Evapotranspiration determined using the energy-budget method at a semi-permanent prairie-pothole wetland in east-central North Dakota, USA was compared with 12 other commonly used methods. The Priestley-Taylor and deBruin-Keijman methods compared best with the energy-budget values; mean differences were less than 0.1 mm d⁻¹, and standard deviations were less than 0.3 mm d⁻¹. Both methods require measurement of air temperature, net radiation, and heat storage in the wetland water. The Penman, Jensen-Haise, and Brutsaert-Stricker methods provided the next-best values for evapotranspiration relative to the energy-budget method. The mass-transfer, deBruin, and Stephens-Stewart methods provided the worst comparisons; the mass-transfer and deBruin comparisons with energy-budget values indicated a large standard deviation, and the deBruin and Stephens-Stewart comparisons indicated a large bias. The Jensen-Haise method proved to be cost effective, providing relatively accurate comparisons with the energy-budget method (mean difference = 0.44 mm d⁻¹, standard deviation = 0.42 mm d⁻¹) and requiring only measurements of air temperature and solar radiation. The Mather (Thornthwaite) method is the simplest, requiring only measurement of air temperature, and it provided values that compared relatively well with energy-budget values (mean difference = 0.47 mm d⁻¹, standard deviation = 0.56 mm d⁻¹). Modifications were made to several of the methods to make them more suitable for use in prairie wetlands. The modified Makkink, Jensen-Haise, and Stephens-Stewart methods all provided results that were nearly as close to energy-budget values as were the Priestley-Taylor and deBruin-Keijman methods, and all three of these modified methods only require measurements of air temperature and solar radiation. The modified Hamon method provided values that were within 20 percent of energy-budget values during 95 percent of the comparison periods, and it only requires measurement of air temperature. The mass-transfer coefficient, associated with the commonly used mass-transfer method, varied seasonally, with the largest values occurring during summer.

Micrometeorological measurements of evapotranspiration (ET) often are affected to some degree by errors arising from limited fetch. A recently developed model was used to estimate fetch-induced errors in Bowen-ratio energy-budget measurements of ET made at a small wetland with fetch-to-height ratios ranging from 34 to 49. Estimated errors were small, averaging −1.90% ± 0.59%. The small errors are attributed primarily to the near-zero lower sensor height, and the negative bias reflects the greater Bowen ratios of the drier surrounding upland. Some of the variables and parameters affecting the error were not measured, but instead are estimated. A sensitivity analysis indicates that the uncertainty arising from these estimates is small. In general, fetch-induced error in measured wetland ET increases with decreasing fetch-to-height ratio, with increasing aridity and with increasing atmospheric stability over the wetland. Occurrence of standing water at a site is likely to increase the appropriate time step of data integration, for a given level of accuracy. Occurrence of extensive open water can increase accuracy or decrease the required fetch by allowing the lower sensor to be placed at the water surface. If fetch is highly variable and fetch-induced errors are significant, the variables affecting fetch (e.g., wind direction, water level) need to be measured. Fetch-induced error during the non-growing season may be greater or smaller than during the growing season, depending on how seasonal changes affect both the wetland and upland at a site.

Calcareous sloping fens are minerotrophic wetland systems that are well known for their high species richness, but little is known about the local processes that govern the spatial patterns of species distribution within these communities. This study was undertaken to document vegetative patterns and to quantify community differences within one such calcareous wetland. A 250-m transect was established along a topographic/hydrologic gradient that intersected several visually distinctive, predominantly herbaceous, wetland plant communities. Vegetation composition was surveyed in July and August 1997 using a non-random, centralized sampling approach. Three 15-m² sampling plots were established for each of four stations along the transect. Vegetation within each 15-m² sampling plot was surveyed using fifteen contiguous 1-m² quadrat frames with visual estimates of cover determined for each species. One hundred thirty taxa were identified within the 180 m² area sampled. Average species richness values ranged from 61 to 76 species per 15-m² sampling plot, with high spatial turn-over of species among plots. Indicator Species Analysis identified taxa with concentrated abundance and fidelity within particular sampling stations. Data for the 15-m² plots were analyzed using non-metric multidimensional scaling that produced ordinations suggesting strong environmental gradients across the site. General community composition was similar to the Carex interior-C. leptalea-C. flava association described by Motzkin and consistent with other calcareous sloping fen communities described in the literature for the southern New England region.

