Classification and inventory of wetlands: A global overview

Classification of wetlands is extremely problematical, definition of the term wetland being a difficult and controversial starting point. Although considerable effort has gone into the development of national and regional wetland classifications, the only attempt at establishing a global system has been under the auspices of the Ramsar Convention on Wetlands of International Importance. In view of the fact that the Ramsar Convention has 70 Contracting Parties world-wide, it is suggested that the Convention's definition and classification system should be adopted generally for international purposes. Much of the world has been covered by preliminary wetland inventories, but there is an urgent need to extend coverage to those areas not yet included. It is essential that all inventory projects give adequate attention to meeting the real information needs of agencies and individuals which have an impact on the conservation and wise use of wetlands. Attention should also be given to providing for wide dissemination and regular updating of information and establishment of procedures for monitoring ecological change at the sites identified.     

武汉东湖水生植被及其恢复途径探讨

１９９２～１９９３年对武汉东湖三个主要湖区（郭郑湖、汤林湖和牛巢湖）水生植被的调查表明,该湖区共有水生植物３２种,优势种为大茨藻、狐尾藻、苦草和菱。金鱼藻呈不断扩大的趋势。植被类型可分为１１个群丛,植被面积约为０．６５ｋｍ￣２,总生物量为１２３６．３９ｔ（湿重）,植被带状分布仅见于汤林湖北部和其他部分湖汊。汤林湖和牛巢湖水生植被正处于自然恢复演替阶段。     

Different responses to changes in phosphorus,P, among lakes. A study of slopes in chl-a = f(P) graphs

The least squares estimator of a linear regression coefficient _L will give an overall expression for the change in with x. In fresh water ecology, however, subgroups, % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiuaSGaci% 4Aaaaa!37BE!\[P\operatorname{k}\], of a parent population may have slopes which differ from the overall slope, _L. By constructing frequency histograms for the set of angles: Arctang % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaci4uaSGaam% yAaiaadQgaaaa!38AE!\[\operatorname{S} ij\],% MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaci4uaSGaam% yAaiaadQgaaaa!38AE!\[\operatorname{S} ij\]= para sa y and x% MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaaiikaiaadM% faliaadMgakiabgkHiTiaadMfaliaadQgakiaacMcacaGGVaGaaiik% aiaadIhaliaadMgakiabgkHiTiaadIhaliaadQgakiaacMcaaaa!42F0!\[(Yi - Yj)/(xi - xj)\], i < j, % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiEaSGaam% yAaOGaeyiyIKRaamiEaSGaamOAaaaa!3BAB!\[xi \ne xj\], peaks in the distribution may be identified and related to ecological phenomenon. To identify peaks we fit Gaussian distributions to the frequency histograms. For a set consisting of 142 observations of chlorophyll-a and total phosphorus (nutrient) concentrations (TP) from 16 lakes we found four Gaussian peaks corresponding to four subgroups, % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiuaSGaci% 4Aaaaa!37BE!\[P\operatorname{k}\]k = 1,4. One group identified a response of chl-a to changes in TP which correspond approximately to the average slope found by least square regression (the slope was 0.49). The second group consisted of steeper response than the average (1.28). A third group showed that there is an enhanced proportion of cases where chl-a does not respond to TP (zero slope, all the three deep lakes > 10 m, included in the date set contributed to this group). The size of the last group, spanning a wide range of slopes, suggested that about 30% of the inter annual changes in chl-a is unrelated to TP. The results are compared to result obtained by simple least squares regression and to the Theil non-parametric slope estimator.     

Regulation of phytoplankton dynamics in a Laurentian Great Lakes estuary

The composition and dynamics of phytoplankton populations were examined in Old Woman Creek estuary, Lake Erie (USA). The centric bacillariophytes,Cyclotella atomus Hust.,Cyclotella meneghiniana Kütz., andAulacoseira alpigena (Grun.) Krammer, and the cryptophytes,Cryptomonas erosa Ehren. andRhodomonas minuta var. nannoplanctonica Skuja, dominated the phytoplankton most of the year. Chlorophytes, euglenophytes, and cyanophytes were observed less frequently. Estuarine and Lake Erie phytoplankton were considered distinct populations; lake taxa were largely confined to the estuary mouth and present only in low biomass. Maxima and minima of estuarine phytoplankton coincided with meteorological and hydrological forcing in the form of rainfall and subsequent storm-water inflows, respectively. Distinct population dynamics between the upper and lower estuary following storm events were attributed to the presence/absence of refugia serving as a source for repopulation by opportunistic taxa, fluctuating light conditions in the water column resulting from influx of particulate matter and resuspension of bottom sediments, and nutrient inputs associated with surface runoff and sub-surface interflow. Additionally, agricultural herbicides introduced by storm-water inflows potentially may affect and/or control the growth and physiological responses of individual taxa.     

