Showing papers in "Landscape and Ecological Engineering in 2019"

Future land use/cover changes in Romania: regional simulations based on CLUE-S model and CORINE land cover database

Abstract: Since 1990, a series of fundamental political and socioeconomic transformations in Romania have led to important structural and functional changes in the land use/cover system. This paper aims to assess the past land use/cover dynamics during the period 1990–2006 and to simulate future changes (2007–2050) to identify the main land use/cover change processes and their potential environmental and land management implications. The simulation was carried out using the Conversion of Land Use and its Effects at Small regional extent (CLUE-S) model with the CORINE Land Cover (CLC) database and several biophysical and socioeconomic explanatory variables associated with the current land use/cover pattern. Using the receiver operating characteristic (ROC) method and cross-classification maps, statistical and spatial validation was assessed to evaluate the performance of the predicted data. The predicted map could represent a useful tool for monitoring and quantifying spatial and temporal land use/cover changes at national and particularly regional level, in order to adopt appropriate land use planning and environmental policy in line with sustainable development principles. In addition, the results could be used for further analyses to examine the consequences of land use/cover changes on landscape diversity and biodiversity, the interaction between land use/cover changes and natural hazards, or the implications for ecosystem services.

Effect of urban function and landscape structure on the urban heat island phenomenon in Beijing, China

Abstract: Rapid urbanization has aggravated the urban thermal risk and highlighted the urban heat island (UHI) effect. To improve understanding on the effect of urbanization on the UHI effect, it is essential to determine the relationship between the UHI effect and the complexities of urban function and landscape structure. For this purpose, 5116 urban function zones (UFZs), representing the basic function units of urban planning, were identified in Beijing. Land cover and land surface temperature (LST) values were extracted based on remote sensing data. UFZ, land cover, and LST were used to represent the urban function, landscape, and UHI characteristics, respectively. Then, the effects of urban function and landscape structure on the UHI effect were examined. The results indicated that the urban thermal environment exhibited obvious spatiotemporal heterogeneity due to the variation of urban function and landscape complexity: (1) UFZs showed significantly different LST characteristics for different functions and seasons, and the mean LST gap among different types of UFZ can reach 1.72–3.85 °C. (2) During warm seasons, the UHI region is mainly composed of residential, industrial, and commercial zones, while recreational zones contribute as an important UHI source region during cold seasons. (3) Urban developed land and forest are the most important landscape factors contributing to the UFZ effect in the urban thermal environment. These findings have useful implications for urban landscape zoning to mitigate the UHI effect.

The effects of tree characteristics on rainfall interception in urban areas

Abstract: Trees in urban areas have significant effects on the urban ecosystem. They can be used to improve the water cycle in urban areas by increasing evaporation and reducing runoff through rainfall interception. Street trees placed in planters on impervious areas reduce runoff by intercepting rainfall and by temporarily storing raindrops on leaves. Therefore, understanding tree canopy geometry and the effect of rainfall interception is important in urban hydrology. In this study, we assessed the effect of tree canopy morphology on rainfall interception using four major street tree species, Sophora japonica L., Ginkgo biloba L., Zelkova serrata (Thunb.) Makino, and Aesculus turbinata Blume, in Seoul, South Korea. We measured throughfall for each tree and also derived three-dimensional data of tree canopy morphology with a terrestrial laser scanner. Tree height, canopy crown width, leaf area index (LAI), leaf area density, mean leaf area, and mean leaf angle were used to determine canopy morphology. The interception rate was mostly affected by the LAI; a higher LAI tended to result in a higher interception rate. Leaf area affected the rainfall interception rate when trees had similar LAIs. These findings on individual tree canopy rainfall interception can help us to understand the importance of rainfall interception in hydrology and for ecological restoration when planning urban green spaces.

How to renew soil bioengineering for slope stabilization: some proposals

Abstract: Mountain environments play a crucial role in maintaining biodiversity despite becoming more vulnerable to colluvial processes primarily induced by extreme meteorological events. Soil bioengineering stabilizes mountain slopes and limits impacts on ecosystems and is increasingly used worldwide, yet its effectiveness requires better assessment through post-intervention environmental monitoring. However such studies are only rarely performed even though they are essential to improve future intervention. This study reports soil and vegetation monitoring data of an area in the Italian Alps in which soil bioengineering work was carried out to restore an area hit by landslides. The monitoring involved an analysis of the floristic-vegetational and ecological features of the plant communities of the area of the soil bioengineering intervention (and in adjacent areas), as well as an analysis of the chemical–physical characteristics of the soils (texture, pH, organic matter, nitrogen content, roots depth) where these communities were established. The results of the monitoring, analyzed in the overall framework of the state of the art of the sector, have highlighted some lines of research and action that should be undertaken by technicians, researchers, and politicians to innovate and to make work aimed at the stabilization of landslides more effective. In particular, it would be extremely useful to study the biotechnical characteristics of herbaceous plants that are still “unknown” in soil bioengineering and to evaluate their possible effects on ecosystems in order to produce seed mixtures that, besides being useful for soil stabilization, can accelerate vegetation dynamics, therefore maximizing the success of such works.

