the socioeconomic and demographic components, whereas a negative connection was found between the forestland and BDH indicators. These findings are essential for understanding the significant drivers of LCLU changes and the influence of environmental performance on the landscape pattern.

Habitat configuration influences mammal populations at a wider spatial extent than habitat composition: a meta-analysis of forest mammal datasets

ContextThe spatial extent at which landscape variables most strongly influences wildlife populations (i.e., scale of effect) is of key importance to ecology and conservation. Many factors can influence scales of effect, but these relationships are poorly understood. In particular, the way scales of effect vary with different landscape metrics has not been extensively tested.ObjectivesOur study tested whether metrics of landscape configuration have wider or narrower scales of effect than habitat composition. We also examined how species traits and landscape context influence the magnitude of differences in scales of effect between metrics.MethodsWe calculated scales of effect for four metrics of habitat configuration and one metric of composition directly from species presence/absence data in online repositories including 102 species of forest mammals from 33 studies across the globe. We then compared the magnitudes and variability of scales of effect using Hedge’s g.ResultsTwo metrics of configuration (flux and patch density) had significantly wider scales of effect than habitat composition, while the differences between the other two metrics of configuration and composition were not statistically significant. The magnitude of the difference between metrics varied among samples, but none of the factors tested explained this variability.ConclusionsFor forest mammals, the scale of effect of a configuration metric can be expected to be 15–20% wider than a composition metric. However, this pattern may not hold for metrics of configuration that do not quantify attributes of the landscape that mediate species dispersal or that are correlated with the metric of composition.

Research on Urban Garden Landscape Planning and Construction Based on Ecological Concepts

Abstract As an important part of urban ecology, the planning and construction of ecological landscape gardens is an effective way to improve the quality of urban life. The biodiversity of urban gardens is measured using species diversity indicators such as species richness, Simpson, Shan-Wiener, and Pielou evenness in this paper. The landscape single dynamic attitude, landscape comprehensive dynamic attitude and landscape patch transfer matrix were selected to construct a landscape dynamic change model, and the six urban areas of H city were used as the research object to analyze the landscape pattern of vegetation cover in urban gardens and landscapes. The results showed that among the area indexes on the landscape level in the study area of H city from 2018 to 2022, the maximum patch index, patch density and edge density indexes increased year by year, with an increase of 0.24, 3.42 m*hm−2, and 0.21 hm−2, respectively, in five years. Among the aggregation indexes, the effective particle size index showed an increasing trend, with an increase of 4301.3ha2 in 2022 compared with that in 2018, and the aggregation index showed a gradual decreasing trend, with a decrease of 0.4 in 2022 compared to 2018. By analyzing the landscape pattern, the changes in the landscape pattern can be described, and then the internal mechanism affecting the landscape pattern can be determined, which is of significant significance for the study of urban garden landscape planning and construction.

Divergent effect of landscape patterns on stream water chemistry and seasonal variations across mountainous watersheds in a Northwest Pacific island

The impacts of landscape pattern on water quality of streams are intricate and influenced by spatiotemporal scales. Untangling the interactions between landscapes and water, and identifying the pivotal indicators that drive spatial and temporal changes in nutrient dynamics, are essential steps towards facilitating sustainable water resource management. This study explored the relationship between landscape patterns and annual and seasonal (wet and dry seasons) exports of major cations (Na+, K+, Ca2+, and Mg2+) and anions (Cl-, SO42-, NO3-N, and PO4-P) in 43 watersheds across subtropical mountainous regions of Taiwan during the 2015–2016 period. Multiple stepwise regression models were constructed to elucidate the crucial landscape variables influencing variations in stream ion exports across different time scales, and spatial extent, ranging from watershed to various riparian buffer widths (100, 200, 500, 1000, 1500, and 2000 m). The findings indicated that the buffer width of 200 m emerged as the optimal scale for illustrating the connections between landscape patterns and water chemistry, outperforming larger scales. Nevertheless, there were minor deviations in the optimal scale for Na+ and Cl- (ranging from 100 to 500 m). Landscape-level configuration metrics (PD [patch density], CONTAG [Contagion], and IJI [Interspersion and Juxtaposition]) played a significant role in explaining the majority of data variations in cations. This suggest that overall landscape fragmentation tends to enhance cations exports, regardless of land cover types. On the contrary, class-level configuration metrics (EDBUD [edge density of buildup], PDBAR [patch density of bareland], and IJIAGR [Interspersion and Juxtaposition of agriculture]) played a primary role in interpreting data variations of anions. This indicated that the configurations of specific land cover types, such as buildup, agriculture and bareland, are the primary factors influencing anion exports. Furthermore, the regression models exhibited robust performance during both wet and dry seasons, implying their consistent efficacy in estimating ion exports. This synthesis illustrated the benefits of utilizing this cost-effective approach to assess landscape-water connections in challenging mountainous regions, assisting water resources management.

