Linking habitat suitability and seed dispersal models in order to analyse the effectiveness of hydrological fen restoration strategies

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.     

A decision support system for restoration planning of stream valley ecosystems

Despite efforts that have been put into conservation, there is a continuing loss of species and ecosystems in Western Europe. There is a growing awareness that restoration is an essential step to stop this tide. Unfortunately, there is lack of understanding about the multitude of functions and the complexity of spatial interactions in a landscape. The focus of this paper is to demonstrate that an Integrated Decision Support System (IDSS) is indispensable to offer insight in this complexity and to design efficient restoration programmes. The IDSS is applied in a lowland catchment on the border between The Netherlands and Belgium and leads to the following recommendations: (1) The site conditions on the location where restoration is planned must be close to the range that is required for the target ecosystem. (2) The manager has to decide for the most attainable targetecosystem, and accept the inevitable loss of other ecosystems as a result from this choice. (3) Restoration planning involves that the optimal measure for each catchment, subcatchment or region is assessed, being ecological, urban or agricultural. (4) For each ecosystem an optimal set of measures must be selected. An analysis of the restoration efficiency (ecological gain divided by economic costs) is crucial for this selection.     

Dependency of local mesotrophic fens on a regional groundwater flow system in a poldered river plain in the Netherlands

The effect of regional, subregional and local groundwater flow systems on mesotrophic fen ecosystems was studied in the polders of the Vecht River plain that borders the Pleistocene ice-pushed moraine of Het Gooi. Variation in the vegetation and in the habitat factors (groundwater and peat soil) of fens depends whether or not the fens are connected to the outflow of the regional groundwater system.Changes in the regional groundwater flow system, caused by changes in the water management of the polders, are probably responsible for the deterioration of mesotrophic fens. Drastic measures will have to be taken to restore the hydrology on a regional scale if the mesotrophic fens are to be saved from extinction.Hydrological research that integrates the results of regional and local studies is essential if the ecology of fen ecosystems is to be understood.     

Vegetation-mediated feedback in water, carbon, nitrogen and phosphorus cycles

Since the industrial revolution, industry, traffic and the manufacture and application of nitrogenous fertilizers have increased carbon dioxide emissions and accelerated the nitrogen (N) cycle. The combined effects of a warming climate, CO₂ fertilization, land-use change and increased N availability may be responsible for primary productivity increases in many parts of the world. Enhanced productivity may lead to shifts in albedo and transpiration, which feed back to the water cycle through heat fluxes and precipitation. Plants may also respond to elevated CO₂ by closing their stomata or by structurally adapting their stomatal density and size, which potentially diminishes transpiration. Intensification of agriculture has also led to an increase in both nitrogenous (N) and phosphorus (P) fertilization. The combined effect of atmospheric N deposition and P fertilization has distorted the balance between N and P availability in many ecosystems. The active role of plants in accessing nutrients from the soil may trigger switches in nutrient availability, triggering shifts in plant productivity and species composition in these ecosystems and therefore also in the carbon (C) cycle. In response to global change, the above plant responses may influence each other positively or negatively and may impact on the elemental cycles of C, N and P and the water cycle. We are only beginning to understand how these four cycles interact, the role of plant processes and vegetation in these interactions, and the net outcome for plant competition, vegetation distribution, landscape development and directions of global change. In this paper we have integrated a number of recent research findings into known relationships that together elucidate interactions between these cycles through vegetation, and could potentially have unexpected effects on landscapes and larger-scale systems (continental, global). These interactions include processes operating at very distinct temporal and spatial scales, in which terrestrial ecosystems and their spatial organization in the landscape are key. We argue that to better understand the effects of changes in land cover and land use on biogeochemical and biogeophysical fluxes, it is necessary to account for feedbacks via vegetation and how these interfere with elemental cycles. Finally, we suggest directions for further research to fill the current knowledge gaps.