Rainwater storage/infiltration function of rain gardens for management of urban storm runoff in Japan

Abstract: Rain gardens have recently gained popularity in Japan for the management of urban storm runoff. However, due to limited expertise regarding the technical capacity of such facilities, the level of their optimality in urban development remains unclear. To help elucidate rain garden capacity, research on two such facilities (referred to here as RG1 and RG2) was conducted in Kyoto, Japan, to clarify the characteristics of their storage/infiltration function. Rainfall and groundwater levels were monitored for 134 days between summer and autumn (a period incorporating the typhoon season) with the consideration of groundwater levels and soil water characteristics in six soil layers. Soil constitution and hydraulic conductivity in a saturated state were also evaluated to help clarify the infiltration function of the rain gardens. The results showed that RG2 had a higher water storage volume (109.54 m3) than RG1 (92.14 m3) due to the difference in area and soil porosities. Across both the rain gardens, the saturated hydraulic conductivity of each layer averaged to 0.227 cm/s, indicating a low risk of ponding. The soil available water capacity of dressing layers and existing soil layers at the greening site were excellent (> 12%) and good (between 8 and 12%). The results of the study indicated favorable storage/infiltration functions in both gardens and the potential to control more than 60% of storm runoff. The application of rain gardens may, therefore, be recommended in other urban areas of Japan.

Estimating the heights and diameters at breast height of trees in an urban park and along a street using mobile LiDAR

Abstract: Because trees can positively influence local environments in urban ecosystems, it is important to measure their morphological characteristics, such as height and diameter at breast height (DBH). However, measuring these data for each individual tree is a time-consuming process that requires a great deal of manpower. In this study, we investigated the feasibility of using mobile LiDAR to estimate tree height and DBH along urban streets and in urban parks. We compared measurements from a mobile LiDAR unit with field measurements of tree height and DBH in urban parks and streets. The height-above-ground and Pratt circle fit methods were applied to calculate tree height and DBH, respectively. The LiDAR-estimated tree heights were highly accurate albeit slightly underestimated, with a root mean square error of 0.359 m for the street trees and 0.462 m for the park trees. On the other hand, the estimated DBHs were moderately accurate and overestimated, with a root mean square error of 3.77 cm for the street trees and 8.95 cm for the park trees. Densely planted trees in the park and obstacles in urban areas result in “shadows” (areas with no data), reducing accuracy. Irregular trunk shapes and scanned data that did not include full data point coverage of every trunk were the reasons for the errors. Despite these errors, this study highlights the potential of tree measurements obtained with mobile terrestrial LiDAR platforms to be scaled up from point-based locations to neighborhood-scale and city-scale inventories.

Using unmanned aerial vehicles for vegetation mapping and identification of botanical species in wetlands

Abstract: High-resolution aerial photographs have important applications in vegetation mapping, especially in environments, such as wetlands, which are not easily accessible by ground operators. Unmanned aerial vehicles (UAVs), equipped with cameras capable of taking photographs of < 1 cm pixel resolution, are promising not only for the vegetation mapping but also for the identification of plant species. This paper illustrated the results of three different flight heights (5 m = 3.5126 mm/pixel; 10 m = 7.0252 mm/pixel; 25 m = 17.5630 mm/pixel), using 12MP images and their magnification, on the identification of vegetation and botanical species in a rewetted peatland populated mainly by Phragmites australis and Myriophyllum aquaticum within the Massaciuccoli Lake basin (Northern Tuscany, Italy). Among the obtained images, we selected the best flight height for the vegetation mapping and the botanical identification of the plant species using both visual and automated image analyses. Images taken from flights at 25 m of height proved to be useful for a sufficiently detailed mapping, while those from 10 m of height were more suitable for the detection of plant microcommunities. However, the most accurate identification of the species (at the taxonomic level of genus/species) was possible only with the images taken from 5 m of height.

Hydrological performance of extensive green roofs in response to different rain events in a subtropical monsoon climate

