scholarly journals Forest Structure and Anthropogenic Disturbances Regulate Plant Invasion in Urban Forests

2021 ◽  
Author(s):  
Prakash Chandra Aryal ◽  
Chandramani Aryal ◽  
Kiran Bhusal ◽  
Devendra Chapagain ◽  
Man Kumar Dhamala ◽  
...  
Keyword(s):  
Invasive Species ◽  
Forest Structure ◽  
Urban Forest ◽  
Urban Forests ◽  
Principal Component ◽  
Anthropogenic Disturbances ◽  
Invasion Success ◽  
Anthropogenic Factors ◽  
Forest Patches ◽  
Factors Affecting

Abstract Urban forest ecosystems, the structure and functions therein, are subjected to anthropogenic disturbances. Native and sensitive species from those forests might be lost due to such disturbances. At the same time, supplemented anthropogenic resources might create opportunities for exotic and invasive species. Although, invasive species are considered as one of the major threats to the urban biodiversity and ecosystems, the researches on invasion dynamics in the Himalayas have mostly focused on the impacts of invasion on forest structure and productivity. This study aims to understand the influence of forest structure and anthropogenic factors in invasion success that are poorly covered in the existing literature. We selected 11 urban forest patches for the study considering the presence-absence of selected invasive species and structural attributes. We used Principal Component Analysis (PCA) to reduce co-linearity in the covariates and generalized linear mixed effects model (GLMM) to identify the factors affecting the invasion success. We found that the structural attributes of the forests and anthropogenic disturbances regulated invasion success in urban forests. This implies that maintaining urban forest structural attributes, especially maintaining the stands with large-sized trees, are essential to regulate and control invasion in the context of urbanization.

scholarly journals Study of the Spatiotemporal Variation Characteristics of Forest Landscape Patterns in Shanghai from 2004 to 2014 Based on Multisource Remote Sensing Data

2018 ◽  
Vol 10 (12) ◽  
pp. 4397 ◽  
Author(s):  
Yang Li ◽  
Chunyan Xue ◽  
Hua Shao ◽  
Ge Shi ◽  
Nan Jiang
Keyword(s):  
Spatial Distribution ◽  
Landscape Pattern ◽  
Urban Forest ◽  
Urban Forests ◽  
Urban Ecosystem ◽  
Landscape Patterns ◽  
Forest Landscape ◽  
Forest Patches ◽  
Forest Coverage ◽  
High Degree

The landscape patterns of urban forests not only reflect the influence of urbanization on urban forests, but also determines its function in urban ecosystem services. In the case of mastering the overall forest landscape pattern of a city, a study of the structure of urban forest landscapes at different scales and in urbanized regions is beneficial to a comprehensive understanding of the forest characteristics of a city. In the present study, an attempt was made to map and monitor the spatio-temporal dynamics of an urban forest in Shanghai from 2004 to 2014 using remote sensing techniques. Methods of landscape ecology analysis are followed to quantify the spatiotemporal patterns of an urban forest landscape by urban and rural gradient regionalization. The results show that the spatial structure of an urban forest landscape is essentially consistent with an urban landscape pattern. Due to strong interference from human activities, the ecological quality of forest landscapes is low. At the landscape level, the urban forest coverage rate increased from 11.43% in 2004 to 16.02% in 2014, however, the number of large patches decreased, there was a high degree of urban forest landscape fragmentation, landscape connectivity was poor, landscape patch boundaries were uniform, and weak links were present between ecological processes. Different urban and rural gradient division methods exhibit obvious gradient characteristics along the urban–rural gradient in Shanghai. The regional differences in the urban forest landscape ecological characteristics have further increased as a result of urban planning and zoning. The total amount of urban forest is located closer to the urban center, which has the smallest total amount of forest; however, in terms of urban forest coverage, the suburbs have more coverage than do the outer suburbs and the central urban areas. The urban forest landscape’s spatial distribution area is evidently different. Urbanization affects the areas closest to urban residential areas, which are markedly disturbed by humans, and the urban forest landscape has a high degree of fragmentation. The forest patches have become divided and unconnected, and the degree of natural connectivity has gradually decreased over the past 10 years. At the landscape class level, broadleaf forests are dominant in Shanghai, and their area exhibits an increasing trend; shrublands and needleleaf forests, however, show a decreasing trend. Compared with other forest types, the spatial distribution of broadleaf forest is concentrated in the suburbs, and the aggregation effect is relatively apparent. From the perspective of urban forest landscape pattern aggregation characteristics in Shanghai, the spatial distribution of urban forest landscape point patterns in the study area exhibit extremely uneven characteristics. The point density of urban forest patches larger than 1 ha in Shanghai increased from 2004 to 2014. However, the total number of patches with areas larger than 5 ha decreased, and this decrease plays an important role in the ecological environment. In the past 10 years, the concentration characteristics of urban forests with large patches has gradually decreased. In 2014, the urban forest landscapes decreased by 5 km compared to the intensity of aggregates in 2004, which also indicates that urban forests in Shanghai tend to be fragmented. The results of this study can be useful to help improve urban residents’ living environments and the sustainable development of the urban ecosystem, and they will also be vital to future management.