Microatoll microbialites of Lake Clifton,Western Australia: Morphological analogues ofCryptozoön proliferum Hall,the first formally-named stromatolite

Summary The Linnaean nameCryptozo?n proliferum Hall was proposed in 1883 for a previously undescribed life-form preserved in spectacular exposures of Cambrian limestones in New York State, USA. It is now recognised that these are exposures of stromatolitic microbialites, laminated organosedimentary structures formed from interaction between a benthic microbial community (BMC) and the environment. Microbialites are neither fossil organisms nor trace fossils. These complex structures are the products of dissipative, self-organising systems involving a BMC, the external environment and the accreting microbialite. Functionally analogous BMCs of different species compositions may build similar structures in similar environments in quite separate periods. The type exposures ofCryptozo?n proliferum show objects composed of complex, concentric rings, up to a metre in diameter, that have grown laterally without any restriction other than that provided by neighbouring structures. They are not the relicts of domes truncated by penecontemporaneous erosion or Pleistocene glaciation, but depositional forms in which upward growth was restricted. Analogous modern structures occur on a reef platform along the north east shore of hyposaline Lake Clifton, Western Australia. These are tabular thrombolitic microbialites that vary lakeward across the reef platform from low, compound structures to discrete, concentric structures up to 50 cm high. The Lake Clifton forms are, in turn, morphological analogues of microatolls found on coral reef platforms. Coral microatolls are coral colonies with flat, dead tops and living perimeters in which upward growth is constrained by the sea surface. In shallow water they form circular rims of laterally growing coral around a dead centre. In deeper water they form coral heads that develop flat tops on reaching sea level. It is concluded that both the tabular microbialites of Lake Clifton and the type exposures ofCryptozo?n proliferum are analogous to coral microatolls in both form and origin-structures that have been able to grow laterally, but in which upward growth is restricted by subaerial exposure. Similar microatoll microbialites have been described from other modern environments, including Great Salt Lake, Utah, USA and Stocking Island, Exuma Cays, Bahamas. Ancient examples may include some of the “tufa” deposits of the Basal Purbeck Formation in Dorset, UK, as well as the coalesced domal bioherms of the Upper Cambrian Arrinthrunga Formation of the Georgina Basin, Central Australia, and the “washbowl” structures described from the B?tsfjord Formation of the Varanger Peninsula, north Norway. Progress towards a reliable interpretation of ancient microbialites depends on an understanding of modern environments in which analogous structures are forming. This study of microatolls has demonstrated that other sessile life forms may create colonial ecomorphs that, used cautiously, can serve as analogues for understanding the factors controlling the growth and form of microbialites. The surprising lack of pre-Pleistocene examples of microatolls recorded to date has simply been due to their lack of recognition in the geological record. They occur in sequences from the Proterozoic onwards, and provide powerful environmental indicators of ancient reef platforms on which biological growth was adjusted to contemporary sea level.     

Experimental evaluation of realized niche models for predicting responses of plant species to a change in environmental conditions

Abstract. We estimated, using logistic regression techniques, the realized niches of the four dominant species in an experimental marsh complex located in the Delta Marsh, Manitoba, Canada. These models were then used to predict the probability of occurrence of these species in selected elevation ranges when water levels were raised in 1985 either 0, 30 or 60 cm above the long-term normal water level. These realized-niche models were calculated using elevation and species data collected in 1980. After having been eliminated by two years of deep flooding, the emergent vegetation in this complex had been re-established during a drawdown beginning in either 1983 or 1984. Our hypothesis was that from 1985 to 1989 the frequencies of occurrence of species in selected elevation ranges would converge to their probabilities predicted from the 1980 logistic models. This was not borne out by our results. Actual frequencies and predicted probabilities of occurrence of a species were similar at best less than 40% and then mostly in the control (0 cm) treatment. The realized-niche models were not adequate to predict the distribution of emergents after an increase in water level in the short term because the emergent species did not migrate upslope. Emergent species in the medium and high treatments either (1) died out - Scolochloa festucacea and Scirpus lacustris - after 3 yr because they could not survive permanent flooding, (2) stayed where they were - Phragmites australis - because they were unable to move upslope through clonal growth, or (3) became more widespread - Typha glauca only because of the expansion of small local populations already established in 1985 in areas dominated formerly by other species.     

