Landscape and Ecological Engineering最新文献

Abstract

Mangroves are estuarine and coastal ecosystems strongly influenced by the local tidal regime and climate, so there is a strong variation between seasons of the year. Assessing seasonal characteristics and fluctuations allows for an understanding of changes in mangrove ecosystems during each period of the year. In this study, we used images collected from the Multispectral Unmanned Aerial Vehicle (UAV) to determine the current status and fluctuations between summer and winter of the mangrove area of Dong Rui commune according to five vegetation indicators, including the Normalized Difference Vegetation Index (NDVI), Green Normalized Difference Vegetation Index (GNDVI), Enhanced Vegetation Index (EVI), Visible Atmospherically Resistant Index (VARI), and Green Chlorophyll Index (GCI). The results show that the current state of mangroves in the UAV flight area is relatively good, with the value of vegetation indicators at a high level. In the summer, the value of vegetation indicators is stable and higher than in the winter. In low-tide areas, vegetation index values fluctuate higher than in high-tide areas. Based on the results of the analysis of vegetation indicators, the degree of correlation between NDVI and the remaining four values was determined. The results showed that the correlation coefficient was at a high level, with the highest being between NDVI and SAVI with a correlation coefficient of approximately equal to 1, followed by NDVI and EVI with a correlation coefficient above 0.9. We propose that UAV is an effective tool for monitoring and assessing fluctuations, serving the management and conservation of mangrove ecosystems.

Semi-captive elephants have been extensively used in the tourism sector in Myanmar. However, these elephants have not been provided with the range of habitats they require, resulting in increased Human-Elephant Conflict (HEC) within the local community. In addition, there are very limited studies on the assessment of their home ranges, habitat preferences, and preferred food plants. We aimed to address three research questions: (1) What is the size of semi-captive elephants’ daily home range? (2) In which habitat types do they prefer to stay? (3) What are their preferred food plants? We fitted GPS devices on the six semi-captive elephants 3–4 times a month in three study sites over seven months. The sample collection of food plants was carried out at each site. The results indicated that the mean average size of the daily home range for semi-captive elephants was 0.90 km² (95% KDE), with a range of 0.38 to 2.38 km². We found that the habitat provided for semi-captive elephants was not large enough to be inhabited. The analysis of habitat selection showed that elephants prefer to use secondary forests. The Poaceae family was found to be the main food taxon. We suggest that more areas be provided around elephant camps and that the currently permitted habitats be protected from land use that overlaps with other forestry operations.

Recently, rapid urbanization has contributed to an increasingly dominant trend of people congregating around river basins. As a result, significant changes in land use structure occur, leading to alterations in ecosystem structure and gradual degradation of ecological service functions. Using the DLB (Dianchi Lake Basin) in southwestern China as the research area, this essay analyzed its land use structure in 2020 and constructed an urban eco-resilience evaluation system based on the three dimensions of “resistibility, adaptability, and recuperability” derived from the eco-resilience theory. Meanwhile, the physical coupling model was used to calculate the coupling coordination degree of land use and eco-resilience in the area. Research shows: (1) the DLB is a complete and relatively independent ecosystem, with diverse land use types in the watershed, and the land use structure of the watershed is related to altitude and economic development; (2) the overall eco-resilience of the area has significant spatial differences in distribution. The eco-resilience of the lakeside built-up area is the lowest eco-resilience, and the regions with higher resilience are primarily those surrounding the lake or hills. (3) According to the coupling coordination degree model, the calculated coupling degree of land use and eco-resilience is 0.49, and the coordination degree is 0.38, indicating early stages of the coupling coordination progress. This paper developed a comprehensive evaluation model of land use and river basin eco-resilience, and studied the coupling relationship between the two. This holds theoretical and practical significance for ecological protection and sustainable development of DLB.

The underuse of natural resources in the Satoyama landscape, a Japanese socio-ecological production landscape, is one of the factors causing a crucial biodiversity loss in Japan. For biodiversity conservation in the Satoyama landscape, how to build a governance system for ecosystem conservation activities is a challenge. This study reveals a governance system's emergence and development process in two conservation activities linked with administrative planning in the same municipality. Furthermore, we discuss the stakeholders' role in the process and how to build a governance system that can restore the relationship between the people and the Satoyama landscape. The data for this study were collected through interview surveys, observation surveys, and literature reviews of each conservation activity. We presented the structural understanding of what events, actions, and changes occurred among the stakeholders during the processes and identified the crucial phases of the process. Through this study, there were “sharing issues and recognizing values" and "organizing" in the emergence process of governance. In the context of difficulty securing the government’s initiative, the complementing role of leading a governance system by connecting stakeholders across scales is necessary. Furthermore, under the deviation between the people and the Satoyama landscape, exploring and learning the issues of each landscape and values for the local people are the first steps for restoring social-ecological systems.

