Peatland distibution along a north-south transect in the Mackenzie River Basin in relation to climatic and environmental gradients

Climate is a major factor affecting the development and form of peatlands, as well as the distribution of individual bryophyte species. This paper examines the climatic and ecological gradients affecting the distribution of peatland types along a north-south gradient in the Mackenzie River Basin. Based on a TWINSPAN analysis of bryophyte abundance from 82 peatlands in the Mackenzie River Basin, seven peatland types, two with southerly geographical distributions are recognized. In the Mackenzie River Basin, such local factors as surface water chemistry, pH, and solute concentration as well as height above the water table play a significant role in determinining bryophyte species distributions. Climate is secondary. Amongst the climatic variables, precipitation, length of the growing season, and annual temperature are the most signifcant. The seven peatland groups are: widespread poor fens; peat plateaus with thermokarst pools, low-Boreal bogs; bogs and peat plateus without thermokarst pools; low-Boreal dry poor fens; wet moderate-rich fens; and wet extreme-rich fens.     

土壤水分时空变异及其与环境因子的关系

土壤水分的时空变异是指在一定的景观内,不同时间、地点和土层的土壤水分特征存在明显的差异性和多样性。土壤水分时空变异是由多重尺度上的土地利用（植被）、气象（降雨）、地形、土壤、人为活动等诸因子综合作用的结果,但就其某一具体地区而言存在着重点尺度和主控因子,土壤水分时空变异的重点尺度与主控因子的时空关系因时间、空间和尺度而异。本文综述了土壤水分（尤其是黄土高原地区）的时空变异与其环境因子时空关系的研究进展,并提出了广眨开展多重时空尺度上土壤水分的时空变异与其诸因素的时空关系,研究土壤水分时空变异性的尺度转换规律,确定重点尺度及其相应的主控因子。     

The macroinvertebrate communities of two contrasting Norwegian glacial rivers in relation to environmental variables

1. Macroinvertebrate communities in two Norwegian glacial rivers, one in the western fjords (Dalelva) and one in the eastern mountains (Leirungsåi), were investigated during three time periods in 1996 and 1997.
2. Channel stability variables (substratum heterogeneity/Pfankuch index/hydraulic stress) and water temperature accounted for 54% of the total inertia in the principal components analysis (PCA) ordination of environmental variables. The importance of these variables was confirmed by cluster analysis.
3. The two rivers were well separated in the ordinations, with Leirungsåi showing much greater heterogeneity. This is explained by differences in altitudinal range, terrestrial vegetation and the importance and nature of tributary inputs.
4. Channel stability and temperature were also important in determining faunal communities in the two glacial rivers, supporting the main determining variables in the conceptual model of glacial streams ( Milner & Petts, 1994 ). However, clear temporal differences were apparent in the data, the two rivers being more similar during the summer period of high discharge dominated by glacial meltwater. During spring and especially during autumn environmental conditions and the macroinvertebrate fauna differed both within and between rivers.
5. Diamesinae dominated in the upper reaches of both rivers, with Orthocladiinae becoming more common downstream. The dominance of Diamesinae persisted further down Dalelva because of the continued influence of glacial tributaries, whereas in Leirungsåi the influence of non-glacial tributaries led to a change towards a greater proportion of Orthocladiinae. Lakes modified macroinvertebrate communities in both river systems.     

MusselMytilus edulis (Mytilacea) dynamics in relation to environmental gradients and intraspecific interactions

The spatial variations in the densities of adult (>1 year old) musselsMytilus edulis L. in the Exe estuary, South-west England, are investigated in relation to six potentially significant environmental gradients; distance up-estuary and up-shore, substrate softness, mussel bed topography, bed area and proportion covered by algae. The most important correlate of mussel density was the up-shore gradient, as measured by exposure time; mussels were densest just below mid-tide level. The level of recruitment of spat mussels (O yr) to each bed depended on the densities of adults already present; more spat were recruited where adults were denser. Their subsequent mortality was strongly density dependent, with the numbers surviving the winter also being related to the density of adults. Hence the population as a whole was self-sustaining and densities on the individual beds were related to the up-shore gradient of exposure time. The question of how adult densities became established in the first place is therefore discussed. In former times, fishermen laid many mussel beds over the estuary and it is concluded that, once abandoned, only those placed at or below the mid-tide level survived.     

Habitat collapse due to overgrazing threatens turtle conservation in marine protected areas

Marine protected areas (MPAs) are key tools for combatting the global overexploitation of endangered species. The prevailing paradigm is that MPAs are beneficial in helping to restore ecosystems to more ‘natural’ conditions. However, MPAs may have unintended negative effects when increasing densities of protected species exert destructive effects on their habitat. Here, we report on severe seagrass degradation in a decade-old MPA where hyper-abundant green turtles adopted a previously undescribed below-ground foraging strategy. By digging for and consuming rhizomes and roots, turtles create abundant bare gaps, thereby enhancing erosion and reducing seagrass regrowth. A fully parametrized model reveals that the ecosystem is approaching a tipping point, where consumption overwhelms regrowth, which could potentially lead to complete collapse of the seagrass habitat. Seagrass recovery will not ensue unless turtle density is reduced to nearly zero, eliminating the MPA''s value as a turtle reserve. Our results reveal an unrecognized, yet imminent threat to MPAs, as sea turtle densities are increasing at major nesting sites and the decline of seagrass habitat forces turtles to concentrate on the remaining meadows inside reserves. This emphasizes the need for policy and management approaches that consider the interactions of protected species with their habitat.     

