What confines an annual plant to two separate zones along coastal topographic gradients?

We investigated the roles of flooding, salinity, and plant competition in creating a bimodal zonation pattern of the marsh dominant annual plant, Suaeda salsa, along coastal topographic gradients on the Pacific coast of northern China. In two consecutive years, we manipulated salinity and flooding, salinity, and competition for S. salsa seedlings that had been transplanted into the mudflat, the high marsh, and the upland, respectively. S. salsa plants that had been transplanted into the mudflat were completely eliminated in the non-elevated treatments whereas they performed much better in the 10 cm elevated treatments, regardless of salinity treatments. Although the performance of S. salsa transplanted into the high marsh did not differ between the fresh (watered) and the salt (control) treatments, S. salsa seedling emergence in the high marsh was nearly completely inhibited in the salt treatments. In contrast, a large number of S. salsa seedlings did emerge in the fresh treatments. S. salsa transplanted into the upland performed well when neighbors were removed, whereas it appeared to be strongly suppressed when neighbors were present. These data indicated that flooding, salinity, and competition all played a role in determining the zonation pattern of S. salsa. Furthermore, the importance of salinity was found to vary with life-history stage. Based on the results from these field manipulative experiments, we suggest that the marsh plant zonation paradigm may hold true for plant distributions along landscape-scale topographic gradients from mudflats to uplands in general. The relative importance of flooding, salinity, and competition, however, may vary at different elevations within a site and between sites. Handling editor: Pierluigi Viaroli     

Palaeoclimatic signals and anthropogenic disturbances from the peatbog at Nagybárkány (North Hungary)

Investigation of a small peatbog in northern Hungary provides a late Quaternary record of vegetation development effected by climatic changes and anthropogenic disturbances. The aim of this study was to separate climatic signals from the development of a continental eutrophic peatland with the use of plant macrofossil analysis. The development of water catchment is reconstructed using pollen and geochemical analyses. The formation of the lakebed can be traced back to the Late Glacial. A higher water level with oligotrophic conditions can be existed from the Late Glacial to middle Holocene, when the reed beds covered a small area only. This was followed by a hiatus spanning ca. 4400 years, caused by peat cutting during the Imperial Age. The water level decreased and the water quality was more eutrophic. A reed bed evolved around the lake. Terrestrialization started with a bulrush floating mat phase at the close of the árpádian Age, ca. cal yr AD 1400. The initiation of the Sphagnum-bog underwent similar phases as in the other Hungarian peatbogs. Although remarkable anthropogenic disturbances can be reconstructed in the development of the peatbog, some climatic effects and authogenic processes might be separated by palaeoecological analyses. Guest editors: K. Buczkó, J. Korponai, J. Padisák & S. W. Starratt Palaeolimnological Proxies as Tools of Environmental Reconstruction in Fresh Water     

陕西省黄河湿地冬季鸟类群落初步研究

1998～2008年,采用直接计数法对陕西省黄河湿地冬季鸟类群落组成、鸟类物种多样性及数量变化进行了调查.在预先设置的5条调查样带中共记录到鸟类14目33科117种.观察结果表明,该地区鸟类多样性指数和均匀度指数分别为4.497和0.654.栖息地可分为人工渔塘、芦苇沼泽、滩涂湿地、农田和人工林5种类型.这些生境中鸟类组成及物种多样性差异均较大,其鸟类多样性指数分别为2.826、3.571、3.202、1.205、2.496,以芦苇沼泽中的鸟类多样性指数最高,滩涂湿地中鸟类数量最多,农田中鸟类优势度最高.通过对该地区鸟类群落组成及多样性分析研究以及黄河湿地冬季鸟类栖息地现状评价,为湿地鸟类资源的保护提供科学依据.     

Cultural Disturbances and Local Ecological Knowledge Mediate Cattail (<Emphasis Type="Italic">Typha domingensis</Emphasis>) Invasion in Lake Pátzcuaro,México

The influence of local actors and socioeconomic constraints on biological invasions is often ignored. Wetland plant harvesters appeared to intentionally influence cattail (Typha domingensis) invasion around Lake Pátzcuaro, México, by altering their harvesting regimes, according to interviews with 44 expert respondents and botanical surveys. The oldest and most experienced harvesters reported controlling Typha initially, sometimes through organized eradication efforts, in order to protect Schoenoplectus californicus, an economically and culturally valuable wetland plant. Later, outsiders commoditized Typha by introducing new weaving designs popular with tourists, while industrial products and new livelihood activities reduced Schoenoplectus harvest. Harvesters from several communities began to promote Typha re-growth. Some harvesters, however, continued to combat Typha to maintain Schoenoplectus production, especially where supply was limited. Interviews suggested novel ecological cause–effect mechanisms and restoration strategies; some local harvesting regimes could efficiently conserve rare plants. An understanding of local ecological knowledge and incentives can inform invasive species control and conservation policy at a broader scale.     

