Natural trees—neighbourhood-location in a nutshell

Abstract

We present the notion of a natural tree as an efficient method for storing spatial information for quick access. A natural tree is a representation of spatial adjacency, organised to allow efficient addition of new data, access to existing data, or deletions. The nodes of a natural tree are compound elements obtained by a particular Delaunay triangulation algorithm. Improvements to that algorithm allow both the construction of the triangulation and subsequent access to neighbourhood information to be O(N log N). Applications include geographical information systems, contouring, and dynamical systems reconstruction.     

Can vegetation productivity be derived from greenness in a semi-arid environment? Evidence from ground-based measurements

Trends of biomass production and land processes in the Sahel have been widely studied since the droughts of 1970s. Satellite data have been an important source of information because of limited in situ data. Previous studies relied on the assumed existence of a relationship between vegetation productivity and the NDVI, in particular the annually integrated NDVI (iNDVI). This study examines this assumption and its limitations, based on in situ time series measurements of biomass, species composition, NDVI and soil moisture at the Dahra test site in northern Senegal. It is shown that, there are large differences between the NDVI – vegetation productivity relationships, and these differences can be linked to species composition. There is moderate correlation between NDVI and above-ground net primary productivity (ANPP) at the peak season (r² = 0.39). In particular, the species Zornia glochidiata is characterized by high peak NDVI and low ANPP, compared to other common species such as Cenchrus biflorus and Aristida adscensionis. It is concluded that spatial and temporal variations in species dominance is likely to add noise to the relationship between NDVI and biomass. However, the seasonal cyclic fraction of the NDVI – “small seasonal integral” – reduces such noise.     

Mineral magnetism and other characteristics of sediments from an alpine lake (3,410 m a.s.l.) in central China and implications for late Holocene climate and environment

The Qinling Mountain Range (33°–34°30′N, 107°–111°E; 3,767 m a.s.l.) lies south of the Chinese Loess Plateau and functions as the boundary between ‘north’ and ‘south’ China. Taibai Mountain (33°41′–34°10′N, 107°19′–107°58′E; 3,767 m a.s.l.) is the central massif and highest part of the range and is the highest mountain in eastern and central China, east of 105°E. It is also one of two mountains higher than the modern climatic timberline and the only one where high alpine lakes (>2,500 m a.s.l.) exist in eastern and central China. Sediments were recovered from Foye Chi (33°57′N, 107°44′E; 3,410 m a.s.l.), a small lake on the southern slope of the mountain, and measured for magnetic properties. Chronological control was achieved with AMS ¹⁴C dating. Combined with analyses of particle-size, TOC, C/N, δ¹³C_org and pollen in these sediments, and magnetic properties of catchment soils, the mineral-magnetic data reveal late Holocene palaeoenvironmental changes on the high-altitude southern slope of Taibai Mountain. Climate gradually ameliorated about 2,300 cal yr BP and warm and wet conditions occurred afterwards, culminating from 1,700 to 1,510 cal yr BP. The climate began to deteriorate at 1,510 cal yr BP, but was still warmer and wetter than present until ~663 cal yr BP. Cool, arid conditions peaked and were cooler and drier than the present at 663–290 cal yr BP, coincident with the Little Ice Age. Climate became warmer and more humid again after 290 cal yr BP. Data from these less anthropologically-disturbed alpine-lake sediments provide a record of late Holocene palaeoenvironmental change that supplements information from historical documents and literature for eastern and central China.     

Ecology of newly formed sea ice in the Weddell Sea,AntarcticaⅠ.chlorophyll a and nutrients

ＥｃｏｌｏｇｙｏｆｎｅｗｌｙｆｏｒｍｅｄｓｅａｉｃｅｉｎｔｈｅＷｅｄｄｅｌＳｅａ，Ａｎｔａｒｃｔｉ┐ｃａⅠ．ｃｈｌｏｒｏｐｈｙｌａａｎｄｎｕｔｒｉｅｎｔｓＷａｎｇＺｉｐａｎ（王自磐）ＳｅｃｏｎｄＩｎｓｔｉｔｕｔｅｏｆＯｃｅａｎｏｇｒａｐｈｙ，ＳＯＡ，...     

