Above-ground biomass estimation based on NPP time-series − A novel approach for biomass estimation in semi-arid Kazakhstan

Biomass is a sensitive indicator of environmental change and ecological functioning. Quantification of biomass is essential to identify and monitor those areas threatened by degradation and desertification. This is especially important in arid and semi-arid environments. However, robust techniques to monitor carbon stocks over large areas and through time are still missing. The major objective of the presented study is to develop a novel approach for biomass estimation in semi-arid environments using remote-sensing based Net Primary Productivity (NPP) data.The developed methodical concept aims at derivation of above-ground grass and shrub biomass for natural environments. It is based on NPP time-series and plants’ relative growth rates. Fractional cover data provide information about grass and shrub coverage. The developed approach has been applied to three study areas in Kazakhstan, in which field data were collected for validation.Biomass maps were derived that show the spatial distribution of grass and shrub biomass. Validation revealed a moderate correlation (R = 0.68) with field data for grass biomass. For shrub biomass, a high correlation (R = 0.83) is retrieved when fractional cover information from field observations is used.The presented novel approach for biomass estimation is based on remote sensing derived NPP time-series and is thus potentially transferable in space and time. This is a great advantage compared to commonly applied empirical relationships. The presented concept can be adapted to be applied to other vegetation communities. Providing the necessary data about fractional vegetation cover is available, the method will allow for repeated and large-area biomass estimation for natural semi-arid environments as needed for observing changes in biomass and support sustainable land management.     

Understory cover and biomass indices predictions for forest ecosystems of the Northwestern United States

The understory community is a critical component of many processes of forest ecosystems. Cover and biomass indices of shrubs and herbs of forested ecosystems of Northwestern United States are presented. Various forest data were recorded for 10,895 plots during a Current Vegetation Survey, over the National Forest lands of entire Pacific Northwest. No significant relationships between the percent canopy cover and understory percent cover and biomass indices were found for the 129 ecoclasses analyzed. Disturbance time and type, and the soil characteristics significantly influenced the shrub biomass indices (p-values of <0.001, <0.001, and 0.01, respectively). Only disturbance time and type significantly influenced the shrub percent cover (p-values <0.001). There were no significant interactions between these variables. No significant differences were found for herb biomass indices and cover. Climate variables are reasonable predictors of understory cover and biomass indices. Elevation and slope are also influential: understory cover decreases with altitude, while understory biomass increases with slope. Most models showed weak predictive power (adjusted R-squared ≤ 0.27). However, robust models for the maximum/potential understory biomass indices for the forested areas in the Northwestern United States are reported (adjusted R-squared of 0.76 and 0.51 for shrubs and herbs, respectively). Overall, our study provides conceptual and statistical models for the understory of the National Forest lands of the Pacific Northwest. The results are comparable with other models for the area, suggesting that the predictions regarding understory vegetation are inherently difficult.     

Estimating biomass and carbon mitigation of temperate coniferous forests using spectral modeling and field inventory data

Realizing the importance of forest carbon monitoring and reporting in climate change, the present study was conducted to derive spectrally modeled aboveground biomass and mitigation using Landsat data in combination with sampled field inventory data in the coniferous forests of Western Himalaya. After conducting preliminary survey in 2009, 90 quadrats (45 each for calibration and validation) of 0.1 ha were laid in six forest types for recording field inventory data viz. diameter at breast height, height, slope and aspect. Biomass carbon (Mg ha^− 1) was worked out for different forest types and crown density classes (open with 10–40% crown density and closed with > 40% crown density) using recommended volume equations, ratios and factors. Biomass carbon map (aboveground + belowground) was generated for the entire region using geospatial techniques. Normalized difference vegetation index (NDVI) was generated and spectral values were extracted to establish relation (R² = 0.72, p < 0.01) with the field inventory data. The model developed was validated (R² = 0.73, p < 0.01) with 45 sample observations not used earlier for predicting and generating biomass carbon map (2009) for the entire region. The data from field based inventory indicates highest total biomass carbon (171.40, σ ± 23.19) Mg ha^− 1 for Fir–Spruce (closed) which has relatively more mature girth classes and low tree density. This value was found to be significantly higher than other forest types. Lowest biomass carbon was observed for Blue Pine (open) (37.15, σ ± 11.82) Mg ha^− 1. The NDVI values for the entire region ranged from 0 to 0.62 and consequently the spectrally derived aboveground biomass carbon varied from 0 to 600 Mg ha^− 1. The study demonstrates the application of mapping, spectral responses and sampled field inventory for type wise assessment of carbon mitigation in temperate coniferous forests of Himalayas.     

