Herstel van hellingschraallanden : verslag veldwerkplaats Heuvelland, Gulpen, 30 september 2009

Het gaat niet goed met de schaarse reservaten van hellingschraallanden. Al sinds de jaren tachtig wordt geprobeerd om deze unieke ecosystemen te herstellen, maar tot op heden met een tegenvallend resultaat. Onder leiding van het deskundigenteam Heuvelland is van 2004-2008 onderzoek gedaan naar de oorzaken van achteruitgang en de mogelijkheden voor herstel, met de nadruk op de mogelijke beheerstrategieën voor zowel de flora als de fauna. Tijdens deze veldwerkplaats presenteerden twee onderzoekers de resultaten van dit onderzoek en vertelde beheerder Patrick Kloet van Staatsbosbeheer over de pilot gescheperde beweiding

Onderzoek naar de ecologische achteruitgang en het herstel van Zuid-Limburgse hellingschraallandcomplexen

De Zuid-Limburgse hellingschraallanden behoren tot de meest soortenrijke graslandtypen in ons land. Ze liggen op een gradiënt van zure heischrale graslanden bovenaan de helling en basische kalkgraslanden in het middendeel van de helling. Onderaan de helling komen voedselrijkere en dus meer ruige graslandtypen voor. Het oppervlak aan goed ontwikkelde hellingschraallanden is in de 20e eeuw sterk achteruit gegaan en ook de kwaliteit ervan. Om na te gaan wat de oorzaken zijn voor de achteruitgang van flora als fauna en hoe verder herstelbeheer moet plaatsvinden, is in 2005 in het kader van OBN een vierjarig onderzoek gestart. Hieruit blijkt dat er zeker nog perspectief is voor herstel van soortenrijke hellingsschraallanden. Het beheer binnen de hellingschraallanden kan verder geoptimaliseerd worden, zodat meer afvoer van nutriënten plaatsvindt en een meer heterogene vegetatiestructuur ontstaat. Ook moet de sterke mate van versnippering en isolatie van de hellingschraallanden worden aangepakt door het vergroten en onderling verbinden van de huidige reservaten

Carbon storage potential of silvopastoral systems of Colombia

Nine Latin American countries plan to use silvopastoral practices—incorporating trees into grazing lands—to mitigate climate change. However, the cumulative potential of scaling up silvopastoral systems at national levels is not well quantified. Here, we combined previously published tree cover data based on 250 m resolution MODIS satellite remote sensing imagery for 2000–2017 with ecofloristic zone carbon stock estimates to calculate historical and potential future tree biomass carbon storage in Colombian grasslands. Between 2000 and 2017, tree cover across all Colombian grasslands increased from 15% to 18%, with total biomass carbon (TBC) stocks increasing from 0.41 to 0.48 Pg. The range in 2017 carbon stock values in grasslands based on ecofloristic zones (5 to 122 Mg ha−1) suggests a potential for further increase. Increasing all carbon stocks to the current median and 75th percentile levels for the respective eco-floristic zone would increase TBC stocks by about 0.06 and 0.15 Pg, respectively. Incorporated into national C accounting, such Tier 2 estimates can set realistic targets for silvopastoral systems in nationally determined contributions (NDCs) and nationally appropriate mitigation actions (NAMAs) implementation plans in Colombia and other Latin American countries with similar contexts

Nitrogen forms affect root structure and water uptake in the hybrid poplar

The study analyses the effects of two different forms of nitrogen fertilisation (nitrate and ammonium) on root structure and water uptake of two hybrid poplar (Populus maximowiczii x P. balsamifera) clones in a field experiment. Water uptake was studied using sap flow gauges on individual proximal roots and coarse root structure was examined by excavating 18 whole-root systems. Finer roots were scanned and analyzed for architecture. Nitrogen forms did not affect coarse-root system development, but had a significant effect on fine-root development. Nitrate-treated trees presented higher fine:coarse root ratios and higher specific root lengths than control or ammonium treated trees. These allocation differences affected the water uptake capacity of the plants as reflected by the higher sapflow rate in the nitrate treatment. The diameter of proximal roots at the tree base predicted well the total root biomass and length. The diameter of smaller lateral roots also predicted the lateral root mass, length, surface area and the number of tips. The effect of nitrogen fertilisation on the fine root structure translated into an effect on the functioning of the fine roots forming a link between form (architecture) and function (water uptake)

Determinants of immigration strategies in male crested macaques (Macaca nigra).

Immigration into a new group can produce substantial costs due to resistance from residents, but also reproductive benefits. Whether or not individuals base their immigration strategy on prospective costbenefit ratios remains unknown. We investigated individual immigration decisions in crested macaques, a primate species with a high reproductive skew in favour of high-ranking males. We found two different strategies. Males who achieved low rank in the new group usually immigrated after another male had immigrated within the previous 25 days and achieved high rank. They never got injured but also had low prospective reproductive success. We assume that these males benefitted from immigrating into a destabilized male hierarchy. Males who achieved high rank in the new group usually immigrated independent of previous immigrations. They recieved injuries more frequently and therefore bore immigration costs. They, however, also had higher reproductive success prospects. We conclude that male crested macaques base their immigration strategy on relative fighting ability and thus potential rank in the new group i.e. potential reproductive benefits, as well as potential costs of injury

Integrating evolution into ecological modelling: accommodating phenotypic changes in agent based models.

PMCID: PMC3733718This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Evolutionary change is a characteristic of living organisms and forms one of the ways in which species adapt to changed conditions. However, most ecological models do not incorporate this ubiquitous phenomenon. We have developed a model that takes a 'phenotypic gambit' approach and focuses on changes in the frequency of phenotypes (which differ in timing of breeding and fecundity) within a population, using, as an example, seasonal breeding. Fitness per phenotype calculated as the individual's contribution to population growth on an annual basis coincide with the population dynamics per phenotype. Simplified model variants were explored to examine whether the complexity included in the model is justified. Outputs from the spatially implicit model underestimated the number of individuals across all phenotypes. When no phenotype transitions are included (i.e. offspring always inherit their parent's phenotype) numbers of all individuals are always underestimated. We conclude that by using a phenotypic gambit approach evolutionary dynamics can be incorporated into individual based models, and that all that is required is an understanding of the probability of offspring inheriting the parental phenotype

Designing multifunctional landscapes for forest conservation

A multifunctional landscape approach to forest protection has been advocated for tropical countries. Designing such landscapes necessitates that the role of different land uses in protecting forest be evaluated, along with the spatial interactions between land uses. However, such evaluations have been hindered by a lack of suitable analysis methodologies and data with fine spatial resolution over long time periods. We demonstrate the utility of a matching method with multiple categories to evaluate the role of alternative land uses in protecting forest. We also assessed the impact of land use change trajectories on the rate of deforestation. We employed data from Kalimantan (Indonesian Borneo) at three different time periods during 2000–2012 to illustrate our approach. Four single land uses (protected areas (PA), natural forest logging concessions (LC), timber plantation concessions (TC) and oil-palm plantation concessions (OC)) and two mixed land uses (mixed concessions and the overlap between concessions and PA) were assessed. The rate of deforestation was found to be lowest for PA, followed by LC. Deforestation rates for all land uses tended to be highest for locations that share the characteristics of areas in which TC or OC are located (e.g. degraded areas), suggesting that these areas are inherently more susceptible to deforestation due to foregone opportunities. Our approach provides important insights into how multifunctional landscapes can be designed to enhance the protection of biodiversity