Tetraether membrane lipid distributions in water-column particulate matter and sediments: a study of 47 European lakes along a north–south transect

We studied the distribution of glycerol dialkyl glycerol tetraethers (GDGTs) in water-column particulate matter and the top 5 cm of sediment from 47 lakes along a transect from southern Italy to the northern part of Scandinavia. Our objective was to investigate the biological sources and potential palaeoenvironmental applications of GDGTs in lacustrine sediments. Both archaea-derived isoprenoid and bacteria-derived branched GDGTs, produced by yet unknown soil bacteria, were identified in all lake sediments. GDGT distributions varied substantially. Crenarchaeotal GDGTs, including the characteristic GDGT crenarchaeol, were found in varying relative concentrations, and were more dominant in lakes from the Alps and some of the lakes from the more southern part of the latitudinal transect. In some lakes, we observed high amounts of the GDGT with no cyclopentane moieties relative to crenarchaeol. As methanogenic Euryarchaeota are known to biosynthesise this GDGT predominantly, these Archaea, rather than Crenarchaeota, may be its dominant biological source. In most of the lakes, high amounts of soil-bacteria-derived, branched GDGTs (>40% of total GDGTs) indicated a substantial contribution from soil erosion. Branched GDGTs dominated, especially in the northern lakes, possibly related to high soil-erosion rates. In many of the lakes, soil input affects the distribution of isoprenoidal GDGTs and prevents the reliable application of the TEX₈₆ temperature proxy for lake water temperature, which is based on in situ crenarchaeotal GDGTs production. In 9 out of the 47 lakes studied, the TEX₈₆ temperature proxy could be used reliably. When we compared the TEX₈₆ correlation with annual and winter lake-surface temperature, respectively, the relationship between TEX₈₆ and winter temperature was slightly stronger. This may indicate the season in which these GDGT-producing organisms have their peak production.     

Laghi di Monticchio (Southern Italy,Region Basilicata): genesis of sediments—a geochemical study

The sedimentation record of Lago Grande di Monticchio (LGM) is one of the most prominent paleoclimatic archives in the non-glaciated areas of Europe. However, the modern lake system has never been the subject of intense limnological studies. On the basis of hydrochemical water profiles, detailed investigations of sediment short cores and in situ pore water profiles from the littoral to the profundal zone, we elucidate spatial variations of sediment genesis within the lake basin and the importance of various depth sections for the lake’s internal nutrient cycling. Sediments from the smaller meromictic Lago Piccolo di Montichio are discussed as a reference. Our study demonstrates: (i) distinctly higher sediment accumulation for the centre of the lake basin by focussing of the settling particle flux; (ii) decline of carbonate from the littoral to the profundal zones; (iii) non-synchronous change of calcite net-accumulation for various water depths; (iv) exceptionally high cation release from sediments covering the steeply inclining sector of the lake basin; (v) relatively constant dissolved silica concentrations in the pore waters (SiO₂ ∼42 mg/l) independent of water depth and sediment composition; (vi) influx of oxygen-bearing groundwater into the anoxic hypolimnion after heavy rainfall and the associated precipitation of Fe-oxihydroxides; (vii) higher release of NH₄ by anaerobic degradation of organic matter at a water depth of 23 m than for sediments at a maximum water depth of 32 m, whereby the latter reflects the importance of seasonal sediment re-oxidation for anaerobic degradation of organic debris; (viii) although seasonal re-oxidation of sediments from various water depths is quite different, Oxygen Index values of LGM sediments fall in a small range, which reflects rapid microbial consumption of seasonally re-generated easily bio-degradable organic molecules.     

