ITE Merlewood Land Classification of Great Britain

Abstract. The Institute of Terrestrial Ecology (ITE) has classified the 1 km squares in Great Britain (GB) into thirty-two environmental strata, termed land classes, as a basis for ecological survey. The classes have been used in biogeographical studies of the distribution of individual species and species assemblages. The concept behind the technique is that there is an association between the environmental character of land and ecological parameters. The initial classification was based on a sample of squares drawn from a regular grid. The data for the 12121 km squares classified were drawn from published maps; the number of squares was limited by the available computing power. Subsequently the availability of more powerful computers and the need to improve geographical definition have led to the allocation of every 1 km square to its appropriate class. This paper has been written to summarise the principles involved in the development of the system and indicate the range of projects for which it has been used. The extension of the classification from a sample to the complete coverage of GB revealed the importance of the structure and style of data used to produce the classification. The significance of these conclusions for future work is discussed, with particular reference to automated methods of data capture.     

Statistics of RNA melting kinetics

We present and study the behavior of a simple kinetic model for the melting of RNA secondary structures, given that those structures are known. The model is then used as a map that. assigns structure dependent overall rate constants of melting (or refolding) to a sequence. This induces a landscape of reaction rates, or activation energies, over the space of sequences with fixed length. We study the distribution and the correlation structure of these activation energies. Correspondence to: P. Schuster     

Carbon dioxide consumption during soil development

Carbon is sequestered in soils by accumulation of recalcitrant organic matter and by bicarbonate weathering of silicate minerals. Carbon fixation by ecosystems helps drive weathering processes in soils and that in turn diverts carbon from annual photosynthesis-soil respiration cycling into the long-term geological carbon cycle. To quantify rates of carbon transfer during soil development in moist temperate grassland and desert scrubland ecosystems, we measured organic and inorganic residues derived from the interaction of soil biota and silicate mineral weathering for twenty-two soil profiles in arkosic sediments of differing ages. In moist temperate grasslands, net annual removal of carbon from the atmosphere by organic carbon accumulation and silicate weathering ranges from about 8.5 g m^–2 yr^–1 for young soils to 0.7 g M^–2 yr^–1 for old soils. In desert scrublands, net annual carbon removal is about 0.2 g m^–2 yr^–1 for young soils and 0.01 g m^–2 yr^–1 for old soils. In soils of both ecosystems, organic carbon accumulation exceeds CO₂ removal by weathering, however, as soils age, rates of CO₂ consumption by weathering accounts for greater amounts of carbon sequestration, increasing from 2% to 8% in the grassland soils and from 2% to 40% in the scrubland soils. In soils of desert scrublands, carbonate accumulation far outstrips organic carbon accumulation, but about 90% of this mass is derived from aerosolic sources that do not contribute to long-term sequestration of atmospheric carbon dioxide.     

生态交错带（Ecotone）理论研究进展

生态交错带（Ｅｃｏｔｏｎｅ）理论研究进展高洪文（东北师范大学草地研究所,长春１３００２４）ＡｄｖａｎｃｅｍｅｎｔｏｆＴｂｅｏｒｅｔｉｃａｌＲｅｓｅａｒｃｈｉｎＥｃｏｔｏｎｅ．￥ＧａｏＨｏｎｇｗｅｎ（ＩｎｓｔｉｔｕｔｅｏｆＧｒａｓｓｌａｎｄＲｅ－ｓｅａ...     

旅游生态学—生态学应用的一个新领域

旅游生态学──生态学应用的一个新领域刘鸿雁（北京大学城市与环境学系,１００８７１）ＲｅｃｒｅａｔｉｏｎＥｃｏｌｏｇｙ─—ＡＮｅｗＡｒｅａｏｆＡｐｐｌｉｅｄＥｃｏｌｏｇｙ．￥ＬｉｕＨｏｎｇｙａｎ（ＤｅｐａｒｔｍｅｎｔｏｆＵｒｂａｎａｎｄＥｎｖｉｒｏｎｍ...     

Meristem culture of Ophiopogon japonicus and production of embryo-like structures

Meristems of Ophiopogon japonicus (Liliaceae) were grown on a modified MS medium without auxins or cytokinins and plantlets and embryogenic callus were obtained at a low frequency. When meristems growing on modified basal medium were briefly soaked in 0.54 mM naphtaleneacetic acid (NAA) or temporarily grown on medium that contained NAA or NAA and benzyladenine, a larger proportion of meristems developed into plantlets or produced callus and additional plantlets following their return to basal medium. Calluses grown in liquid culture without auxins or cytokinins produced abundant single cells and cell aggregates. Larger cell aggregates formed embryo-like structures that produced roots, cotyledons, and then plantlets following transfer to soilid medium. Prolonged liquid culture produced embryo-like structures directly in liquid medium. These structures met many of the criteria for somatic embryos and developed into normal plantlets when placed on solid medium.     

