Abstract:After 50 years of coal mining, Huaibei Mine, located at 50 km southeast of Xuzhou City in East China, has grown to a middle-size city of 600,000 people from a small village of 2000 farmers. The Zhahe Valley, with 400 km² of a built-up area and more than 100 km² of subsided peri-urban wetland at the city center, is surrounded by eight exhausted old mines and communities. In cooperation with the local city government, an ecological landuse change assessment and eco-city planning project has been carried out with a focus on the assessment, restoration and enhancement of the wetland as an eco-service to the community. The assessment includes relationships to Green House Gas emissions and heat island effects, as well as measures for a livable, workable, affordable and sustainable human settlement development through industrial transition, landscape design and capacity building. This paper will briefly introduce the main ecological approaches and results of the assessment, including measures such as changing the car-dominated transportation network to a rail-dominated network, transforming the coal-oriented high-carbon industry to a service-oriented low-carbon industry, the C-shape urban form to an O-shape with a green–blue core at the center, and the fragmentized collapsed land to integrative eco-service land.

Abstract:Fire is considered as an extreme disturbance in Mediterranean grasslands or shrublands as it often brings about many sudden changes in the vegetation structure, composition, and diversity patterns. In addition, it creates opportunities for exotic plant species to establish successfully in foreign habitat, and to outperform dominating native species. Monitoring and simulating post-fire successional changes, therefore, are essential tasks to efficiently restore native grasslands or shrublands. In this paper, we develop a theoretical framework for simulating fire-induced successional changes, mainly for Mediterranean vegetation, based on a three-level hierarchy of successional causes. Within this proposed framework, fire effects are considered by associating it with the number of burned sites open-up and specific changes at the burned sites relative to unburned sites. Three distinct site-specific neighborhoods are constructed; changes within each neighborhood allow sequential replacement of plant species by another plant species with greater maximum size, age and lower maximum growth rates and dispersal abilities. The proposed framework can be used to develop a spatially explicit individual-based model which will be useful for monitoring and predicting successional changes and hence for restoring native grasslands or shrublands.

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Abstract:The background concentration of selected alkali and alkaline earth metals (sodium, potassium, calcium and magnesium) in some macrophytes was explored in the wetland system of Keoladeo National Park, Bharatpur, India. Changes in the concentration of these elements in the course of macrophyte decomposition were also studied. The species selected were Paspalum distichum, Paspalidium punctatum, Cyperus alopecuroides, Pseudoraphis spinescens, Ipomoea aquatica, Neptunia oleracea and Hydrilla verticillata, which dominate the aquatic vegetation of the Park. Litterbag decomposition experiments were carried out with nylon bags of two different mesh sizes (0.14 and 0.375 mm) in the laboratory and in the field. Among the macrophytes, Hydrilla was the fastest decaying species with the lowest half-life (12.65 days) and Paspalidium the slowest with the highest half-life (385.08 days). Overall, the grasses had low decay rate and high half-life. Background concentration of Na, K, Ca and Mg varied among the plant species. During decomposition and towards the end of the experiment, Na, K and Ca gradually declined whereas Mg increased. The variation was significant (ANOVA, P <0.05) among metals and macrophytes. Na showed no correlation with the weight loss of decomposing macrophytes in the field or in the laboratory tanks. In the field, the K concentration, in contrast with the observations in the tanks, was negatively correlated with the biomass and positively correlated with Ca content. Ca concentration in the biomass was negatively correlated with the weight of the remaining biomass, while Mg was positively correlated with the biomass in the litterbags.