Abstract: Rapid urbanization transforms permeable land into developed areas with predominantly impervious surfaces, significantly increasing stormwater runoff and exacerbating the risk of pluvial flooding. Green roofs provide an attractive strategy for increasing surface permeability by mimicking pre-development hydrologic functions and mitigating flood risks in compact cities. However, the potential of this strategy has not been rigorously assessed, despite advances in global stormwater management. This is mainly due to insufficient scientific knowledge of hydrologic performance and a lack of experimental studies of rainwater-harvesting capacity under specific climatic conditions. This study evaluated the hydrologic performance of a real-scale extensive green roof (EGR) constructed in a subtropical monsoon climate in Nanjing, China. Overall, the EGR showed considerable ability to retain rainfall (mean retention ~ 60%, accumulated retention ~ 30%), although retention performance varied from 11% to 100% depending on the rainfall event considered, and decreased with increasing rainfall. Event-based rainfall–runoff comparisons demonstrated that the EGR retained rainwater efficiently during the early stages of a rainfall event and significantly attenuated peak runoff flows compared to bare roofs. Statistical analysis showed that total rainfall depth, rainfall duration, and substrate layer moisture influenced the overall retention most strongly, but also the percentage retention and runoff depth, highlighting the impact of substrate properties in addition to rainfall characteristics on EGR hydrologic performance. These findings provide new knowledge of and important insights into the hydrological performance of green roofs in subtropical monsoon climates, which could be used to guide EGR construction to increase landscape permeability, mitigate the risk of pluvial flooding, and enhance the climatic resilience of urban regions.

Does helimulching after severe wildfire affect vegetation recovery in a coastal area of Northwest Spain

Abstract: Helimulching is commonly applied after high-severity wildfires in North America because of its effectiveness in reducing post-fire runoff and erosion. However, its use in other parts of the world is still very limited and information about its effects in different environments is scarce. In this study, the effects of helimulching on vegetation recovery and species composition were assessed in 70 experimental plots (80 m2 each) established in five shrubland areas in Northwest Spain affected by wildfire in summer 2013. The effects on shrub, forb, fern and grass cover, and on total vegetation cover, as well as on species richness, Shannon diversity index and heterogeneity were studied over the 2 years following the fire. The impacts of soil burn severity and mulch depth on these variables were also considered. Overall, the mulching treatment had little effect on the cover variables. Although it had a positive effect on forb cover, these species represented only a small portion of the total vegetation cover. Soil burn severity was not a significant factor in explaining the variation in the variables under study. The treatment had a low impact on species composition. In the mulched plots only three non-native species were recorded and these displayed a limited capacity to act as invasive species as they were absent at the end of the period of study. The results indicate that helimulching is a feasible soil stabilization treatment with neutral effects on vegetation cover and the composition of shrubland in coastal areas of Northwest Spain.

High resilience of aquatic community to a 100-year flood in a gravel-bed river

Abstract: Our understanding of ecosystem responses to exceedingly large rare flood events is currently limited. We report the resilience of aquatic community to a 100-year record-high flood, and how it varies depending on levels of water pollution, in a fourth-order gravel-bed river in northern Japan. We used data on riparian landscape structure, channel morphology, and community structure of aquatic fauna, which were collected in sites with and without effluent before (1 month–3 years) and after (10 months) the flood. Carbon and nitrogen stable isotope ratios of consumers and basal resources were measured only before (1 year) the flood. We observed aquatic food web with introduced rainbow trout (Oncorhynchus mykiss) as the top predator, with variable relative contributions of basal resources and their pathways to the rainbow trout, under the effects of water pollution. Biofilm-originating dietary carbon became the more dominant resource, with a slightly shorter food-chain length in the polluted sites. The flood led to a loss of riparian forest and a substantial increase in the proportion of exposed gravel bars (5–24%). While the average river-bed elevation changed a little, the localized scours of river bed down to > 2 m were observed with lateral shifts of channel thalweg. Despite the landscape-level physical and structural changes of ecosystem, aquatic community showed a remarkably high resilience exhibiting negligible changes in abundance, except in the polluted site where only fish abundance showed a slight decrease. This study suggests that the abundance of aquatic organisms in gravel-bed rivers is resilient to a flood of unprecedented magnitude in recent history.

Extinction debt in a biodiversity hotspot: the case of the Chilean Winter Rainfall-Valdivian Forests

Abstract: Habitat fragmentation has become a major concern of conservation because of negative influences on plant species declines and extinctions. However, local extinction of species can occur with a temporal delay following habitat fragmentation, which is termed extinction debt. Many studies about extinction debt rely on community equilibrium from relationships between species richness and habitat variables. We assumed that the distribution of many vascular plant species in the coastal range of south-central Chile is not in equilibrium with the present habitat distribution. The aim of this research is to quantify patterns of habitat loss and to detect extinction debt from relationships between the current richness of different assemblages of vascular plants (considering longevity and habitat specialization) and both past and current habitat variables. The results showed that native forests have been fragmented and reduced by 53%, with an annual deforestation rate of 1.99%, in the study area between 1979 and 2011. Current richness of plant species was mostly explained by past habitat area and connectivity. Past habitat variables explained best richness of long-lived specialist plants, which are characterized by restricted habitat specialization and slower population turnover. We also showed that habitat fragmentation has resulted in a significant reduction in long-lived plant species’ “dwelling patch sizes (DPS)” between 1979 and 2011. Our analyses provide the first evidence of predicted future losses of plant species in a South American temperate biodiversity hotspot. Consequently, an unknown proportion of the plants in the study area will become extinct if no targeted restoration and conservation action is taken in the near future.

