Plant biomass and nutrient levels of a tropical macrophyte (Cyperus papyrus L.) receiving domestic wastewater

The aboveground biomass and nutrient content ofCyperus papyrus were determined in a small tropical swamp receiving domestic wastewater. It was found that the biomass (4,955 g.m^–2 dry weight) was the highest ever reported for papyrus. The levels of both nitrogen and phosphorus in the plant organs were very high. The nitrogen concentrations of the various plant organs were 4.8% roots, 8.4% rhizomes, 4.5% scales, 4.8% culms, and 6.2% umbels on dry weight basis. As to phosphorus the concentrations were 0.09% roots, 0.11% rhizomes, 0.09% scales, 0.10% culms, and 0.13% umbels. The high biomass and nutrient contents of the plants may have been caused by the high nutrient levels in the surrounding water. Comparison of the nitrogen to phosphorus ratios in the plants to those in the surrounding water showed that the plants stored very high amounts of nitrogen.     

Effects of a cyperus papyrus L. swamp on domestic waste water

The effectiveness of a papyrus swamp for the removal of nutrients from domestic waste water was investigated in a small tropical swamp in Kenya. The study was conducted in a man-made impoundment transformed into a swamp which receives sewage effluents discharged into a stream.Spatial and temporal distribution of nutrients were determined in the swamp from October 1980 to August 1981. They included the measurement of nitrogen and phosphorus, together with temperature, pH, conductivity and dissolved oxygen.A comparison between the water quality characteristics of the input versus the output from the swamp indicated significant decreases in the mean temperature and conductivity by 20 and 23%, respectively. Dissolved oxygen was reduced by 85%, ammonium by 77% and orthophosphate by 80%.The results obtained indicate that papyrus swamps are efficient in nutrient removal for the purpose of domestic waste water renovation.     

Effects of an organic sediment on performance of young Phragmites australis clones at different water depth treatments

Performance of young Phragmites australis plants was examined after 7 weeks on an artificial nutrient-enriched inorganic substrate and on the same substrate to which an organic sediment from a eutrophic lake was added, at three different water depth treatments. Growth decreased, and proportional allocation of biomass to roots increased, with the addition of sediment. These differences were significant in shallow and deep water, but not at a medium depth. Concentrations of phosphorus and nitrogen in plant biomass decreased, and concentration of iron increased, with addition of sediment.The effects of sediment addition may have resulted from a decreased availability of nutrients in the substrate or from an impaired root functioning. Nutrient exhaustion in the substrate, due to a fast plant growth, can explain the relatively strong effects in shallow water. Deep water, on the other hand, probably restricted oxygen transport to the roots, resulting in an impaired root functioning in the low-redox sediment environment. The results show that, especially in relatively deep water, growth of undisturbed plants of P. australis may be inhibited by eutrophication of sediments, probably because of an impaired root functioning in sediments containing reduced toxic compounds (e.g. ferrous iron).     

典型冷暖季沉水植物凋落物分解特性及沉积物微生物群落变化

为研究湿地沉水植物腐败分解对水体的污染状况,选择典型沉水植物金鱼藻（暖季植物）和菹草（冷季植物）进行了为期60 d的凋落物分解实验。结果表明金鱼藻和菹草凋落物分解规律相似,0—15 d快速分解,15—60 d缓慢分解,60 d凋落物失重率分别达到60.43%和66.72%。菹草的有机物释放量明显高于金鱼藻,N和P释放量相反,分解释放的N主要是NH4+-N和有机氮。三维荧光光谱（Excitation-Emission Matrix Spectroscopy, EEMs）结合平行因子分析法解析出一种类色氨酸物质C2和3种类腐殖质物质C1、C3、C4,易降解的类色氨酸有机物先增加后减少,难降解的类富里酸和类腐殖酸有机物逐渐增加。EEMs和四种组分的最大荧光强度百分比表明,溶解性有机物（Dissolved organic matter, DOM）在0—15 d以易降解有机物为主,15—60 d以难降解有机物为主。两种植物凋落物分解释放的DOM含量及特性不同,整体上呈低腐殖化特征,可能是水中难降解DOM的一个重要来源。植物凋落物的分解促进了沉积物中微生物的丰富度,降低了微生物的多样性;参与分解的主要微生物包括4 d时的Pseudomonas属（26%—35%）、15 d和30 d时的Malikia属（>8%）和Bacillus属（2.6%—9%）,分解难降解有机物的微生物逐渐增加,如Flavobacterium属;沉积物中微生物群落结构的变化受营养物质可利用性变化的影响。分析发现植物凋落物分解对水质的影响具有阶段性,0—15 d,N和P释放量增加暂时导致了水质恶化;15—60 d,N和P释放量降低,难降解有机物含量逐渐增加,可能会加剧水体甚至是沉积物的腐殖化程度。因此,在植物衰亡期应及时打捞或者做好植物平衡收割管理,避免因植物大量腐败导致水质恶化。     