In the Everglades, the majority of fish detrital inputs occur during the dry season, when water-level drawdown reduces aquatic habitat. While these mortality events are highly seasonal, the remineralization and recycling of fish detrital nutrients may represent an important stimulus to the ecosystem in the following wet season. The goal of this study was to quantify the rate of detrital fish decomposition during three periods of the year to determine seasonal variations in decomposition patterns in this ecosystem. A multiple regression analysis showed that hydroperiod and water depth both played a role in determining fish decomposition rates within this ecosystem. Decomposition rates ranged from a low of 13% day⁻¹ in December 2000 to a high of 50% day⁻¹ in April 2001, the height of the dry season. Phosphorus analysis showed that Gambusia holbrooki, the dominant small fish species in the Everglades, contains 7.169 ± 1.46 mg P g⁻¹ wet fish weight. Based on the observed decomposition rates and the average biomass added, the estimated daily flux of phosphorus from the experimental detrital loading ranged from a low of 27.04 mg P day⁻¹ to a high of 108.14 mg P day⁻¹ during the decomposition period. We estimated that these inputs could represent an input of 43 μg P m⁻² day⁻¹ to the total temporal Everglades phosphorus budget. Although much of this phosphorus is likely incorporated into the macroinvertebrate pool, detrital inputs peak during the dry season when nutrients are most likely to be incorporated into the soil and occur when decomposition of vegetative material is moisture-limited. These inputs may therefore play an important role in stimulating vegetative production during the early wet season.

Agriculture and urbanization in the upland landscape often generate stressors, such as sedimentation and eutrophication, that may negatively impact wetland plant communities. Individual plant species responses to stressors are also likely influenced by the hydrologic and geomorphologic characteristics of different wetland hydrogeomorphic (HGM) subclasses. The goal of this study was to determine to what extent the two stressors listed above influence the growth and development of wetland plant species and how these responses vary across HGM subclasses. The impacts of the two stressors on wetland plant species emergence and growth were examined in a 2 × 2 factorial greenhouse experiment, using soil moisture and organic matter content to simulate three HGM subclasses. Both stressors elicited significant responses in species establishment and growth, but overall trends in stressor responses differed by wetland type. For instance, sedimentation reduced the emergence of four species in simulated riparian depressions but only affected one species in simulated slope wetlands and none in simulated headwater floodplains. Sedimentation had little impact on any species establishment or growth in headwater floodplains. Approximately half of the species showed an increase in at least one growth variable in response to nitrogen enrichment. Additionally, the conditions used to simulate HGM subclasses appeared to impact a species performance and sensitivity to stressors. Therefore, further investigation of the impacts of HGM subclass conditions on species performance is needed. We expected differences in species responses to be related to their natural distribution across pristine and impacted wetlands; however, no obvious relationships were found. Our results suggest that it will be difficult to make generalizations about species responses to stressors because responses varied by stressor type, stressor interactions, and HGM subclass. Therefore, perhaps the next step in formulating broad generalizations and predictions about wetland plant community composition will require a shift from species-based approaches to a trait-based approach for examining how species composition may change in response to future disturbances.

The goal of this study was to identify and characterize the range of variation in riparian forests across Lower Michigan, USA as a basis for assessing the utility of map-based information in the characterization of riparian environments. We obtained a regional sample of riparian forests and valley-bottom physiography from 94 locations throughout Lower Michigan and distinguished seven major riparian forest types using hierarchical clustering and NMDS ordination. NMDS ordination distances accounted for more than 70% of the distances in species space and achieved excellent discrimination among riparian types. We then evaluated a set of map-based variables indicative of regional climate, catchment hydrology, and valley character relative to ordination axes and interpretations of the autecology of principal tree species from each forest group. Map-based predictors accounted for 83% of the variation in sample scores along NMDS Axis 1 and explained 42% of the variation in Axis 2. Species and riparian types varied along two principal gradients, one associated with climate and geology along a north-south gradient, the second associated with flood duration and power. Map-based interpretations of regional climate and hydroperiod dynamics agreed closely with species-based interpretations of riparian character, although in certain cases, a similar biotic response arose from apparently distinct hydrogeomorphic contexts. Such dynamic patterns underscore the need for better and more explicit linkages between the controls of riparian hydrology and more proximal physical cues on biotic communities in order to understand the drivers of spatial variation in riparian ecosystem structure and composition.