scholarly journals Breeding density of the Tawny Owl Strix aluco in urban forests of Ljubljana City (Central Slovenia)

Acrocephalus ◽  
2017 ◽  
Vol 38 (172-173) ◽  
pp. 31-35
Author(s):  
Tjaša Pršin ◽  
Darja Kušar ◽  
Tanja Obermajer ◽  
Al Vrezec
Keyword(s):  
Urban Areas ◽  
Urban Forest ◽  
Urban Forests ◽  
Forest Patches ◽  
Tawny Owl ◽  
Point Count ◽  
Strix Aluco ◽  
Nature Park ◽  
Territory Density ◽  
Point Count Method

SummaryResults of the survey carried out in the territories of Tawny Owl Strix aluco in Ljubljana urban forests (Tivoli, Rožnik and Šišenski hrib Nature Park and Golovec Hill) were compared with the species territory density in non-urban forest of Mt. Krim. Surveys were performed with the point count method using playback in the springs of 2002 and 2016. The density established at Golovec Hill was 9.3 territories / 10 km2, while in Tivoli, Rožnik and Šišenski hrib Nature Park it reached 10.4 territories / 10 km2, which was higher than at Mt. Krim (4.1-5.8 territories / 10 km2), although densities between sites were not statistically different. Based on our surveys, the estimated population size of the urban Tawny Owl in Ljubljana would consist of 57 to 65 pairs. Our results suggest that the Tawny Owl can adapt well to the living conditions in the city urban forests and indicate the importance of the forest patches in urban areas.

scholarly journals Evaluation of Forest Edge Structure and Stability in Peri-Urban Forests

Forests ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 338
Author(s):  
David Hladnik ◽  
Andrej Kobler ◽  
Janez Pirnat
Keyword(s):  
Urban Forest ◽  
Residential Buildings ◽  
Canopy Structure ◽  
Urban Forests ◽  
Forest Edge ◽  
Canopy Height ◽  
Forest Edges ◽  
Forest Patches ◽  
Forest Patch ◽  
Edge Structure