Abstract:The variations in the size, composition and diversity of the germinable soil seed bank were studied along an altitudinal gradient in the northwestern Red Sea region. The standing vegetation and the germinable seed bank were studied in 58 stands distributed along the altitudinal range from sea level to coastal mountain peaks. The classification of the germinable seed bank by the two-way indicator species analysis (TWINSPAN) led to the recognition of five groups representing different altitudinal ranges. Detrended correspondence analysis (DCA) shows that these groups are clearly distinguished by the first two DCA axes. The results demonstrate significant associations between the floristic composition of the seed bank and the edaphic factors such as CaCO₃, electrical conductivity, organic carbon and soil texture. Species richness, Shannon index of diversity and the size of the germinable seed bank show a hump-shaped curve along the altitudinal gradient, whereas evenness shows a weak increase with elevation increasing. Beta diversity of the seed bank declines with altitude increasing. The similarity between the standing vegetation and the seed bank approaches a U-shaped pattern along the elevation gradient. About 34.8% of the species that constitute the standing vegetation are vulnerable to elimination from the standing vegetation because they are not represented in the seed bank. Soil seed bank can be used for restoration of the vegetation at some of the degraded sites.

Abstract:The genus Dysoxylum is a large genus comprising of about a dozen species, distributed in India. This is the genus which is rich in compounds like terpenoids and alkaloids. The isolated compounds from the genus were reported to have interesting biological activities. This review contains the chemical structures, along with their biological activities reported in the literature.

Abstract:The main research results of nitrous oxide (N₂O) emission from paddy fields in China were summarized. Paddy fields are an important source of N₂O emission. Denitrification process exists not only in the upper flooded cultivated layer in paddy fields but also in the underground saturated soil layer. The cropping system with rice–wheat rotation and the water regime with mid-season aeration (MSA) in paddy fields of China are not only the controlling factors of N₂O emission but also the main factors influencing methane (CH₄) emission. There is a trade-off relationship between N₂O and CH₄ emissions from paddy fields. Straw amendment reduced N₂O emission but promoted CH₄ emission. Therefore, effects of both CH₄ and N₂O emissions from rice fields on the global warming potential (GWP) should be taken into consideration when any mitigation options are to be established.

Abstract:As the largest carbon pool of the terrestrial ecosystem, forest plays a key role in sequestrating and reserving greenhouse gases. With the method of replacing space with time, the typical restoration ecosystems of herb (dominated by Deyeuxia scabrescens, P1), shrub (dominated by Salix paraqplesia, P2), broadleaf (dominated by Betula platyphylla, P3), mixed forest (dominated by Betula spp. and Abies faxoniana, P4), and climax (dominated by Abies faxoniana, P5) were selected to quantify the carbon stock and allocation in the subalpine coniferous forest in Western Sichuan (SCFS). The results indicated that the soil organism carbon (SOC) stock decreased with the depth of soil layer, and the SOC per layer and the total SOC increased largely with the vegetation restoration. The contribution of SOC to the carbon stock of ecosystems decreased with the vegetation restoration from 89.45% to 27.06%, while the quantity was from 94.00 to 223.00 t C hm^-2. The carbon stock in ground cover increased with the vegetation restoration, and its contribution to the carbon stock of ecosystems was similar (3–4% of the total). Following the vegetation restoration, the plant carbon stock multiplied and reached to 430.86 ± 49.49 t C hm^-2 at the climax phase. During the restoration, the carbon stock of different layers increased, and the contribution of belowground to the carbon stock of ecosystems decreased sharply. The carbon stock on ecosystem scale of the climax phase was 5.89 times that of the herb phase. Our results highlighted that the vegetation restoration in SCFS was a large carbon sink.

Abstract:Villages represent the source of human disturbance in mountain regions, but how they alter surrounding landscapes and further affect plant diversity distribution along altitudinal gradient is still not well documented. Although the unimodal pattern along latitudinal gradient and the hypothesis of immediate disturbance (IDH) have been supported in many studies, their coupling effects on plant diversity distribution have been given less attention. In this paper, the coupling effects surrounding mountain villages were detected: (1) altitude determined the mountain landscape at regional scale, while human disturbance altered landscape fragmentation and diversity at local scale surrounding villages. (2) With the reducing human disturbance away from villages, plant diversity decreased, then increased, and finally decreased in different land uses. The plant diversity of shrubs reached the lowest. With the increasing altitude, plant diversity of the forest represented the unimodal trend, but other land use types had different properties. (3) The mechanism of the coupling effects is that the combination of topographic and soil factors determines plant diversity distribution at both landscape and plant community levels surrounding villages.