Urban heat island effects on moss gardens in Kyoto, Japan

Abstract: Urban heat islands (UHIs) represent a serious problem for urban biodiversity and landscapes. The impact of UHIs on Japanese gardens are of particular concern because these gardens use moss as a ground cover, and moss can be strongly affected by UHIs due to their sensitivity to drought stress. We studied 17 historical gardens in Kyoto, Japan, and propose an effective management strategy for moss gardens that takes into account the influence of UHIs on these gardens. The study sites included gardens covered by large patches of hygrophilous moss, gardens covered by mosses including small patches of hygrophilous moss, gardens covered by relatively drought-resistant moss, and gardens with small patches of mosses. We measured temperature and relative humidity within the gardens and determined the surrounding land-use types. A comparison of microclimates showed significant differences among garden types. Hygrophilous gardens had the lowest temperature and highest relative humidity, whereas gardens with small patches of moss had the highest temperature and lowest relative humidity. Using structural equation models, we determined that urbanization within 1000 m from the gardens increased temperature and decreased relative humidity, strongly affecting the type of garden. These effects could be attributed to the sensitivity of mosses to changes in microclimate caused by UHIs. Taken together, the results indicate that urban planning—e.g., increasing green space—within 1000 m of moss gardens can maintain those gardens by mitigating the influence of UHIs.

Soil infiltration rate of forestland and grassland over different vegetation restoration periods at Loess Plateau in northern hilly areas of China

Abstract: Vegetation restoration practices play an important role in environmental management and could mitigate soil and water losses in the Chinese Loess Plateau. The main objective of this study was to ascertain the influence of vegetation durations on soil infiltration rate and other related soil properties. Undisturbed soil columns in triplicate from the same plot, with different locations, were collected to estimate the accumulated soil infiltration over different vegetation periods (9, 15, and 25 years) of grassland and forestland at different time intervals. The highest cumulative infiltration and wet front movement speed was recorded after 25 years of grassland and increased with the vegetation restoration duration. Low root biomass density (g cm−3) and soil organic matter (g kg−1) were recorded in the 9-year plantation of forestland and grassland; however, maximum root biomass densities of 1.614 ± 0.95 mg cm−3 and 0.938 ± 0.03 mg cm−3 were recorded after 25 years of forestland and grassland. Furthermore, root images scanner analysis showed that the 25 years of grassland has higher root length density and root surface area density of 5.917 ± 0.86 cm cm−3 and 2.058 ± 0.95 cm2 cm−3 at surface and subsurface soil layers. We therefore suggest that for revegetation periods of less than 25 years, grassland would be better for soil infiltration and related soil properties particularly in areas of the Chinese Loess Plateau.

Long-term effects of salvage logging after a catastrophic wind disturbance on forest structure in northern Japan

Abstract: Many reports on the effects of conventional salvage logging—the removal of fallen and damaged trees after a catastrophic windthrow—on subsequent forest restoration have focused on short-term results occurring over less than 20 years; however, this time scale is inadequate, especially for boreal forests, because of the time required for tree growth. Here, we examine the long-term effects of salvage logging after a catastrophic windthrow event in 1954 on the resilience of a boreal forest by assessing the continuous recruitment of coniferous trees, dominance of typical coniferous tree species, and potential for future recruitment. We targeted two regions with different proportions of coniferous trees that were subject to three disturbance and management histories: windthrow (WT: fallen trees left intact), windthrow and salvage (WT+SL: salvage logged after the windthrow), and old growth (OG: not affected by the windthrow). In both regions, past salvaging has had serious negative impacts on the continuous recruitment of coniferous trees and potential for future recruitment. Negative impacts on the dominance of typical coniferous tree species were only observed in mixed forests. Our results suggest that in comparison to the coniferous forest, the mixed forest was less resilient, i.e.; the capability of a forest to maintain its identity as assessed by the dominance and recruitment of typical conifer species after wind disturbance and salvage logging. We found that salvage logging could affect forest structure, even 60 years later, by destroying advanced growth, including potential mother trees, and nursery beds for seedlings of typical conifer tree species.

Influences of plant spacing on root tensile strength of Schefflera arboricola and soil shear strength

Abstract: Mechanical root reinforcement depends not only on root biomechanical properties but also on root biomass. Although it is known that plant spacing can affect root growth, it is not clear how it affects root tensile strength. We interpreted a set of field data to study the effects of spacing of Schefflera arboricola on root area ratio (RAR), root tensile strength and their combined effects on soil shear strength (also termed root cohesion). S. arboricola was transplanted into compacted silty sand at a spacing of 0.5 m, 0.8 m and 1.1 m. After 20 months of growth in the field, the root systems were excavated for root tensile testing and post-test trait measurements. Plant spacing affected the growth and tensile strength of roots. More closely spaced plants had higher RAR but lower root tensile strength, especially for roots 0.5–2 mm in diameter. According to the existing root breakage and fibre bundle models used in this study, which calculate root cohesion as the product of RAR and root tensile strength, the effects of plant spacing on root cohesion were minimal for most soil depths apart from 0.4- to 0.5-m depth.