In the presented research, we studied the forest edge structure of urban and peri-urban forests on the outskirts of Ljubljana (Slovenia) consisting of a number of patches covering the collective surface of 1884 ha. They differ from each other according to the degree of fragmentation and by the share of the interior forest area. On the basis of LiDAR data, we conducted an analysis of the edges of the persistent forest patches and estimated them with regard to the land use they bordered on. The horizontal estimation of forest edges and the changes of forest edges, in the last decades, were estimated using digital orthophoto images of cyclic aerial surveys of Slovenia, from 1975 to 2018. The data, provided by LiDAR, were used to obtain an accurate estimate of forest edges and the metrics of their vertical canopy structure. On the basis of the canopy height model (CHM), we determined the height classes, the heights of the tallest trees, and indices of canopy height diversity (CHD) as variables subjected to a k-means cluster analysis. To determine the forest edge and trees stability, their heights and diameters at breast height (DBH) were measured and their canopy length and h/d (height/diameter) dimension ratios were estimated. In the study area of the Golovec forest patch, more than half of the forest edge segments (56%) border on residential buildings. After the construction of buildings, 54% of the newly formed forest edges developed a high and steep structure. Unfavorable h/d dimension ratio was estimated for 16% of trees, more among the coniferous than among the deciduous trees. Similar characteristics of newly formed forest edges bordering on built-up areas were determined in other sub-urban forest patches, despite the smaller share of such forest edges (19% and 10%, respectively). Tools and methods presented in the research enable the implementation of concrete silvicultural practices in a realistic time period and extend to ensure that adequate forestry measures are taken to minimize possible disturbances.

scholarly journals Measuring Multi-Scale Urban Forest Carbon Flux Dynamics Using an Integrated Eddy Covariance Technique

2019 ◽  
Vol 11 (16) ◽  
pp. 4335 ◽  
Author(s):  
Kaidi Zhang ◽  
Yuan Gong ◽  
Francisco J. Escobedo ◽  
Rosvel Bracho ◽  
Xinzhong Zhang ◽  
...  
Keyword(s):  
Eddy Covariance ◽  
Green Infrastructure ◽  
Urban Forest ◽  
Scale Effects ◽  
Atmospheric Stability ◽  
Urban Forests ◽  
Co2 Flux ◽  
Forest Patches ◽  
Multi Scale ◽  
Co2 Dynamics

The multi-scale carbon-carbon dioxide (C-CO2) dynamics of subtropical urban forests and other green and grey infrastructure types were explored in an urbanized campus near Shanghai, China. We integrated eddy covariance (EC) C-CO2 flux measurements and the Agroscope Reckenholz-Tänikon footprint tool to analyze C-CO2 dynamics at the landscape-scale as well as in local-scale urban forest patches during one year. The approach measured the C-CO2 flux from different contributing areas depending on wind directions and atmospheric stability. Although the study landscape was a net carbon source (2.98 Mg C ha−1 yr−1), we found the mean CO2 flux in urban forest patches was −1.32 μmol m−2s−1, indicating that these patches function as a carbon sink with an annual carbon balance of −5.00 Mg C ha−1. These results indicate that urban forest patches and vegetation (i.e., green infrastructure) composition can be designed to maximize the sequestration of CO2. This novel integrated modeling approach can be used to facilitate the study of the multi-scale effects of urban forests and green infrastructure on CO2 and to establish low-carbon emitting planning and planting designs in the subtropics.

Assessment of the spatial–temporal variations on the water quality of stagnant Haihe River, Tianjin, North China

2017 ◽  
Vol 18 (3) ◽  
pp. 1103-1116
Author(s):  
Zhiwei Zhang ◽  
Ling Xiao ◽  
Min Ji ◽  
Can Wang
Keyword(s):  
Water Quality ◽  
Control Strategies ◽  
Principal Component ◽  
Temporal Variations ◽  
Quality Parameters ◽  
Anthropogenic Factors ◽  
Haihe River ◽  
Factors Affecting ◽  
And Cluster Analysis

Abstract Spatial–temporal variations in 13 selected water quality parameters from four stations located in the stagnant Haihe River from 2012 to 2014 were analysed. Principal component analysis and cluster analysis were applied. The main latent anthropogenic factors affecting the water quality of Sanchakou, Sixin Bridge, Liulin, and Erdao Gate were combined sewer overflow, organic matter, domestic sewage, and agricultural diffuse source, respectively. External inputs mainly affected quality water in the summer–autumn season. By contrast, intrinsic biochemical processes were highly correlated with water quality in the winter–spring season. Ranges of total nitrogen (TN) and total phosphorus (TP) of four sampling sites measured 1.2 mg/L to 11.4 mg/L and 0.04 mg/L to 2.06 mg/L, respectively. TN/TP (mass ratio) was mainly between 9 and 23, indicating severely eutrophicated mainstream of the Haihe River and sufficient amounts of nutrients for phytoplankton growth and reproduction. Hence, dual nutrients control strategies should be implemented in this stagnant urban river.

