Implications of Land Use Changes on Carbon Dynamics and Sequestration—Evaluation from Forestry Datasets, India

Forests and soils are a major sink of carbon, and land use changes can affect the magnitude of above ground and below ground carbon stores and the net flux of carbon between the land and the atmosphere. Studies on methods for examining the future consequences of changes in patterns of land use change and carbon flux gains importance, as they provide different options for CO₂ mitigation strategies. In this study, a simulation approach combining Markov chain processes and carbon pools for forests and soils has been implemented to study the carbon flows over a period of time. Markov chains have been computed by converting the land use change and forestry data of India from 1997 to 1999 into a matrix of conditional probabilities reflecting the changes from one class at time t to another class time t+1. Results from Markov modeling suggested Indian forests as a potential sink for 0.94 Gt carbon, with an increase in dense forest area of about 75.93 Mha and decrease of about 3.4 Mha and 5.0 Mha in open and scrub forests, if similar land use changes that occurred during 1997–1999 would continue. The limiting probabilities suggested 34.27 percent as dense forest, 6.90 as open forest, 0.4 percent mangrove forest, 0.1 percent scrub and 58 percent as non-forest area. Although Indian forests are found to be a potential carbon sink, analysis of results from transition probabilities for different years till 2050 suggests that, the forests will continue to be a source of about 20.59 MtC to the atmosphere. The implications of these results in the context of increasing anthropogenic pressure on open and scrub forests and their contribution to carbon source from land use change and forestry sector are discussed. Some of the mitigation aspects to reduce greenhouse gas emissions from land use change and forestry sector in India are also reviewed in the study.     

Climatic changes and their impact on socio-economic sectors in the Bhutan Himalayas: an implementation strategy

This paper contributes to an enhanced understanding of present climatic conditions, observed climate trends and regional climate vulnerability of the Bhutan Himalayas. Bhutan’s complex, often high-altitude terrain and the severe impact of the Indian summer monsoon leads to a strong exposure of the countries’ key economic sectors (agriculture, forestry, hydropower generation and tourism) to climatic changes. Climate change also threatens Bhutan’s vast biodiversity and increases the likelihood of natural hazards (e.g. glacier lake outburst floods, flash floods, droughts and forest fires). A better understanding of Bhutan’s climate and its variability, as well as observed and possible climate impacts, will help in improving the handling of regional social, economic and ecologic challenges not limited to the Himalayas. Only a few climatological studies exist for the eastern Himalayas. They mainly focus on adaptation to immediate threats by glacier lake outbursts. In contrast, this paper (1) investigates the average spatial and inner-annual diversity of the air temperature regime of Bhutan, based on local meteorological observations, (2) discusses past temperature variability, based on global datasets, and (3) relates effects of observed warming to water availability, hydropower development, natural hazards, forests, biodiversity, agriculture, human health and tourism in the Bhutan Himalayas. Results indicate a large spatial and temporal temperature variability within Bhutan and considerably increasing temperatures especially over recent decades. Implications of regional climatic changes on various socio-economic sectors and possible adaptation efforts are discussed.     

不同碳源条件下草菇内切型纤维素酶基因（eg1）转录表达的分析

利用Northernblot方法分析了不同碳源条件下草菇切型纤维素酶基因(eg1)的表达.结果发现,在含有纤维素的液体培养基中生长10d,eg1在草菇菌丝中有高效表达;纤维二糖、α-乳糖、β-乳糖,也能诱导eg1的表达,但和纤维素相比,eg1的表达量相对较低,并且它们的诱导效应在加入这类糖12h后迅速减弱;槐糖和龙胆二糖的诱导作用非常弱.在天然稻草为基质的固体栽培料生长时,草菇eg1的表达和草菇菌丝生长与出菇相对应,在菌丝生长期(d8)可见eg1的表达,d12时菌丝已长满,表达减弱,在出菇及菇体的分化及增大期,eg1的表达量逐渐增强,在成熟期达到最高水平;表明在草菇菇体发育中需要更多碳源及能源的补充,eg1在这方面起着非常重要的作用.图4参14     

Genital abnormalities in white-tailed deer (Odocoileus virginianus) in west-central Montana: pesticide exposure as a possible cause

From spring, 1996, to early spring, 2000, accident-killed and injured white-tailed deer, Odocoileus virginianus, in the Bitterroot Valley of west-central, Montana, U.S.A., were collected and examined for genital abnormalities at the Bitterroot Wildlife Rehabilitation Center. Of the 254 male deer examined, 133 were fawns aged 3 months to 1 yr, 29 were 1 to 1 1/2 yrs of age, and 92 were 1 1/2 to 3 yrs of age. Approximately 33% were normal; the remaining 67% showed varying degrees of apparent genital developmental anomalies, specifically mispositioned and undersized scrota and ectopic testes, and this percentage held through all age groups. The sex ratio of fawns and fetuses was skewed towards males, significantly so for the 1996 fawn cohort and for the total of all fawns and fetuses in the study. Although possible causes of the genital anomalies, centering on endocrine disrupting pesticides, are discussed, no conclusions of cause and effect can be currently justified.     