Biogeochemical properties of a tropical swamp forest ecosystem in southern Thailand

The distributions of organic matter in the tropical swamps in southern Thailand are reported. The concentrations of particulate and dissolved organic carbon (POC and DOC) in the Bang Nara River, which drains swamp forests and nearby paddy fields, were 2.9 ± 2.0 and 6.2 ± 1.3 mg C l⁻¹, respectively. Although the variation was large, DOC concentration in the Bang Nara River seemed to be higher than POC in November 1992 (DOC/POC ratio, 2.8 ± 2.2). River waters from the upland areas were characterized by low POC and DOC concentrations as compared with Bang Nara River water. The δ¹³C values of POC and river sediments were useful to distinguish between organic matter originating in upland and swamp areas. It is suggested that the distributions of organic matter and its isotopic composition reflect the difference in drainage characteristics between lowland swamp and upland areas. Isotopic analyses of plant leaves and soils revealed that the swamp forest ecosystems were characterized by low δ¹³C and low δ¹⁵N values, which suggested low efficiency of water use by plants and large contributions of atmospheric deposition of nitrogen, respectively. Although CO₂ recycling in the forest might be an important factor determining the δ¹³C values of understory plants, the main process in carbon metabolism of tropical swamp forests would be CO₂ exchange between the atmosphere and forest canopy. Received: May 1, 2001 / Accepted: September 28, 2001     

The relative importance of sediment and water column supplies of nutrients to the growth and tissue nutrient content of the green macroalga Enteromorpha intestinalis along an estuarine resource gradient

Large blooms of opportunistic green macroalgae such as Enteromorpha intestinalis are of ecological concern in estuaries worldwide. Macroalgae derive their nutrients from the water column but estuarine sediments may also be an important nutrient source. We hypothesized that the importance of these nutrient sources to E. intestinalis varies along a nutrient-resource gradient within an estuary. We tested this in experimental units constructed with water and sediments collected from 3 sites in Upper Newport Bay estuary, California, US, that varied greatly in water column nutrient concentrations. For each site there were three treatments: sediments + water; sediments + water + Enteromorpha intestinalis (algae); inert sand + water + algae. Water in units was exchanged weekly simulating low turnover characteristic of poorly flushed estuaries. The importance of the water column versus sediments as a source of nutrients to E. intestinalis varied with the magnitude of the different sources. When initial water column levels of dissolved inorganic nitrogen (DIN) and soluble reactive phosphorus (SRP) were low, estuarine sediments increased E. intestinalis growth and tissue nutrient content. In experimental units from sites where initial water column DIN was high, there was no effect of estuarine sediments on E. intestinalis growth or tissue N content. Salinity, however, was low in these units and may have inhibited growth. E. intestinalis growth and tissue P content were highest in units from the site with highest initial sediment nutrient content. Water column DIN was depleted each week of the experiment. Thus, the water column was a primary source of nutrients to the algae when water column nutrient supply was high, and the sediments supplemented nutrient supply to the algae when water column nutrient sources were low. Depletion of water column DIN in sediment + water units indicated that the sediments may have acted as a nutrient sink in the absence of macroalgae. Our data provide direct experimental evidence that macroalgae utilize and ecologically benefit from nutrients stored in estuarine sediments.     

Passive irrigation and functional morphology of crustacean burrows in a tropical mangrove swamp

Flushing measurements and a resin cast of a burrow inhabited by Sesarma messa and Alpheus cf macklay were taken from a Rhizophoraspp. forest. The burrow had 9 openings and occupied a swamp surface area of 0.64 m². Passive irrigation of the burrow was investigated by recording change in conductivity of burrow water in a chamber 45 cm below the swamp surface during tidal inundation of the swamp. The chamber was completely flushed within approximately one hour, i.e. by a single tidal event. Burrow morphology was determined by means of resin casting. The investigated burrow was of discrete structure, with an overall depth of 1.2 m and a total volume of 68 l, i.e. ca. 9% of the volume of swamp soil. The below ground surface area of chambers and tunnels was 3.8 m². The mean and maximum chamber/tunnel diameter was 7 cm and 11 cm respectively. The soil in the close vicinity of the burrow was extensively penetrated by roots, and any two parts of the burrow were located no further than 20 cm away from each other. By reducing diffusion distances within the soil and by being well flushed, the burrows provide an efficient mechanism for removal of excess salt accumulated in the soil around mangrove roots due to exclusion.     