Spatial-temporal changes of landscape and habitat quality in typical ecologically fragile areas of western China over the past 40 years: A case study of the Ningxia Hui Autonomous Region.

In this paper, we use the InVEST model and five periods of land use data from 1980 to 2020 to assess the habitat quality of the Ningxia Hui Autonomous Region in Western China, which has characteristics of a typical fragile ecosystem. We further analyse the spatial and temporal characteristics of habitat quality evolution and its relationship with land use and landscape pattern indices to explore the close relationship between regional habitat quality changes and human natural resource conservation and utilization. The research results show that the overall habitat quality of Ningxia Hui Autonomous Region was stable and at a moderate level (0.57-0.60) during the 40 years from 1980 to 2020; Habitat patches (2020) with low (24.89%), high (22.45%) and very high (29.81%) quality occupy a larger proportion of the area, followed by very low (13.31%) and moderate levels (9.54%). Over the past 40 years, there have been 275 sample sites in Ningxia where habitat quality has deteriorated, 1593 sample sites where the habitat quality has remained stable, and 184 sample sites where the habitat quality has increased. From 1980 to 2020, the Mean Patch Area of landscape types in Ningxia decreased by 25.9 hm2. The Patch Density increased by 0.06 /hm2. The Largest Patch Index decreased by 15.69%. The Edge Density increased by 2.5 m/hm2. The Contagion Index decreased by 2.99%. The Area-Weighted Mean Patch Fractal Dimension remained basically unchanged (0.01). The Landscape Shape Index showed a trend of first increasing and then decreasing, increasing by 13.94. The Area-Weighted Mean Shape Index has been reduced by 9.45. The Shannon Diversity Index and Shannon Evenness Index both show an increasing trend, but the amplitude is relatively small, with 0.09 and 0.04, respectively. There was a significant spatial aggregation of high and low habitat quality in Ningxia, with high values usually distributed in the northern and southern areas with good natural conditions and low values distributed in areas with frequent human activities and poor natural conditions. The decrease in habitat quality in Ningxia was mainly due to the expansion of cultivated land and construction land, the increase in landscape fragmentation and the resulting decrease in connectivity. On the other hand, due to the implementation of ecological protection measures, such as the project of returning farmland to pasture and grass to forest, the quality of habitats in Ningxia increased. The conclusions of this study support the idea that the conservation of habitat quality in ecologically fragile areas should fully preserve the original natural habitats and reduce the interference of human activities to increase the habitat suitability of the landscape and the habitat connectivity between patches. At the same time, targeted ecological protection policies should be developed to restore the areas where the habitat quality has been damaged and ultimately maintain the stability of biodiversity and ecosystems in ecologically fragile areas. Meanwhile, for ecologically fragile areas with similar ecological characteristics to those of Ningxia, our research supports the idea of increasing the protection of the stability of the original habitats, increasing the proportion of ecological restoration projects, financial investment and seeking cooperation with local community managers and residents will help to improve the quality of the regional habitats and the enrichment of the biodiversity, and ultimately promote the harmonious coexistence of human beings and nature in the modernized sense of the word.

Modulating selective ionic enrichment and depletion zones in straight nanochannels via the interplay of surface charge modulation and electric field mediated fluid-thickening.