A condition for the formation of Antarctic Bottom Water in Prydz Bay， Antarctica

ＡｃｏｎｄｉｔｉｏｎｆｏｒｔｈｅｆｏｒｍａｔｉｏｎｏｆＡｎｔａｒｃｔｉｃＢｏｔｔｏｍＷａｔｅｒｉｎＰｒｙｄｚＢａｙ，ＡｎｔａｒｃｔｉｃａＬｉａｎｇＸｉａｎｇｓａｎ（梁湘三）（ＳｅｃｏｎｄＩｎｓｔｉｔｕｔｅｏｆＯｃｅａｎｏｇｒａｐｈｙ，ＳＯＡ，Ｈａｎｇ...     

Inferring organic content of sediments by scanning reflectance spectroscopy (380–730 nm): applying a novel methodology in a case study from proglacial lakes in Norway

Reflectance spectroscopy in the visible spectrum (VIS-RS) is a method that has been successfully applied for inferring organic content of sediments. In this study, we test the applicability of VIS-RS to lake sediments in Norway. On the one hand we use conventional, established algorithms for inferring organic content of sediments, on the other hand we test the potential of multivariate calibration techniques to infer organic content. For absolute quantification of organic content, conventional C_org measurements are needed when using conventional algorithms as well as when employing multivariate calibration techniques. Both, conventional algorithms and multivariate calibrations, result in estimates of organic content closely mirroring loss-on-ignition measurements. When using multivariate calibration techniques, a conventional C_org measurement every 5 cm is sufficient to obtain estimates of organic matter that are more accurate than those obtained by means of conventional algorithms. Therefore, the potential of multivariate calibration techniques and VIS-RS to substitute measurements of more time consuming and costly sediment parameters (e.g. clay minerals) should be tested.     

On coordinated development of oasis and environment in arid area

1 Formation and evolution of oasisBoth physical environment and human activities influence the formation and evolution of oasis. Natural oasis is a kind of ecological landscape formed mainly by water without human intervention. Its prosperity and adversity primarily depends on the flow direction and discharge of a river. With the increment of intensity of human activities, however, great changes have taken place in oasis in arid area. The evolution of oasis has been transformed from the contr…     

Fishing in a congested sea: What do marine protected areas imply for the future of the Maltese artisanal fleet?

Inshore artisanal fishing in Malta is under intense spatial competition as the coastal zone is fragmented by multiple uses and designations including maritime transport, infrastructure, industrial fisheries, aquaculture, tourism and recreation. This research, adopting a grounded visualization methodology, explains how the artisanal fishing sector has undergone and been affected by ‘spatial squeezing’. Our results show that artisanal fishermen have been forced to give up fishing grounds or co-exist with other uses to the point where the ability to fish is becoming increasingly challenging. These difficulties might escalate with the advent of the marine protected areas (MPAs) which encompass nearly half of the inshore fishing zones. Since there does not seem to be effective MPA consultation mechanisms that elicit the real social, cultural and economic value of artisanal fishing grounds, fishermen feel threatened, alienated and disempowered. This study urges for a more holistic approach to spatial marine planning and accentuates the need of realizing the dependency of the artisanal sector on the inshore zones in the implementation of conservation measures, such that the prolonged existence of the coastal fishing communities is not jeopardized.     

Effect of the environment in Antarctica on immune function and electroencephalogram

ＥｆｆｅｃｔｏｆｔｈｅｅｎｖｉｒｏｎｍｅｎｔｉｎＡｎｔａｒｃｔｉｃａｏｎｉｍｍｕｎｅｆｕｎｃｔｉｏｎａｎｄｅｌｅｃｔｒｏｅｎｃｅｐｈａｌｏｇｒａｍＹｕＹｏｎｇｚｈｏｎｇ（于永中）；ＷａｎｇＺｏｎｇｈｕｉ（王宗惠）；ＺｈａｎｇＷｅｎｃｈｅｎｇ（张文诚）...     