Classifying movement behaviour in relation to environmental conditions using hidden Markov models

1.  Linking the movement and behaviour of animals to their environment is a central problem in ecology. Through the use of electronic tagging and tracking (ETT), collection of in situ data from free-roaming animals is now commonplace, yet statistical approaches enabling direct relation of movement observations to environmental conditions are still in development.
2.  In this study, we examine the hidden Markov model (HMM) for behavioural analysis of tracking data. HMMs allow for prediction of latent behavioural states while directly accounting for the serial dependence prevalent in ETT data. Updating the probability of behavioural switches with tag or remote-sensing data provides a statistical method that links environmental data to behaviour in a direct and integrated manner.
3.  It is important to assess the reliability of state categorization over the range of time-series lengths typically collected from field instruments and when movement behaviours are similar between movement states. Simulation with varying lengths of times series data and contrast between average movements within each state was used to test the HMMs ability to estimate movement parameters.
4.  To demonstrate the methods in a realistic setting, the HMMs were used to categorize resident and migratory phases and the relationship between movement behaviour and ocean temperature using electronic tagging data from southern bluefin tuna ( Thunnus maccoyii ). Diagnostic tools to evaluate the suitability of different models and inferential methods for investigating differences in behaviour between individuals are also demonstrated.     

Seed bank strategies in Patagonian semi-arid grasslands in relation to their management and conservation

We addressed the following questions: (a) May different seed bank functional types (SBFT), defined on the basis of singularities of their persistence in soil, be identified in the Festuca pallescens grasslands? (b) Do different above-ground vegetation states modify the expression of SBFT singularities? (c) Is the potential for vegetation recovery from the soil seed bank associated with the characteristics of their SBFT? To address these questions we examined the sizes of immediately and non-immediately-germinable seed banks (IGSB and NIGSB, respectively) in four different vegetation states of the steppe of F. pallescens resulting from the combined effects of topography and grazing. The results show that four lifeforms (perennial grasses, perennial graminoid non-grasses, annual dicots and annual grasses) display three characteristic SBFT. These are: (1) a transient type constituted by perennial grasses (SBFT1), (2) an intermediate type represented by annuals (SBFT2), and (3) a persistent type characteristic of one perennial graminoid non-grass (SBFT3). Other lifeforms (perennial dicots and biennials) could not be assigned to any of these types or characterized into a definite one. Seed bank functional types do not change among vegetation states in terms of the relative proportions of IGSB and NIGSB, although differences in the absolute and the relative size of each SBFT could be found. Species with persistent or mixed persistent/non-persistent seed bank types (SBFT2, SBFT3, etc.) colonize habitats disturbed by grazing with more success than those with non-persistent seed banks (SBFT1). Species with persistent seed banks are over-represented in the soil seed bank in relation to their contribution to above-ground cover. Management strategies for conservation in these grasslands could conveniently be targeted to increase the seed rain of perennial grasses as well as to the creation of suitable micro-environmental conditions to enhance their establishment.     

Significance of transovarial infections of Amblyospora sp. (Microspora:Thelohaniidae) in relation to parasite maintenance in the mosquito Culex salinarius

Adult females of Culex salinarius, transovarially infected with the microsporidium Amblyospora sp., showed no significant differences in overall fecundity, physiological longevity, and preoviposition periods when compared to healthy adults under laboratory conditions. Development times and survival rates for congenitally infected young to reproductive age were also indistinguishable from those of healthy controls. A significant reduction of 52% in egg hatch was observed for infected eggs when compared to healthy eggs. Prevalence rates of infection for progeny produced by infected females declined with each successive gonotrophic cycle and averaged 90%. Transovarial transmission is not sufficient for the maintenance of the microsporidium in a population of mosquitoes. An alternate host is suggested as a mechanism whereby the microsporidium can reenter a healthy mosquito population.     

Innovative use of controlled availability fertilizers with high performance for intensive agriculture and environmental conservation

A variety of slow release fertilizers, controlled release (availability) fertilizers (CAFs),and stability fertilizers have been developed in response to the serious drawbacks of the conventional fertilizers since the early 1960's. Of these fertilizers, CAFs which are coated with resin are consumed in the largest quantity in the world. Selecting CAFs with higher performance, the author will discuss about: 1) Innovation of agro-technologies for various field crops including new concepts of fertilizer application, 2) high yielding of field crops, 3) enhancing quality and safety of farm products, and 4) controlling the adverse effect of intensive agriculture on the environment.     