Burial depth and diameter of the rhizome fragments affect the regenerative capacity of a clonal shrub

Clonal plants in highly disturbed habitats are often broken into small fragments of various sizes and buried at various soil depths. As a storage organ, rhizome fragments play an important role in enabling plants to survive in such habitats. But few studies have been concerned about the regenerative capacity of rhizome fragments of clonal shrubs of different rhizome diameter and at different burial depths. Here, we investigated whether deeper burial decreased, and diameter of the rhizome fragment increased, the regenerative capacity of a clonal shrub. Research samples of rhizome fragment (rhizome diameters of 2, 5, 10, 15, and 20 mm) of the clonal shrub Calligonum arborescens were buried at different depths (0, 1, 5, 10, and 20 cm). Increasing the diameter of the rhizome fragments significantly increased the survival rate of fragments, and increased the above-ground, below-ground and total biomass production of fragments. Vegetative reproduction ability also increased with an increase in diameter of the rhizome fragments. With an increase in sand burial depth, above-ground, below-ground, total biomass production and vegetative reproduction ability first decreased and then increased, and no fragments survived at the 0 cm burial depth. These results indicate that sand burial depth and diameter of the rhizome fragments significantly affected the regeneration capacity of C. arborescens. Sand burial is one of the essential prerequisites for C. arborescens rhizome fragments’ survival. Moderate burial depth (5 cm) and larger fragment diameter (20 mm diameter) were more suitable for biomass production and vegetative reproduction. These results indicate that reserves stored in rhizome fragments can contribute greatly to the regeneration capacity of the C. arborescens—responses that are very important for C. arborescens survival and establishment in frequently disturbed habitats.     

Frugivorous birds visit fruits of emerging alien shrub species more frequently than those of native shrub species in the South African Mediterranean climate region

We compared daily visitation frequency indices by 4 large (> 150 g), 7 medium-size (50–150 g), 5 small (30–50 g) and 8 and tiny (< 30 g) frugivorous bird species on fleshy fruits of two native shrubs (Olea europaea subsp. africana and Chrysanthemoides monilifera subsp. monilifera), two established alien shrubs (Solanum mauritianum and Lantana camara) and two emerging alien shrubs (Myoporum tenuifolium and Pittosporum undulatum) at nine different sites in the Cape Floristic Region. Large, medium-size and tiny birds as groups displayed significantly higher visitation frequency indices on fruits of both emerging alien shrub species than the other shrub species. Small birds as a group displayed insignificantly different visitation frequency indices on fruits of both emerging and established alien shrub species but significantly higher visitation frequency indices on fruits of both emerging and established alien shrub species than on fruits of the native shrub species. However, there were significant differences in foraging frequency indices of the bird species included within each of these body size groups on fruits of the different shrub species. Among the large birds, Columba guinea and among the medium size birds Sturnus vulgaris, Streptopelia senegalensis, Turdus olivaceus and Onychognathus morio all exhibited significantly higher visitation frequency indices on fruits of both emerging alien shrub species than on fruits of the other shrub species. These findings indicate that alien plant control measures should be focused on eradicating localised populations of emerging aliens to limit preferential consumption of their fruits by birds and consequent dispersal of their seeds that germinate readily into natural areas.     

