Strong effects of a plantation with Pinus patula on Andean subpa´ramo vegetation: a case study from Colombia

Abstract The effect of a pine plantation on a native subpa´ramo system in the Andes of Colombia (3100 m above sea level) was studied. The vegetation of an 8 year-old plantation with Pinus patula was compared to that of the surrounding native subpa´ramo. 59 plots made in the subpa´ramo vegetation contained 121 vascular plant species. These plots were classified into three subpa´ramo communities and one Andean scrub community. Sixty-four plots made in the pine plantation contained 76 vascular plant species and were subdivided into four classes of pine cover. With increasing pine cover, pine plantation plots tended to become less similar to the subpa´ramo communities. Habitat-specific subpa´ramo species tended to disappear with increasing pine cover. After controlling for the effects of environmental variables in a partial canonical correspondence analysis, pine cover had a significant impact on plant species patterns. It is concluded that afforestation with Pinus patula resulted in strong negative effects on diversity and composition of the subpa´ramo vegetation at the study site. # 2003 Elsevier Ltd. All rights reserved. Resumen Se realizo´un estudio comparativo entre la vegetacio´n de una plantacio´n con Pinus patula con la del subpa´ramo en los alrededores de la plantacio´n, a 3100 m de altura sobre el nivel del mar en los Andes de Colombia. En el subpa´ramo se hicieron 59 levantamientos en donde se registraron 121 especies de plantas vasculares. Estos levantamientos se clasificaron en tres comunidades herba´ceas de subpa´ramo y una comunidad de bosque andino bajo. En la plantacio´n se hicieron 64 levantamientos en donde se encontraron 76 especies de plantas vasculares. Los levantamientos en las plantaciones se clasificaron segu´n clases de cobertura de Pinus patula. Entre ma´s alta la cobertura de Pinus patula en los levantamientos en la plantacion, ma´s baja la similaridad entre estos y los levantamientos en el subpa´ramo. Las especies del subpa´ramo que mostraron una especificidad de habitat alta mostraron la ma´s baja persistencia en la plantacio´n. Despue´s de haber controlado por el efecto de variables ambientales en una ordinacio´n cano´nica parcial, la cobertura de Pinus patula mostro´un impacto significante en los patrones de especies. Se concluye que la aforestacio´n con Pinus patula tiene una influencia negativa fuerte sobre la diversidad y la composicio´n de la vegetacio´n del subpa´ramo en el sitio de estudio.

Modeling mussel bed influence on fine sediment dynamics\ud on a Wadden Sea intertidal flat

Mussel beds are coherent colonies of mussels and are\ud widespread in the Dutch Wadden Sea and the Eastern\ud Scheldt estuary. Mussel beds are known to be an\ud important factor in biogeomorphological processes,\ud primarily because of the influence on fine sediment\ud dynamics. Ongoing research to explore the use of\ud mussels as bio-tools makes predictive modeling\ud desirable.\ud In this study a process-based model of the\ud interaction between a young mussel bed and fine\ud sediment was set up for use in Delft3D-FLOW. The\ud model encompasses the hydraulic roughness of the\ud mussel bed, active capture of suspended sediment by\ud filter feeding and changed properties of sediment\ud inside the mussel bed to account for the presence of\ud biodeposited matter. The mussel bed implementation\ud in Delft3D-FLOW was tested in a Wadden Sea\ud intertidal mudflat model. Two current dominated\ud summer months were simulated. The effects of\ud different patterns, known to occur in young mussel\ud beds, were evaluated.\ud It was concluded that roughness and filtration\ud rate of mussel beds are important factors in mussel\ud bed influence on fine sediment. A combination of\ud active deposition via filtration and slow down of the\ud flow due to increased roughness leads to high net\ud deposition in the mussel bed. In addition, the ability\ud of young mussels to quickly climb on top of\ud deposited material results in rapid trapping of large\ud amounts of fine sediment. In the wakes of the mussel\ud bed deposition is also high because of reduced flow\ud velocities. Patchiness and specifically striped patterns\ud cause mussel beds to experience less sedimentation\ud than uniformly covered beds of the same size

Effectiveness of community-based mangrove management for coastal protection : A case study from Central Java, Indonesia

Management and restoration of mangrove forests to protect coasts are promoted in many countries, including Indonesia. Indonesian mangrove forests are actively restored and managed by local communities for their ecosystem services, including coastal protection. Whether community-based mangrove management (CBMM) is effective is still debated. Our study analysed the effectiveness of different CBMM practices in four Central Javan communities by analysing the capacity of their mangrove forests to protect against coastal hazards. We used complementary interviews, field assessments and literature reviews to collect the necessary information. The overall CBMM performance and success significantly differed for each community's mangrove rehabilitation effort and the resulting coastal protection service. Of the four communities, Bedono performed best in terms of mangrove coverage, forest structure and restored coastal protection service. This is explained by multiple factors, such as application of long-term and integrated CBMM approaches, involving appropriate maintenance and additional measures to reduce wave energy. Our results can help governments, practitioners and communities to better understand the factors that contribute to CBMM's success and failure when restoring and managing mangrove forests and protecting coasts

How to restore mangroves for greenbelt creation along eroding coasts with abandoned aquaculture ponds

