[Long-term changes of land use/cover in the Three Gorges Reservoir Area of the Yangtze River, China.] / 长江三峡库区土地利用/覆盖的长期变化.

Understanding the temporal and spatial dynamics of land use/cover (LUC) can contri-bute to reveal the impacts of climate change and human activities on ecosystems and thus be an important prerequisite for ecosystem management. As an ecologically vulnerable area in China, the Three Gorges Reservoir Area (TGRA) of the Yangtze River presented significant complexity in the response to environmental changes. However, there is a general lack of understanding in the underlying mechanism. In this study, we interpreted the time series remote sensing images derived from the Landsat sensors to map the LUC of the TGRA, and aimed to analyze the long-term changes in the distribution and structure of LUC and elucidate the evolution process of LUC, which could provide a scientific basis to understand the complexity of ecosystem changes and regional ecosystem management in ecologically fragile regions. The results showed that the TGRA presented the significant changes in spatial heterogeneity of LUC structure from 1990 to 2015. Meanwhile, the landscape changed from farmland to woodland (forest and shrubland). Farmland decreased from 66.2% to 40.4%, but woodland increased from 31.3% to 53.5%, buildings and water area increased gradually. Forest gradually spread to the middle of the TGRA, while the buildings presented a scattered expansion. In the altitude zone of 500-1000 m and slope zone of 15°-25°, woodland increased noticeably, and the coniferous forest, mixed forest and shrubland had a higher growth rate. In the study period, due to the urban construction and the various ecological restoration projects in the TGRA, the LUC structure varied with the dam's impoundment and was characterized by the ecosystem restoration. Ecological restoration projects were helpful to reduce the negative impacts of urban construction and economic development on the environment.

[Ecological risk assessment of typical karst basin based on land use change: A case study of Lijiang River basin, Southern China]. / åŸºäºŽåœŸåœ°åˆ©ç”¨å˜åŒ–çš„å ¸åž‹å–€æ–¯ç‰¹æµåŸŸç”Ÿæ€é£Žé™©è¯„ä¼°­­ä»¥æ¼“江流域为例.

Taking Lijiang River basin as study area, and based on the remote sensing images of 1973, 1986, 2000 and 2013, the land-use data were extracted, the ecological risk index was constructed, and the characteristics of spatiotemporal variation of ecological risk were analyzed by "3S" technique. The results showed that land use structure of Lijiang River basin was under relatively reasonable state and it was constantly optimizing during 1973-2013. Overall, the ecological risk of Lijiang River basin was maintained at a low level. Lowest and lower ecological risk region was dominant in Lijiang River basin, but the area of highest ecological risk expanded quickly. The spatial distribution of ecological risk was basically stable and showed an obvious ring structure, which gra-dually decreased from the axis of Xingan County Town-Lingchuan County Town-Guilin City-Yangshuo County Town to other regions. Region with lowest ecological risk mainly distributed in natural mountain forest area of the north and mid-eastern parts of Lijiang River basin, and region with highe-st ecological risk concentrated in Guilin City. The ecological risk distribution of Lijiang River basin presented significant slope and altitude differences, and it decreased with increasing slope and altitude. During the study period, the area of low ecological risk converted to high ecological risk gra-dually decreased and vice versa. On the whole, the ecological risk tended to decline rapidly in the Lijiang River basin.

[Research progress on remote sensing of ecological and environmental changes in the Three Gorges Reservoir area, China].

The Three Gorges Reservoir area (TGR area) , one of the most sensitive ecological zones in China, has dramatically changes in ecosystem configurations and services driven by the Three Gorges Engineering Project and its related human activities. Thus, understanding the dynamics of ecosystem configurations, ecological processes and ecosystem services is an attractive and critical issue to promote regional ecological security of the TGR area. The remote sensing of environment is a promising approach to the target and is thus increasingly applied to and ecosystem dynamics of the TGR area on mid- and macro-scales. However, current researches often showed controversial results in ecological and environmental changes in the TGR area due to the differences in remote sensing data, scale, and land-use/cover classification. Due to the complexity of ecological configurations and human activities, challenges still exist in the remote-sensing based research of ecological and environmental changes in the TGR area. The purpose of this review was to summarize the research advances in remote sensing of ecological and environmental changes in the TGR area. The status, challenges and trends of ecological and environmental remote-sensing in the TGR area were further discussed and concluded in the aspect of land-use/land-cover, vegetation dynamics, soil and water security, ecosystem services, ecosystem health and its management. The further researches on the remote sensing of ecological and environmental changes were proposed to improve the ecosystem management of the TGR area.

A dipeptide-based multicolored-switching luminescent solid material: when molecular assemblies meet mechanochemical reaction.

Color schemes: A mechanochromic material composed of two types of peptides bearing a pyrene group and rhodamine B moieties, respectively, displays multiluminescent colors, such as blue, green, and reddish in one sample (see picture). The mechanochromic behavior is based on a combined switching of molecular assemblies and chemical structure.

Reversible tuning luminescent color and emission intensity: a dipeptide-based light-emitting material.

A smart luminescent material whose emission color and emission intensity can be separately modulated by external force is demonstrated. The rational manipulation of rich noncovalent interactions and fluorophore packing style promotes an in-depth understanding between supramolecular structure and photophysical property and offers an effective strategy to modulate the light-emitting property in a predicative way.

Polymorphism of amino acid-based dendrons: from organogels to microcrystals.

There is a delicate balance for a low-weight molecule to behave as a gelator or crystal. The synthesis of two novel amino acid-based naphthalene-dendrons, Nap-G1 and Nap-G2 is described. Both dendrons display polymorphic properties in organic solvents. Nap-G1 developed a fibrous network with ß-sheet architecture in cyclohexane but exhibited a spherulitic network in mixed solvents (chloroform/petroleum ether 1:5, v/v). On the other hand, Nap-G2 acted as an efficient organogelator in chloroform but formed crystalline fibers in relatively high polarity solvents (such as acetone and methanol). Combinations of characterizations have been employed to study the polymorphism.

[Evaluation of landscape connectivity based on least-cost model].

Landscape connectivity, as a dominant factor affecting species dispersal, reflects the degree to which the landscape facilitates or impedes organisms' movement among resources patches. It is also an important indicator in sustainable land use and biological conservation. Least-cost model originates from graph theory, and integrates the detailed geographical information with organisms' behavioral characteristics in the landscape. Through cost distance analysis, this model can describe the species connectivity in heterogeneous landscape intuitively and visually. Due to the simple algorithm performed in GIS packages and the demand of moderate data information, least-cost model has gained extensive attention in the evaluation of large-scale landscape connectivity. Based on the current studies of landscape connectivity, this paper elaborated the significance, principles, and operation processes of least-cost model in evaluating landscape connectivity, and discussed the existing problems of the model in its practical applications, which would benefit the further related studies and biodiversity conservation.