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Melman, Th.C.P., A.G.M. Schotman, H.A.M. Meeuwsen, R.A. Smidt, B. Vanmeulebrouk en H. Sierdsema, 2016. Ex-ante-evaluatie ANLb-2016 Ex-ante evaluation ANLb2016 for learning management; a first look at size and spatial quality of managed units in the new agri-environmental system in the Netherlands.Outine: An ex ante evaluation was performed for the new system for agricultural nature and landscape in the Netherlands (ANLb-2016), in which managers (collectives of farmers) have more responsibility as before. Objects were size, location in suitable areas and spatial coherence of the managed plots. Special attention is paid to the quality as meadow bird habitat. A comparison is made with 2010. Attention is paid to four agricultural habitats: grassland, arable fields, dry and wet veining. The focus is put on meadow birds: much knowledge is available and the greater part of the managed area concerns this group. Results: the managed area declined from about 143,000 to 90,000 ha (of which approx 23.000ha concerns expiring contracts of which continuation is uncertain). Meadow bird management is about 62-64% in suitable area (58% in 2010); 65% of it is fairly concentrated, 35% more or less dispersed. With the so called heavy management, as far as situated within suitable area, is expected to result for about 50% into a reasonable to good quality habitat. Recommendation: To improve the management it is crucial to come to objectified insights, shared by all parties concerned: managers (collectives of farmers), scientists and policy-makers. Basic items for this moment are reconnition of suitable areas, lower limits for spatial coherence and habitat quality. Here, so called learning management (learning by doing, bench mark, sharing knowledge and experience) may be very important to come to ecological effects.Trefwoorden: Agrarisch natuurbeheer, leefgebiedtypen, ruimtelijke kwaliteit, ruimtelijke samenhang

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Question:To assess the acidification process, nationwide information about soil pH on a site level is called for. Measurements of soil pH may be used, however there are not sufficient measurements available to map soil pH nationwide on site level. Instead we developed a soil pH map based on vegetation data. Location: Natural terrestrial areas in The Netherlands. Methods: 271,693 vegetation plots were used to estimate average soil pH per plot with indicator values, based on field measurements, of plant species. By spatial interpolation average pH values between the plots, with the soil type, groundwater table and vegetation management type as ancillary explanatory variables we created a soil pH map. The map covers all terrestrial nature areas (all areas that are not built up areas, agricultural areas and infrastructural areas) in the Netherlands with a map resolution of 25 × 25 m 2 raster cells. Results:The predicted pH of the map varied between 3.0 and 8.6 with standard errors between 0.13 and 0.93. Most of the standard errors range from 0.4 to 0.55, with an average just below 0.5 pH unit. Cross-validation shows that for 33% the difference between observed and predicted is between −0.1 and 0.1 pH-unit and for 83% the difference is between −0.5 and 0.5 pH-unit. Validation shows that the pH map is unbiased (mean error is almost zero), accurate (root mean squared error is 0.64) and nicely captures spatial patterns (r = 0.77). We applied the pH map to assess the impact of acidification on the abiotic quality of nature areas in the Netherlands. Conclusions:The model fit in the predicted soil pH is in good resulting in a low standard error and a high correlation. The measures taken to prevent acidic deposition causing further acidifying of nature areas can be considered as successful. K E Y W O R D S acidity, kriging, pH, relevé, soil type, vegetation 190 | Applied Vegetation Science WAMELINK Et AL.

In het werk van de WOT Natuur & Milieu voor PBL-producten zoals de Balans van de Leefomgeving, het Compendium voor de Leefomgeving, de Lerende Evaluatie van het Natuurpact en de Natuurverkenning worden verschillende basiskaarten voor natuuromvang en-ligging gebruikt. Het gaat bijvoorbeeld om de Basiskaart Natuur, Landelijk Grondgebruik Nederland (LGN) en de Beheertypenkaart. Het probleem daarbij is dat het gebruik van verschillende kaarten kan doorwerken in de indicatoren en de modelresultaten en kan zorgen voor inconsistenties. Deze rapportage doet verslag van het ontwerpen en bouwen van een gestandaardiseerde procedure waarmee een Basisbestand Natuur en Landschap (BNL) kan worden samengesteld dat regelmatig kan worden vernieuwd. Het BNL is een rasterbestand met een resolutie van 2,5 meter, dat bestaat uit verschillende lagen en wordt gemaakt met behulp van een GIS-script. De Top10NL is de geometrische basis van de kaart en is beschouwd als weergave van de werkelijke situatie in het veld. De beheertypenkaart van provincies (IMNaB) is als bronbestand voor areaal en typering van natuur genomen. De kaart is een belangrijk onderdeel van het natuurbeleid wat betreft subsidie voor natuurbeheer en om de natuurkwaliteit te bepalen. Het BNL sorteert voor op het Status A-Kwaliteitstraject van de WOT.

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