Grazing-induced morphological and growth rate changes in Anarthrophyllum rigidum,a Patagonian leguminous shrub

Grazing influences the morphology and growth rate of shrubs, and consequently, their population dynamics. It has been shown that grazing directly affects the growth of shrubs. On the other hand, the reduction of grass biomass by herbivores reduces soil–water competition between grasses and shrubs, and indirectly, could enhance the growth of shrubs. However, the assessment of the long-term effects of grazing on the growth of shrubs in the arid Patagonia has been hampered by the lack of long and homogeneous records of plant population dynamics and primary production. In this study, we combined growth-ring and allometric analyses to assess the long-term effect of grazing on individuals of Anarthrophyllum rigidum, a leguminous shrub widely distributed across the Patagonian steppe. A. rigidum has evergreen leaves rich in proteins that constitute an important complement to the diet of sheep, particularly in winter when the abundance of grasses is reduced. Our observations indicate that individuals of A. rigidum nearby the water source used by livestock were smaller in size (35.5 cm vs. 67.39 cm), presented a larger number of basal branches (23 vs. 12), and showed slower rates of growth (8.2 mm year^?1 vs. 14.3 mm year^?1) than individuals located far from the water source. This first quantification of the long-term effects of grazing on A. rigidum in the dry Patagonian steppe suggests that beneficial effects of grazing through the reduction of grasses that compete with shrubs for soil–water should be more obvious for livestock non-preferred than preferred shrubs     

Removal of total nitrogen by Cyperus alternifolius from wastewaters in simulated vertical-flow constructed wetlands

The vertical-flow constructed wetland (VFCW) is a promising engineering technique for removal of excess nutrients and certain pollutants from wastewaters. This study investigated the uptake and removal of total nitrogen (TN) by Cyperus alternifolius from domestic wastewaters in simulated VFCWs. A total of eight simulated VFCW treatments, including two different substrates, two different wet-to-dry ratios, and with and without C. alternifolius species (2 × 2 × 2 = 8), were employed for an operation period of 2 years in this study. Results show that more TN was removed from the influent with the presence of C. alternifolius compared to without this plant species. A linear correlation existed between the aboveground biomass and its TN content. An increase in total biomass by 100 g resulted in an increase in TN accumulation in the aboveground biomass by 2.4 g. Large amounts of TN were removed by the aboveground biomass compared to those by substrate adsorption. Results suggest that C. alternifolius played a discernable role in removal of TN from wastewaters in the simulated VFCWs.     

Forest biomass and volume estimation using airborne LiDAR in a cool-temperate forest of northern Hokkaido,Japan

Trees are recognized as a carbon reservoir, and precise and convenient methods for forest biomass estimation are required for adequate carbon management. Airborne light detection and ranging (LiDAR) is considered to be one of the solutions for large-scale forest biomass evaluation. To clarify the relationship between mean canopy height determined by airborne LiDAR and forest timber volume and biomass of cool-temperate forests in northern Hokkaido, Japan, we conducted LiDAR observations covering the total area of the Teshio Experimental Forest (225 km²) of Hokkaido University and compared the results with ground surveys and previous studies. Timber volume and aboveground tree carbon content of the studied forest stands ranged from 101.43 to 480.40 m³ ha^–1 and from 30.78 to 180.54 MgC ha^–1, respectively. The LiDAR mean canopy height explained the variation among stands well (volume: r² = 0.80, RMSE = 55.04 m³ ha^–1; aboveground tree carbon content: r² = 0.78, RMSE = 19.10 MgC ha^–1) when one simple linear regression equation was used for all types (hardwood, coniferous, and mixed) of forest stands. The determination of a regression equation for each forest type did not improve the prediction power for hardwood (volume: r² = 0.84, RMSE = 62.66 m³ ha^–1; aboveground tree carbon content: r² = 0.76, RMSE = 27.05 MgC ha^–1) or coniferous forests (volume: r² = 0.75, RMSE = 51.07 m³ ha^–1; aboveground tree carbon content: r² = 0.58, RMSE = 19.00 MgC ha^–1). Thus, the combined regression equation that includes three forest types appears to be adequate for practical application to large-scale forest biomass estimation.     