We report the possibilities of achieving highly controlled segregation of ion-enriched and ion-depleted regions in straight nanochannels. This is achieved via harnessing the interplay of an axial gradient of the induced transverse electric field on account of electrical double layer phenomenon and the localized thickening of the fluid because of intensified electric fields due to the large spatial gradients of the electrical potential in extreme confinements. By considering alternate surface patches of different charge densities over pre-designed axial spans, we illustrate how these effects can be exploited to realize selectively ion-enriched and ion-depleted zones. Physically, this is attributed to setting up of an axial concentration gradient that delves on the ionic advection due to the combined effect of an externally applied electric field and induced back-pressure gradient along the channel axis and electro-migration due to the combinatorial influences of the applied and the induced electrostatic fields. With an explicit handle on the pertinent parameters, our results offer insights on the possible means of imposing delicate controls on the solute-enrichment and depletion phenomena, a paradigm that remained unexplored thus far.

Analysis of the Impact of Land Use Change on Grain Production in Jiangsu Province, China

Located in the Yangtze River Delta region, Jiangsu Province has become the major grain production area of China and plays an important role in ensuring national food security. With rapid economic development and urbanization, the amount of cultivated land has decreased, which greatly affects food security. Based on the statistical data of grain production in Jiangsu Province since 2000 and the remote sensing data of 2000, 2010, and 2020, this paper used the stochastic frontier production function to calculate the output elasticity of various factors and the technical efficiency of grain production. The agglomeration effect of food production was investigated by using spatial correlation analysis. Finally, regression analysis was applied to examine the impact of land use change on grain yield and the technical efficiency of production. The results show that the grain-sown area is the decisive factor for the increase in grain output in Jiangsu Province. The technical efficiency of grain production in the province has been maintained at a relatively high level since 2000, showing a fluctuating upward trend, and the efficiency value in southern Jiangsu Province is greater than that in central and northern Jiangsu. The analysis of the spatial distribution characteristics of grain production technical efficiency shows that grain production has an agglomeration effect. The regression results showed that the complexity of land use and the density of the cultivated land patch were negatively correlated with grain yield and grain production technical efficiency, while the location of cultivated land was positively correlated with grain yield and grain production technical efficiency. The conclusion of this paper has important policy significance for promoting food production and ensuring food security.

Natural habitat connectivity and organic management modulate pest dispersal, gene flow, and natural enemy communities.

The simplification and fragmentation of agricultural landscapes generate effects on insects at multiple spatial scales. As each functional group perceives and uses the habitat differently, the response of pest insects and their associated natural enemies to environmental changes varies. Therefore, landscape structure may have consequences on gene flow among pest populations in space. This study aimed to evaluate the effects of local and landscape factors, at multiple scales, on the local infestation, gene flow and broad dispersion dynamics of the pest insect Bemisia tabaci (Genn.) Middle East-Asia Minor 1 (MEAM-1, former biotype B) (Hemiptera: Aleyrodidae) and its associated natural enemies in a tropical agroecosystem. We evaluated the abundance of B. tabaci populations and their natural enemy community in 20 tomato farms in Brazil and the gene flow between farms from 2019 to 2021. Landscapes dominated by agriculture resulted in larger B. tabaci populations and higher gene flow, especially in conventional farms. A higher density of native vegetation patches disfavored pest populations, regardless of the management system. The results revealed that whitefly responds to intermediate spatial scales and that landscape factors interact with management systems to modulate whitefly populations on focal farms. Conversely, whitefly natural enemies benefited from higher amounts of natural vegetation at small spatial scales, while the connectivity between natural habitat patches was beneficial for natural enemies regardless of the distance from the focal farm. The resulting dispersion model predicts that the movement of whiteflies between farms increases as the amount of natural vegetation decreases. Our findings demonstrate that landscape features, notably landscape configuration, can mediate infestation episodes, as they affect pest insects and natural enemies in opposite ways. We also showed that landscape features interact with farm traits, which highlights the need for management strategies at multiple spatial scales. In conclusion, we demonstrated the importance of the conservation of natural areas as a key strategy for area-wide ecological pest management and the relevance of organic farming to benefit natural enemy communities in tropical agroecosystems.