The response of an insect parasitoid,Ormia ochracea (Tachinidae), to the uncertainty of larval success during infestation

Ormia ochracea is a parasitoid fly which lays its larvae on its hosts, the field crickets Gryllus integer and Gryllus rubens, in two distinct modes: (1) directly on the host and (2) around the host. In the field, 12.7% of male crickets were parasitized and 3.2% were super-parasitized. Despite the disadvantages of parasitizing infested hosts, there was no evidence that O. ochracea avoided superparasitism. This and other experiments suggest that the host assessment ability of O. ochracea is less than that reported for many hymenopteran parasitoids. by manipulating the number of larvae in each cricket, we determined that four to five larvae per host resulted in the largest number of adult flies. However, as larval number per host increased from one to six, pupal size, and hence adult size, declined. In the field, hosts were found with a mean of 1.7 ± 1.0 (SD) larvae per cricket, suggesting that there may be some selection pressure against larger clutch sizes. Nevertheless clutch sizes larger than the host can support were sometimes found in the field. During the first mode of larviposition, gravid flies deposited no more than three larvae directly onto the host. Larvae deposited directly on the host had a high probability of infesting it. During the second mode of larviposition, gravid flies laid a larger number of larvae around the host (6.1 ± 5.2). Larvae that were laid around the host were less likely to infest a cricket than were larvae that were deposited directly onto it. O. ochracea is unique in that its two different modes of larviposition have different probabilities of larval success. Even though the success rate for larvae laid during the second mode of larviposition was low, the possibility of parasitizing more hosts appears to have selected for flies laying more larvae (e.g. increasing clutch size) than is optimal if all the larvae successfully entered a single host.     

Microbial methylation of mercury in the water-level fluctuation zone of the Three Gorges Reservoir, China

正Methylmercury(MeHg)is an organic form of the global pollutant mercury(Hg)which readily accumulates in fish tissue.A majority of Hg methylation is a result of microbial activity and the abundance of inorganic Hg within the water reservoirs(Eckley et al.,2017).Compared to natural lakes and rivers,reservoirs have elevated Hg levels from the decomposition of recently flooded organic material which promote Hg     

Editorial: Effect of root anatomy and apoplastic barrier development on cadmium uptake in rice

<正>Cadmium (Cd) is a toxic metal with high mobility from soil and known translocation into plants (Song et al., 2015).Because the main source of human exposure to Cd is from food consumption, there has been increased research examining Cd uptake in agricultural plants (Li et al., 2014; Rizwan et al., 2016; Song et al., 2015). Rice (Oryza sativa L.) has been identified as a major crop that contains relatively high     

Exploring the Relationship Between Hydrologic Parameters and Nutrient Loads Using Digital Elevation Model and GIS – A Case Study from Sugarcreek Headwaters, Ohio, U.S.A.

Ohio is typical among the Midwestern and Eastern United States with high levels of water pollutants, the main sources being from agriculture. In this study, we used a digital elevation model in conjunction with hydrological indices to determine the role of landscape complexity affecting the spatial and temporal variation in pollutant levels, in one of the most impaired headwater streams in Ohio. More than eighty five percent of the study area is dominated by agriculture. Spatial distribution of slope (S), altitude and wetness index along with other watershed parameters such as flow direction, flow accumulation, stream networks, flow stream orders and erosion index were used within a Geographic Information Systems framework to quantify variation in nitrate and phosphate loads to headwater streams. Stream monitoring data for nutrient loads were used to correlate the observed spatial and temporal patterns with hydrological parameters using multiple linear regressions. Results from the wetness index calculated from a digital elevation model suggested a range of 0.10–16.39, with more than 35% having values less than 4.0. A Revised Universal Soil Loss Equation (RUSLE) predicted soil loss in the range of 0.01–4.0 t/ha/yr. Nitrate nitrogen levels in the study area paralleled precipitation patterns over time, with higher nitrate levels corresponding to high precipitation. Atmospheric deposition through precipitation could explain approximately 35% of total nitrate levels observed in streams. Among the different topographic variables and hydrological indices, results from the step-wise multiple regression suggested the following best predictors, (1) elevation range and upstream flow length for nitrate, (2) flow direction and upstream flow length for ammonia-nitrogen and slope, and (3) elevation range for phosphate levels. Differences in the landscape models observed for nitrate, phosphate and ammonia-nitrogen in the surface waters were attributed partly to differences in the chemical activity and source strengths of the different forms of these nutrients through agricultural management practices. The results identify geomorphologic and landscape characteristics that influence pollutant levels in the study area.