Effects of plant diversity on biomass production and substrate nitrogen in a subsurface vertical flow constructed wetland

Most biodiversity experiments have been conducted in grassland ecosystems with nitrogen limitation, while little research has been conducted on relationships between plant biomass production, substrate nitrogen retention and plant diversity in wetlands with continuous nitrogen supply. We conducted a plant diversity experiment in a subsurface vertical flow constructed wetland for treating domestic wastewater in southeastern China. Plant aboveground biomass production ranged from 20 to 3121 g m^?2 yr^?1 across all plant communities. In general, plant biomass production was positively correlated with species richness (P = 0.001) and functional group richness (P = 0.001). Substrate nitrate concentration increased significantly with increasing plant species richness (P = 0.046), but not with functional group richness (P = 0.550). Furthermore, legumes did not affect biomass production (P = 0.255), retention of substrate nitrate (P = 0.280) and ammonium (P = 0.269). Compared to the most productive of the corresponding monocultures, transgressive overyielding of mixed plant communities did not occur in most polycultures. Because greater diversity of plant community led to higher biomass production and substrate nitrogen retention, thus we recommend that plant biodiversity should be incorporated in constructed wetlands to improve wastewater treatment efficiency.     

Utilization of ground-based digital photography for the evaluation of seasonal changes in the aboveground green biomass and foliage phenology in a grassland ecosystem

We investigated the usefulness of a ground-based digital photography to evaluate seasonal changes in the aboveground green biomass and foliage phenology in a short-grass grassland in Japan. For ground-truthing purposes, the ecological variables of aboveground green biomass and spectral reflectance of aboveground plant parts were also measured monthly. Seasonal change in a camera-based index (rG: ratio of green channel) reflected the characteristic events of the foliage phenology such as the leaf-flush and leaf senescence. In addition, the seasonal pattern of the rG was similar to that of the aboveground green biomass throughout the year. Moreover, there was a positive linear relationship between rG and aboveground green biomass (R² = 0.81, p < 0.05), as was the case with spectra-based vegetation indices. On the basis of these results, we conclude that continuous observation using digital cameras is a useful tool that is less labor intensive than conventional methods for estimating aboveground green biomass and monitoring foliage phenology in short-grass grasslands in Japan.     

Environmental driving factors affecting plant biomass in natural grassland in the Loess Plateau,China

Plant biomass is a key parameter for estimating terrestrial ecosystem carbon (C) stocks, which varies greatly as a result of specific environmental conditions. Here, we tested environmental driving factors affecting plant biomass in natural grassland in the Loess Plateau, China. We found that above-ground biomass (AGB) and below-ground biomass (BGB) had a similar change trend in the order of Stipa bungeana > Leymus secalinus > Artemisia sacrorum > Artemisia scoparia, whereas shoot ratio (R/S) displayed an opposite change trend. There was a significantly positive linear relationship between the AGB and BGB, regardless of plant species (p < 0.05). Furthermore, more than 50% of the AGB were found in 20–50 cm of plant height in Compositae plants (A. sacrorum, A. scoparia), whereas over 60% of the AGB were found in 20–80 cm of plant height in Gramineae plants (S. bungeana, L. secalinus). For each plant species, more than 75% of the BGB was distributed in 0–10 cm soil depth, and 20% was distributed in 10–20 cm soil depth, while less than 5% was distributed in 20–40 cm soil depth. Further, AGB and BGB were highly affected by environmental driving factors (soil properties, plant traits, topographic properties), which were identified by the structural equation model (SEM) and the generalized additive models (GAMs). In addition, AGB was directly affected by plant traits, and BGB was directly affected by soil properties, and soil properties associated with plant traits that affected AGB and BGB through interactive effects were 9.12% and 3.59%, respectively. However, topographic properties had a weak influence on ABG and BGB (as revealed by the lowest total pathway effect). Besides, soil organic carbon (SOC), soil microbial biomass carbon (MBC), and plant height had a higher relative contribution to AGB and BGB. Our results indicate that environmental driving factors affect plant biomass in natural grassland in the Loess Plateau.     