Analysis on areal relationship between regional environment and socioeconomy—taking the Chinese Yellow Sea coastal zone as a case

Since the reform and open-up,the economy in the Yellow Sea coastal zone has rapidly developed and the regional structure of socio-economy has changed a lot,but meanwhile it has also caused increasingly serious environmental problems. The discussion on relationship between economic development and environment[1-12] has become the focus of research. The present research mainly focuses on the following aspects: first, the study on coordinately development of regional PRED system, including de…     

Recent morphological channel changes in a deltaı̈c environment. The case of the Rhône River,France

Channel morphological changes were measured at two sites within the Rhône delta along the main channel of the Rhône River over one century. Results show an average erosion rate of 2.8 mm year⁻¹ during the 20th century and decreasing to <1.5 mm year⁻¹ since the 1960s. Erosion affected site 2 more than site 1 but cross-sections can alternately be in erosion or accretion depending on bed topography and/or floor lithology. Riverbed adjustments are partly explained by the boundary shear stress and specific stream power but local factors also influence the Rhône River evolution. Results compared with those obtained upstream or in other European rivers suggest that the lower Rhône River has developed an original response to external stresses: the first part of the 20th century is characterised by an important degradation followed by a decrease in the incision rate since the 1960s. The initiation of the erosion phase is assumed to be linked to the end of the Little Ice Age, to the reforestation of the alpine hillsides, to the earlier management and to the reduction of the sedimentary yield (according to the literature). The second phase possibly corresponds to the relaxation period. In this perspective, the effects of dams are probably less significant than we would suppose up to now. It implies that such a large river records morphological responses which may vary all along the fluvial system in relation to the time and space scales involved.     

Inter-hemispheric comparisons of geospace environment in the polar regions—A proposed cooperative research program between China and Norway

The Chinese Zhongshan Station in Antarctica and the stations in Svalbard (Auroral station at Longyearbyen and NP station at Ny lesund) are closely magnetic conjugate. All of them are equipped similar measurement instruments dealing with upper atmospheric physics. Therefore, there is a good reason to conduct a cooperative research program between China and Norway to do the inter hemispheric comparisons of geospace environment in the polar regions. It will make significant contribution to further understanding of the coupled magnetosphere ionsphere system. The scientific aims of the cooperative project are: to experimentally verify the modeled complicated conjugate relationship between Zhongshan Station in the Antarctic and Svalbard in the Arctic. To derive knowledge from the conjugate characteristics of auroral formations, ionospheric features and space plasma waves in the polar regions, which in turn will lead to better understanding of the solar wind magnetosphere ionosphere coupling processes. The proposed research contents, research methods and experimental techniques are discussed, and the manners of the cooperative research are suggested in the paper.     

The harmonious relationship between land use and environment in Xi’an

1 Introduction Generally, it is the urbanization that causes the structural change of landscape environment, and the structure, scale, benefit and effectiveness of LUCC are all the spatial appearance and important results of Xi’an’s urbanization. It no…     

Diatom–environment relationships and a transfer function for conductivity in lakes of the Badain Jaran Desert, Inner Mongolia, China

We describe a dataset of 26 modern diatom samples and associated environmental variables from the Badain Jaran Desert, northwest China. The influence of electrical conductivity (EC) and other variables on diatom distribution was explored using multivariate analyses and generalized additive modeling of species response curves. A transfer function was derived for EC, the variable with the largest unique effect on diatom variance, as shown by partial canonical correspondence analysis. Weighted-averaging partial least squares regression and calibration provided the best model, with a high coefficient of determination ( $ {\text{r}}_{\text{boot}}^{2} $  = 0.91) and low prediction error (RMSEP_boot = 0.136 log₁₀ μS cm^?1). To assess its potential for palaeosalinity and palaeoclimate reconstructions, the EC transfer function was applied to fossil diatom assemblages from ²¹⁰Pb-dated short sediment cores collected from two subsaline lakes of the Badain Jaran Desert. The diatom-inferred (DI) EC reconstructions were compared with meteorological data for the past 50 years and with remote sensing data for the period AD 1990–2012. Changes in DI–EC were small and their relationship with climate was weak. Moreover, remote sensing data indicate that the surface areas and water depths of these lakes did not change, which suggests that water loss by evaporation is compensated by groundwater inflow. These results suggest that the response of these lakes to climate change is mediated by non-climatic factors such as the hydrogeological setting, which control recharge from groundwater, and may be non-linear and non-stationary.     