Zonal classification of microclimates and their relationship with landscape design parameters in an urban park

Abstract: Microclimates in urban areas arise through the interaction between prevailing weather conditions and landscape design parameters. A well-arranged landscape creates a pleasant outdoor environment. Additionally, the classification of microclimates helps to illustrate variations therein and analyze influencing factors. This study classified microclimate zones (MZs) based on a statistical method and identified influential landscape design parameters with the aim of enhancing human comfort. We conducted our study at Yeouido Park in Seoul, Korea, which has various landscape design parameters, including tree canopy cover and ground surface type. A novel MZ classification method was developed in this study, then stepwise regression was used to analyze the relationship between microclimate and landscape design parameters. It was found that the MZ classification effectively demonstrated spatial microclimatic differences and characteristics on a park scale. The efficiency with which trees improved the microclimate depended on the ground surface type. However, the significant effects of landscape design parameters on the microclimate and human comfort differed by season and time of day. This study provides a statistical method for analyzing an urban microclimate and serves as a reference regarding how to effectively modify the meteorological environment on a microscale via landscape design, in both summer and winter urban outdoor spaces.

Changes in quantity, quality, and pattern of farmland in a rapidly developing region of China: a case study of the Ningbo region

Abstract: Analyses of the quantity, quality, and pattern of farmlands are important to adequately understand the changing trajectories of farmlands, and the effectiveness of farmland protection policies in rapidly developing China. In this study, an integrated approach incorporating remote sensing images, random forest (RF) classification, geographic information system (GIS), digital elevation model (DEM), land quality score (SQ), and landscape pattern indices was applied to analyze the features of farmland use change in China, taking the Ningbo region as an example. RF classification was chosen to extract farmland use information from Landsat images; GIS and DEM were applied to quantify changes in farmland areas and their spatial variations; SQ and landscape pattern indices were used to detect changes in farmland quality and pattern. The results showed a trend of decrease followed by increase in farmland quantity, a continuously decreasing trend in farmland quality, and continuously increasing trends in both farmland fragmentation and dispersion in the Ningbo region. Besides, there was also a distinct trend of farmland advancing upwards into hills with slopes larger than 6° and elevations higher than 20 m. Farmland protection policies, represented by the overall land use plans of Ningbo, proved to be effective in protection of only farmland quantity, rather than quality and pattern. Suggestions were given for the optimization of farmland protection policies by considering not only quantity and quality but also the farmland pattern in China.

The influence of microclimate on bryophyte diversity in an urban Japanese garden landscape

Abstract: Japanese gardens play an important role in the conservation of bryophyte diversity. Previous studies have indicated that diverse garden landscapes and their maintenance as well as garden microclimates can be related to high bryophyte diversity, although it has not been examined how these microclimates differ from those in other land use types and how they affect bryophyte diversity. Therefore, this study analyzed the relationships among microclimate, garden landscape, and bryophyte diversity. The study sites comprised the renowned Saihoji Temple in Kyoto, Japan, and surrounding residential areas and forests. Seventeen 1-m-radius circular plots were established within the study sites, and bryophyte species richness and cover, landscape elements, and microclimates (temperature and relative humidity) were recorded in these plots. Sixty-seven species were identified, including four endangered species, and garden plots showed higher species richness and cover than surrounding areas. Garden microclimates were characterized by significantly lower temperature and higher relative humidity, which can be attributed to a combined influence of garden elements such as large vegetation cover and water surface. Notably, these microclimates can significantly and positively affect bryophyte diversity by mitigating drought stress. Thus, Japanese gardens featuring large vegetation cover and water surface can function as conservation sites for drought-sensitive species, increasing urban bryophyte diversity. Conservation of bryophytes might be beneficial to urban biodiversity and resilience reinforcement by promoting biological interactions among several species and improving ecological functions.

Geostatistical estimation of surface soil carbon stock in Mt. Wakakusa grassland of Japan

Abstract: Although nation-wide assessments on the grassland soil carbon storage have been conducted in Japan, the uncertainty of the estimation accuracy remains with its local variability. In the present study, using geostatistical approach, we assessed the spatial variability and distribution pattern of organic carbon (OC) and estimated its total stock in the surface soils (0–5 cm) over Mt. Wakakusa grassland (30.2 ha) of Central Japan. The exploratory statistics indicated that the surface soils had 1.88 ± 0.28 kg C m−2 of soil OC density on average (n = 147) with a moderate variability (CV = 18.8%), while the geostatistical analysis unveiled that its semivariogram was well fitted by a spherical model (R2 = 0.93, RSS = 1.15E−05) and had a strong spatial dependency (nugget–sill ratio = 0.31). Based on these results, we constructed an interpolated map and estimated total OC stock to 552 Mg C in the surface soil of Mt. Wakakusa grassland.

