Can tree species choice influence recruitment of ancient forest species in post-agricultural forest?

Germination and establishment of ancient forest species are bottlenecks in forest habitat restoration. We hypothesised that tree species can influence these processes on acidification sensitive soils through their effects on the soil. Seeds of seven ancient forest species were sown in soil collected in a post-agricultural forest under four different tree species, notably Acer pseudoplatanus, Alnus glutinosa, Fagus sylvatica and Populus x euramericana. Germination of four species was affected by tree species, while only Scilla non-scripta was indifferent and germination of Anemone nemorosa and Paris quadrifolia was unsuccessful. The acid intolerant Primula elatior only germinated in the soil of P. x euramericana but also the acid tolerant Lonicera periclymenum and Stellaria holostea performed best in the soil of P. x euramericana and worst in the soil of A. glutinosa. Lamium galeobdolon preferred the soil of A. pseudoplatanus. Germination of competitive seed bank species was much more successful in the soil of P. x euramericana than in soil of other tree species. From our results we deduce that tree species selection can affect germination of ancient forest species. Forest managers should be aware of the effects of tree species on their colonisation chances and favour trees with good decomposable litter especially on acidification sensitive soils

Can we successfully monitor a population density decline of elusive invertebrates? A statistical power analysis on Lucanus cervus

Monitoring global biodiversity is essential for understanding and countering its current loss. However, monitoring of many species is hindered by their difficult detection due to crepuscular activity, hidden phases of the life cycle, short activity period and low population density. Few statistical power analyses of declining trends have been published for terrestrial invertebrates. Consequently, no knowledge exists of the success rate of monitoring elusive invertebrates. Here data from monitoring transects of the European stag beetle, Lucanus cervus, is used to investigate whether the population trend of this elusive species can be adequately monitored. Data from studies in UK, Switzerland and Germany were compiled to parameterize a simulation model explaining the stag beetle abundance as a function of temperature and seasonality. A Monte-Carlo simulation was used to evaluate the effort needed to detect a population abundance decline of 1%/year over a period of 12 years. To reveal such a decline, at least 240 1-hour transect walks on 40 to 100 transects need to be implemented in weekly intervals during warm evenings. It is concluded that monitoring of stag beetles is feasible and the effort is not greater than that which has been found for other invertebrates. Based on this example, it is assumed that many other elusive species with similar life history traits can be monitored with moderate efforts. As saproxylic invertebrates account for a large share of the forest biodiversity, although many are elusive, it is proposed that at least some flagship species are included in monitoring programmes

Forest herbs show species-specific responses to variation in light regime on sites with contrasting soil acidity: an experiment mimicking forest conversion scenarios

Forest conversion from native deciduous forests to coniferous stands has been performed in many European regions and resulted in dramatic shifts in understorey plant community composition. However, the drivers for changes in specific understorey plant species remained unclear. Here, we experimentally determine the species-specific effects of light availability and chemical soil characteristics, on the vegetative and regenerative performance of five herbaceous forest understorey plants. Topsoil samples from both spruce and deciduous stands at four locations, with two levels of soil acidity, were collected and used in a common garden experiment. Additionally, three different light levels were applied, i.e., 'light deciduous', 'dark deciduous' (extra light reduction during summer) and 'evergreen' (light reduction during winter). In a second experiment we evaluated the germination of two of these species against the acidity and tree species at the site of origin of the soil samples. The light regime affected both the vegetative and regenerative performance of the understorey species: compared to light deciduous, Anemone nemorosa had a significantly lower performance under the evergreen light regime, Convallaria majalis under dark deciduous and Luzula luzuloides and Galium odoratum under both light regimes. The vegetative performance was lower in soil from acid sites for the acid-sensitive species G. odoratum and Primula elatior. Differences between the soils sampled under deciduous or spruce stands had no effect on the vegetative, or the regenerative performance of these species. By contrast, the germination of L. luzuloides and R elatior was higher in soils sampled in deciduous stands and in neutral sites. Species-specific responses in vegetative and regenerative performance of adult plants to a changed light regime and soil acidification could be a reason for the changed vegetation composition in converted stands. Also lower germination and establishment of forest understorey species in spruce stands could influence the species distribution after conversion

Understorey vegetation shifts following the conversion of temperate deciduous forest to spruce plantation

