Low-altitude Valley Research Articles

Evaluation of natural resistance to smut in elite sugarcane varieties (lines)

<p indent=0mm>Sugarcane smut is a systemic fungal disease that seriously affects the development of sugarcane industry in China. Different sugarcane varieties have various resistance to smut. Screening and planting resistant varieties are the most economical and effective measure to control smut disease. In order to determine the smut resistance of elite varieties (lines) bred in China in recent year and screen resistant varieties for application in production, the resistance of 100 Chinese elite sugarcane varieties (lines) were evaluated by artificial inoculation with the impregnation method in smut epidemic area Yuanjiang, Yunnan Province. The results revealed that 56 of the 100 elite varieties (lines) were highly resistant to moderately resistant, accounting for 56%, and 44 were moderately susceptible to highly susceptible 2, accounting for 44%. The results showed that current large-scale planted and promoted varieties (lines) Mintang 69-421, ROC 22, Liucheng 03-182, Liucheng 03-1137, Guitang 42, Yuegan 26, Guitang 02-351, and Yunzhe 09-1601 were highly susceptible. And the sugarcane varieties (lines) bred in recent years, Funong 15, Funong 36, Funong 1110, Funong 07-3206, Funong 11-2907, Mintang 11-610, Yuegan 39, Yuegan 43, Yuegan 48, Yuegan 49, Yuegan 50, Yuetang 00-236, Ganzhe 02-70, Yunzhe 99-596, Yunzhe 03-258, Yunzhe 04-241, Yunzhe 06-80, Yunzhe 07-2800, Yunzhe 08-2060, Yunzhe 10-2698, Yunzhe 13-1139, Yunrui 10-701, Dezhe 09-84, Dezhe 12-88, Guitang 08-1589, and Zhongzhe 1 were highly resistant to smut disease. It was suggested that in the high incidence area of sugarcane smut in low altitude valley, efforts should be carried out to eliminate the elite varieties susceptible to the disease and popularize and apply the superior varieties resistant to the disease in order to achieve the rational distribution of varieties, control the outbreak and epidemic of sugarcane smut, and provide guarantee for the high-quality development of sugarcane industry.

Changes of wet and dry climate in the past 205 years indicated by Pseudotsuga forrestii of river valley from southeastern Tibetan Plateau, China

The residual chronology of tree-ring width was constructed using Pseudotsuga forrestii collected from the low-altitude valley in the Chayu County, southeastern Tibetan Plateau of China. Pearson correlation analysis was carried out between the residual chronology of tree-ring width and climatic factors. The changes of Palmer drought severity index (PDSI) from April to May between 1812 and 2016 in the southeastern Tibetan Plateau were reconstructed by linear regression method (the variance interpretation was 47%). There was a significantly positive correlation between the PDSI index and tree-ring width index (r=0.69, P<0.01). The PDSI reconstructed sequence had four wet periods (1831-1844, 1853-1863, 1938-1948 and 1988-2002) and three dry periods (1864-1876, 1908-1926 and 2003-2016). Compared with other reconstructed sequences and historical records, our reconstructed sequence could better express dry and wet changes in the study area. The spatial analysis showed that the reconstructed sequence was consistent with the variation trend of PDSI index in southeastern Tibetan Plateau, with a strong spatial representation. Multiple tapers spectral analysis demonstrated that the PDSI reconstructed sequence had remarkable 19-20, 3.9, 3.2, 2.4 and 2.1 years quasi-periodic changes for the past 205 years, probably related to Asian summer monsoon and ENSO activities.

Potential vectors of bluetongue virus in high altitude areas of Yunnan Province, China

BackgroundBluetongue disease of ruminants is a typical insect-borne disease caused by bluetongue virus (BTV) of the genus Orbivirus (family Reoviridae) and transmitted by some species of Culicoides (Diptera: Ceratopogonidae). Recently, the detection of BTV in yaks in high altitude meadows of the Shangri-La district of Yunnan Province, China, prompted an investigation of the Culicoides fauna as potential vectors of BTV.MethodsA total of 806 Culicoides midges were collected by light trapping at three sites at altitudes ranging from 1800 to 3300 m. The species were identified based on morphology and the DNA sequences of cytochrome c oxidase subunit 1 (cox1). PCR and quantitative PCR following reverse transcription were used to test for the presence of BTV RNA in Culicoides spp. A phylogenetic analysis was used to analyze the cox1 sequences of some specimens.ResultsFour species dominated these collections and cox1 barcoding revealed that at least two of these appear to belong to species new to science. Culicoides tainanus and a cryptic species morphologically similar to C. tainanus dominated low altitude valley collections while C. nielamensis was the most abundant species in the high-altitude meadow. A species related to C. obsoletus occurred at all altitudes but did not dominate any of the collections. BTV RT-qPCR analysis detected BTV RNA in two specimens of C. tainanus, in one specimen closely related to C. tainanus and in one specimen closely related to C. obsoletus by barcode sequencing.ConclusionsThis study suggests that BTV in high altitude areas of Yunnan is being transmitted by three species of Culicoides, two of which appear to be new to science. This research may be useful in improving understanding of the effects of global warming on arboviral disease epidemiology and further study is important in research into disease control and prevention.

