Search

We evaluated whether the kind of nutrient limitation (N, P, or K) may affect species richness--productivity patterns and subsequently may explain variation in species richness and in richness of threatened species. We present a data set from previous studies in wetlands in Poland, Belgium, and The Netherlands and examine species richness--productivity patterns for vascular plants in all 150 sites together as well as for N-, P-, and K-limited sites separately. The kind of nutrient limitation was assessed by N:P, N:K, and K:P ratios in the vegetation. Critical values for these ratios were derived from a literature review of fertilization experiments. The kind of nutrient limitation influenced species richness--productivity patterns in our 150 sites through large differences in productivity. P (co)-limitation occurred only at low productivity, K (co)-limitation up to intermediate productivity, and N limitation along the entire productivity gradient. There was a decreasing trend in species richness with increasing productivity for K (co)-limited sites, whereas for both the N-limited sites and P (co)-limited sites a sort of 'filled hump-shaped curve' was observed. The species richness-productivity relationship for threatened species was restricted to a much narrower productivity range than that for all species. Richness of threatened species was higher in P (co)-limited sites than in N-limited sites, suggesting that increased P availabilities in wetlands may be particularly important in causing disappearance of threatened species in western Europe. The role of nutrient limitation in species richness--productivity relationships not only reveals mechanisms that may explain variation in species richness and occurrence of threatened species, but it also may be important for nature management practice. Key words: biodiversity; hump-shaped curve; limiting resources; nutrient limitation; productivity--diversity relationships; species diversity; species richness.

1 We tested whether patterns of species density are controlled not only by variations in community biomass but also by variations in environmental conditions, which may be related or unrelated to community biomass. Environmental variables (soil characteristics, acidity, water regime, nutrient availabilities) were measured in 46 sites in wet meadows and fens, and related to above-ground biomass and to densities of all vascular plants and of threatened species. 2 Both meadows and fens showed a hump-backed species density--biomass relationship, although there was much variability and the study did not include very highly productive sites. In fens a significant quadratic relationship was observed ([R.sup.2] = 0.42). 3 Environmental factors could explain 57% (in meadows) and 40% (in fens) of variation in species density. The majority of the variance explained was attributable to factors that were not related to community biomass (increasing pH in meadows) or the organic soil-mineral soil gradient in fens. 4 Density of threatened species vs. biomass was also consistent with a hump-back curve covering a narrow biomass range. Density of threatened species increased with decreasing P availability, regardless of whether P availability was related to biomass (as in meadows) or not (fens). Key-words: acidity, hydrology, mineralization, nutrient availability, productivity, species richness, species pool, wetland vegetation

SUMMARY (1) Relationships between vegetation composition and nutrient and major ion concentrations in groundwater and peat were examined in 58 stands of fen vegetation in the Biebrza mire, Poland. The 58 stands included rich fens with a large standing biomass, rich fens with lower standing biomass and poor fens. (2) The highly productive rich fen (i.e. rich fen with large standing biomass) receives moderately eutrophic river water. The rheophilous part of the mire that is not, or only occasionally flooded contains gradients from quite productive rich fens to less productive rich fens and poor fens. In this part of the gradient, occasional river flooding appeared to be an important source of K and was probably responsible for the presence of quite productive rich fen vegetation. (3) Upward seepage of calcium-rich and phosphate-poor groundwater keeps phosphate concentration low in the superficial mire water and the peat from the lower productive rich fen. Phosphate concentration is higher in the mire water and the peat from the poor fen which is fed by downward-flowing rainwater. (4) Nitrogen concentration in mire water and peat is only poorly correlated with species composition and vegetation structure.

Investigates the direct effects and effects through community biomass of ferns and meadows. Measurement of environmental variables; Indication of the species density-biomass relationship between meadows and ferns; Consistency of the threatened species density between biomass.