Seasonal dynamics and key drivers of pharmaceutical pollution in a peri-urban watershed

Peri-urban ecosystems are strongly influenced by their natural environmental conditions and surrounding landscape. However, landscape patterns and landscape-related variables driving pharmaceutical pollution in peri-urban watersheds with rapid urbanization remain poorly understood. Herein, we investigated the occurrence and spatiotemporal distribution of 28 pharmaceuticals and their potential influencing factors in a peri-urban watershed (Zhangxi River Watershed) in Zhejiang province, Eastern China. Paraxanthine (detection frequency 97 %, mean concentration 223.07 ng/L) and anhydro-erythromycin (95 %, 4.01 ng/L) were the most prevalent compounds. Total pharmaceutical concentrations (sum of all target compounds) were significantly higher in the wet season (summer and autumn) than in the dry season (spring and winter; P < 0.05). Information theoretic-based analysis revealed that landscape pattern and dissolve organic matter were the main drivers of watershed-scale pharmaceutical pollution rather than water quality parameters and topographic characteristics. Correlation analysis showed that total pharmaceutical concentrations were more highly correlated with landscape pattern during the dry season than the wet season. The importance analysis and indicator interaction analysis revealed that interspersion and juxtaposition index (IJI), mean patch size (AREA-MN), patch density (PD), terrestrial humic-like substances C2, dissolved organic carbon (DOC) and fluorescent dissolved organic matter (FDOM) played a vital role in the occurrence and distribution of pharmaceutical in the watershed. Maintaining natural landscape is conducive to reduce antibiotic concentration in Zhangxi River. These results suggest that landscape patterns and dissolved organic matter strongly influence pharmaceutical pollution in the peri-urban ecosystem at a watershed scale.

Feral pig (Sus scrofa) disturbance facilitates establishment of resource‐acquisitive species in Hawaiian forest understories

Abstract Invasive mammals exert pervasive effects on vegetation communities in island systems through several pathways, including by introducing novel disturbances. In Hawai‘i, feral pigs pose a particular threat to endemic species that evolved in the absence of native ungulates. The effects of pig soil disturbance on understory vegetation are contingent on the distribution and density of disturbed patches and subsequent species responses influenced by traits conferring growth and reproductive strategies. However, little is known about how these traits influence native‐ non‐native species turnover in response to pig disturbance, or how such disturbances affect trait‐mediated responses to other environmental variables. Here we quantify the effects of leaf traits and dispersal attributes on species responses to pig soil disturbance at two spatial scales—0.5 m2 patches embedded along 20 m transects within sites—across a gradient of pig density in a Hawaiian montane wet forest using Bayesian mixed models. Native and non‐native species demonstrated divergent responses, with increasing presence and abundance of non‐native species in the understory as soil disturbance within patches and sites increased. Dominant patterns in measured traits tracked the leaf economic spectrum (LES), with non‐native species tending toward resource‐acquisitive traits. Species with resource‐acquisitive traits, regardless of identity, were favoured with disturbance and responded positively to light availability in disturbed sites. Models showed species primarily dispersed by wind were more prevalent in disturbed patches and sites than those dispersed by endozoochory, while seed mass had no effect. Our results suggest pig activity influences community composition and favours non‐native species establishment, and these effects are mediated in part by traits conferring rapid resource acquisition. We also show that the extent of disturbance at the site‐scale is relevant for the influence of leaf architecture on understory responses to light availability, demonstrating how the effects of disturbance are scale‐dependent and can influence species sorting along independent environmental gradients. Read the free Plain Language Summary for this article on the Journal blog.

Identifying the Relationships between Landscape Pattern and Ecosystem Service Value from a Spatiotemporal Variation Perspective in a Mountain–Hill–Plain Region