Analogous to ‘seed banks,’ ‘egg banks’ are important for seasonal succession and maintenance of invertebrate species diversity throughout wet and dry cycles in the prairie pothole region. Further, recruitment of invertebrates from relic egg banks in the sediments and dispersal of eggs into wetlands is believed to be important for reestablishment of invertebrates in recently restored wetlands. Alhough tens-of-thousands of wetlands have been restored in the prairie pothole region of the United States, studies have not been conducted to evaluate the recovery of invertebrate egg banks in restored wetlands. We used taxon richness and abundance as indicators of potential egg bank recovery and compared these parameters in restored wetlands to those of non-drained and drained wetlands with a history of cultivation and also to reference wetlands with no history of cultivation. We found few significant differences among wetland categories within three physiographic regions (Glaciated Plains, Missouri Coteau, and Prairie Coteau). Most statistical comparisons indicated that restored wetlands had invertebrate egg banks similar to reference, non-drained, and drained wetlands. The one exception was drained seasonal wetlands in the Glaciated Plains, which had significantly lower taxon richness and invertebrate abundance than the other wetland categories. Trends did suggest that invertebrate egg bank taxon richness and abundance are increasing in restored seasonal wetlands relative to their drained analogues, whereas a similar trend was not observed for restored semi-permanent wetlands. Although recovery was not related to years since restoration, comparisons of restored wetlands with reference wetlands suggest that recovery potential may be inversely related to the extent of wetland drainage and intensive agriculture that varies spatially in the prairie pothole region. Our research suggests that periodic drawdowns of semi-permanent restored wetlands may be needed to promote production and development of invertebrate egg banks. Inoculation of restored wetlands may also be needed in areas where extensive wetland drainage has resulted in fewer wetland habitats to provide sources of passively dispersed eggs to newly restored wetlands.

Nutrient (e.g., phosphorus) retention is an important function of wetlands that can improve water quality. We examined soil physical and chemical characteristics and phosphorus (P) sorption capacities in three recently restored herbaceous wetlands (RWs) on previously cultivated soils and three adjacent natural forested wetlands (NWs) on Kent Island, Maryland, USA. Our objective was to compare P retention in these two wetland types. As hypothesized, NW soils differed fundamentally in soil chemistry and had significantly higher total organic carbon (TOC) contents than RW soils (5.7 ± 1.7% vs. 1.2 ± 0.1%, respectively, p < 0.05). A number of soil properties (bulk density, pH, labile organic and microbial P, total N, and total N: total P ratios) differed between natural and restored wetlands, as expected from the differences in TOC. Concentrations of pyrophosphate-extractable (organically-bound) Al (Al_p) were an order of magnitude larger in NW than in RW soils (2099.1 ± 365.5 vs. 767.0 ± 194.7 kg/ha, respectively). Although past studies have suggested that higher concentrations of organically-bound Al can enhance P sorption, P-sorption capacities were significantly greater in the RW soils, likely due to differences in soil chemistry. In the RWs, 15 soil chemical parameters were significantly correlated with P sorption (based on single factor regression), including residual Al, oxalate-extractable Al and Fe, clay, HCl-extractable Fe and pyrophosphate-extractable Fe (r² = 0.90, 0.89, 0.87, 0.85, 0.83 and 0.82, respectively). In contrast, P sorption in the NWs was correlated only with Al_p (r² = 0.68). As restored wetland soils are likely in transition from a non-hydric to a hydric state, they should be reevaluated periodically to determine the ultimate effects of this transition on their capacity to retain P.

This study describes the macrophyte assemblages of temporary floodplain wetlands situated on the floodplain of the Murray River, southeast Australia. Wetlands in the study are subject to flooding, the frequency, duration, and magnitude of which are dictated by the current, regulated river-flow regime. Our aim was to examine the influence of the existing flooding regime on macrophyte assemblages and to trial a monitoring program, based on a multiple before-after-control-impact (MBACI) design, to detect the impact of proposed environmental water allocations (EWAs) on the wetlands. Two categories of flooding regime were identified based on the flow magnitudes required for flooding to occur (flooding thresholds). In this scheme, wetlands with relatively low flooding thresholds are classed as ‘impact’ and those with higher thresholds are classed as ‘control.’ The wetlands were surveyed over a two-year period that incorporated at least one wetting-drying cycle at all wetlands. Results showed significant differences between survey times (season and year), but differences between flooding regime categories were significant only for some components of macrophyte assemblages. Differences between survey dates appear to reflect largely short-term responses to the most recent flood events. However, macrophyte differences observed between control and impact wetlands reflected the cumulative effect of flood events over several years. Differences between control and impact wetlands were strongest for post-flooding surveys based on full assemblages (using ANOSIM) and among specific taxa and functional groups (using ANOVA). Power to detect differences between control and impact wetlands was greatest for species richness and total abundance, but taxa with low variability among wetlands, and hence good power, were actually less sensitive to hydrologic change. We conclude that the MBACI design used in this study will be most effective in detecting wetland ecosystem responses to the implementation of EWAs if response variables are carefully chosen based on their sensitivity to hydrologic change.