沼泽、盐化沙丘过渡带和沙丘生境下芦苇的光合及生理生化特性

对于田地区3种不同生境(沼泽、盐化沙丘过渡带和沙丘顶)芦苇的生长环境特征、光合特性、渗透调节及抗氧化系统的特征进行研究。结果表明:芦苇叶片的Pn日变化在沼泽生境呈单峰曲线,在盐化沙丘过渡带和沙丘顶部均为双峰曲线,光合"午休"现象明显,气孔导度降低是其主要原因。脯氨酸和可溶性糖含量随根区土壤水分减少和盐分加剧增加显著,其中可溶性糖含量变化剧烈,对抵御干旱和盐渍化危害的贡献较大。芦苇叶片超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性随干旱及盐分加剧增加显著,两者对水分亏缺的响应较盐分敏感,且可有效缓解沙丘生境由于缺水所造成的氧化损伤,使丙二醛(MDA)含量维持在相对较低水平。过氧化物酶(POD)活性在沙丘和盐渍化生境内都比较高,对抵抗盐渍化和干旱起着同样重要的作用。     

Water source utilization and foliar nutrient status differs between upland and flooded plant communities in wetland tree islands

Tree islands in the Everglades wetlands are centers of biodiversity and targets of restoration, yet little is known about the pattern of water source utilization by the constituent woody plant communities: upland hammocks and flooded swamp forests. Two potential water sources exist: (1) entrapped rainwater in the vadose zone of the organic soil (referred to as upland soil water), that becomes enriched in phosphorus, and (2) phosphorus-poor groundwater/surface water (referred to as regional water). Using natural stable isotope abundance as a tracer, we observed that hammock plants used upland soil water in the wet season and shifted to regional water uptake in the dry season, while swamp forest plants used regional water throughout the year. Consistent with the previously observed phosphorus concentrations of the two water sources, hammock plants had a greater annual mean foliar phosphorus concentration over swamp forest plants, thereby supporting the idea that tree island hammocks are islands of high phosphorus concentrations in the oligotrophic Everglades. Foliar nitrogen levels in swamp forest plants were higher than those of hammock plants. Linking water sources with foliar nutrient concentrations can indicate nutrient sources and periods of nutrient uptake, thereby linking hydrology with the nutrient regimes of different plant communities in wetland ecosystems. Our results are consistent with the hypotheses that (1) over long periods, upland tree island communities incrementally increase their nutrient concentration by incorporating marsh nutrients through transpiration seasonally, and (2) small differences in micro-topography in a wetland ecosystem can lead to large differences in water and nutrient cycles.     

The influence of Procambarus clarkii (Cambaridae,Decapoda) on water quality and sediment characteristics in a Spanish floodplain wetland

This study describes the effects of the American red swamp crayfish, Procambarus clarkii Girard, on water quality and sediment characteristics in the Spanish floodplain wetland, Las Tablas de Daimiel National Park. Our short term enclosure study during a summer drawdown revealed that crayfish acted as a nutrient pump that transformed and translocated sediment bound nutrients to the water column. Water quality impoverishment was mainly due to the increase of dissolved inorganic nutrients (soluble reactive phosphorus and ammonia), and a significant increase of total suspended solids occurred likely as a result of crayfish associated bioturbation. At the same time, crayfish reduced the content of organic matter in the sediment and we observed a slight increase of total sediment phosphorus and nitrogen content as a result of crayfish benthic activity. P. clarkii effects, in terms of internal nutrient loading (229.91 mg TP m^–2 d^–1), were shown to be important on a local scale, indicating the significance of internal nutrient supply to water column primary producers particularly under low external supply (summer). Extrapolations to the whole ecosystem, however, revealed a negligible crayfish contribution (0.06%) to total internal nutrient loading (0.035 mg TP m^–2 d^–1). Hence, crayfish spatial heterogeneity patterns are important in global and local matter fluxes and nutrient cycles in wetlands.     