Prediction of Anopheles minimus habitat in India—a tool for malaria management

This paper reports research to predict the distribution of An. minimus, a malaria vector in forest fringe areas using GIS to support precision surveys for malaria control. Because An. minimus is a forest‐associated species, generalized thematic maps (1:6?000?000) of forest cover, soil type, altitude, rainfall and temperature were used. Digitization, overlaying, integration and analysis of thematic maps were done using Arc/Info 8.1 NT and Arc/View 3.2 (GIS, ESRI) software. GIS delineated favourable areas for An. minimus where the species is likely to be found, and precision surveys can be conducted. Precision field surveys in selected locations of favourable/non‐favourable areas were carried out. The species could be found in all locations designated as a favourable area and was absent in non‐favourable areas. In two districts, one where the species is reported to have disappeared in the early 1950s and the other where it was not reported in earlier surveys, GIS helped in precision surveys, and An. minimus was found. The technique can quickly cover vast and inaccessible areas and is easy to duplicate in other parts of the world to assist cost‐effective control of malaria. It can also delineate areas favourable for any species of flora and fauna to help precision surveys.     

Shrubs proliferated within a six-year exclosure in a temperate grassland—Spatiotemporal relationships between vegetation and soil variables

Overgrazing has been considered one of the maj or causes that trigger shrub encroachment of grassland. Proliferation of shrubs in grassland is recognized as an important indicator of grassland degradation and desertification. In China, various conservation measures, including enclosures to reduce livestock grazing, have been taken to reverse the trend of grassland desertification, yet shrubs have been reported to increase in the grasslands over the past decades. In late 2007, we set up a 400-m-by-50-m exclosure in a long-term overgrazed temperate grassland in Inner Mongolia, with the ob- jective to quantify the spatiotemporal relationship between vegetation dynamics, soil variables, and grazing exclusion. Soil moisture was continuously monitored within the exclosure, and cover and aboveground biomass of the shrubs were measured inside the exclosure in 2007, 2009, 2010, 2012, and 2013, and outside the exclosure in 2012 and 2013. We found the average shrub cover and biomass significantly increased in the six years by 103 % and 120%, respectively. The result supported the hypothesis that releasing grazing pressure following long-term overgrazing tends to trigger shrub invasion into grassland. Our results, limited to a single gradient, suggest that any conservation measures with quick release of overgrazing pressure by enclosure or other similar means might do just the opposite to accelerate shrub en- croachment in grassland. The changes in vegetation cover and biomass were regressed on the temporal average of the soil moisture content by means of the generalized least square technique to quantify the effect of the spatial autocor- relation. The result indicates that the grass cover and biomass significantly increased with the top, but decreased with the bottom layer soil moisture. The shrub cover and biomass, on the other hand, decreased with the top, but increased with bottom soil moisture, although the regression coefficients for the shrubs were not statistically significant. Hence this study supports the two-layered soil model which assumes grasses and shrubs use belowground resources in dif- ferent depths.     

Vertical distribution and seasonal variation in ice algae biomass in coastal sea ice off Zhongshan Station， East Antarctica

何剑锋，陈波ＶｅｒｔｉｃａｌｄｉｓｔｒｉｂｕｔｉｏｎａｎｄｓｅａｓｏｎａｌｖａｒｉａｔｉｏｎｉｎｉｃｅａｌｇａｅｂｉｏｍａｓｓｉｎｃｏａｓｔａｌｓｅａｉｃｅｏｆｆＺｈｏｎｇｓｈａｎＳｔａｔｉｏｎ，ＥａｓｔＡｎｔａｒｃｔｉｃａ￥Ｈｅｊｉａｎｆｅｎｇａｎ...