The identity and composition of the overstorey trees can have large impacts on the understorey vegetation in temperate forests. Here, we assess the effects of the conversion of mixed deciduous forests to Norway spruce (Picea abies) plantations on the understorey vegetation composition and diversity. We also investigated whether the effects of this conversion depend on the soil fertility and if they affect the species pool at the landscape scale. The study area contained ancient deciduous woodlands mainly consisting of Quercus spp., Fagus sylvatica and Carpinus betulus in the Gaume, an area with a mild temperate climate in southern Belgium. Spruce plantations were established 30–50 years ago in this matrix of deciduous woodlands. Differences in overstorey and understorey vegetation, forest floor and soil characteristics between 40 paired plots in spruce plantations and adjacent deciduous forest were compared along a soil fertility gradient. The forest floor mass was higher and the soil pH was lower in spruce plantations. The composition of the understorey vegetation differed between deciduous forest and spruce plantations: the spruce stands contained more light-demanding and acid-tolerant understorey species than the adjacent deciduous stands. The mean understorey species diversity, i.e., the local species diversity in a plot (a-diversity) as well as the total number of species (c-diversity), did not differ significantly between the deciduous and spruce stands. Hence, the differing species composition of the spruce plantations contributes to a larger overall species pool and higher across site b-diversity. Although the differences in the environmental variables within a plot pair increased along the fertility gradient, the differences in understorey vegetation diversity between deciduous and spruce stands showed no relationship with the gradient. Only the difference in Ellenberg indicator value for soil reaction (R) within a pair increased with increasing soil fertility. In line with the abiotic changes, the understorey vegetation composition had shifted towards a more acid-tolerant vegetation type 30–50 years after conversion to spruce plantations. The increase in light-demanding species was probably due to a more intensive thinning management in the spruce stands.status: publishe

Clear-felling effects on colonization rates of shadetolerant forest herbs into a post-agricultural forest adjacent to ancient forest

Question: Does clear-felling influence forest herb colonization into postagricultural forest? Location: A stand of poplar cultivars with a dense understorey of Acer pseudoplatanus in Muizen forest (northern Belgium), planted in 1952 on farmland adjacent to ancient forest and clear-felled in 1997. Methods: Shade-tolerant forest herbs were surveyed in 112 grid-based sample plots: just before clear-felling, and 5 and 10 yr afterwards. Shade-tolerant herbs were subdivided into ancient forest species (AFS) and other shade-tolerant species (OSS). Effects of clear-felling on species number per plot, total cover per plot and colonization rate of species groups were compared using nonparametrical tests. Species number per plot was modelled by means of generalized linear mixed models (GLMMs), with inventory time, distance to the nearest parcel edge, and cover of light-loving species (LS) as explanatory variables. The C-S-R signature (competitive, stress-tolerant and ruderal strategies, respectively) shift of sample plots was calculated on the selected shadetolerant species. Results: Frequency of most species increased during the 10-yr period. Number of OSS increased more and faster than that of AFS. OSS increased to the level of the adjacent forest, but was lower where LS cover remained high. There was a positive correlation between the change of the colonization rate and the competitive plant strategy. Conclusions: We assume that clear-felling stimulated generative reproduction of shade-tolerant herbs, whereas quickly emerging woody species controlled competitive exclusion by LS. Succession of dark and light phases, such as provided by an understorey managed as a coppice, could promote colonization of shade-tolerant herbs into post-agricultural forest. Introduction Many forest plant species are slow, short-distance colonizers that are shade-tolerant and dependent on a long and continuous coverstatus: publishe

Clear-felling effects on colonization rates of shade-tolerant forest herbs into a post-agricultural forest adjacent to ancient forest

Question: Does clear-felling influence forest herb colonization into post-agricultural forest? Location: A stand of poplar cultivars with a dense understorey of Acer pseudoplatanus in Muizen forest (northern Belgium), planted in 1952 on farmland adjacent to ancient forest and clear-felled in 1997. Methods: Shade-tolerant forest herbs were surveyed in 112 grid-based sample plots: just before clear-felling, and 5 and 10 yr afterwards. Shade-tolerant herbs were subdivided into ancient forest species (AFS) and other shade-tolerant species (OSS). Effects of clear-felling on species number per plot, total cover per plot and colonization rate of species groups were compared using non-parametrical tests. Species number per plot was modelled by means of generalized linear mixed models (GLMMs), with inventory time, distance to the nearest parcel edge, and cover of light-loving species (LS) as explanatory variables. The C-S-R signature (competitive, stress-tolerant and ruderal strategies, respectively) shift of sample plots was calculated on the selected shade-tolerant species. Results: Frequency of most species increased during the 10-yr period. Number of OSS increased more and faster than that of AFS. OSS increased to the level of the adjacent forest, but was lower where LS cover remained high. There was a positive correlation between the change of the colonization rate and the competitive plant strategy. Conclusions: We assume that clear-felling stimulated generative reproduction of shade-tolerant herbs, whereas quickly emerging woody species controlled competitive exclusion by LS. Succession of dark and light phases, such as provided by an understorey managed as a coppice, could promote colonization of shade-tolerant herbs into post-agricultural forest