辽东湾芦苇湿地对陆源营养物质净化作用的初步研究

通过廊道系统自净和ｌｙｓｉｍｅｔｅｒ汉滤实验进行了辽东湾芦苇湿地对陆源营养物质净化作用的初步研究,结果表明,营养物质Ｎ、Ｐ和ＣＯＤｃｒ在廊道系统中的自净率为４１．７－６４．７１％,不同深度的土壤－芦苇系统对陆源营养物质Ｎ、Ｐ和ＣＯＤｃｒ的净化率为６０．０％－７５．９２％,Ｎ、Ｐ营养物质经湿地系统地滤后可满足海水水质２类标准,通过收获地上部生物量可使营养物质在陆地和湿地之间形成良性循环,不会造成污染     

安徽枞阳湿地植被及植物资源的研究

枞阳湿地地处安徽省长江干流中段北岸 ,大约北纬 30°39′～ 31°0 5′,东经 1 1 7°0 4′～1 1 7°44′。该区有 4种湿地类型 ,即湖泊湿地、长江二级河流湿地 ,江心洲及江滩湿地和库塘湿地等 ,其中湖泊湿地面积最大 ,约 2 1 3.6km2 。该湿地计有水生及湿生维管植物 1 0 1种 ,分属37科 67属。文中分析了湿地维管植物的生活型、生态习性、群丛特征及价值 ,提出了湿地资源保护和利用措施。     

Alnus glutinosa – dominated wetland forests of the Baltic Region: community structure,syntaxonomy and conservation

Community structure, syntaxonomy and conservation aspects of Alnus glutinosa-dominated forests in the Baltic States, Central Europe, southern Fennoscandinavia and north-western part of the Commonwealth of Independent States are surveyed. Communities of the black alder wetlands, subjected to cluster analysis (TWINSPAN, GROUPAGE) and correspondence analysis (CANOCO) and synsystematically treated following the Braun-Blanquet approach, belong to Alnion (Carici elongatae-Alnetum Schwick. 33 with two subassociations, Sphagno squarrosi-Alnetum Sol.-Gorn. ex Pried. 96) and Alno-Ulmion (mainly Circaeo-Alnetum Oberd. 53) forests in the Baltic Region. The indicator values sensu Ellenberg, site ecology, floristic assemblages and the phytogeographical features point at a high affinity of these forests in a wide geographical area. Eleven syntaxonomical approaches by classifying central and north-eastern European alderwoods have been analysed. These differ in Alnion classification and distinguish from 2 to more than 10 syntaxa at the level of association. The actual distribution of less disturbed black alder wetlands and areas under these forests in Europe suggests that the SE part of the Baltic Region could be the key area for Alnus glutinosa-dominated wetlands. Thus, it deserves an establishment of an international network of standard protected areas so as to maintain the diverse community samples and elaborate the principles of sustainable management. Abbreviations: In figures CLT PALU means Caltha palustris, CAL PALU – Calla palustris. Abbreviations of all other species follow first 3 and 4 letters of the genus and species name, respectively. Nomenclature: Tabaka et al. (1988) for vascular plants, Abolina et al. (1984) for mosses.     

辽河三角洲湿地的景观破碎化分析

利用遥感、ＧＩＳ手段对辽河三角洲的湿地景观进行研究,并选用６种不同的方法对研究区的景观破碎化程度进行分析．结果表明,研究区的景观破碎化程度较低,总体斑块密度为０．２８６个·ｋｍ－２,廊道密度为１．０９８ｋｍ·ｋｍ－２,聚集度指数为０．９５５．景观破碎化与人类活动密切相关,随着人类活动的增加,景观破碎化程度加深．廊道景观的发展是景观破碎化的前提与动因．     

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.     

Temperature and salinity tolerance of Mesopodopsis africana O. Tattersall in the freshwater-deprived St. Lucia Estuary, South Africa

Mesopodopsis africana is a key species in the St. Lucia Estuary, Africa's largest estuarine lake. This system is currently undergoing an unprecedented crisis due to freshwater deprivation. A reversed salinity gradient has persisted with hypersaline conditions (> 300) occurring in the upper regions of the estuarine lake. In the context of climate change, rising temperatures will not only push the thermal tolerance limits of estuarine organisms, but increased evaporation from this lake's large surface area will lead to further salinity increases. The present study aims to determine the temperature and salinity tolerance of M. africana, both through in situ studies and the use of laboratory experiments. Results indicate that M. africana is a broad euryhaline species. Mysids were recorded at salinity levels ranging from 2.55 to 64.5 in situ. While experiments revealed a narrower salinity tolerance, acclimation resulted in a significant increase in the tolerance range of this species. It is probable, however, that slower acclimation times may increase survival rates even further, particularly in the higher salinity treatments. M. africana was especially tolerant of the lower salinity levels. In the 20 °C acclimation experiment, LS₅₀ at 1 and 2.5 was only reached after 8 and > 168 h, respectively. Survival at 10 and 40 °C was negligible at all salinity levels. This concurs with field results which documented mysids at temperatures ranging from 16.2 to 30.9 °C. Salinity and temperature increases associated with global climate change may, therefore, have significant implications for these mysid populations, with cascading effects on the higher trophic levels which they support.     