Trace elements in Phragmites australis growing in constructed wetlands for treatment of municipal wastewater

Biomass of Phragmites australis growing in four constructed wetlands with horizontal sub-surface flow (HF CWs) designed for treatment of municipal sewage in the Czech Republic have been analyzed for 19 trace elements. The biomass was harvested during the peak standing crop in early September and divided into stems, leaves, flowers, roots and rhizomes. Concentrations of monitored elements in both aboveground and belowground plant tissues were similar to those found in plants growing in natural stands. The highest concentrations were recorded for Al, Fe, Mn, Ba and Zn while the lowest concentrations were those of Hg, U and Cd. Concentrations decreased in the order of roots > rhizomes > leaves > stems. The root/leaf ratio averaged 70 and varied between 1.4 for molybdenum and 392 for cobalt. The belowground/aboveground concentration ratio ranged between 0.9 and 69.5 with an average value of 19. Due to average aboveground/belowground biomass ratio > 1, the belowground/aboveground standing stock ratios were lower with six elements (Ba, Zn, Se, Hg, Mo, and Mn) having this ratio < 1.     

Morphological variations,biomass and ion accumulation of the aboveground shoots of Desmostachya bipinnata (L.) Stapf

The present study aimed to evaluate the morphological characteristics and biomass of Desmostachya bipinnata and their relation to the environmental variables in three main habitats (canal banks, railway and roadside shoulders) where it is found in Egypt. In addition, the ability of this plant is evaluated to accumulate nutrients and heavy metals in its aboveground shoots. Twenty five quadrats (1 m × 1 m per quadrat) were selected along five sites representing the different habitats of D. bipinnata for this study. The aboveground shoots displayed considerable morphological variations, differing in the different habitats. The above ground biomass, number of spikes and leaves, rachis length and diameter, leaf length, width and area, leaf sheath length, and spike length and diameter were in the order: road sides > canal banks > railway shoulders. A regression equation: biomass = (67.37 × density) + 108.2, was used to estimate the shoot biomass from the plant growth density. Metal uptake capability from soil to grass is in the order Fe > Zn > Cu > Mn, and all of them are in safe concentration ranges. These heavy metals had a transfer factor more than unity, which indicates that D. bipinnata is a powerful accumulator for heavy metals. In addition, the plant shoots exhibit high accumulation of inorganic and organic nutrients.     

Growth responses of Zostera capricorni to estuarine sediment conditions

This study comprised (1) a field survey of intertidal seagrass (Zostera capricorni) biomass, cover and photosynthetic potential and sediment characteristics at a range of contrasting sites in three New Zealand harbours, and (2) a microcosm experiment comparing plant responses to sediments from extant versus historical seagrass sites. The field survey showed that the sediment physico-chemical characteristics were generally consistent with the limited previous reports for Zostera environments, although the total P concentration range was higher (0.08–0.72 mg P g⁻¹). Overall, 52% of variation in seagrass cover was explained by sediment water content (R = 0.54) and organic content (R = −0.56). Twenty-two percent of variation in seagrass biomass was explained by sediment total P and redox potential (both R = −0.35). Intra-harbour seagrass–sediment relationships were more significant (explaining up to 82% of plant variation) but harbour-specific. In the microcosm experiment, threefold higher Z. capricorni biomass was maintained on extant than historical sediments but not conclusively linked to measure sediment characteristics. Overall, the results of this study demonstrate that significant relations can exist between estuarine sediment conditions and Z. capricorni growth responses, and suggest that detrimental change in sediment conditions may be a contributing factor in seagrass decline.     