Abstract:The impacts of small hydropower plants (SHPs) on zooplankton assemblages were investigated in six cascaded SHPs along the Xiangxi River in October 2005. Five sites were sampled at each SHP. Fifty-six rotifer species which belong to 21 genera of 13 families and a nauplius species were identified in this study. Most rotifers were benthic species. The dominant rotifer species were Rotaria tardigrada, R. rotatoria, Philodina erythrophthalma, Colurella adriati, C. uncinata, Cephalodella catellina, Euchlanus dilatata, Lecane crenata and Keratella cochlearis. The Jaccard similarity index among these sections was very low, ranging from 24.33 to 58.54. The chlorophyll a (Chl a) of phytoplankton ranged from 0.37 to 1.22 ug/l, and the highest appeared in Xiaodangyang SHP. The richness, Simpson, Shannon–Wiener and Margalef diversity indices of zooplankton ranged in 4.8–21.4, 0.53–0.89, 1.12–2.58 and 0.42–1.64, respectively. In Xiangxi River, zooplankton density was low, no more than 9000 ind./m³, and the highest was observed at the down section of the river, while the lowest was at the up section of the river. Nevertheless, the richness and density in Xiaodangyang SHP were very high, only second to those in Zhaojun SHP. Apart from Xiaodangyang SHP, richness and diversity indices of zooplankton increased gradually from the upstream to the downstream. Xiangxi River was disturbed by human activities due to the cascaded development of SHPs. From Xiaodangyang SHP to Cangpinghe SHP, the richness and diversity indices of zooplankton were relatively higher at Site 3, whereas in Houzibao SHP and Zhaojun SHP, the lowest were at Site 3. The dam of SHP had significant effects on the zooplankton community. The outlet of SHP had no effect on the zooplankton community.

Abstract:Forest landscape models simulate forest change through time using spatially referenced data across a broad spatial scale (i.e. landscape scale) generally larger than a single forest stand. Spatial interactions between forest stands are a key component of such models. These models can incorporate other spatio-temporal processes such as natural disturbances (e.g. wildfires, hurricanes, outbreaks of native and exotic invasive pests and diseases) and human influences (e.g. harvesting and commercial thinning, planting, fire suppression). The models are increasingly used as tools for studying forest management, ecological assessment, restoration planning, and climate change. In this paper, we define forest landscape models and discuss development, components, and types of the models. We also review commonly used methods and approaches of modeling forest landscapes, their application, and their strengths and weaknesses. New developments in computer sciences, geographic information systems (GIS), remote sensing technologies, decision-support systems, and geo-spatial statistics have provided opportunities for developing a new generation of forest landscape models that are increasingly valuable for ecological research, restoration planning and resource management.

Abstract:Recent decades, more and more noxious plants developed fast in tropical and subtropical region. Guangdong Province, located in lower subtropical region, is densely populated and its economy is developing very quickly, it is vulnerable to be damaged. It was observed that there were many noxious plants affected forest ecosystem in this area. It is crucial to understand the destructive status and the distribution of the noxious plants. Thus, we conducted investigations of noxious plant in Baiyun Mountain and Xiqiao Mountain, Guangdong Province through point, line and plot methods. The results showed that there were 39 noxious plant species from 26 families in the two sites (Baiyun Mountain and Xiqiao Mountain). Most noxious plants reached III grade, 13 species reached III grade in Baiyun Mountain and 18 species reached III grade in Xiqiao Mountain. The exotic plant Wedelia trilobata(L.) Hitchc was the most abundant species, followed by another exotic plant Ipomoea cairica (Linn.) Sweet (Fig. 2B). All the 39 noxious plants covered over 273 hm² in the two sites, about occupied 10% of the forests. Over 90% of the noxious plants are lianas, the rest are herbs or shrubs. Of the 39 noxious species, six species were exotic plants, while 33 species were indigenous, suggesting that more attention should be paid to indigenous plants when we concerned invasive plants. Furthermore, global climate change (e.g., global warming, elevated CO₂) may shorten the latency of the plants and trigger the expansion of the noxious plants. Further studies are needed to reveal the relationship between global climate change and noxious plants, and to study why more and more native plants turned to threaten the ecosystem.