Gorillas (Gorilla gorilla gorilla) in the Likouala swamp forests of north central Congo: Preliminary data on populations and ecology

Until recently it was generally believed that gorillas avoid water. In two recent, independent faunal surveys in the Likouala swamp of north central Congo, we have found that gorillas occur at high densities, extending the known range of Gorilla gorilla gorillavery close to the Oubangui River. The gorillas in this area fed on the abundant ground vegetation of herbaceous monocotyledons in the swamp forest. In adjacent islands of terra firmathere was little evidence of gorilla nesting or feeding, indicating that they spend at least part of the year almost exclusively in the swamp forests. Recent reports from several sites in West Africa indicate that swamp forests may generally provide abundant food resources that are used regularly by gorillas.     

Ceratophyllum demersum – phosphorus interactions in nutrient enriched aquaria

High macrophyte density in shallow lakes is often associated with clear water, especially when the non-rooted, submerged angiosperm Ceratophyllum demersum is dominant. Lack of true roots and high surface area:volume ratio suggest that nutrient uptake from the water column by C. demersum may be high. Therefore, possible competition for nutrients, including phosphorus (P), could contribute to phytoplankton inhibition. C. demersum ability to absorb and store P at four nutrient levels (unenriched + three enrichment treatments) was investigated in a 34-day laboratory experiment using agar-based nutrient diffusing substrates (NDSs). P uptake rates and abatement potential by C. demersum were assessed from total phosphorus concentration (TP) patterns in the water column. Changes in C. demersum biomass (wet weight) also were determined. C. demersum took up P quickly. Some P release occurred during the experiment, especially under high nutrient conditions. Initial net P uptake by C. demersum was high, but medium-term (five weeks) average uptake was relatively low. Projected long-term net P uptake approached zero. Plant biomass loss and production of macrodetritus (plant fragments >1 mm) were highest in unenriched aquaria. Biomass loss in the lower enriched treatments was equally divided between loss as macrodetritus and as dissolved organic matter (DOM), but loss as DOM was four times higher than loss as macrodetritus in the highest nutrient treatment. The results suggest that medium- and long-term low phytoplankton biomass in C. demersum-rich lakes is achieved via mechanisms other than direct competition for nutrients from the water column.     

Effect of flooding with sewage water on three wetland sedges

Plants of three wetland sedges, Carex vesicaria, C. rostrata, and C. gracilis, were subjected to flooding with diluted pig farm sewage water in a sand-culture experiment lasting for one growing season (20 weeks). Sewage water application altered growth dynamics and accumulation of dry matter in all three species; it shifted the distribution of dry matter in favor of above-ground parts; it depressed root growth both in dry mass and length; and it increased percentages of major nutrients (nitrogen, phosphorus, and potassium) in plant dry matter. In the root structure, sewage water application inhibited formation of gas spaces in the cortex, differentiation of exodermis and endodermis, and formation of starch grains in the cortex. The changes in root growth and structure are ascribed to the combination of (1) high nutrient availability, and (2) oxygen deficiency, which developed in the root medium following addition of sewage water. In view of these findings, Carex species are not well suited for use in the treatment of wastewaters rich in both mineral nutrients and organic matter.     

东太湖四角菱（Trapa quadrispinosa）生长特性

通过室外受控实验,研究了在不同沉积物类型及不同水体营养水平条件下东太湖四角菱的生长特性.结果表明:沉积物类型对菱的各项生长指标均有显著影响.在营养相对丰富的湖泥中,菱的相对生长率、同化根与吸收根的生物量以及株高增长率分别为相对贫瘠的岸泥的4.3、2.4、7.3、2.5倍,菱盘直径增长率在湖泥中为16.5%,在岸泥中则为负增长(-13.2%).水体营养盐浓度升高在一定程度上也促进了菱的生长,而且营养盐浓度(尤其是磷)升高对菱生长的促进作用在岸泥中要比在湖泥中显著得多.探讨了沉积物类型与水体营养水平对菱生长的作用机理,并认为水体富营养化的加剧及湖泊沼泽化所造成的氮、磷等营养物质在沉积物中的大量积累是东太湖菱种群迅速扩张的重要原因之一.     