Globally, erosion of muddy tropical coasts that are dominated by aquaculture ponds, is an increasing problem. Restoration of mangrove greenbelts may counteract such erosion, by restoring the sediment balance. Hence, we aim to unravel the processes controlling natural mangrove regeneration in both “landward” (i.e., into aquaculture ponds) and seaward direction, using the fast eroding coastline of Demak (Indonesia) as case study. Firstly, we investigated which physical and chemical factors drive landward mangrove expansion by relating them to the presence/absence of mangrove seedlings in abandoned aquaculture ponds. Secondly, we investigated which physical parameters control seaward mangrove expansion by relating them to expansion and retreat at the sea-side of mature mangrove stands. Landward mangrove expansion into abandoned aquaculture ponds was positively related to both emergence time (%) and sediment stability (i.e., shear strength), which are in turn both associated to bed level elevation and pond drainage. Surprisingly, there was no effect of soil chemistry. Seaward expansion of existing mangrove stands was strongly associated to foreshore morphology. Mangroves only expanded in the presence of an elevated mudflat, whereas the absence of a mudflat in combination with a concave (hollow) profile was associated with mangrove retreat. Our findings suggest that restoration of a mangrove greenbelt can be stimulated landward by improving drainage of abandoned aquaculture ponds. This enhances sediment stability and allows ponds to accrete. Seaward expansion can be induced by restoring foreshore morphology. Present results are discussed in the context of large-scale applications

Damming deltas: a practice of the past? Towards nature-based flood defenses

There is extensive experience in adaptive management of exposed sandy coastlines through sand nourishment for coastal protection. However, in complex estuarine systems, coastlines are often shortened through damming estuaries to achieve desired safety levels. The Dutch Deltaworks illustrate that this approach disrupts natural sediment fluxes and harms ecosystem health, which negatively affects derived ecosystem services, such as freshwater availability and mussel and oyster farming. This heavily impacts local communities and thus requires additional maintenance and management efforts. Nevertheless, the discussion on coastline shortening keeps surfacing when dealing with complex coastal management issues throughout the world. Although adaptive delta management accompanied by innovative approaches that integrate coastal safety with ecosystem services is gaining popularity, it is not yet common practice to include adaptive pathways, a system-based view and ecosystem knowledge into coastal management projects. Here, we provide a first attempt to integrate ecosystem-based flood risk reduction measures in the standard suite of flood risk management solutions, ranging from structural to non-structural. Additionally, for dealing with the dynamic and more unpredictable nature of ecosystems, we suggest the adaptive delta management approach that consists of flexible measures, measurable targets, monitoring and intervention, as a framework for embedding ecosystem-based alternatives for flood risk mitigation in the daily practice of engineers and coastal planners

Data presented in the paper: To Plant or Not to Plant: When can Planting Facilitate Mangrove Restoration?

We studied the natural and assisted processes of mangrove expansion in Demak Regency, Indonesia. We studied expansion in both landward direction (i.e. the aquaculture pond zone) and seaward direction (i.e. the coastal zone) from the current coastline in the project area (the old coastal road). The pond zone in the study area is characterized by active traditional aquaculture ponds, and drowning abandoned aquaculture ponds towards the coast. The coastal zone in the study is defined as the area ranging from MHW to MLW (the maximum depth at which the EMR-dams are placed), which ranges roughly 0 to 600 meters from the shoreline. In order to shed light on best practices for mangrove recovery, we aimed to answer four research questions: : 1) how has mangrove expansion occurred in seaward and landward direction in the past, mainly through planting or mainly through natural expansion?; 2) Can hydrological EMR measures (e.g. sluice gate management) induce natural mangrove recovery in the pond zone (i.e. would enough propagules be available at landward sites if hydrological connectivity to target ponds was increased)?; 3) Can wave-reducing and sediment-trapping measures (EMR-dams) induce natural mangrove recovery at challenging sites in the coastal zone by increasing the chances of a) new seedling establishment or b) survival of established seedlings? and; 4) Can mangrove planting in combination with EMR-dams accelerate mangrove recovery at challenging coastal sites

Tales of island tails : biogeomorphic development and management of barrier islands

The Frisian islands (Southern North Sea) have extensive island tails, i.e. the entire downdrift side of an island consisting of salt marshes, dunes, beaches and beach plains, and green beaches. Currently, large parts of these tails are ageing and losing dynamics, partly due to human influence. This may mean a loss of young stages on the long term, and current management is not enough to counteract this. To aid the development of new interventions aiming at (re)introducing natural dynamics, a conceptual model of island-tail development under natural and disturbed conditions was developed, based on existing data, field visits and literature. The development of an island tail follows the general pattern of biogeomorphic succession. The first phase consists of a bare beach plain. In the second phase, embryonic dunes form. In the third phase, green beaches, dunes and salt marshes form, including drainage by creeks and washovers. In the fourth phase, vegetation succession continues and the morphology stabilises. Human interference (such as sand dikes and embankments) reduces natural dynamics and increases succession speed, leading to a reduction in the diversity in landforms and vegetation types. Both for natural and human-influenced island tails, succession is the dominant process and large-scale rejuvenation only occurs spontaneously when large-scale processes cause erosion or sedimentation. Island tails cannot be kept permanently in a young successional stage by reintroducing natural dynamics through management interventions, as biogeomorphic succession is dominant. However, such interventions may result in local and temporal rejuvenation when tailored to the specific situation