A multivariate analysis integrating ecological,socioeconomic and physical characteristics to investigate urban forest cover and plant diversity in Beijing,China

Understanding the factors driving the variation in urban green space and plant communities in heterogeneous urban landscapes is crucial for maintaining biodiversity and important ecosystem services. In this study, we used a combination of field surveys, remote sensing, census data and spatial analysis to investigate the interrelationships among geographical and social-economic variables across 328 different urban structural units (USUs) and how they may influence the distributions of urban forest cover, plant diversity and abundance, within the central urban area of Beijing, China. We found that the urban green space coverage varied substantially across different types of USUs, with higher in agricultural lands (N = 15), parks (N = 46) and lowest in utility zones (N = 36). The amount of urban green space within USUs declines exponentially with the distance to urban center. Our study suggested that geographical, social and economic factors were closely related with each other in urban ecological systems, and have important impacts on urban forest coverage and abundance. The percentage of forest as well as high and low density urban areas were mainly responsible for variations in the data across all USUs and all land use/land cover types, and thus are important constituents and ecological indicators for understanding and modeling urban environment. Herb richness is more strongly correlated with tree and shrub density than with tree and shrub richness (r = −0.472, p < 0.05). However, other geographic and socioeconomic factors showed no significant relationships with urban plant diversity or abundance.     

Potential of restoration and phytoremediation with Juncus roemerianus for diesel-contaminated coastal wetlands

Oil spills may considerably damage sensitive coastal wetlands. In this study, the tolerance limits of a dominant coastal salt marsh plant, Juncus roemerianus, to diesel oil and its phytoremediation effectiveness in wetland environments were investigated in the greenhouse. J. roemerianus was transplanted into salt marsh sediment contaminated with diesel fuel at concentrations of 0, 20, 40, 80, 160, 320, and 640 mg diesel g^?1 dry sediment. Plant stem density, shoot height, aboveground biomass and belowground biomass were detrimentally impacted at high oil dosages even 1 year after transplantation. Tolerance limits were estimated between 160 and 320 mg g^?1 based on various plant variables. Importantly, J. roemerianus enhanced oil degradation; at the 40 mg/g diesel dosage, concentrations of residual total petroleum hydrocarbons (TPH) in the sediment planted with J. roemerianus were significantly lower than those of unplanted sediments 1 year after treatment initiation. Furthermore, concentrations of total targeted polycyclic aromatic hydrocarbons (PAHs) and n-alkanes in the J. roemerianus planted treatment were, respectively, about 3% and 15% of the unplanted treatment. Concentration reduction in all categories of hydrocarbons suggested that J. roemerianus effectively phytoremediated the diesel-contaminated wetlands.     

Growth responses of Zostera capricorni to estuarine sediment conditions

This study comprised (1) a field survey of intertidal seagrass (Zostera capricorni) biomass, cover and photosynthetic potential and sediment characteristics at a range of contrasting sites in three New Zealand harbours, and (2) a microcosm experiment comparing plant responses to sediments from extant versus historical seagrass sites. The field survey showed that the sediment physico-chemical characteristics were generally consistent with the limited previous reports for Zostera environments, although the total P concentration range was higher (0.08–0.72 mg P g⁻¹). Overall, 52% of variation in seagrass cover was explained by sediment water content (R = 0.54) and organic content (R = −0.56). Twenty-two percent of variation in seagrass biomass was explained by sediment total P and redox potential (both R = −0.35). Intra-harbour seagrass–sediment relationships were more significant (explaining up to 82% of plant variation) but harbour-specific. In the microcosm experiment, threefold higher Z. capricorni biomass was maintained on extant than historical sediments but not conclusively linked to measure sediment characteristics. Overall, the results of this study demonstrate that significant relations can exist between estuarine sediment conditions and Z. capricorni growth responses, and suggest that detrimental change in sediment conditions may be a contributing factor in seagrass decline.     