Bacteria should be excellent indicators of the early signs of degradation caused by human intervention because they have the highest surface area to volume ratio of all organisms. We determined the utility of a simple procedure that measures aerobic bacterial metabolic diversity (BIOLOG EcoPlates) as a reliable tool for assessing the effects of cattle grazing on spring ecosystems of the Bonneville Basin, Utah, USA. Marshes disturbed by cattle could be distinguished from protected marshes using EcoPlate analyses. The diversity of organic compounds used by bacteria was greater in grazed versus ungrazed marshes. A separate genetic analysis (DGGE) provided corroborating evidence. Greater metabolic diversity (EcoPlates) corresponded to greater bacterial assemblage diversity in grazed versus protected marshes. Greater plant diversity at grazed sites might account for the greater diversity of organic substrates used by bacteria in grazed sites. However, the results were not conclusive. In some marshes, a greater diversity of organic substrate use occurred where there was greater plant diversity, whereas in other marshes the diversity of organic substrates used by bacteria was lower where plant diversity was greatest. Regardless of the mechanism, aerobic bacterial metabolic diversity (EcoPlates) is a potentially valuable tool for assessing the early signs of degradation in wetland ecosystems.

The major objective of this research is to determine whether pollution trends could be reconstructed from sediment records at the downstream wetlands of the Huolin River. Sediment cores, representing a range of watershed characteristics and anthropogenic impacts, were collected from two marshes at the Xianghai Wetlands in order to trace the historical variation of heavy metals, accumulation rates, and chemical forms. Cores were ²¹⁰Pb- and ¹³⁷Cs-dated, and these data were used to calculate sedimentation rates and sediment accumulation rates that were compared with environmental change. Ranges of dry mass accumulation rates and sedimentation rates were 0.27–0.96g/ cm² /yr and 0.27–0.90 cm/yr. After normalization to Al, the anthropogenic enrichment of Cu, Zn, Cr, and Pb occurred in the upper layer of sediments and indicated that heavy metal contamination coming from the hydrologic inputs primarily occurred after the 1980s. This result was consistent with two decades of surface coal-mining history within the upstream region of Huolin River. Sediment inputs of most heavy metals at Xianghai Wetlands began to increase over background levels at around 1885 and were generally consistent with the time of the Qing Dynasty's immigration settlement. The anthropogenic inputs of Cu, Zn, Fe, Mn, Cr, and Pb have been 1.20–3.67 times greater than values of their natural inputs after the 1980s, which may be a result of increased input of heavy metal-rich alluvial deposits derived from surface coal-mining activities in the watershed. Sequential extraction was used to describe partitioning of heavy metals among different mineralogical components in sediments, and results showed that heavy metals in sediment cores were mostly associated with the lithogenic bonding forms (residual fraction) and least with the exchangeable fraction (except Pb). The major fraction of Pb was in the Fe-Mn oxide fraction (mean: 40.7–48.6%), indicating that Pb in these sediments had greater mobility and suggested that it might be primarily from anthropogenic sources.

The delta of the Paraná River in Argentina forms islands as it progrades into the Rio de la Plata estuary. In order to understand plant succession patterns, we analyzed cover-abundance and soil data along transects across topographic gradients of three islands. Using multivariate classification (TWINSPAN) and ordination (DCA and CCA), we developed a conceptual model of plant succession for these islands. The general pattern is that the bulrush, Schoenoplectus californicus, first colonizes bars and incipient islands that eventually accumulate sediments to become mature islands with levees dominated by the tree, Erythrina crista-galli, and interior emergent marshes at lower elevations also dominated by a bulrush, Scirpus giganteus. In contrast to earlier descriptions of a unique pathway of primary succession, we used elevation gradients, sediment composition, and inferred hydrologic regime to differentiate two major pathways of species colonization and persistence. During levee formation, colonization of high-energy environments by the bulrush leads to replacement by a mixture of forbs, and finally by a E. crista-galli forest. It is possible that further enrichment of the forest with other tree species is now obscured by Salicaceae plantations (Salix spp. and Populus spp.). Levee formation isolates the interior of islands hydrologically. There, nearly permanent flooding and lack of flushing allow dominance by S. giganteus. The persistence of this species is evidenced by its recovery after fire and its reestablishment after Salicaceae plantations are abandoned. It is noteworthy that two bulrush, S. californicus and S. giganteus, form the simplest stands in terms of richness and structure at highest and lowest energy environments, respectively. At any given site, species composition appears to respond to changes in topographic position, hydrologic regime, and sediment composition.

