According to the Seventh National Forest Inventory (2004-2008), China's forests cover an area of 195.45 million ha, or 20.36% of the total land area. China has the most rapidly increasing forest resources in the world. However, China is also a country with serious forest pest problems. There are more than 8,000 species of potential forest pests in China, including insects, plant diseases, rodents and lagomorphs, and hazardous plants. Among them, 300 species are considered as economically or ecologically important, and half of these are serious pests, including 86 species of insects. Forest management and utilization have a considerable influence on the stability and sustainability of forest ecosystems. At the national level, forestry policies always play a major role in forest resource management and forest health protection. In this paper, we present a comprehensive overview of both achievements and challenges in forest management and insect pest control in China. First, we summarize the current status of forest resources and their pests in China. Second, we address the theories, policies, practices and major national actions on forestry and forest insect pest management, including the Engineering Pest Management of China, the National Key Forestry Programs, the Classified Forest Management system, and the Collective Forest Tenure Reform. We analyze and discuss three representative plantations-Eucalyptus, poplar and Masson pine plantations-with respect to their insect diversity, pest problems and pest management measures.
Drylands cover more than 40% of the Earth's land surface and play a key role in global carbon sequestration (Schimel, 2010). Drylands are also home to one-third of human population, who constitutes about half of the residents living below the United Nations poverty line (UNEP, 2011). As one of the most environmentally fragile and economically vulnerable regions, drylands are at the margin of sustainability and are often threatened by severe water stress (Huang et al., 2016). Recent studies have shown that many declining hotspots of terrestrial water storage (TWS) (Famiglietti, 2004), an integration of surface waters, glaciers, canopy water, soil moisture, and groundwater, are concentrated on global drylands (
Rising
CO2 concentration and temperatures in urban areas
are now well-known, but the potential of an emerging oxygen crisis
in the world’s large cities has so far attracted little attention
from the science community. Here, we investigated the oxygen balance
and its related risks in 391 global large cities (with a population
of more than 1 million people) using the oxygen index (OI), which is the ratio of oxygen consumption to oxygen production.
Our results show that the global urban areas, occupying only 3.8%
of the global land surface, accounted for 39% (14.3 ± 1.5 Gt/yr)
of the global terrestrial oxygen consumption during 2001–2015.
We estimated that 75% of cities with a population more than 5 million
had an OI of greater than 100. Also, cities with larger
OI values were correlated with more frequent heatwaves
and severe water withdrawals. In addition, cities with excessively
large OI values would likely experience severe hypoxia
in extremely calm weather. Thus, mitigation measures should be adopted
to reduce the urban OI in order to build healthier and
more sustainable cities.
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