scholarly journals Forest structure and anthropogenic disturbances regulate plant invasion in urban forests

2021 ◽  
Author(s):  
Prakash Chandra Aryal ◽  
Chandramani Aryal ◽  
Kiran Bhusal ◽  
Devendra Chapagain ◽  
Man Kumar Dhamala ◽  
...  
Keyword(s):  
Forest Structure ◽  
Plant Invasion ◽  
Urban Forests ◽  
Anthropogenic Disturbances

Island biogeography theory and the urban landscape: stopover site selection by the silver-haired bat (Lasionycteris noctivagans)

2022 ◽  
Author(s):  
Hannah Adams ◽  
Liam McGuire
Keyword(s):  
Island Biogeography ◽  
Urban Forest ◽  
Natural Habitat ◽  
Negative Relationship ◽  
Urban Forests ◽  
Forest Patches ◽  
Stopover Site ◽  
Island Biogeography Theory ◽  
The Impact ◽  
Lasionycteris Noctivagans

Many migratory bats require forested sites for roosting and foraging along their migration path, but increased urbanization and intensive agricultural practices may reduce the availability of stopover sites. Urban forests may provide important stopover habitat, maintaining landscape connectivity in regions where the majority of natural habitat has been cleared for development. Island biogeography theory can be applied to urbanized temperate forest biomes where small urban forests represent islands separated from the larger “mainland” forest. We used acoustic monitoring during the fall migration period to investigate the use of urban forest habitat by the migratory species Lasionycteris noctivagans Le Conte, 1831. We predicted that recorded activity would have a positive relationship with forest patch area and shape and a negative relationship with isolation from other forest patches, as suggested by island biogeography theory. We observed greater activity at larger forest patches, and although relationships for shape and isolation were not statistically supported the observed patterns were consistent with predictions. Our results demonstrate the need for more in-depth research on the habitat requirements for both migratory and resident bat species and the impact that ongoing urbanization has on local bat populations.

scholarly journals Occurrence and Activity of Roe Deer in Urban Forests of Warsaw

2020 ◽  
Vol 3 (1) ◽  
pp. 35
Author(s):  
Karolina D. Jasińska ◽  
Mateusz Jackowiak ◽  
Jakub Gryz ◽  
Szymon Bijak ◽  
Katarzyna Szyc ◽  
...  
Keyword(s):  
Predation Risk ◽  
Urban Area ◽  
Roe Deer ◽  
Urban Forests ◽  
Anthropogenic Disturbances ◽  
Camera Traps ◽  
Human Disturbances ◽  
Human Presence ◽  
Big Cities ◽  
High Level

Human presence or activities are perceived by animals as those associated with predation risk so activity and exploration patterns of animals should be shaped by indices of anthropogenic disturbances. The high level of human disturbances is noticed in big cities. Therefore, the aim of the study was to determine the occurrence of roe deer in Warsaw and its activity in the Warsaw urban forests. We used snow tracking on transect routes (winter seasons 2016, 2017, 2018; 115.1 km in total) to determine roe deer occurrence in four habitats: forests, open areas, parks, and built-up areas. The number of tracks was highest in forests (4.6 tracks/1 km/24 h), followed by open areas, built-up areas, and parks. We used camera traps to determine the activity of roe deer in selected urban forests. We collected 697 observations of roe deer in Warsaw forests in the years 2016–2019 (per 4826 trap-days in total). The peak of roe deer activity was noticed between 4:00 and 5:00 a.m. Animals were least active at 1:00–2:00 p.m. and between 11:00 p.m.–01:00 a.m. Our research showed that roe deer inhabiting the urban area avoided human presence by using well-covered habitats and being active in periods when humans’ disturbances’ level is lower.