Wetlands are considered multi-functional ecosystems with important protection and use functions. However, before the 1980s, wetlands in the middle reaches of the Yangtze River, China were mainly reclaimed as paddy fields. In wetland restoration since 1998, there has been an urgent need to develop ecological industry substitutes that are economically efficient while having no negative effects on wetland ecology. Based on the research projects conducted in this region, five industry options were recommended, including 1) growing hydrophytes with high economic value, 2) raising livestock on the seasonal grasslands, 3) planting commercial seasonal vegetables, 4) developing aquaculture in the low-lying paddy fields, and 5) ecological tourism. Policies promoting these industries were aimed at solving problems concerning 1) input shortages and local farmers' unfamiliarity with required agricultural technologies and 2) integrated use of the regional ecological environment with wildlife protection.

Freshwater reclaimed marshes along the European Atlantic coast are highly suitable for European eels (Anguilla anguilla). However, European eel stocks have declined, and the coastal marshes have been subjected to major disturbances. The objective of our study was to analyze the processes governing patterns of European eel microhabitat distribution of four eel size classes (from <160 mm to >360 mm) in a reclaimed marsh (France). Analyses were conducted using artificial neural network (ANN) techniques and ecological profiles. Our ANN results showed that eel densities were significantly related to three major influencing variables: the width of ditch section, the silt depth, and the density of emergent plants. Such ecological profiles were significantly different between small (<240 mm) and large eels (>360 mm): small eels were more widespread than large eels. Large eels were absent or at low densities in shallow ditches with a high aquatic plant cover obstructing the water column and a large quantity of silt. These characteristics seem to define the ditches not directly connected with the main river where dredging operations were rare. Management of regular dredging operations in the channels by maintaining a mosaic of permanent aquatic habitats and avoiding the heavy silt loads in most ditches should be promoted. This dredging operation was probably one of the most promising ways for restoring inland eel stocks.

Anthropogenic habitat alterations and water-management practices have imposed an artificial spatial scale onto the once contiguous freshwater marshes of the Florida Everglades. To gain insight into how these changes may affect biotic communities, we examined whether variation in the abundance and community structure of large fishes (SL > 8 cm) in Everglades marshes varied more at regional or intra-regional scales, and whether this variation was related to hydroperiod, water depth, floating mat volume, and vegetation density. From October 1997 to October 2002, we used an airboat electrofisher to sample large fishes at sites within three regions of the Everglades. Each of these regions is subject to unique water-management schedules. Dry-down events (water depth < 10 cm) occurred at several sites during spring in 1999, 2000, 2001, and 2002. The 2001 dry-down event was the most severe and widespread. Abundance of several fishes decreased significantly through time, and the number of days post-dry-down covaried significantly with abundance for several species. Processes operating at the regional scale appear to play important roles in regulating large fishes. The most pronounced patterns in abundance and community structure occurred at the regional scale, and the effect size for region was greater than the effect size for sites nested within region for abundance of all species combined, all predators combined, and each of the seven most abundant species. Non-metric multi-dimensional scaling revealed distinct groupings of sites corresponding to the three regions. We also found significant variation in community structure through time that correlated with the number of days post-dry-down. Our results suggest that hydroperiod and water management at the regional scale influence large fish communities of Everglades marshes.