• Abundance of NTFP species was negatively related to woody species richness. • Disproportionately few NTFP species determined >50% of NTFP abundance. • Both taxonomic and structural plant diversity indicators predicted NTFP abundance. • Additional conservation efforts need to include NTFP abundant ecosystems. Despite the importance of non-timber forest products (NTFPs) for local livelihoods in tropical countries and the increasing attention for biodiversity-ecosystem services relationships, it remained unclear how the ecosystem service of NTFP provisioning is related to plant diversity. Although it is generally assumed that plant diversity is positively related to ecosystem services, this had not been assessed for NTFP provisioning. We applied bivariate and multiple regression models to explore the relationships between the abundance of 58 commercially relevant NTFP species and woody plant diversity across 287 plots of tropical forests in Northern Suriname. We found that NTFP abundance showed both positive and negative relationships to plant diversity indicators. In contrast to expectations, NTFP abundance was negatively related to woody species richness. In addition, across the plots disproportionately few (2–6) NTFP species determined >50% of NTFP abundance. The occurrence and the identity of these 'NTFP oligarchs' was associated to specific floristic compositions. Overall, more than half, i.e. 55.9%, of the observed variation in NTFP abundance could be explained by a combination of taxonomic and structural plant diversity indicators. Our case study findings are relevant for conservation policies in general. In most countries NTFPs are not on the agenda of governments and current tropical conservation policies often focus on forests with high species richness and/or carbon stocks. Our findings indicate that current policies may not cover valuable forests in terms of high NTFP abundance. To support sustainable NTFP provisioning, additional conservation efforts would need to include those vegetation types with high NTFP abundance. [ABSTRACT FROM AUTHOR]

How interactive simulation systems can improve the support of environmental management is not fully understood. We therefore cross-analyzed questionnaires with logfiles and videos of workshops in which an interactive simulation system for peatland management was applied, to derive an in-depth perspective of its added values. The workshop participants explored the physical system dynamics, implementing measures, and the social system dynamics, brokering deals with other stakeholders. The system enabled capacity building at individual and group level, through iterative exploration of possible measures. As a result, cooperation among the stakeholders was enhanced and their understanding of problems and action perspectives regarding the peatlands was increased. Interventions that stimulated deliberation during the workshops were shown to prevent individualistic strategies, and instead fostered cooperative attitudes. The embeddedness in preceding Science‒Policy Interfaces enhanced the credibility and legitimacy of the system, whereas salience was strengthened by abundant detailed information, realistic visual quality, and short calculation times. • Peatland management strategies were interactively simulated in ten workshops. • Participants explored both physical and social system dynamics. • They consistently perceived high added values for cooperation and learning. • The workshops enabled capacity building at individual and group level. • Deliberation of governmental measures fostered cooperative attitudes. [ABSTRACT FROM AUTHOR]

When rivers flood, nutrients exchange between the river and the floodplain, enhancing floodplain vegetation productivity, as described by the flood pulse concept. However, river water may not reach the edge of the floodplain if there are other sources of inundation water. Also, particulate nutrients travel less far from the river than dissolved nutrients and are more likely to remain available to vegetation during the growing season. This would mean that high nutrient input by river water, and associated high floodplain plant productivity, likely occurs only in the vicinity of the river channel. This paper tests 3 hypotheses derived from these observations related to the validity of the Flood Pulse concept and the relation between floodplain plant productivity and dissolved resp. particulate nutrients. We mapped particulate nutrient and dissolved nutrient concentrations in floodplain inundation water across the Biebrza floodplain (Poland), and assessed their spatial relationships with topographical parameters, aboveground biomass and species richness. Particulate nitrogen (N) and phosphorus (P) deposition and dissolved N decreased significantly with distance from the river and with elevation, and increased significantly with water depth. Dissolved P was not significantly correlated with topographical parameters or water depth. Aboveground biomass correlated significantly with particulate N and P deposition, but not with dissolved N or P. We conclude the edge of inundation is a poor predictor of the zone of high productivity. Nutrient input is higher near the river channel due to deposition of particulate nutrients, which are thus more relevant for vegetation productivity than dissolved nutrients. Spatial particulate nutrient patterns should therefore be integrated in monitoring programmes for policy and research. We further recommend refining the flood pulse concept to take into account the spatial deposition of river derived particulate nutrients, as well as non river-derived inundation water sources. [ABSTRACT FROM AUTHOR]