Out in the Cold: Trophic Resource Use by the Common Frog (Rana temporaria) Populations Inhabiting Extreme Habitats

We studied trophic resource use and availability in three populations of the common frog (Rana temporaria): one from the subarctic (Kilpisjarvi, Finland), and two (alpine and low-altitude valley populations) from the Retezat Mountains (Southern Carpathians, Romania). We used stomach flushing to sample consumed prey, and estimated prey availability using pitfall traps and netting. In addition, we analyzed the geographical pattern of feeding based on published records covering the entire range of the species. Feeding intensity varied, both spatially and according to frog size. Adults consumed prey of higher richness and more prey items than juveniles. There was latitudinal variation in prey consumption, with populations from extreme habitats (alpine and arctic) having the highest prey richness. This high feeding plasticity partly explains why Rana temporaria is widespread and reaches high altitudes and latitudes in Europe.

Estimation of net primary productivity and its driving factors in the Ili River Valley, China

Net primary productivity (NPP), as an important variable and ecological indicator in grassland ecosystems, can reflect environmental change and the carbon budget level. The Ili River Valley is a wetland nestled in the hinterland of the Eurasian continent, which responds sensitively to the global climate change. Understanding carbon budget and their responses to climate change in the ecosystem of Ili River Valley has a significant effect on the adaptability of future climate change and sustainable development. In this study, we calculated the NPP and analyzed its spatio-temporal pattern of the Ili River Valley during the period 2000–2014 using the normalized difference vegetation index (NDVI) and an improved Carnegie-Ames-Stanford (CASA) model. Results indicate that validation showed a good performance of CASA over the study region, with an overall coefficient of determination (R2) of 0.65 and root mean square error (RMSE) of 20.86 g C/(m2•a). Temporally, annual NPP of the Ili River Valley was 599.19 g C/(m2•a) and showed a decreasing trend from 2000 to 2014, with an annual decrease rate of–3.51 g C/(m2•a). However, the spatial variation was not consistent, in which 55.69% of the areas showed a decreasing tendency, 12.60% of the areas remained relatively stable and 31.71% appeared an increasing tendency. In addition, the decreasing trends in NPP were not continuous throughout the 15-year period, which was likely being caused by a shift in climate conditions. Precipitation was found to be the dominant climatic factor that controlled the inter-annual variability in NPP. Furthermore, the correlations between NPP and climate factors differed along the vertical zonal. In the medium-high altitudes of the Ili River Valley, the NPP was positively correlated to precipitation and negatively correlated to temperature and net radiation. In the low-altitude valley and high-altitude mountain areas, the NPP showed a negative correlation with precipitation and a weakly positive correlation with temperature and net radiation. The results suggested that the vegetation of the Ili River Valley degraded in recent years, and there was a more complex mechanism of local hydrothermal redistribution that controlled the growth of vegetation in this valley ecosystem.

Spatio-Temporal Characteristics of Global Warming in the Tibetan Plateau during the Last 50 Years Based on a Generalised Temperature Zone - Elevation Model

Temperature is one of the primary factors influencing the climate and ecosystem, and examining its change and fluctuation could elucidate the formation of novel climate patterns and trends. In this study, we constructed a generalised temperature zone elevation model (GTEM) to assess the trends of climate change and temporal-spatial differences in the Tibetan Plateau (TP) using the annual and monthly mean temperatures from 1961–2010 at 144 meteorological stations in and near the TP. The results showed the following: (1) The TP has undergone robust warming over the study period, and the warming rate was 0.318°C/decade. The warming has accelerated during recent decades, especially in the last 20 years, and the warming has been most significant in the winter months, followed by the spring, autumn and summer seasons. (2) Spatially, the zones that became significantly smaller were the temperature zones of −6°C and −4°C, and these have decreased 499.44 and 454.26 thousand sq km from 1961 to 2010 at average rates of 25.1% and 11.7%, respectively, over every 5-year interval. These quickly shrinking zones were located in the northwestern and central TP. (3) The elevation dependency of climate warming existed in the TP during 1961–2010, but this tendency has gradually been weakening due to more rapid warming at lower elevations than in the middle and upper elevations of the TP during 1991–2010. The higher regions and some low altitude valleys of the TP were the most significantly warming regions under the same categorizing criteria. Experimental evidence shows that the GTEM is an effective method to analyse climate changes in high altitude mountainous regions.