Disturbance frequency and community structure in a twenty-five year intervention study

Models of community regulation commonly incorporate gradients of disturbance inversely related to the role of biotic interactions in regulating intermediate trophic levels. Higher trophic-level organisms are predicted to be more strongly limited by intermediate levels of disturbance than are the organisms they consume. We used a manipulation of the frequency of hydrological disturbance in an intervention analysis to examine its effects on small-fish communities in the Everglades, USA. From 1978 to 2002, we monitored fishes at one long-hydroperiod (average 350 days) and at one short-hydroperiod (average 259 days; monitoring started here in 1985) site. At a third site, managers intervened in 1985 to diminish the frequency and duration of marsh drying. By the late 1990s, the successional dynamics of density and relative abundance at the intervention site converged on those of the long-hydroperiod site. Community change was manifested over 3 to 5 years following a dry-down if a site remained inundated; the number of days since the most recent drying event and length of the preceding dry period were useful for predicting population dynamics. Community dissimilarity was positively correlated with the time since last dry. Community dynamics resulted from change in the relative abundance of three groups of species linked by life-history responses to drought. Drought frequency and intensity covaried in response to hydrological manipulation at the landscape scale; community-level successional dynamics converged on a relatively small range of species compositions when drought return-time extended beyond 4 years. The density of small fishes increased with diminution of drought frequency, consistent with disturbance-limited community structure; less-frequent drying than experienced in this study (i.e., longer return times) yields predator-dominated regulation of small-fish communities in some parts of the Everglades. Electronic Supplementary Material Supplementary material is available for this article at     

Mitigation under Section 404 of the Clean Water Act: where it comes from, what it means

The requirement to mitigate impacts to wetlands and streams is a frequently misunderstood policy with a long and complicated history. We narrate the history of mitigation since the inception of the Clean Water Act Section 404 permit program in 1972, through struggles between the US Environmental Protection Agency and the US Army Corps of Engineers, through the emerging importance of wetland conservation on the American political landscape, and through the rise of market-based approaches to environmental policy. Mitigation, as it is understood today, was not initially foreseen as a component of the Section 404 permitting program, but was adapted from 1978 regulations issued by the Council on Environmental Quality as a way of replacing the functions of filled wetlands where permit denials were unlikely. EPA and the Corps agreed in 1990 to define mitigation as the three steps of avoidance, minimization, and compensation, principles which must be applied to permit decisions in the form of the environmental criteria in EPA’s 404(b)(1) Guidelines. Through the 1980s and 1990s, the compensation component of mitigation has become nearly the sole focus of mitigation policy development, and has been the subject of numerous guidance documents and memoranda since 1990. Avoidance and minimization have received far less policy attention, and this lack of policy development may represent a missed opportunity to implement effective wetland conservation.

尕海湿地退化演替过程中土壤有机氮组分的变化特征

为探究尕海湿地退化演替过程中土壤有机氮各组分变化规律,采用野外采样与室内分析相结合的方法,研究尕海湿地未退化(UD)、轻度退化(LD)、中度退化(MD)和重度退化(HD)4个退化演替阶段的土壤总氮(TN)和有机氮组分[未知态氮(HUN)、酸解氨态氮(AMN)、酸解氨基酸态氮(AAN)以及氨基糖态氮(ASN)]含量及其分布特征。结果表明: 当尕海湿地退化演替到LD时,0～10 cm层土壤TN、HUN、AMN和AAN含量分别降低17.3%、19.4%、8.6%和-5.6%,MD时分别降低28.0%、19.4%和17.1%和0,HD时分别降低35.8%、28.8%、28.6%和55.6%;10～20 cm层,LD时上述氮素含量分别降低4.0%、10.3%、2.9%和9.1%;MD时分别降低21.0%、18.3%、-2.9%和-9.1%;HD时分别降低9.9%、38.9%、21.2%和51.4%;而20～40 cm无显著变化;4个退化阶段各酸解氮组分占TN比例大小顺序为HUN(25.9%～32.5%)> AMN(6.7%～11.1%)> AAN(4.8%～11.1%)> ASN(1.2%～4.4%)。冗余分析显示,土壤含水量是土壤有机氮组分变化的主要驱动因子。尕海湿地退化显著降低了0～10 cm层土壤TN及酸解氮各组分含量,减弱了土壤氮“汇”功能,AAN和ASN对湿地退化最为敏感。     

鹭鸟栖息对杭州湾湿地土壤磷累积及形态分布的影响

土壤中磷含量对维持生态系统平衡起着重要作用。为研究杭州湾湿地迁徙候鸟栖息以及鸟粪的输入对栖息地土壤生态环境的影响,开展了鹭鸟筑巢树林下（影响区）和无鹭鸟筑巢树林下（对照区）土壤磷累积、土壤及鸟粪磷形态分布研究。结果表明：鹭鸟影响区土壤有机碳（Soil Organic Carbon,SOC）、全氮（Total Nitrogen,TN）、全磷（Total Phosphorus,TP）、有效磷（Available Phosphorus,AP）含量显著高于对照区（P<0.05）;对照区土壤TP含量为718.33 mg/kg,影响区土壤TP平均含量最高可达2040 mg/kg,其中钙结合态磷（Ca-bound P,Ca-P）含量最高,约占55.22%-62.96%,其次是残渣态磷（Residual Phosphorus,RP）、有机磷（Organic Phosphorus,OP）、铁铝结合态磷（Fe/Al-bound P,（Al+Fe）-P））、交换态磷（Exchangeable P,Exch-P）。鸟粪中有机碳（Organic Carbon,OC）、TN、TP含量分别是表层土壤的11.18-40.90倍,94.22-148.11倍,15.41-43.22倍,差异极显著（P<0.01）。TP含量与Exch-P、（Fe+Al）-P、Ca-P、AP极显著正相关,与RP显著正相关,与pH显著负相关。结果表明鸟粪输入使杭州湾湿地土壤TP含量显著提高,Exch-P、（Fe+Al）-P、Ca-P、AP含量均有提高,且占TP百分比增大,鸟粪输入造成了该地土壤磷素累积的同时增加了土壤磷素的流失风险。