The dynamics and retention of phosphorus in lentic and lotic patches of two river-lake systems

Two river-lake systems in a mosaic, lowland postglacial landscape (Masurian and Suwalskie Lakelands, northeastern Poland) of different length and flow were studied. The concentration of total and dissolved phosphorus (in water and in seston) and the retention of these two forms of P were analysed at several hydrological occasions in lakes of various morphometry and trophy, and in several stream fragments. The concentration and retention is equally highly variable in lake (lentic patches) and stream fragments (lotic patches) of the system. The polluted stream fragments at all occassions as well as the lakes in summer, are mainly exporting phoshorus. The patches which act as sources occur alternatively with patches which are P-sinks. This makes the whole system more or less balanced with respect to P movement in the landscape.     

Heat tolerance of marine ectotherms in a warming Antarctica

Global warming is affecting the Antarctic continent in complex ways. Because Antarctic organisms are specialized to living in the cold, they are vulnerable to increasing temperatures, although quantitative analyses of this issue are currently lacking. Here we compiled a total of 184 estimates of heat tolerance belonging to 39 marine species and quantified how survival is affected concomitantly by the intensity and duration of thermal stress. Species exhibit thermal limits displaced toward colder temperatures, with contrasting strategies between arthropods and fish that exhibit low tolerance to acute heat challenges, and brachiopods, echinoderms, and molluscs that tend to be more sensitive to chronic exposure. These differences might be associated with mobility. A dynamic mortality model suggests that Antarctic organisms already encounter temperatures that might be physiologically stressful and indicate that these ecological communities are indeed vulnerable to ongoing rising temperatures.     

Human-modified landscapes driving the global primate extinction crisis

The world's primates have been severely impacted in diverse and profound ways by anthropogenic pressures. Here, we evaluate the impact of various infrastructures and human-modified landscapes on spatial patterns of primate species richness, at both global and regional scales. We overlaid the International Union for the Conservation of Nature (IUCN) range maps of 520 primate species and applied a global 100 km² grid. We used structural equation modeling and simultaneous autoregressive models to evaluate direct and indirect effects of six human-altered landscapes variables (i.e., human footprint [HFP], croplands [CROP], road density [ROAD], pasture lands [PAST], protected areas [PAs], and Indigenous Peoples' lands [IPLs]) on global primate species richness, threatened and non-threatened species, as well as on species with decreasing and non-decreasing populations. Two-thirds of all primate species are classified as threatened (i.e., Critically Endangered, Endangered, and Vulnerable), with ~86% experiencing population declines, and ~84% impacted by domestic or international trade. We found that the expansion of PAST, HFP, CROP, and road infrastructure had the most direct negative effects on primate richness. In contrast, forested habitat within IPLs and PAs was positively associated in safeguarding primate species diversity globally, with an even stronger effect at the regional level. Our results show that IPLs and PAs play a critical role in primate species conservation, helping to prevent their extinction; in contrast, HFP growth and expansion has a dramatically negative effect on primate species worldwide. Our findings support predictions that the continued negative impact of anthropogenic pressures on natural habitats may lead to a significant decline in global primate species richness, and likely, species extirpations. We advocate for stronger national and international policy frameworks promoting alternative/sustainable livelihoods and reducing persistent anthropogenic pressures to help mitigate the extinction risk of the world's primate species.     

Edge effects influence the composition and density of reef residents on subtidal restored oyster reefs

Within estuarine and coastal ecosystems globally, extensive habitat degradation and loss threaten critical ecosystem functions and necessitate widescale restoration efforts. There is abundant evidence that ecological processes and species interactions can vary with habitat characteristics, which has important implications for the design and implementation of restoration efforts aimed at enhancing specific ecosystem functions and services. We conducted an experiment examining how habitat characteristics (presence; edge vs. interior) influence the communities of resident fish and mobile invertebrates on restored oyster (Crassostrea virginica) reefs. Similar to previous studies, we found that restored reefs altered community composition and augmented total abundance and biomass relative to unstructured sand habitat. Community composition and biomass also differed between the edge and interior of individual reefs as a result of species-specific patterns over small spatial scales. These patterns were only weakly linked to oyster density, suggesting that other factors that vary between edge and interior (e.g. predator access or species interactions) are likely more important for community structure on oyster reefs. Fine-scale information on resident species' use of oyster reefs will help facilitate restoration by allowing decision makers to optimize the amount of edge versus interior habitat. To improve the prediction of faunal use and benefits from habitat restoration, we recommend investigations into the mechanisms shaping edge and interior preferences on oyster reefs.