Recent spread and climatic ecological niche of the invasive guava fruit fly, Bactrocera correcta, in mainland China

The guava fruit fly, Bactrocera correcta (Bezzi) (Diptera:Tephritidae), is a harmful exotic insect pest in mainland China, which was first recorded in Yuanjiang County of Yunnan province in 1982. In order to elucidate its rate of spread, extensive field surveys were conducted during 2003–2011. Through 2011, B. correcta was found in areas below 1,500 m in altitude within the Longitudinal Range-Gorge Region of southwestern China (21–28°N latitude, 97–107°E longitude). The northernmost site where B. correcta was found was in Miyi County (26.48°N Latitude, 102.00°E longitude, Alt. 1,060 m) in Sichuan province. Within the currently infested area of mainland China, B. correcta mainly occurred in low-altitude valleys and basins, and displayed a patchy distribution. The mountain chains tend to run south to north, forming a natural barrier to insect flight eastward and westward. Human-assisted transport of infested fruits was the likely factor by which B. correcta moved across mountain chains. The analysis indicated that high-altitude portions of the northern Longitudinal Range-Gorge Region may block B. correcta spread northward.

Fine- and landscape-scale spatial genetic structure of cushion rockjasmine, Androsace tapete (Primulaceae), across southern Qinghai-Tibetan Plateau

The cushion rockjasmine, Androsace tapete (Primulaceae), is among the angiosperms with highest altitudal distribution in the world. Cushion rockjasmine is a prominent pioneer species in alpine deserts and alpine flowstone slope habitats up to 5,300 m on Qinghai-Tibetan Plateau. In this study, we use inter simple sequence repeat (ISSR) markers to investigate the spatial genetic structure of A. tapete at both fine-scale and landscape-scale, with emphasis on testing the hypothesis that the low-altitude valley of the Brahmaputra River, running from west to east across Qinghai-Tibetan Plateau, has significant effects on the spatial population structure of A. tapete. A total of 235 individuals were collected from five populations in disjunct ridges (i.e. two populations located in the north, and three in the south of the Brahmaputra River), including 158 individuals that were spatial explicitly sampled from a 30 m x 90 m plot. At fine scale, spatial autocorrelation analysis indicates a significant genetic structure within a short distance (less than 10 m), which is probably due to limited gene dispersal via pollen and/or seeds. At landscape scale, however, AMOVA suggests that most of the total genetic variation (85%) is among individuals within populations; and the Brahmaputra River plays a weak role in shaping the spatial population structure of A. tapete. In addition, the results of PCA and STRUCTURE assignment show significant genetic associations between the populations across the Brahmaputra River. The historical gene exchanges and slow genetic drift may be responsible for the lack of deep genetic differentiation among topographically separated populations in A. tapete.

Regional relief characteristics and denudation pattern of the western Southern Alps, New Zealand

The Southern Alps of New Zealand are the topographic expression of active oblique continental convergence of the Australian and Pacific plates. Despite inferred high rates of tectonic and climatic forcing, the pattern of differential uplift and erosion remains uncertain. We use a 25-m DEM to conduct a regional-scale relief analysis of a 250-km long strip of the western Southern Alps (WSA). We present a preliminary map of regional erosion and denudation by overlaying mean basin relief, a modelled stream-power erosion index, river incision rates, historic landslide denudation rates, and landslide density. The interplay between strong tectonic and climatic forcing has led to relief production that locally attains ∼2 km in major catchments, with mean values of 0.65–0.68 km. Interpolation between elevations of major catchment divides indicates potential removal of l0 1–10 3 km 3, or a mean basin relief of 0.51–0.85 km in the larger catchments. Local relief and inferred river incision rates into bedrock are highest about 50–67% of the distance between the Alpine fault and the main divide. The mean regional relief variability is ± 0.5 km. Local relief, valley cross-sectional area, and catchment width correlate moderately with catchment area, and also reach maximum values between the range front and the divide. Hypsometric integrals show scale dependence, and together with hypsometric curves, are insufficient to clearly differentiate between glacial and fluvial dominated basins. Mean slope angle in the WSA ( ψ = 30°) is lower where major longitudinal valleys and extensive ice cover occur, and may be an insensitive measure of regional relief. Modal slope angle is strikingly uniform throughout the WSA ( φ = 38–40°), and may record adjustment to runoff and landsliding. Both ψ and φ show non-linear relationships with elevation, which we attribute to dominant geomorphic process domains, such as fluvial processes in low-altitude valley trains, surface runoff and frequent landsliding on montane hillslopes, “relief dampening” by glaciers, and rock fall/avalanching on steep main-divide slopes.