The tree species composition has a significant impact on the biogeochemical cycle of forest ecosystems, which in turn affects nutrient leaching and stream water quality. We have formulated a hypothesis that nutrient leaching varies depending on the tree species composition owing to the properties of surface soil chemistry characterized by the tree species composition. To test this hypothesis, we have collected soil water samples below the root zone in Japanese cedar plantations (CF) and natural forests (NF) and compared nutrient leaching. We analyzed major ion chemical characteristics, net N mineralization, and net nitrification in the surface soil (A layer) to determine possible causes for differences in nutrient leaching. Our results revealed that calcium (Ca²⁺) and nitrate (NO₃⁻) concentrations in soil water below the root zone were significantly higher in CF than in NF. Additionally, the Ca²⁺ and NO₃⁻ contents in surface soil were higher in CF than in NF, which may explain the higher concentrations of Ca²⁺ and NO₃⁻ in soil water in CF. In contrast, there was no significant difference in soil net nitrification rates between CF and NF. Correlations between NO₃⁻ and Ca²⁺ concentrations in soil solution suggest that the higher availability of Ca²⁺ from surface soils in CF could partially account for the higher NO₃⁻ leaching from CF. Our study suggests that the properties of surface soil chemistry characterized by the tree species composition are responsible for causing the differences in nutrient leaching.

Since its inception, land-use planning (LUP) has faced many challenges; most of these challenges have been due to the incompatibility of LUP with multi-layer situations. Lack of adaptability in planning has led to increased social conflicts and many environmental issues, especially in global southern countries. Paying attention to the context in which LUP takes place is necessary to adapt to the nonlinear land-use changes. LUP theories have formed two general processes including top-down (comprehensive planning) and bottom-up (collaborative planning) processes to influence land use. However, the processes that shape the transformations of land uses are more sophisticated than being placed in this or that theory. Land-use transformations are rooted in contextual conditions that are shaped by the mutual interactions of social structures and power relations at different spatial levels which are different for each society. This research explores the challenges of the incompatibility of LUP general processes with contextual conditions. The study reviews the compliance of contextual conditions with the LUP main elements, including cognition, decision-making process, goal setting, and policy selection. The results showed that LUP to comply with the multi-layer nature of various situations needs a continuous connection of its elements. Efficient knowledge of changing forces enables planning adaptability and flexibility. This knowledge provides the opportunity to redefine the decision-making process. This research can be the triggering point for LUP to comply with different conditions.

The heterogeneity of urban landscapes has effects on the environmental characteristics and fish composition of individual urban streams, even within a single water system. It is, therefore, imperative to assess the influence of physiochemical properties on urban streams by analyzing the spatial distribution of fish communities at the local scale. However, conventional fish surveys encounter time and labor constraints when selecting and surveying dense sampling points under 2 km in stream networks. In this study, environmental DNA (eDNA) metabarcoding was used as an innovative survey methodology to identify the effects of land use and stream order on fish composition and tolerance guild in an urban area. The eDNA sampling was conducted in 31 sites of the Anyang stream network in Korea, including part of the stream undergoing ecological restoration. The eDNA survey detected 12 of 17 species (70.6%) that appeared in the historical data, and 12 of 18 species (66.7%) identified in a conventional field survey with kick nets and casting nets. The proportions of urban area, forest and grassland were positively correlated with abundance (p < 0.05) and richness (p < 0.05) in multiple regression analyses, while the proportion of agricultural area showed a negative correlation (p < 0.05). For abundance, richness, and diversity within the fish community from first- to third-order streams, there was a significant decrease in sensitive species (p < 0.05) alongside a significant increase in tolerant species (p < 0.01) across all three indices. The results of this study highlight variations in fish composition across sites within the local scale of the urban stream network, underscoring the need for detailed monitoring to understand the ecological function of urban streams.

Abstract

Migration and the dependence of rural communities on forest resources for subsistence have profoundly altered the composition and spatial structure of the landscapes of the border municipality of Kasenga in the southeast of DR Congo. The spatio-temporal dynamics of anthropogenic effects on forest ecosystems were mapped and quantified in the municipality of Kasenga using Landsat image classification from 1989 to 2022, combined with landscape ecology metrics to analyze spatial patterns. Our results show that the landscape has undergone profound disturbances. The area of large patches of forest that used to dominate the landscape has been reduced by a factor of 4 from 1989 to 2022, thus indicating the anthropogenic impact on the fragmentation of forest ecosystems. If in 33 years (from 1989 to 2022) forest has lost more than a third of their coverage through the dissection, fragmentation and attrition of patches, agriculture, grassland and wetland, and built-up and bare land have recorded a progressive dynamic resulting from the creation and aggregation of patches. These anthropogenic transformations, coupled with a lack of land management planning, will compromise the future of forest ecosystems since the level of landscape disturbance has quintupled from 1.1 to 5.5 in 33 years. There is then an urgent need to develop an integrated and participatory land management strategy to preserve forest resources and guarantee their resilience.

In this study, we analyzed the effect of forest damage caused by forest fires or shallow landslides on the rainfall thresholds needed to initiate bedload transport in mountain watersheds. Two bedload monitoring systems were used: a slot sampler and a hydrophone. These were installed in a forest fire-damaged site, a shallow landslide-damaged site, and a control site. A total of 199 effective rainfall-bedload data were collected from 2014 to 2016. Total rainfall amount (TR) and peak rainfall intensity (PRI) were found to be the most effective rainfall indices to predict bedload transport initiation. We also used linear functions to estimate percent threshold lines of the rainfall indices and used performance evaluations to select a representative threshold line for each site. As a result, the forest fire-damaged and shallow landslide-damaged sites had lower TR and PRI reference values than the control site, indicating that lower TR and PRI values can initiate bedload transport in damaged mountain forest areas. Although our study results may be limited by different characteristics between the study sites and insufficient data collection, it still indicates that forest damage caused by forest fires and shallow landslides affects bedload transport. Future studies are needed to further confirm these findings.