Omnidirectional connectivity of urban open spaces provides context for local government redevelopment plans

Abstract: Governance of large cities requires local planning and administration, and most cities contain nested levels of government. There are challenges for coordinating urban planning and development among these local governments, which lead to the need to assess regional or city-wide contexts that can be used by smaller administrative units. Urban metabolism treats a city as a system within which the movement of resources can be estimated. In this study, we employed an urban metabolism approach to estimate the permeability of open space within an entire megacity, Seoul, the capital of South Korea. We provide district-level relative permeability scores for the 25 district governments to use in assessments and incentivize cooperation to improve the city’s overall open space connectivity. We analyzed the relative level of open space of 69 classes using Seoul’s land use map, and used Omniscape, a modeling tool that charts the level of suitability and resistance of every grid cell to every other grid cell using a moving window. This is an omnidirectional continuous approach that does not require open space “cores” or least-cost “paths”. We modeled two scenarios, one where open water is a barrier and contributes little to open space, and the other where open water is considered an attractive element to open space. We used the modeled outputs to define five levels of permeability and then compared the relative permeability scores for the 25 districts. Five districts had over 30% of their area in the lowest level, and eight of the 10 largest impermeable areas spanned across districts under water suitable scenario. The comparable metrics permit intra-district assessments to improve open space access, but also expect creative approaches to overcome issues including limited availability for open spaces.

Early-stage vegetation recovery in forests damaged by oak wilt disease and deer browsing: effects of deer-proof fencing and clear-cutting

Abstract: Oak wilt disease and deer browsing have depleted the canopy and forest floor of secondary Quercus serrata and Quercus variabilis forests in Japan. Small-scale clear-cuttings enhance sprouting, and are, therefore, recommended for restoration of the damaged forests. However, most damaged forests are composed of mature stands, and it is not clear whether they would sprout successfully when cut. Moreover, little is known about the regeneration of forests damaged by both oak wilt disease and deer browsing. To determine the appropriate treatment for restoration of damaged Q. serrata and Q. variabilis forests, we established a study site with three different treatments (10 × 30 m each) in Kyoto City: clear-cut and fenced, removed dead oak trees and fenced, and removed dead oak trees and unfenced. After 1-year treatment, the number of species and individual saplings tended to increase at the lower slope of each treatment site with dominance of Ilex pedunculosa. The largest species and individual numbers were observed at the clear-cut fenced site, where pioneer species such as Mallotus japonicus were found. A few seedlings of Q. serrata were found at each treatment site, and no Q. variabilis was recorded. The emergence of Q. serrata seedlings was explained by their location at the slope and not by the treatment. Moreover, many sprouts of Q. serrata and Q. variabilis were observed at the clear-cut fenced site. Although further monitoring is needed, clear-cutting and fencing appear to be an effective method for the rehabilitation of depleted forests.

Landscape structure and network characteristics of the greenway system in Guangzhou City, South China

Abstract: Greenways help to conserve natural areas and improve the quality of life for residents, especially in cities experiencing rapid urbanization. In this study, we evaluated the landscape structure and network characteristics of Guangzhou’s greenway system and analyzed the potential effects of natural and socioeconomic factors on the construction of urban greenways. The total length and density of the greenway system in Guangzhou was 1319.3 km and 0.18 km/km2, respectively. The greenway density in the urban regions was > 1.5 km/km2, which met the optimal threshold requirement for an urban greenway system. Guangzhou’s greenway system had a total of 609 branches and 366 nodes, more than in Xiamen City (China) and Phoenix (AZ), which indicated a high level of network connectivity. The built-up area (area with residential, commercial, or industrial buildings) and the number of intersections of the transportation network were positively and linearly related (R2 = 0.46 and 0.78, respectively) to the length of Guangzhou’s greenways in each 1-km2 pixel grid. Population density (R2 = 0.47, p < 0.001) and gross domestic product per capita (R2 = 0.75, p < 0.001) were positively correlated with the density of Guangzhou’s greenways in each district. These results suggested that greenways were well distributed in the urban regions of Guangzhou. The slope was < 5° for 82.8% of Guangzhou’s greenway system, which made it suitable for walking and biking; 43.7% of the 265 scenic spots were within 400 m, and 64.9% within 800 m, of the nearest greenway, indicating their high accessibility from greenways. However, nearly 50% (273 km) of the waterfront greenways in Guangzhou were adjacent to poor-quality water bodies. The future priority for optimizing Guangzhou’s greenways should be the balancing of environmental protection with social and economic development.

