Richard Chevalier

Contribution of forest management artefacts to plant diversity at a forest scale

Abstract• IntroductionMost temperate forests are managed for wood production, and some forestry practices generate typical environmental features such as roads, paths, ditches and tractor ruts, which are likely to affect forest species distribution.• MethodsWe studied the influence of forestry artefacts on the overall forest-understory plant diversity in an ancient oak-dominated French forest with a long history of management. Two designs (grid design and paired design) were built in order to record the occurrence frequency of artefacts and to estimate the originality of the plant assemblage that they host.• ResultsWe recorded 897 plots on the grid design: 68.3% of the plots were more than 4 m away from any artefact, 23.3% were within 4 m of an artefact and 8.4% were located on an artefact. The artefact contribution to total floristic richness would lie between 8.0% and 22.6%, depending on whether the artefact surroundings were included or not in the artefact contribution. Road verges were the least frequent artefacts but provided the richest contribution to overall plant diversity (82%), whereas paths were the poorest (with only a 42% contribution). Thirteen species appeared to prefer artefacts over control plots: six forest species, five non-forest species and two generalist species.• DiscussionWe show that forestry artefacts are key components of the floristic diversity in managed forests; therefore, forest management should take them into consideration.

Effet de l’exposition sur la richesse et la composition floristique des lisières forestières dans le Gâtinais oriental (Loiret)

Les lisières forestières marquent la limite de la forêt, le terme de forêt désignant par convention une association d’arbres formés de troncs et de houppiers d’une hauteur d’au moins 5 m constituant une unité physionomique (Otto, 1998). Elles forment une zone de transition entre l’environnement relativement stable de la forêt et les larges fluctuations microclimatiques du milieu ouvert adjacent (Chen et al., 1995) qui, dans les paysages ruraux, est souvent anthropisé (cultures, prairies...). Ainsi, les conditions environnementales (température, humidité de l’air et du sol) mais aussi la structure et la composition de la végétation sont modifiées dans l’environnement proche des lisières. Ces modifications sont appelées « effet de lisière » (Murcia, 1995 ; Ries et al., 2004). Des études montrent que ces modifications s’observent en général jusqu’à 20 m de part et d’autre de la lisière (Cadenasso et al., 1997) mais peuvent atteindre parfois plusieurs centaines de mètres à l’intérieur de la forêt (Chen et al., 1995 ; Ries et al. 2004 ; Pellissier et al., 2013).

LE CONCEPT DE FORÊT ANCIENNE S’APPLIQUE-T-IL AUX PEUPLERAIES CULTIVÉES ? TEST DE PERTINENCE AVEC LA FLORE DES VALLÉES DE CHAMPAGNE

This study aims to establish whether the concept of “ancient forest” can be applied to the case of poplar plantations. To answer this question, we used 107 phytoecological survey points in poplar plantations and subnatural forests located in the large valleys of the Champagne area. In addition, we examined: — the plots’ past land uses, from Ordnance Survey maps from 1830-40 (1/40 000 scale) and several aerial photographs from 1950 to now, — ancient forest plants listed by Hermy et al. (1999) and Dupouey et al. (2002). Conventional poplar plantations, both historically forested and not, cannot be distinguished on the basis of their wealth of ancient forest species, whereas ancient subnatural forests host significantly more ancient forest plants than recent subnatural forests. Hence, poplar plantations cannot be investigated in the same way as ancient forests. From a more general point of view, these results lead us to think that reforestation projects implying heavy soil disturbances can alter the ancient forest status to various degrees. Thus, beyond the particular case of poplar plantations, we need to study the impact of reforestation practices on the ancient forest flora. In the meantime, we suggest that reforestation of ancient subnatural forests with plantations should be avoided, or at least, be performed using the least invasive methods for forest ecosystem

Impact des routes forestières sur la biodiversité floristique : synthèse de trois études menées en forêt de plaine

Three studies conducted in two State forests (Orleans and Montargis) highlight the multiple roles played by forest roads in relation to plant biodiversity: roadsides provide habitats for non-forest species but are detrimental to some forest species. Protected species and neophytes species are also found on roadsides. Two areas of concern are highlighted: (1) the forest paths opened for regeneration felling and harvesting machine traffic that increase the span of the road effect up to 60 m by facilitating introductions of non-forest species in the interior of forest stands and pushing forest species much further from the road; (2) the use of limestone gravel for road improvement in a native nutrient-poor environment increases soil pH and is detrimental to acidophilic species. To protect forest soil and plant biodiversity, we recommend reducing reconsidering the density of forest roads and forest paths and using road materials that do not modify the pH of the adjacent forest soils.

Biodiversité floristique dans les peupleraies cultivées de Champagne-Ardenne

This article essentially presents findings in the area of floristic biodiversity associated with poplar plantations in the large valleys of the Champagne area as compared to those in meadows and sub-natural forests. In addition to the current use of the soil, this study considers various factors of variation for poplar stands such as age, the presence of an understory and cropping history. The strongest effects relate to the age of the poplar stand and the presence or absence of an understory. The poplar stands of Champagne-Ardenne show significant floristic biodiversity due to their rapid dynamics (‘nested’ succession) and the divergences of plant communities depending on whether or not an understory is present. Poplar stands that have an understory are more favourable to forest communities, while poplars stands with no understory are more favourable to the flora typical of magnophorba.