Nitrogen and phosphorus accumulation and cycling by Nymphoides peltata (Gmel.) O. Kuntze (Menyanthaceae)

In 1980, the seasonal changes in nitrogen and phosphorus concentration of various plant parts of Nymphoides peltata (Gmel.) O. Kuntze, together with aspects of nitrogen and phosphorus cycling by this species were studied in an oxbow lake of the river Waal (The Netherlands). The nitrogen and phosphorus stores of the water, seston, sediment and macrophyte compartments were assessed each month.The underground Nymphoides structures had high nitrogen and phosphorus concentrations before and after the main growing season, while during summer the aboveground plant parts had high nutrient contents. Nymphoides peltata accumulated maximum amounts of nitrogen (334 mmol m⁻²) and phosphorus (56.6 mmol m⁻²) in July. The upper layers of the bottom appeared to be an enormous nutrient reservoir (94–99% of total) of which the largest part was not directly available to Nymphoides. Nutrient uptake from the sediments by N. peltata is suggested by the fact that the bottom and/or interstitial water of the sample station devoid of rooted macrophytes, contained higher concentrations of nitrogen and phosphorus than that of the Nymphoides stands. The annual flux of nutrients from Nymphoides to the detritus compartment was estimated to be ca. 1200 mmol nitrogen and 164 mmol phosphorus per m² of littoral. During breakdown of the detritus there was a relatively fast net conversion of organically bound nitrogen and phosphorus to inorganic forms, especially at higher temperatures.Nymphoides has the potential to function as an important nitrogen and phosphorus pump, which regenerates sediment nutrients.     

增温对冻土区泥炭沼泽土壤孔隙水甲烷关联微生物和溶解性有机碳的影响

多年冻土区泥炭沼泽土壤孔隙水甲烷关联微生物及底物的研究有助于深入理解气候变化背景下寒区湿地生态系统甲烷循环过程。选取大兴安岭连续多年冻土区柴桦-泥炭藓和狭叶杜香-泥炭藓两种典型植被群落泥炭沼泽,设置开顶箱(Open Top Chamber,OTC)增温实验。于生长季(6月、7月、8月和9月)采集土壤孔隙水样品,对比分析OTC内外土壤孔隙水中产甲烷菌数量、甲烷氧化菌数量及溶解性有机碳(Dissolved Organic Carbon,DOC)浓度的动态变化特征,并探究土壤孔隙水甲烷关联微生物与DOC浓度的关系。结果表明:增温提高了生长季大兴安岭多年冻土区土壤孔隙水中产甲烷菌数量和DOC浓度,而对甲烷氧化菌数量的影响因月份而异。生长季柴桦-泥炭藓和狭叶杜香-泥炭藓泥炭沼泽土壤孔隙水中产甲烷菌数量的平均增加幅度分别为54.52%和44.97%,DOC浓度的平均增加幅度分别为34.16%和28.33%。增温使得生长季柴桦-泥炭藓和狭叶杜香-泥炭藓泥炭沼泽土壤孔隙水中甲烷氧化菌平均数量分别降低了46.20%和31.42%。一元线性回归分析结果表明,土壤孔隙水中DOC浓度可分别解释柴桦-泥炭藓和狭叶杜香-泥炭藓泥炭沼泽土壤孔隙水中产甲烷菌数量变化的29.00%和24.10%(P<0.01),而对两种植被群落下土壤孔隙水中甲烷氧化菌数量的影响并不显著(P>0.05)。     

Nucleotide diversity of mitochondrial DNAs between the swamp and the river types of domestic water buffaloes,Bubalus bubalis,based on restriction endonuclease cleavage patterns

Cleavage patterns of mitochondrial DNAs (mtDNAs) by 15 restriction endonucleases were analyzed for 10 swamp and 13 river types of domestic water buffaloes. Digestions with nine enzymes exhibited polymorphisms giving two or three kinds of cleavage patterns. Five mtDNA types were identified, three types in the swamp buffaloes of the Philippines, Vietnam, and Indonesia (S-types) and two types in the river buffaloes of Bangladesh and Pakistan (R-types). Nucleotide diversities ranged from 0.2 to 0.6% within the S- and R-types and from 1.9 to 2.4% between the R-types and the S-types. These values indicated that R-type and S-type mtDNAs differentiated at thesubspecific level of other mammalianspecies reported. The possibility of polyphyletic domestication in different places is discussed for the origin of two distinct types of domestic water buffaloes.     