Innovative use of controlled availability fertilizers with high performance for intensive agriculture and environmental conservation

A variety of slow release fertilizers, controlled release (availability) fertilizers (CAFs), and stability fertilizers have been developed in response to the serious drawbacks of the conventional fertilizers since the early 1960's. Of these fertilizers, CAFs which are coated with resin are consumed in the largest quantity in the world. Selecting CAFs with higher performance, the author will discuss about: 1) Innovation of agro-technologies for various field crops including new concepts of fertilizer application, 2) high yielding of field crops, 3) enhancing quality and safety of farm products, and 4) controlling the adverse effect of intensive agriculture on the environment.     

Patterns of tree growth in relation to environmental variability in the tropical dry deciduous forest at Mudumalai, southern India

Tree diameter growth is sensitive to environmental fluctuations and tropical dry forests experience high seasonal and inter-annual environmental variation. Tree growth rates in a large permanent plot at Mudumalai, southern India, were examined for the influences of rainfall and three intrinsic factors (size, species and growth form) during three 4-year intervals over the period 1988–2000. Most trees had lowest growth during the second interval when rainfall was lowest, and skewness and kurtosis of growth distributions were reduced during this interval. Tree diameter generally explained <10% of growth variation and had less influence on growth than species identity or time interval. Intraspecific variation was high, yet species identity accounted for up to 16% of growth variation in the community. There were no consistent differences between canopy and understory tree growth rates; however, a few subgroups of species may potentially represent canopy and understory growth guilds. Environmentally-induced temporal variations in growth generally did not reduce the odds of subsequent survival. Growth rates appear to be strongly influenced by species identity and environmental variability in the Mudumalai dry forest. Understanding and predicting vegetation dynamics in the dry tropics thus also requires information on temporal variability in local climate.     

The role of macrofungi in environmental conservation

Abstract

The motives for the conservation of fungi are briefly outlined. The data and methods needed for successful use of fungi in environmental conservation are mentioned. A survey is given of the main habitats of threatened fungi in Western and Central Europe, including data on the significance of their mycoflora, the causes of decrease and possible measures to improve the situation. The value of macrofungi as bio-indicators for environmental quality is discussed and demonstrated with three examples: the indicator value of wood-inhabiting fungi for undisturbed forest sites; of ectomycorrhizal fungi for air pollution stress in forests and of saprotrophic fungi for the duration of undisturbed grassland use. Lists of indicator species with different indicator values for air pollution stress and grassland use are provided.     

Meiofauna of springs in Finland in relation to environmental factors

The meiofauna was studied from springs in Finland which wascompletely ice-covered during the last glacial epoch. Of the31springs that were examined, 15 were in areas considered to bein anatural state and 16 had catchment areas subject toanthropogenicdisturbance from one of four sources: agriculture,inhabitation,gravel extraction or winter road de-icing with NaCl. The taxarecorded were a mixture of those already described fromepigeicwaters or groundwaters and some which may be regarded ascharacteristic of springs Statistical analysis revealeddifferencesin the meiofaunal taxa in relation to the water quality orcatchment area variables. Of the major meiofaunal groups thenematodes favoured springs influenced by agriculture,oligochaeteswere most tolerant of road de-icing, cladocerans and copepodspreferred springs in a natural state, ostracods couldwithstand theinfluence of road de-icing and gravel extraction, whilstdipteranlarvae could withstand the influence of agriculture.Oligochaetescomprised 13.4% of meiofaunal numbers. The most abundantspecieswas Aeolosoma quaternarium, which was most numerous insprings in a natural state, while Dero digitatapreferredeutrophic conditions. Harpacticoids comprised 14.1% ofindividualsand clearly preferred a natural state, Bryocamptusechinatusand Moraria brevipes being the most abundant species.Ostracods, of which the most abundant species was Potamocyprispallida, were the most numerous animal group, constituting21% ofthe meiofaunal population, and their numbers were greatest insprings influenced by road de-icing or gravel extraction.Dipteranlarvae, of which the majority were chironomids, comprised14.9% ofindividuals. The ostracods Potamocypris pallida andthreespecies of Candona and the harpacticoid Bryocamptuscuspidatus are new records for Finland.     

Breeding bird diversity in relation to environmental gradients in China

Geographic variation in species richness has been explained by different theories such as energy, productivity, energy–water balance, habitat heterogeneity, and freezing tolerance. This study determines which of these theories best account for gradients of breeding bird richness in China. In addition, we develop a best-fit model to account for the relationship between breeding bird richness and environment in China. Breeding bird species richness in 207 localities (3271 km² per locality on average) from across China was related to thirteen environmental variables after accounting for sampling area. The Akaike's information criterion (AIC) was used to evaluate model performance. We used Moran's I to determine the magnitude of spatial autocorrelation in model residuals, and used simultaneous autoregressive model to determine coefficients of determination and AIC of explanatory variables after accounting for residual spatial autocorrelation. Of all environmental variables examined, normalized difference vegetation index, a measure of plant productivity, is the best variable to explain the variance in breeding bird richness. We found that species richness of breeding birds at the scale examined is best predicted by a combination of plant productivity, elevation range, seasonal variation in potential evapotranspiration, and mean annual temperature. These variables explained 47.3% of the variance in breeding bird richness after accounting for sampling area; most of the explained variance in richness is attributable to the first two of the four variables.