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Most rivers of the world are supersaturated with carbon dioxide (CO2), resulting in a large gas flux that has only recently been included in global carbon budgeting. However, little is known about CO2 emissions from urban river networks suffering anthropogenic disturbance in the context of global urbanization. We surveyed the partial pressure of carbon dioxide (pCO2) and CO2 flux from 84 locations in the Chongqing metropolitan river network, with an area of 5494 km2. The overall mean pCO2 and CO2 fluxes were 2152 µatm and 163.0 mol C m−2 yr−1, respectively, with 318.9 mol C m−2 yr−1 from rivers in the completely urban area and 49.6 mol C m−2 yr−1 from the least urbanized area. The riverine pCO2 level increased with the proportion of urban land, with 2–4 times higher CO2 flux in the urban areas than the remote rural ones. Sites with low flow velocity, narrow channel, and factitious bottom sediment appeared to be local hot spots of CO2 emission. The pCO2 and CO2 degassing was positively correlated with the nutrients content of surface water (i.e., nitrogen and phosphorus). Carbon was released to the atmosphere as CO2 from Chongqing metropolitan river network at a rate of 12.3 × 109 mol C yr−1. pCO2 exhibited a clear seasonality with lower values in March 2015 and June 2015 but a higher value in September 2014, which was coregulated by temperature, flood dilution, and in situ photosynthesis. The results highlight that rapid urbanization, with increasing nutrients loading and anthropogenic activities, will alter the carbon biogeochemical cycle in the terrestrial‐aqueous‐atmospheric ecosystem and then impact global CO2 budgets.

Low-elevation islands face threats from sea level rise (SLR) and increased storm intensity. Evidence of endangered species' population declines and shifts in vegetation communities are already underway in the Florida Keys. SLR predictions indicate large areas of these habitats may be eliminated in the next century. Using the Florida Keys as a model system, we present a process for evaluating conservation options for rare and endemic taxa. Considering species characteristics and habitat, we assess central issues that influence conservation options. We contrast traditional and controversial options for two animal and two plant species giving special emphasis to perceptions of ecological risk and safety from SLR and suggest courses of action. Multiple strategies will be required to spread extinction risk and will be effective for different time periods. Global climate change presents an uncertain, perhaps no-analog future that will challenge land managers and practitioners to re-evaluate equilibrium-state-conceived laws and policies not only for these taxa, but for many facing similar threats. To embrace conservation in a changing world will require a new dialogue that includes controversial ideas, a review of existing laws and policies, and preparation for the oncoming change.

We assessed the current status of plant conservation translocation efforts in China, a topic poorly reported in recent scientific literature. We identified 222 conservation translocation cases involving 154 species, of these 87 were Chinese endemic species and 101 (78%) were listed as threatened on the Chinese Species Red List. We categorized the life form of each species and, when possible, determined for each case the translocation type, propagule source, propagule type, and survival and reproductive parameters. A surprisingly large proportion (26%) of the conservation translocations in China were conservation introductions, largely implemented in response to large-scale habitat destruction caused by the Three-Gorge Dam and another hydropower project. Documentation and management of the translocations varied greatly. Less than half the cases had plant survival records. Statistical analyses showed that survival percentages were significantly correlated with plant life form and the type of planting materials. Thirty percent of the cases had records on whether or not individuals flowered or fruited. Results of information theoretic model selection indicated that plant life form, translocation type, propagule type, propagule source, and time since planting significantly influenced the likelihood of flowering and fruiting on the project level. We suggest that the scientific-based application of species conservation translocations should be promoted as part of a commitment to species recovery management. In addition, we recommend that the common practice of within and out of range introductions in nature reserves to be regulated more carefully due to its potential ecological risks. We recommend the establishment of a national office and database to coordinate conservation translocations in China. Our review effort is timely considering the need for a comprehensive national guideline for the newly announced nation-wide conservation program on species with extremely small populations, which is expected to stimulate conservation translocations for many species in the near future.

Southwestern China including Guangxi Province is one of nine world hotspots for orchid. Warming in the region in the past century was around 0.5°C, slightly lower than the global average of 0.7°C, while rainfall has remained the same. It is projected that the warming trend will continue for the next two centuries, while precipitation will increase slightly, and soil moisture level will decrease. We identify a number of threats due to climate changes to orchid community in the Yachang Orchid Nature Reserve in Guangxi (hereafter refer to as Yachang Reserve), a good representative of the region. Firstly, decreased soil moisture is likely to have a negative effect on growth and survival of orchids, especially terrestrial and saprophytic ones. Sixty eight (50%) orchid species in the Yachang Reserve are in this category. Secondly, the greater majority of the orchids in Yachang Reserve (72%) have populations on or close to the limestone mountain tops. These populations are likely to shrink or even become extinct as the warming continues because they have no higher places to which they are able to migrate. Natural poleward migration is unlikely for these populations because of the complex terrain, small size of the reserve and human-dominated surroundings. Species with narrow distributions (14%) and/or small population sizes (46%) will be the most vulnerable. In addition, populations represent the southern limit of the species (24%) are also prone to local extinction. Thirdly, extreme rainfall events are projected to occur more frequently, which can exacerbate erosion. This may impact orchid populations that grow on steep cliffs. Fifty seven species (42%) of the orchids in Yachang have cliff populations. Fourthly, the majority of orchid species have specialized insect pollination systems. It is unknown whether the change or lack of change in plant phenology will be in synchrony with the potential phenological shifts of their pollinators. Fifty four (40%) orchid species in Yachang Reserve flower in the spring and are potentially subject to this threat. Finally, mycorrhizal fungi are vital for seed germination for all orchids and important for post-seedling growth for some species. Yet there is a lack of knowledge of the nature of mycorrhiza on all orchids in the region, and little is known on the responses of these vital symbiotic relationships to temperature and soil moisture. Overall, 15% of the orchid species and a quarter of the genera bear high risk of population reduction or local extinction under the current projection of climate change. While studies on predicting and documenting the consequences of climate change on biodiversity are increasing, few identified the actual mechanisms through which climate change will affect individual species. Our study provides a unique perspective by identifying specific threats to a plant community.

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Overharvesting is one of the greatest threats to species survival. Farming overharvested species is a conservation strategy that can meet growing market demand and conserve wild populations of the target species. This strategy is compatible with the international community's desire to uphold the right of local communities to use biological resources to support their livelihoods. However, studies investigating whether farming can alleviate poaching pressure have focused almost exclusively on animals. To address the shortfall in plant-focused studies, we compiled information on commercial cultivation of threatened plants to assess its conservation benefits. Because China's rising middle class has rapidly intensified demand for wildlife products, we searched the scientific literature published in Chinese (China National Knowledge Infrastructure and Baidu) and in English. We found 32 reports that contained data on 193 internationally or nationally threatened plant species that were under commercial cultivation. These reports showed that cultivations of 82% of the 193 species were sustained by collecting whole plants from the wild periodically or continuously. Although based on a small sample size, species that were maintained in cultivation only through artificial propagation or seeds collected in the wild were likely associated with a reported reduction in wild harvesting of whole plants. Even so, results of correlation analyses suggested that production system, scale, and when a species began being cultivated had little effect on conservation status of the species, either globally or in China. However, species brought into cultivation relatively recently and on a smaller scale were more likely to have undergone a reduction in collecting pressure. Farming of nonmedicinal plants was most problematic for species conservation because wild plants were laundered (i.e., sold as cultivated plants). For effective conservation, policy to guide cultivation operations based on the target species' biological characteristics, cultural significance, market demand, and conservation status is needed.

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