Leaf litter decomposition in a tropical peat swamp forest in Peninsular Malaysia

It has long been assumed that the peat underlying tropical peat swamp forests accumulates because the extreme conditions (water logged, nutrient poor, anaerobic and acidic—pH 2.9–3.5) impede microbial activity. Litterbag studies in a tropical Malaysian peat swamp (North Selangor peat swamp forest) showed that although the sclerophyllous, toxic leaves of endemic peat forest plants (Macaranga pruinosa, Campnosperma coriaceum, Pandanus atrocarpus, Stenochlaena palustris) were barely decomposed by bacteria and fungi (decay rates of only 0.0006–0.0016 k day⁻¹), leaves of M. tanarius, a secondary forest species were almost completely decomposed (decay rates of 0.0047–0.005 k day⁻¹) after 1 year. Thus it is intrinsic properties of the leaves (that are adaptations to deter herbivory in the nutrient poor environment) that impede microbial breakdown. The water of the peat swamp was very high in dissolved organic carbon (70–84 mg l⁻¹ DOC). Laboratory studies revealed initial rapid leaching of DOC from leaves (up to 1,720 mg l⁻¹ from 4 g of leaves in 7 days), but the DOC levels then fell rapidly. The leaching of DOC resulted in weight loss but the physical structure of the leaves remained intact. It is suggested that the DOC is used as a substrate for microbial growth hence lowering the concentration of DOC in the water and transferring energy from the leaves to other trophic levels. This would explain how nutrient poor tropical peatswamps support diverse, abundant flora and fauna despite low nutrient levels and lack of rapid litter cycling such as occurs in other types of tropical rainforests.     

Zooplankton of a swamp water ecosystem

The Great Dismal Swamp, located in southeastern Virginia and extending into northeastern North Carolina, is a unique ecosystem which has undergone severe alteration over the last 200 years due to agricultural, municipal and timbering development. The swamp is presently about 50% of its late 1700 size when George Washington commissioned the construction of the first of a series of drainage ditches that have subsequently reduced the swamp aquatic environs to a ditch network draining into Lake Drummond located near the swamp's center. The swamp waters are characterized by a brown color, high suspended organic matter, high acidity and low nutrient levels. This paper presents the first comprehensive study of the zooplankton assemblages of the Great Dismal Swamp.Zooplankton was collected for one year at 14 stations and was dominated by rotifers. Of the 84 species identified, 61 were rotifers, 18 were Cladocera and 5 were copepods. Many of the species collected were cosmopolitan and acid tolerant forms. Dominant lake rotifers included Polyarthra vulgaris, Conochiloides dossuarius, Keratella cochlearis, Trichocerca similis, Synchaeta longipes and Microcodon clavus. Dominant crustaceae included Bosmina longirostris, Diaphanosoma leuchtenbergianum, Mesocyclops edax, and Tropocyclops prasinus.Usually the ditch zooplankton was the same as that of the lake. Of the seven ditches studied, the most unique chemically and biologically were Interior, Washington, and Portsmouth. Measurable alkalinity was detected in Interior and Washington Ditches. Alkaline water rotifers such as Brachionus, Mytilina, Filinia, Notholca Platyias and Keratella earlinae were found in these ditches. The rotifer, Keratella valga, was only found from Portsmouth Ditch, during a period when water was flowing into the lake and it contained high nutrient levels.Research funded in part by the Virginia Academy of Sciences and the Center for Environmental Studies, Virginia Polytechnic Institute and State University.     

Species richness in boreal swamp forests of SE Norway: The role of surface microtopography

Question: What is the relative importance of environmental gradients and surface microtopography (variation in vertical level within sampling units) for fine‐scale plant species richness in Picea abies swamp forests? Location: 11 swamp forests in SE Norway. Methods: We recorded species richness (number of species of vascular plants, mosses, Sphagnum and hepatics), depth to water table, soil base status and vertical range (microtopographic relief) in 2400 microplots, (each 1/16 m²), in 150 1‐m² plots in the 11 swamp forests. Relationships between species richness and environmental predictors were modelled by GLMM. Results: Moss and hepatic species richness increased with increasing microtopographic relief, most strongly for wet acid sites, in which similar trends were also found for Sphagnum. Relief was a poor predictor of vascular plant species richness. Conclusions: Microtopographic relief is a good predictor of local species richness in Picea abies swamp forests, partly because larger vertical variability means higher within‐plot habitat diversity with respect to the wet‐dry gradient, and partly because qualitatively new microhabitats associated with steep slopes are added in drier sites. The relationship between species richness and microtopographic relief is context dependent, differing in complex ways among species groups and among sites with different environmental conditions.