Conservation of salt lakes

Salt lakes have a variety of important uses and values, including especially both economic and scientific ones. These uses and values have been and are increasingly subject to degradation from a variety of impacts: diversion of inflows, pollution, agricultural practices, and introduction of exotic species are among the more important. Recognition of these impacts upon salt lakes has led to some international and national measures for their conservation, but considerably more effort in this direction is needed. Against this background, Mono Lake, California, USA, and the Aral Sea, central Asia, are discussed as two localities which bring into sharp focus the various matters discussed in the paper. Finally, attention is drawn to the need to conserve the Akrotiri Salt Lake, Cyprus.     

A population model for the alkali fly at Mono Lake: depth distribution and changing habitat availability

The densities of alkali fly larvae and pupae were measured in relation to depth and substrate type at six locations around Mono Lake. Samples representing a mixture of different bottom features were taken to a depth of 10 m (33 ft) using SCUBA. This is at or near the depth limit of fly larvae and pupae. The biomass of larvae and pupae on hard substrate were maximum and approximately equal at depths of 0.5 m and 1 m, substantially lower at intermediate depths of 3 m and 5 m, and over an order of magnitude further reduced at 10 m. Densities of flies on hard or rocky substrates (mainly calcareous tufa deposits), were significantly greater than those found on soft substrates such as mud or sand, at all but the greatest depth surveyed.Bathymetric maps of the areas of hard and soft substrate occurring at different lake depths were used to estimate the fly population size over the whole lake, based on the density distribution of larvae and pupae with depth on different substrates. The mapped areas of soft and hard substrates were also calculated for different lake levels, and applying the same procedure, a population model comparing the abundance of flies at different lake levels was developed. This habitat-based population model predicts that the abundance of the alkali fly is maximized at 6380 ft (1945 m) lake surface elevation. Most of the tufa substrate submerged at this lake level will become exposed and unavailable as habitat as the lake declines to 6370 ft (1942 m). In late 1991, the lake level was just over 6374 ft (1943 + m).     

Responses of radial growth and stable carbon isotopes to climate in the northern Tianshan Mountains

Climate change has profound effects on forest ecosystems. Schrenk spruce (P. schrenkiana) is a natural conifer species endemic to the arid inland areas of Asia. In this study, the relationship between tree-ring parameters of P. schrenkiana and major meteorological factors were analyzed, and the main limiting factors for tree radial growth and stable carbon isotope fractionation were explored. Our results indicate that moisture stress before and during the growing season have an important influence on radial growth of P. schrenkiana, especially, the correlation coefficient between tree-ring width and vapor pressure deficit (VPD) from previous August to current July is as high as −0.622 (n = 51, p < 0.01). Collinearity analysis further supports the conclusion that the limiting factor for the radial growth of P. schrenkiana is moisture. Although the correlation analysis results show that the tree-ring δ¹³C_corr is significantly positively correlated with sunshine duration (SD), additional analysis based on first order difference variables suggests that the climate factor may not be the only limiting factor for the stable carbon isotope fractionation of tree rings in the Sayram Lake Basin. This lays the foundation for the assessment of forest management practices and carbon sink capacity in light of future climate change.     

Prehistoric land use as recorded in a lake-shore core at Lake Constance

The second part of a pollen profile from Hornstaad/Lake Constance (Germany), containing the Atlantic and Subboreal (6400 cal B.C. to 700 cal B.C.) is presented. The diagram has a sampling interval of 1 cm and an average time resolution of 10 years. The cereal curve provided the basis for cereal zones, which are used to classify the human impact. Twenty-six cereal zones can be distinguished, most of them divided into subzones, from 5500 cal B.C. to 700 cal B.C. They correspond to both known and, mostly, unknown settlements in the surrounding landscape from the Early Neolithic to the Late Bronze Age. Charcoal and chemical analyses as well as sediment accumulation, confirmed by accelerator dates, provide evidence for human impact on the environment.A contribution to the 8th IPC, Aix-en-Provence, Sept. 1992