Identifying the changes in landscape pattern and ecosystem service value (ESV) and clarifying their relationship in temporal changes and spatial variations can provide insight into regional landscape features and scientific support for regional landscape planning. Leveraging land use data from the Yihe River Basin, we quantitatively assessed the landscape pattern and ESV shifts spanning from 2000 to 2018 using the landscape pattern indexes and the equivalence factor method. We employed Pearson correlation metrics and the geographically weighted regression model to explore the interrelation of their spatiotemporal variations. Our results show the following: (1) Forestland represents the most expansive land cover category. Apart from construction land, all other types experienced a decline in area. The most notable change occurred in the area of construction land. (2) The aggregation of the overall landscape shows a downward trend. The levels of fragmentation, landscape diversity, and richness increased. (3) Throughout the entire study period, the overall ESV gradually decreased, and the land cover type with the greatest contribution to the ESV was forestland. (4) In terms of temporal changes, the patch density and edge density of the overall area are significantly negatively correlated with total ESVs. The largest values for the patch index, perimeter–area fractal dimension (PAFRAC), and aggregation are significantly positively correlated with total ESVs. (5) In terms of spatial variation, the contagion index (CONTAG), PAFRAC, and the Shannon diversity index (SHDI) were noticeably correlated with ESVs. The CONTAG is positively correlated with ESVs upstream, but negatively midstream and downstream. The SHDI is negatively correlated with ESVs upstream, but positively midstream and downstream. The PAFRAC exhibits a positive correlation with ESVs for the most part. The association between the landscape pattern indexes and ESVs exhibits temporal and spatial inconsistencies in most instances, suggesting a spatiotemporal scale effect in their relationship. This study recommends that the local government devises a long-term strategy for urban development and exercises stringent control over the unregulated expansion of construction land. Through reasonable territorial spatial planning, government departments could enhance the connectivity of the overall landscape pattern of the Yihe River Basin to achieve the reasonable allocation and sustainable development of regional resources.

Fire refugia are robust across Western US forested ecoregions, 1986–2021

In the Western US, area burned and fire size have increased due to the influences of climate change, long-term fire suppression leading to higher fuel loads, and increased ignitions. However, evidence is less conclusive about increases in fire severity within these growing wildfire extents. Fires burn unevenly across landscapes, leaving islands of unburned or less impacted areas, known as fire refugia. Fire refugia may enhance post-fire ecosystem function and biodiversity by providing refuge to species and functioning as seed sources after fires. In this study, we evaluated whether the proportion and pattern of fire refugia within fire events have changed over time and across ecoregions. To do so, we processed all available Landsat 4–9 satellite imagery to identify fire refugia within the boundaries of large wildfires (405 ha+) in 16 forested ecoregions of the Western US. We found a significant change in % refugia from 1986–2021 only in one ecoregion—% refugia increased within fires in the Arizona/New Mexico Mountain ecoregion (AZ/NM). Excluding AZ/NM, we found no significant change in % refugia across the study area. Furthermore, we found no significant change in mean refugia patch size, patch density, or mean distance to refugia. As fire size increased, the amount of refugia increased proportionally. Evidence suggests that fires in AZ/NM had a higher proportion of reburns and, unlike the 15 other ecoregions, fires did not occur at higher elevation or within greener areas. We suggest several possibilities for why, with the exception of AZ/NM, ecoregions did not experience a significant change in the proportion and pattern of refugia. In summary, while area burned has increased over the past four decades, there are substantial and consistent patterns of refugia that could support post-fire recovery dependent on their spatial patterns and ability to function as seeds sources for neighboring burned patches.

Application of Remote Sensing and Geographic Information System in Identification of Urban Growth nodes: A Case of Surat City, India

With the passage of time, the city's growth behavior will not change unless and until the government intervenes, and thus its identity will shift from monocentric to polycentric to meet the needs of citizens. As a result, this study is being conducted to identify emerging growth nodes within a selected area of Surat City, as well as their growth drivers over a 30-year period. Quantified built-up area within a patch size of 1km x 1km was used to compute patch density at five-year intervals from 1991 to 2021. In addition, the spatial changes that occurred within patches over the same time period were examined. Both analyses aid in determining the emerging growth nodes over a 30-year period. From 1991 to 2021, the city was driven by socioeconomic criteria such as land price, availability of good health and educational facilities, water and sewerage networks, fire stations, proximity factors such as proximity to major roads, bridges, bus stations, metro, railway stations, airport, environmental factors such as the development of riverfront and linear park, bio-diversity park, and government interventions in terms of Town Planning Schemes. This study thus aids urban planners and decision-makers in selecting which growth nodes to plan for new development and type of development, what to connect, and what to protect in the years to come.