Impact of plant choice on rainfall runoff delay and reduction by hedge species

Abstract: Soil sealing and a decrease in vegetation cover in urban areas increase the likelihood and frequency of localised flooding. Populating the remaining green areas with vegetation, which can efficiently capture excess rainfall, is therefore important. We argue that urban hedges can be a useful tool in mitigating rainfall, so the understanding of optimal plant choice, and underlying traits which enable most rain attenuation, is needed. We tested the hypothesis that higher plant evapo-transpiration rates and larger canopy size can be linked with reduced rainfall runoff in urban hedge species. We first characterised seven hedge species grown in individual containers. These were both deciduous and evergreen species, with a range of inherent canopy sizes and water requirements. We assessed their plant water use, leaf stomatal conductance, canopy rainfall retention, and runoff delay and reduction capacity. The species showing highest and lowest potential for runoff reduction were then investigated for their outdoor performance, when planted in a hedge-like form. Our findings suggest that—after 3 days between rainfall events—species such as Cotoneaster and Crataegus with larger and wide canopies, and with high evapo-transpiration/water use rates, delayed the start of runoff (by as much to 10–15 min compared to bare substrate) as well reduced the volume of rainfall runoff. For example, 40% in bare substrate. Substrate moisture content at the time of rainfall (which is linked to plants’ ET rate) was the key explanatory variable.

Ecological resilience of ecosystems to human impacts: resilience of plants and animals

Abstract: Climate change associated with global warming has already caused extreme weather in various regions of the world. Especially in the East Asia, heavy typhoons and rainy season fronts have frequently caused the damage of heavy rain, floods, and sediment in recent years (Japan Meteorological Agency 2014). And it is expected that these weather disasters will expand in the future (Ministry of Environment et al. 2018). Furthermore, influences of extreme weather on natural ecosystems are also predicted, i.e., changes in water quality and flow regime due to altered precipitation characteristics, and changes in distribution of vegetation and wildlife due to the rise of air temperature and water temperature. Rockström et al. (2009) raised nine earth-system processes essential for survival of humanity, and showed the planetary boundary defining the safe operating space for humanity with respect to the Earth system. They also claimed that human activities can undermine the resilience of ecosystems and can increase the risk of crossing the planetary boundary. Hence, the quantification and enhancement of ecosystem resilience are required for the adaptation to climate change and global warming (Angeler et al. 2018). To what extent does the ecosystems on the earth have the resilience to such severe natural disturbances? Originally, natural disturbance favors biodiversity (D’Odorico and Bhattachan 2012) and builds biological capacity to adapt to or resist change (Palmer et al. 2008; Dee et al. 2018). And it has an important attribute conferring resilience within ecosystems (Li et al. 2012). But will the artificially modified ecosystems have enough resilience to combat intensifying natural disturbances? We still do not have much knowledge on it (Côté and Darling 2010; Andersson 2018).

Identifying corridors for landscape connectivity using species distribution modeling of Hydnocarpus kurzii (King) Warb., a threatened species of the Indo-Burma Biodiversity Hotspot

Abstract: Modeling habitat corridors for landscape connectivity may serve as an efficient tool for assisting the colonization of threatened and endemic species in the event of environmental change. We demonstrate this through a population survey, species distribution modeling, and the least cost path method. As an example, we used Hydnocarpus kurzii (King) Warb., a threatened and endemic medicinal tree species distributed in the Indo-Burma Biodiversity Hotspot covering northeast India, Myanmar, and Bangladesh. We assessed its population in the wild and characterized its current habitats. We also predicted its potential habitats and modeled the connectivity between its potential habitats in the state of Tripura, northeast India. Overall, 18 wild populations of the species comprising 36 mature trees were recorded from glen and upland habitats. About 4 % (~ 443 km2) of the total area of Tripura is predicted to be suitable for H. kurzii. Maxent outputs duly validated by field surveys revealed that the habitat corridors are concentrated mostly in the hill tracts, and that glen types of habitat offer suitable ecological conditions for the species compared to uplands. All the identified areas can form connective corridors among the existing populations. Since ~ 84 % of this suitable area has > 50 % tree cover, these corridors should effectively assist the threatened and endemic plant species in propagule dispersal and support its regeneration and establishment.

Effect of pruning material compost on the nitrogen dynamic, soil microbial biomass, and plant biomass in different soil types

Abstract: Compost prepared using pruning material (PM) contains a higher amount of mineralizable carbon (C) than conventional compost, readily causing nitrogen (N) immobilization in soil due to the multiplication of microorganisms and subsequently likely causing N starvation for plant growth inhibition. However, organic matter mineralization in soil is affected by soil microbial activity, which correlates with the total C and N contents. Therefore, we hypothesized that application of PM compost to different fertility soils have different effects on plant growth depending on soil microbial activity. Using an incubation experiment, we found that the application of PM compost had a priming effect in forest soil and subsoil, causing N immobilization in both soils. However, the period of N immobilization depended on soil microbial activity, being shorter when the soil microbial activity was higher. To test the effects of PM compost on plant growth, we grew komatsuna (Brassica rapa L. var. perviridis LH Bailey) in different soils with equal applications of PM compost for 1 month. We found that PM compost application significantly inhibited plant growth in the subsoil (P < 0.05), but significantly accelerated plant growth in the forest soil (P < 0.05), suggesting that different effects are observed on plant growth in soils with different microbial activities. In conclusion, these findings indicate that the application of PM compost to soil can accelerate plant growth in soils with high microbial activities, but can inhibit plant growth in soils with low microbial activities.