Long-term effects of drainage and hay-removal on nutrient dynamics and limitation in the Biebrza mires,Poland

To provide a reference for wetlands elsewhere we analysed soil nutrients and the vegetation of floodplains and fens in the relatively undisturbed Biebrza-valley, Poland. Additionally, by studying sites along a water-table gradient, and by comparing pairs of mown and unmown sites, we aimed with exploring long-term effects of drainage and annual hay-removal on nutrient availabilities and vegetation response. In undrained fens and floodplains, N mineralization went slowly (0–30 kg N ha⁻¹ year⁻¹) but it increased strongly with decreasing water table (up to 120 kg N ha⁻¹ year⁻¹). Soil N, P and K pools were small in the undisturbed mires. Drainage had caused a shift from fen to meadow species and the disappearance of bryophytes. Biomass of vascular plants increased with increasing N mineralization and soil P. Annual hay-removal tended to have reduced N mineralization and soil K pools, but it had increased soil P. Moreover, N concentrations in vascular plants were not affected, but P and K concentrations and therefore N:P and N:K ratios tended to be changed. Annual hay-removal had induced a shift from P to K limitation in the severely drained fen, and from P to N limitation in the floodplain. The low nutrient availabilities and productivity of the undisturbed Biebrza mires illustrate the vulnerability of such mires to eutrophication in Poland and elsewhere. In nutrient-enriched areas, hay removal may prevent productivity increase of the vegetation, but also may severely alter N:P:K stoichiometry, induce K-limitation at drained sites, and alter vegetation structure and composition.     

Seed banks of a southern Australian wetland: the influence of water regime on the final floristic composition

The sediments of a southern Australian wetland complex were investigated to determine the germinable seed bank. The number of seeds ranged from 22,000 to 78,000 m^–2. Non-metric multi dimensional scaling (NMS) ordination based upon species composition separated the four basins but each contained the representatives of the major functional groups: terrestrial, amphibious and submerged. To test the influence of water regime on the final floristic composition derived from these seed banks, sediments were positioned at three elevations (0, 30 and 80 cm) and subjected to three hydrologic regimes (static water level, and draw down rates of 2.5 and 7 cm week^–1). Species compositions were analysed after 98 days via ordination. Despite significant differences in the initial seed bank composition the final floristic compositions were correlated with the water regime and independent of the initial seed bank composition. Species groups were segregated on a basis of whether sediments were continuously exposed to the atmosphere, the rate of draw down and the water depth. Moist sediments were dominated by species belonging to all the main functional groups. Sediments subject to rapid drying were dominated by terrestrial species whereas sediments that were flooded for the majority of the time were dominated by submerged species.     

河南石山口水库水鸟调查

石山口水库为河南水鸟种类与数量最多的典型湿地,位于大别山西北麓的浅山丘陵地域,属北亚热带向暖温带过渡的大陆性季风气候区,每年的秋末(11—12月)、初春(2—3月)及夏季(6—7月)湿地水鸟的种类与种群数量呈现明显的高峰期。本文共记录石山口水库湿地水鸟计8目、15科、85种,其中国家重点保护种类9种,《中日保护候鸟协定》指定种类55种,《濒危野生动植物种国际公约》(CITES)指定种类10种,省保护种类9种。     

Effects of agriculture and wetland restoration on hydrology, soils, and water quality of a Carolina bay complex

We compared hydrology, soils, and water quality of an agricultural field (AG), a two-year-old restored wetland (RW), and two reference ecosystems (a non-riverine swamp forest (NRSF) and a high pocosin forest (POC)) located at the Barra Farms Regional Wetland Mitigation Bank, a Carolina bay complex in Cumberland County, North Carolina. Our main objectives were to: 1) determine if the RW exhibited hydrology comparable to a reference ecosystem, 2) characterize the soils of the AG, RW, and reference ecosystems, and 3) assess differences in water quality in the surface outflow from the AG, RW, and reference ecosystems. Water table data indicated that the hydrology of the RW has been successfully reestablished as the hydroperiod of the RW closely matched that of the NRSF in 1998 and 1999. Jurisdictional hydrologic success criterion was also met by the RW in both years. To characterize soil properties, soil cores from each ecosystem were analyzed for bulk density (D_b), total carbon (C_t), nitrogen (N_t), and phosphorus (P_t), extractable phosphate (PO_4w), nitrogen (N_ex), and cations (Ca_ex, Mg_ex, K_ex, Na_ex), as well as pH. Bulk density, P_t, Ca_ex, Mg_ex, and pH were greatly elevated in the AG and RW compared to the reference ecosystems. Water quality monitoring consisted of measuring soluble reactive phosphorus (SRP), total phosphorus (TP), nitrate + nitrite (NOX), and total nitrogen (TN) concentrations in surface water from the AG, RW, and reference outflows. Outflow concentrations of SRP, TP, and NOX were highest and most variable in the AG, while TN was highest in the reference. This study suggested that while restoration of wetland hydrology has been successful in the short term, alteration of wetland soil properties by agriculture was so intense, that changes due to restoration were not apparent for most soil parameters. Restoration also appeared to provide water quality benefits, as outflow concentrations of SRP, TP, NOX, and TN were lower in the RW than the AG.     

论湿地生态系统服务的多维度价值评估方法

为了维系湿地生态系统的功能并制定合理的保护与开发规划,有必要量化湿地生态系统服务的价值。目前学术界尚未形成统一的湿地价值评估方法,而不同的选取方法、评估角度、评估对象等,会导致计算结果存在很大差异,尤其是在对时空差异性服务价值评估和湿地生态系统服务的总价值评估中存在难以量化和重复计算现象。针对上述问题,从湿地生态系统服务的定义、分类和受益人出发,提出了多维度价值评估方法,以定量计算时空差异性服务价值和系统的总服务价值,并探讨了该方法在淮河流域八里河湿地生态系统中的应用以及对其他类型生态系统服务研究的借鉴意义。