Nearly all the techniques used to quantify how plants are linked to environmental gradients produce results in general terms, such as low to high elevation, xeric to mesic, and low to high concentration. While ecologists comprehend these imprecise scales, managers responsible for making decisions affecting these gradients need more precise information. For our study, we preserved the measurement scale and units of a dominant environmental gradient by using non-linear models to fit plant frequency to a water-level gradient ranging from shallow ground water to standing water along the Platte River in central Nebraska, USA. Non-linear models, unlike polynomials, have coefficients that can be interpreted with a biological meaning such as population peak, optimum gradient position, and ecological amplitude. Sixty-three riparian grassland species had sufficient information to link their plant frequency to the water-level gradient. From among 10 water-level summary statistics evaluated for a subset of 22 species, the best plant-frequency response curves were obtained by using the growing season 10% cumulative frequency water level, followed closely by the growing season 7-day moving average high water level and two other high water-level statistics. This suggests that for Platte River riparian grasslands, high water levels are more influential than mean, median, or low water levels. Land-management practices (i.e., grazing, haying, and extended rest) affected six species by a change in frequency or a shift in position along the water-level gradient. Four general plant communities composed of species responding individually to the water-level gradient and other factors were identified for Platte River riparian grasslands: emergent, sedge meadow, mesic prairie, and dry ridge. Plant response curves are the first step toward predicting how plants responding to riparian-grassland water levels might also respond to river management.

Emergence traps were used to sample insects along a transect through a river delta wetland on Green Bay, Lake Michigan in an attempt to document spatial and temporal patterns in insect emergence. Various abiotic factors were also measured to determine which factors influenced these dynamics. Significant decreasing gradients in dissolved oxygen and pH with distance from the river, coupled with trends in sum nitrate (nitrate nitrite), revealed that riverine water was mixing with wetland water up to 100 m from the wetland-river interface. Annual emerging insect densities decreased exponentially with distance from the river while emerging insect biomass decreased linearly with distance, both of which were significant. Insects were largely comprised of Chironomidae, which represented 7–88% of the insects emerging. Loss of biomass was largely due to emergence of Aeshnidae (0–34%), Libellulidae (0–69%), Coenagrionidae (0–23%), Siphlonuridae (0–63%), and Chironomidae (1–25%). Major Chironomidae emergence events occurred from early spring until early summer and again from late summer to early fall. These events were likely an important source of energy needed for avian egg production, duckling growth, or migratory flights. Spatial and temporal patterns revealed the importance of wetland areas adjacent to the Peshtigo River to emerging insects, as well as to the transient organisms that use them as a food source.

Kushiro wetland in northeastern Japan is a Ramsar-designated wetland of international importance (1980) that is characterized by high biodiversity and spatial heterogeneity. These characteristics of the wetland also present innumerable challenges for mapping and monitoring such unique ecosystems. Recent advances in remote sensing technology have provided many sensors with different spatial and spectral scales and resolutions. However, they are still inadequate for mapping wetland vegetation at a large scale for various reasons, such as inadequate resolution and high costs. This study was designed to evaluate the potential of balloon aerial photography to acquire high resolution (15 cm pixel size) imagery for mapping wetland vegetation in the Akanuma marsh. We used a standard 28-mm non-metric camera (Nikon-F-801), which was mounted on helium-filled balloons operated by a remote radio-controlled system. By creating digital vegetation maps from visual interpretation of mosaicked photos, ten general types of vegetation and twenty-seven specific categories (species mixes) were successfully delineated. It was possible to classify small shrubs mixed with herbaceous plants; moss bogs with pools; dwarf shrubs with sedges; and moss with alpine plants. From this research, it seems that balloon aerial photography is a powerful tool for mapping temperate wetland vegetation, allowing classification of specific and typical vegetation types to the genus and species level.

Lythrum salicaria (purple loosestrife) is an invasive wetland perennial in North America native to Eurasia. Because light environment may limit the species' distribution, information on the relationship of forest canopy coverage to relative height and seed set in its native environment could give insight into its control in North America. This study examined the effect of various light environments related to forest canopy structure on seed set and stem height in L. salicaria in three biogeographical regions of Turkey spanning latitudes from 36 to 39° N. In Turkey, Lythrum salicaria grows in discrete patches in the canopy gaps of riverine forests, which often are dominated by Populus alba. The mean number of seeds per individual and stem height increased with decreasing canopy coverage (10437 ± 284 to 20652 ± 664 seeds individual⁻¹ and 116 ± 2 to 173 ± 2 cm, respectively). A number of insect seed herbivores were noted on these Turkish populations, most notably a seed predator (Nanophyes marmoratus), which destroyed all seeds in infested capsules. Our study suggested that the light characteristics associated with canopy gaps influenced the seed set and height of L. salicaria. Other factors likely played a role, such as insect herbivores, soil fertility, and competition with other species, which may also be affected by the light levels provided at various levels of canopy coverage.