Exfiltration of anoxic Fe-rich groundwater into surface water and the concomitant oxidative precipitation of Fe are important processes controlling the transport of phosphate (PO 4 ) from agricultural areas to aquatic systems. Here, we explored the relationship between solution composition, reaction kinetics, and the characteristics of the produced Fe hydroxyphosphate precipitates in a series of aeration experiments with anoxic synthetic water and natural groundwater. A pH stat device was used to maintain constant pH and to record the H + production during Fe(II) oxidation in the aeration experiments in which the initial aqueous P/Fe ratios ((P/Fe) ini ), oxygen concentration and pH were varied. In general, Fe(II) oxidation proceeded slower in the presence of PO 4 but the decrease of the PO 4 concentration during Fe(II) oxidation due to the formation of Fe hydroxyphosphates caused additional deceleration of the reaction rate. The progress of the reaction could be described using a pseudo-second-order rate law with first-order dependencies on PO 4 and Fe(II) concentrations. After PO 4 depletion, the Fe(II) oxidation rates increased again and the kinetics followed a pseudo-first-order rate law. The first-order rate constants after PO 4 depletion, however, were lower compared to the Fe(II) oxidation in a PO 4 -free solution. Hence, the initially formed Fe hydroxyphosphates also affect the kinetics of continuing Fe(II) oxidation after PO 4 depletion. Presence of aqueous PO 4 during oxidation of Fe(II) led to the formation of Fe hydroxyphosphates. The P/Fe ratios of the precipitates ((P/Fe) ppt ) and the recorded ratio of H + production over decrease in dissolved Fe(II) did not change detectably throughout the reaction despite a changing P/Fe ratio in the solution. When (P/Fe) ini was 0.9, precipitates with a (P/Fe) ppt ratio of about 0.6 were formed. In experiments with (P/Fe) ini ratios below 0.6, the (P/Fe) ppt decreased with decreasing (P/Fe) ini and pH value. Aeration experiments with natural groundwater showed no principal differences in Fe(II) oxidation kinetics and in PO 4 immobilisation dynamics compared with synthetic solutions with corresponding P/Fe ratio, pH and oxygen pressure. However, aeration of groundwater with relative high DOC concentrations and a low salinity lead to P-rich Fe colloids that were colloidally stable. The formation of a Fe hydroxyphosphate phase with a molar P/Fe ratio of 0.6 can be used for predictive modelling of PO 4 immobilisation upon aeration of pH-neutral natural groundwater with an (P/Fe) ini ratio up to 1.5. These findings provide a solid basis for further studies on transport and bioavailability of phosphorus in streams, ditches and channels that receive anoxic Fe-rich groundwater. [ABSTRACT FROM AUTHOR]

Highlights: [•] Flooding drives ecological processes in river floodplains. [•] According to the Flood Pulse Concept, river water connects the entire floodplain. [•] Contrastingly, groundwater and atmospheric water are dominating water sources. [•] These three water sources appear in a spatial pattern in the Biebrza floodplain. [•] Our findings urge for a revision of the Flood Pulse Concept. [ABSTRACT FROM AUTHOR]

Abstract: River flooding is important for the ecological functioning of river floodplains. It is implicitly assumed that in many river floodplains during floods, river water is spreading all over the floodplain. We hypothesize that during flood events a spatial distribution of water types exists, which is correlated to different water sources (river water, atmospheric water and groundwater) and to the spatial distribution of vegetation types. The objective of this paper is to assess a new methodology to determine the extent of flooding and the spatial distribution of different water sources during the flood, using GPS, multispectral remote sensing and hydrochemical analyses. This methodology is applied to the Biebrza River Lower Basin, which has little human impact. Remote sensing resulted in a map distinguishing inundated areas from dry areas, which showed 85% agreement with GPS field measurements. Principal Component Analyses and Cluster Analyses on the measured water chemistry identified different water sources during the flood (river water, groundwater, rainwater) and showed the effects of human impact on water quality. River flood water dominated the entire inundation zone in the northern Lower Basin, which is narrower and steeper than the southern Lower Basin where groundwater and rainwater were significant contributors to the major part of the inundated area. Vegetation in the river flood zone is distinctly different from the rest of the floodplain. Due to mixing of ground- and rainwater, correlation analyses between vegetation and water type were not possible outside the river flood zone. The new methodology is effective in distinguishing inundated areas from dry regions and in separating river flood water from other water sources during a flood. [Copyright &y& Elsevier]

