Qinghai-Tibetan Plateau is the most sensitive region to global warming on Earth. Qinghai Lake, the largest lake on the plateau, has experienced evident area variation during the past several decades. To quantify the area changes of Qinghai Lake, a satellite-based survey based on Landsat images from the 1980s to 2010s has been performed. In addition, meteorological data from all the seven available stations on Qinghai-Tibetan Plateau has been analyzed. Area of Qinghai Lake shrank ~2% during 1987–2005, and then increased ~3% from 2005–2016. Meanwhile, the average annual temperature increased 0.319 °C/10 y in the past 50 years, where the value is 0.415 °C/10 y from 2005–2016. The structural equation modeling (SEM) shows that precipitation is the primary factor influencing the area of Qinghai Lake. Moreover, temperature might be tightly correlated with precipitation, snow line, and evaporation, thereby indirectly causes alternations of the lake area. This study elucidated the significant area variation of water body on the Qinghai-Tibetan Plateau under global warming since 1980s.
The Land Surface Temperature (LST) of a park is lower than the surrounding environment, and thus the parkland forms a Park Cool Island (PCI). However, more case studies are needed to reveal the relationship between park composition, vegetation characteristic and PCI development. The LST and Land Use/Land Cover (LULC) of 18 different sized parks in Changzhou, China were obtained from Landsat-8 and Mapworld Changzhou data. Then, a sample investigation method was used to calculate vegetation characteristics of these parks by an i-Tree Eco model. In order to reduce the impact from the external environment on PCI, the Temperature Drop Amplitude (TDA) and Temperature Drop Range (TR) inside the parks were analyzed by ArcGIS 9.3. Impact factors were tested by Pearson correlation analysis and curve fit to reveal the relationship between these factors and PCI formation. The result shows that a park area threshold of 1.34 to 17 hectares provides the best PCI effect, that park shape (perimeter/area), Leaf Area Index (LAI), density, tree cover, water cover, and impervious surface cover have significant correlation with PCI development, vegetation health and global climate change affect the PCI development. Advice is proposed to improve and maintain PCI effects.
Green roofs can improve urban ecological conditions by mitigating the heat island effect and absorbing harmful gases. Soil additives can improve roof soil properties and promote the stability of the urban ecosystem. As soil additives, biochar and sludge are widely used in the ground, but their application on roofs is still scarce. This study examined the carbon storage potential of green roofs amended with sludge and biochar. The roof soil was composed of soil and varying proportions of the additives (0%, 5%, 10%, 15%, and 20%, v/v); Sedum lineare was then planted. The carbon contents of the soils and plants were measured for one year. The influence of biochar or sludge on the carbon content of the roof soil and the factors affecting the roof carbon storage potential were analyzed. The results showed that the carbon storage potential of a biochar green roof (9.3 kg C m−2) was significantly higher than that of a sludge green roof (7.9 kg C m−2). Biochar increased the carbon content of the green roof by improving the physical properties of the roof soil and promoting plant growth, whereas sludge increased the carbon content of the green roof by improving the chemical properties of the roof soil. Moreover, biochar could not only store large amounts of stable carbon, but also reduce the weight of the green roof, improve soil moisture, and provide a resourceful utilization of municipal sludge. Thus, biochar can be considered a material for promoting carbon storage on green roofs.
Background: Insect-proof nets are commonly used in crop production and scientific research because of their environmental, economic, and agronomic benefits. However, insect-proof nets can unintentionally alter the microclimate inside the screenhouse and therefore greatly affect plant growth and yield. To examine the microclimate and agronomic performance of pesticide-free rice under insect-proof nets, two-year field experiments were carried out in 2011 and 2012.Methods: In the present study, the experiment was conducted by using a split-plot design considering the cultivation environment (open field cultivation (OFC) and insect-proof nets cultivation (IPNC)) as the main plot and the varieties as the subplot (Suxiangjing3 and Nanjing44).Results: IPNC significantly reduced the air speed and solar radiation, and slightly increased the daytime soil temperature, daytime air temperature, and nighttime relative humidity. By contrast, the nighttime soil temperature, nighttime air temperature, and daytime relative humidity were relatively unaffected. The grain yield of both rice cultivars decreased significantly under IPNC, which was largely attributed to the reduced panicle number. The reduced panicle number was largely associated with the decreased maximum tiller number, which was positively correlated with the tillering rate, time of tillering onset, and tillering cessation for both rice cultivars under IPNC. In addition, dry matter accumulation significantly decreased for both rice cultivars under IPNC, which was mainly caused by the decreased leaf area duration resulting from the reduced leaf area index. By contrast, the mean net assimilation rate was relatively unaffected by IPNC.Discussion: Insect-proof nets altered the microclimate in comparison with OFC by reducing the air speed and changing the radiation regime, which significantly affected dry matter production and yield of both japonica rice cultivars. Our results indicated that cultivation measures that could increase the tillering rate and the maximum tiller number under IPNC would lead to a significant increase in panicle number, ultimately increasing grain yield. In addition, maintaining a high leaf area duration by increasing the leaf area index would be important to compensate for the dry matter accumulation losses under IPNC. These findings are critical to provide a theoretical basis for improving agronomic performance of pesticide-free rice under IPNC.