Carbon mineralization characteristics of compost made from pruning material

Abstract: To investigate carbon (C) mineralization characteristics of compost made from pruning material (PM), C mineralization parameters were evaluated, including mineralizable C (C0), apparent activation energy (Ea), and the rate constant of mineralization (k). These properties were also examined in conventional composts made from dung (D), fallen leaves (L), and bark (B). No significant differences among the plant composts (L, B and PM) were observed for Ea. Notably, the values of the respective indicators were significantly greater in PM, L and B than in D. The C0 of PM was significantly greater than that of the other composts. Conversely, the k-value for PM was significantly smaller than that for the other composts. These results indicate that PM supplies a substantial amount of mineralizable C that persists for a long time after the PM has been mixed with soil.

How predictable are the responses of ant and dung beetle assemblages to patch and landscape attributes in fragmented tropical forest landscapes

Abstract: One of the most effective means of evaluating the effects of habitat loss and landscape configuration is to assess the response of bioindicators. The present study aimed to verify which parameters of ant and dung beetle communities (species richness, abundance, unbiased Shannon diversity, and turnover rates) are most useful for evaluating the relative influence of small forest patches (< 50 ha) and landscape in the tropical rainforest of Los Tuxtlas, Mexico. We recorded a total of 106 species of ants and 30 species of dung beetle. The ant and dung beetle assemblages were related in different ways to patch and landscape attributes. Hypogeic ants were more sensitive to patch attributes, particularly vegetation composition, compared to landscape attributes. Epigeic ant assemblages are likely a disturbance indicator, or the assemblages have already homogenized across the region. Arboreal ant assemblages were particularly sensitive to fragmentation and responded to within-patch vegetation and landscape configuration. Dung beetles were more sensitive to landscape composition than to patch attributes. Given these findings, the biomonitoring of ants and dung beetles should focus on both patch and landscape attributes in fragmented landscapes to maintain the different ecosystem functions provided by them.

Delayed fluorescence as a new screening method of plant species for urban greening: an experimental study using four bryophytes

Abstract: Selecting suitable plant species is important in urban greening because urban environments often provide unfavorable conditions for plant growth. We focused on delayed fluorescence (DF), i.e., light emitted from plants immediately following light exposure as a result of back electron transfer in photosynthesis, as an indicator of photosynthetic activity. Moss greening, urban greening using bryophytes, has attracted attention as a new domain of greening that does not require soil. Therefore, tolerance to drying, which is a characteristic environmental factor in cities, of four bryophytes—Bryum argenteum Hedw., Racomitrium japonicum Dozy et Molk., Hypnum plumaeforme Wilson, and Polytrichum commune Hedw.—was evaluated in the laboratory using DF. Assuming an urban environment, experiments were performed to measure the transition of DF following the cessation of irrigation and re-watering. The recovery of accumulated DF values (0–200 s) by rehydration 8 days after irrigation cessation was increased in the order H. plumaeforme ≈ P. commune < R. japonicum < B. argenteum. B. argenteum presented an increase in the accumulated amount of DF 8 h after irrigation cessation, and presented a significantly higher DF when compared with the other three species at 16 h. Together with results of previous studies, these findings of desiccation tolerance in the studied species indicate that DF is a useful method for characterizing desiccation tolerance in plants and selecting potentially useful plants for urban greening.

Special issue: Urban green infrastructure and the ecological functions

Abstract: Sustainable cities in the future will depend on urban green infrastructure and its ecological functions (Mell 2009; Breuste et al. 2015). Green infrastructure is broadly used to describe the multifunctional approach to ecological planning. Various ecological functions, such as regulation of water flows and water purification (Lee et al. 2018), local climate regulation and adaptation (Lehmann et al. 2014), carbon storage and sequestration (Mensah et al. 2016), biodiversity conservation (Watts et al. 2010), accessibility for amenity and recreation, environmental education (Wolsink 2016), and other ecosystem services, can be arranged simultaneously in one green space. This concept of green infrastructure is especially relevant for the urban area, because only limited green spaces are allowed to be conserved or additionally restored in cities. Controversy on whether or not to harmonize the benefits from traditional gray infrastructure and those multipleecological functions from green infrastructure remain in the planning literature (Tiwary and Kumar 2014). Therefore, further studies are needed on the structure and functions of the urban green infrastructure, specifically on how to optimize the solutions in a limited urban area. We can divide the challenges in urban green infrastructure into monitoring and assessment issues. Challenges in monitoring: beyond the LULC map of a city