Abstract:Conservation Biology 41In an attempt to provide a state of the art of the effect of forest management on biodiversity, 42we performed a MA comparing the species richness of managed and unmanaged forests in 47Our MA provides basic ecological knowledge needed for conservation and ecologically 48 sustainable forestry. In this paper, we showed that forest management has a negative effect 49 on the biodiversity of forest dwelling species. Because we were aware of the limitations of 50 our MA, we used caution when discussing the results considering that: (i) the effect is 51 strongly heterogeneous between different taxa; (ii) there is a trend for recovery of biodiversity 52 once management has been abandoned; (iii) no strong conclusion on the effect of different 53 management types could be drawn from our data due to low replication number. The obvious 54 main conclusion of this paper was that research on the subject in Europe was scarce and 55 that more controlled studies may help answer the questions raised. 113always provided negative slopes, except for bryophytes and birds (see Table 3, p. 107). 114Finally, even if the effect of TSA was significant only for carabids, saproxylic beetles and 115 fungi, most of the negative slopes for taxa have much higher value than the slope for all 160(2002): this paper compares old growth with 15 years-old stands, which were not considered 161 as "young regeneration phases" nor "clearfelling stands" in our protocol. We assume that our 162 selection protocol was restrictive enough regarding the number of studies finally included in 163 our MA; if we had been more restrictive in our inclusion criteria (i.e. excluding young stands), 164we would have rejected this paper. 166 Conclusions 167The paper we published does not aim at influencing European forest and conservation 168 policies in any way, but to provide decision-making tools based on scientific facts. Both 169 managed and unmanaged forests are needed to preserve European forest biodiversity, but 170 since there are many managed forests and very few old-growth ones, a special effort should 171 be allocated to create protected reserves, as suggested by Paillet et al. (2010).

No abstract

Natural disturbances, such as avalanches, snow breakage, insect outbreaks, windthrow or fires shape mountain forests globally. However, in many regions over the past centuries human activities have strongly influenced forest dynamics, especially following natural disturbances, thus limiting our understanding of natural ecological processes, particularly in densely-settled regions. In this contribution we briefly review the current understanding of changes in forest cover, forest structure, and disturbance regimes in the mountain forests across the European Alps over the past millennia. We also quantify changes in forest cover across the entire Alps based on inventory data over the past century. Finally, using the Swiss Alps as an example, we analyze in-depth changes in forest cover and forest structure and their effect on patterns of fire and wind disturbances, based on digital historic maps from 1880, modern forest cover maps, inventory data on current forest structure, topographical data, and spatially explicit data on disturbances. This multifaceted approach presents a long-term and detailed picture of the dynamics of mountain forest ecosystems in the Alps. During pre-industrial times, natural disturbances were reduced by fire suppression and land-use, which included extraction of large amounts of biomass that decreased total forest cover. More recently, forest cover has increased again across the entire Alps (on average +4% per decade over the past 25-115 years). Live tree volume (+10% per decade) and dead tree volume (mean +59% per decade) have increased over the last 15-40 years in all regions for which data were available. In the Swiss Alps secondary forests that established after 1880 constitute approximately 43% of the forest cover. Compared to forests established previously, post-1880 forests are situated primarily on steep slopes (>30°), have lower biomass, a more aggregated forest structure (primarily stem-exclusion stage), and have been more strongly affected by fires, but less affected by wind disturbance in the 20th century. More broadly, an increase in growing stock and Europe PMC Funders Group Europe PMC Funders Author ManuscriptsEurope PMC Funders Author Manuscripts expanding forest areas since the mid-19th century have -along with climatic changes -contributed to an increasing frequency and size of disturbances in the Alps. Although many areas remain intensively managed, the extent, structure, and dynamics of the forests of the Alps reflect natural drivers more strongly today than at any time in the past millennium.

No abstract

Variations in the natural C abundance of soil organic matter (SOM) at different depths combined with SOM radiocarbon dating were used to reconstruct the history of the forest-savanna successions over the last millennium in the Gabon coastal area. A chronosequence was established by comparing the δC profiles and the radiocarbon dating of a Gabon savanna with those of a Congolese savanna where the palaeoenvironments are already well known. The palaeoclimatic histories of the two savannas were shown to be strictly identical. The whole Gabon coastal area may well have been forested during the early Holocene, until about 4,000 years ago. The forest fragmented after this initial expansion. Savanna appeared circa 3,000 years ago but the forest did not disappear totally. A new forest transgression started 500-1,000 years ago and expanded over the open areas previously created or enlarged. The marked savanisation and the subsequent and currently ongoing forest expansion explain both the present forest-savanna mosaic and the abundance of secondary species such as Aucoumea klaineana in the coastal forest.Anthropogenic activities over the past decades and centuries have induced local fluctuations in the forest cover, superimposed on the climatic forest-savanna dynamic. This study also confirms that the monospecific, even-aged A. klaineana stands present in the area became established on abandoned cultivation clearings.

Understanding the processes that shape biodiversity patterns is essential for ecosystem management and conservation. Local environmental conditions are often good predictors of species distribution and variations in habitat quality usually positively correlate to species richness. However, beside habitat limitation, species presence-absence may be constrained by dispersal limitation. We tested the relative importance of both limitations on saproxylic beetle diversity, using forest continuity as a surrogate for dispersal limitation and stand maturity as a surrogate for habitat limitation. Forest continuity relies on the maintenance of a forest cover over time, while stand maturity results in the presence of old-growth habitat features. Forty montane beech-fir forests in the French pre-Alps were sampled, under a balanced sampling design in which forest continuity and stand maturity were crossed. A total of 307 saproxylic beetle species were captured using flightinterception traps and Winkler-Berlese extractors. We explored the response of low-versus high-dispersal species groups to forest continuity and stand maturity. Saproxylic beetle diversity increased significantly with stand maturity and was mostly influenced by variables related to deadwood diversity at the stand scale and suitable habitat availability at the landscape scale. Surprisingly, no evidence of dispersal limitation was found, as diversity patterns were not influenced by forest continuity and associated variables, even for low-dispersal species. Our study demonstrates that in an unfragmented forest landscape, saproxylic beetles are able to colonize recent forests, as long as local deadwood resources are sufficiently diversified (e.g. tree species, position, diameter and/or decay stage).

No abstract

No abstract