scholarly journals Quantifying Tree Cover Loss in Urban Forests within Nairobi City Metropolitan Area from Earth Observation Data

2020 ◽  
Vol 3 (1) ◽  
pp. 78
Author(s):  
Francis Oloo ◽  
Godwin Murithi ◽  
Charlynne Jepkosgei
Keyword(s):  
Land Cover ◽  
Metropolitan Area ◽  
Land Surface ◽  
Urban Forest ◽  
Urban Forests ◽  
Earth Observation ◽  
Tree Cover ◽  
Observation Data ◽  
Vegetation Health ◽  
Earth Observation Data

Urban forests contribute significantly to the ecological integrity of urban areas and the quality of life of urban dwellers through air quality control, energy conservation, improving urban hydrology, and regulation of land surface temperatures (LST). However, urban forests are under threat due to human activities, natural calamities, and bioinvasion continually decimating forest cover. Few studies have used fine-scaled Earth observation data to understand the dynamics of tree cover loss in urban forests and the sustainability of such forests in the face of increasing urban population. The aim of this work was to quantify the spatial and temporal changes in urban forest characteristics and to assess the potential drivers of such changes. We used data on tree cover, normalized difference vegetation index (NDVI), and land cover change to quantify tree cover loss and changes in vegetation health in urban forests within the Nairobi metropolitan area in Kenya. We also used land cover data to visualize the potential link between tree cover loss and changes in land use characteristics. From approximately 6600 hectares (ha) of forest land, 720 ha have been lost between 2000 and 2019, representing about 11% loss in 20 years. In six of the urban forests, the trend of loss was positive, indicating a continuing disturbance of urban forests around Nairobi. Conversely, there was a negative trend in the annual mean NDVI values for each of the forests, indicating a potential deterioration of the vegetation health in the forests. A preliminary, visual inspection of high-resolution imagery in sample areas of tree cover loss showed that the main drivers of loss are the conversion of forest lands to residential areas and farmlands, implementation of big infrastructure projects that pass through the forests, and extraction of timber and other resources to support urban developments. The outcome of this study reveals the value of Earth observation data in monitoring urban forest resources.

scholarly journals Assessing the Ecological Value of an Urban Forest Park: A Case Study of Sinhua Forest Park in Taiwan

Forests ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 806
Author(s):  
Wan-Yu Liu ◽  
Yo-Zheng Lin ◽  
Chi-Ming Hsieh
Keyword(s):  
Urban Forest ◽  
Contingent Valuation Method ◽  
Urban Forests ◽  
Green Spaces ◽  
Socioeconomic Background ◽  
Tobit Regression ◽  
Ecological Value ◽  
Forest Park ◽  
Study Results ◽  
Ecological Conservation

Urban forests offer multiple functions: they can balance negative effects from the environment and provide the public with a place for leisure and recreation. Hence, urban forests are crucial to urban ecology and have been widely studied. In addition, relevant study results were applied for policymaking in urban development and forest park management. This study evaluated the ecological value of the Sinhua Forest Park and examined whether the socioeconomic background of participants influences their willingness to pay (WTP) for ecological conservation. Questionnaires were distributed to visitors in the Sinhua Forest Park in Tainan, Taiwan, and the payment card format of the contingent valuation method was employed to evaluate the ecological value. The results showed that the visitors had an annual WTP of $22.01 per person. However, when samples with protest responses were excluded, the WTP rose to $24.58. By considering the total number of visitors of a year, the total ecological value was $1,426,964.14/year and reached $1,593,257.31/year after excluding the protest samples. This study also analyzed participants’ within-variable socioeconomic background (e.g., gender and education) and discovered that male participants who are aged 60 years or older, with an education level of senior/vocational high school, and those who visited green spaces two to three times per week presented a high WTP score on average. A Tobit regression model was employed for examination, and the results indicated that participants’ education and frequency of visiting green spaces significantly influenced their WTP for the ecological conservation of the Sinhua Forest Park.

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