Cirques of the Presidential Range, New Hampshire, and surrounding alpine areas in the northeastern United States

Evidence for rejuvenation of cirque glaciers following wastage of continental ice remains elusive for the Presidential Range and Mount Moosilauke of New Hampshire, Mount Katahdin and the Longfellow Mountains of Maine, and the Adirondack Mountains of New York. At Ritterbush Pond in the northern Green Mountains of Vermont, radiocarbon ages from lake sediment cores suggest that a low-altitude valley head, located up- valley of a series of cross-valley moraines, was ice-free by 11,940 14 C yrs BP (Bierman et al. , 1997). Although some workers argue that these moraines in Vermont are evidence for cirque glaciation, the moraines could have been formed by a tongue of continental ice during deglaciation. At Johnson Hollow Brook valley in the Catskill Mountains of New York, a radiocarbon age from basal sediments in a pond dammed by a moraine suggests that glacier ice may have persisted until 10,860 14 C yrs BP (Lederer and Rodbell, 1998). Because this moraine appears to have been deposited by a cirque glacier, the radiocarbon age provides the best evidence in the northeastern United States for cirque glaciation post-dating recession of continental ice. Cirque morphometric data, compiled from newly available topographic maps, add to the conundrum that these two sites in the Green and Catskill Mountains should not be nearly as favorable for maintaining local glaciers post- dating icesheet recession as higher-altitude and better-developed cirques in the Presidential Range and Mount Katahdin, where evidence for post-icesheet cirque glaciers is lacking.

Determination of mineral and trace elements in total diet by inductively coupled plasma atomic emission spectrometry: comparison of microwave-based digestion and pressurized ashing systems using different acid mixtures

The effectiveness of different acid mixtures for the de-mineralization of total diet samples of different origin and composition by means of a closed microwave-based technique and a pressurized-ashing technique were investigated. The aim was to obtain complete acid solubilization for the subsequent accurate determination of Al, Ca, Cu, Fe, K, Mg, Na, P and Zn by means of inductively coupled plasma atomic emission spectrometry (ICP-AES). The sampling and sample preparation steps for the trace element analysis are described. The special care taken in the sampling design to ensure the representativeness of the sample for the population studied is also mentioned. The regions and population groups were selected from the high mountain valleys, where a high incidence of stomach cancer exists, and a low altitude valley at the foot of the Andes, which is a low stomach cancer incidence region, both located in the state of Tachira, Venezuela. Total diets including breakfast, lunch, supper, snacks and drinks from the whole-day intake of 140 adults were collected. The collection of the total diet was made according to the double-portion technique. The most reliable digestion procedure for the determination of Al, Ca, Cu, Fe, K, Mg, Na, P and Zn in total diet by means of ICP-AES was a microwave-based technique using HNO3 alone or with the mixture HNO3+ H2O2(2 + 1). In comparison, a pressurized-ashing technique is faster although lower values for K (13 and 11%) were obtained. Despite low sensitivity for the ICP-AES measurements, the microwave-based digestion using HNO3+ H2SO4(4 + 1) also gave good agreement for the determination of Al, Ca, Cu, Fe, K, Mg, Na, P and Zn by means of ICP-AES. Because of the simple and rapid procedure, the pressurized-ashing technique using the mixture HNO3+ H2O2(2 + 1) was selected to perform the digestion of the total diet samples collected. The results of the mean daily intake of the population investigated showed for the high mountain valleys (high stomach cancer incidence area, n= 77) as compared with the low altitude valleys (low stomach cancer incidence area, n= 33) significantly higher daily intake with respect to Na (2082 versus 1471 mg), K (1190 versus 731 mg), P (640 versus 381 mg) and a significantly lower daily intake with respect to Ca (925 versus 1379 mg) and Cu (2.78 versus 4.66 mg). No differences were obtained with respect to Al, Fe, Mg and Zn.

Environment, migration and health in Southern Peru

A health questionnaire was given to three populations of Peruvians: low-altitude sedentes, low-altitude migrants and high-altitude migrants, all of whom resided in the same low-altitude valley. Estimates of health were computed for each individual by summing the number of symptoms reported in the questionnaire. In general, male and female high-altitude migrants reported more symptoms than low-altitude sedentes. Female low-altitude migrants also reported more symptoms than did female sedentes, while there were virtually no differences between male low-altitude migrants and sedentes. Differences in numbers of days ill and the inability to work due to illness paralleled the differences in reported symptoms. It is suggested that the population differences are primarily the result of changes in the physical and cultural environments which are related to migration: high-altitude migrants being more affected than low-altitude migrants because of the greater degree of change they experience in migrating from high to low altitude. Specifically male high-altitude migrants reported significantly more gastrointestinal symptoms while both males and females reported significantly greater numbers of respiratory symptoms. Although the source of the former difference is unclear, it is felt that the increase in respiratory symptoms is a result of biological adaptations to high altitude which are no longer functional at low altitude.