Characteristics in coarse woody debris mediated by forest developmental stage and latest disturbances in a natural secondary forest of Pinus tabulaeformis

Coarse woody debris (CWD) characteristics are expected to reflect forest stand features. Few studies evaluated logging-induced stand characteristics of secondary coniferous forests by quantifying the quality and quantity in CWD. After selective logging, the form of secondary forest of Pinus tabulaeformis in the Qinling Mountains is inferior and the regeneration is poor. We measured the CWD characteristics of the forest which had an average CWD biomass amount of 12.56 t hm⁻², and was predominated by abundant logs (65.68%), followed by snags (33.13%). The CWD biomass of P. tabulaeformis and Toxicodendron vernicifluum was significantly higher than that of other species, which took up 85.51% of the total. Although there was no significant difference among different diameter sizes (P > 0.05), the CWD biomass of diameter 30–40 cm occupied 46.26% of the total (5.81 t hm⁻²). Similarly, the CWD biomass of decay class I and II accounted for 39.89% (5.01 t hm⁻²) and 33.04% (4.15 t hm⁻²) of the total CWD biomass respectively, despite no significant difference among those 5 decay classes (P > 0.05). The results indicated that the combination of young forest developmental stage caused by past selective logging and natural and anthropogenic disturbances such as strong wind, tapping lacquer, firewood collection, and illegal tree felling played a crucial role in distribution characteristics of CWD in this secondary forest of P. tabulaeformis.     

Seasonal variation in short-term survival of Zostera noltii transplants in a declining meadow in Portugal

In one decade (from 1986 to 1997), the area occupied by Zostera noltii in the Mondego estuary (western coast of Portugal) decreased from 150,000 to 200 m². Our purpose was to identify the most suitable season for transplantation of Z. noltii, as one of the methodologies included in a broader restoration plan of the local Z. noltii meadows. Each month a short-term transplantation experiment (20 days) was undertaken, where the net growth rate of transplants, the number of lost shoots and the number of surviving shoots was estimated. Transplant loss variation was markedly seasonal (ANOVA, F_1,12 = 13.11, p < 0.01). From spring to middle autumn (April–October), the amount of lost shoots was significantly higher (average = 63%) than during late autumn and winter (average = 26%). Multiple regression results suggest that the number of surviving shoots was negatively related with insolation and NH₄-N concentration. Additionally, the net growth rate of the transplants was negatively related with salinity.In conclusion, we recommend that at southern European latitudes, Z. noltii transplantation be undertaken during late autumn and winter. The success of transplantation at this time of the year seems to be related with the prevailing external conditions, namely, low temperatures and low photon flux densities. Furthermore, we hypothesise that the proportion of aboveground to belowground biomass in Z. noltii may also influence transplant survival. Transplantation success was higher whenever belowground biomass was higher than aboveground biomass. In the Mondego estuary, in autumn and winter, the belowground biomass of Z. noltii represents about 51% of the total plant biomass, while in spring and summer, this value decreases to 31% of the total biomass.     

Dynamics of Typha latifolia L. populations in treatment wetlands in Estonia

The aim of this paper is to evaluate and compare broadleaved cattail (Typha latifolia L.) biomass production and the nitrogen (N) and phosphorus (P) content in phytomass in three treatment wetland systems and to propose suitable areas for treatment wetlands in Estonia for raw material production. The biomass samples (roots/rhizomes, shoots with leaves and spadixes) and litter were collected from 1 m × 1 m plots—15 plots in the Tänassilma semi-natural wetland, 15 plots in the Põltsamaa free water surface (FWS) constructed wetland (CW), and 10 plots in the Häädemeeste FWS CW. The average aboveground biomass of T. latifolia varied from 0.37 to 1.76 kg DW m^?2 in autumn and from 0.33 to 1.38 kg DW m^?2 in winter. The greatest average nitrogen (22,950 mg N kg^?1) concentration was found in spadixes in 2002, and the phosphorus (6500 mg P kg^?1) concentration was measured in roots–rhizomes in 2003. Average standing stock of nitrogen and phosphorus was higher in aboveground than belowground phytomass. In FWS CWs with high hydraulic and nutrient loadings, however, the harvesting of aboveground biomass is not an effective means for the removal of nutrients. Cattail biomass is a valuable insulation material, whereas the fibre from spadixes mixed with clay gives elasticity to clay plasters. According to our estimates, about 5412 km² could be used for Typha cultivation in Estonia.