Abstract: The effectiveness of measures targeted at the restoration of populations of endangered species in anthropogenically dominated regions is often limited by a combination of insufficient restoration of habitat quality and dispersal failure. Therefore, the joint prediction of suitable habitat and seed dispersal in dependency of management actions is required for effective nature management. Here we demonstrate an approach, which links a habitat suitability and a seed dispersal model. The linked model describes potential species distribution as a function of current species distribution, species-specific dispersal traits, the number of successful dispersal events, dispersal infrastructure and habitat configuration. The last two variables were related to water management actions. We demonstrate the applicability of the model in a strategy analysis of hydrological restoration measures for a large fen area in which still numerous endangered plant species grow. With the aid of the linked model, we were able to optimise the spatial planning of restoration measures, taking into account both the constraints of water management practices on abiotic restoration and the effects of habitat fragmentation on dispersal. Moreover, we could demonstrate that stand-alone habitat suitability models, which assume unlimited dispersal, may considerably overestimate restoration prospects. For these reasons, we conclude that linked habitat suitability and dispersal models can provide useful insights into spatially differentiated potentials and constraints of nature restoration measures targeted at the sustainable conservation of endangered plant populations whose habitats have been deteriorated due to undesirable effects of land and water management on abiotic conditions. These insights may contribute to the design of cost-effective nature restoration and conservation measures. [Copyright &y& Elsevier]

Agroecological practices have been shown to control erosion, increase soil fertility, carbon stocks, pollination and biodiversity. As a consequence, these ecosystem services can contribute to a better farm economic resilience on the long-term; however, empirical evidence is scarce. In this study we aim to understand the economic performance of agroecological practices in almond orchards and the relevance of different economic and policy scenarios to incentivise the upscaling of agroecological practices. We investigated the development of the net present value (NPV) of several agroecological practices (no tillage (NT), green manure (GM) and compost (CM)) as compared to conventional tillage (CT), as well as the effect of internalising externalities through payments for soil carbon sequestration and by costs of erosion. Finally, we explored the effects of price premiums and public greening payments, on farm NPV. We found that all management regimes were profitable and that CM had a 17.2% higher NPV than CT, while both GM and NT had lower NPV than CT (69% for GM and 90.1% for NT). We found that despite NT and GM have higher soil organic carbon stocks, these provided a negligible additional income via carbon markets. CT had the highest externality costs of erosion but still its NPV was higher than NT and GM, despite the strong reductions in costs of erosion in NT and GM conferred by vegetation covers. We found that a price premium of 45% was necessary to make NT's economic performance comparable to that of CT, while a 27% price premium would be needed to make GM comparable to CT. Compensation through public greening payments would be in the order of €644 ha−1 y−1 for NT and €387 ha−1 y−1 for GM to have a similar NPV as CT. Our results suggest a trade-off between income from yield and costs from unaccounted externalities. We also find that private and public policy incentives could reverse this outcome, but requiring a large investment. Of the analysed agroecological practices, compost application appears the most promising to be scaled-up to improve both economic and environmental performance, and further research is needed to determine the outcomes of a combination of compost and vegetation covers. • Agroecological practices in rainfed almonds can be profitable • Compost application resulted in higher profitability than conventional tillage • No tillage and green manure had lower profitability than conventional tillage • Public greening payments and price premiums do not fully compensate for opportunity costs • Payments for soil-based environmental services do not compensate for opportunity costs [ABSTRACT FROM AUTHOR]