Plant diversity on skid trails in oak high forests: a matter of disturbance, micro-environmental conditions or forest age?
Diversité floristique sur les cloisonnements de futaies de chêne: est-elle associée à la perturbation, au micro-environnement ou à l'âge du peuplement?
Résumé
Increasingly mechanized timber harvesting and the repeated use of skid trail networks may affect ground vegetation differently at subsequent stages in the forest rotation. At a fine scale, no studies have yet compared the influence of micro-environmental factors and the effects of skid trail disturbance on ground flora diversity. We investigated understory diversity patterns on skid trails in 30-, 50- and 63-year-old oak forests in the northern half of France. Subplots were placed on skid trail center, wheel track, skid trail edge plus an off-trail control. At each subplot, we measured soil moisture, soil compaction (penetration resistance and bulk density) and photosynthetic active radiation and recorded the abundance of all vascular plants. The richness and abundance of ground flora were calculated based on the classification of their life form, seed bank persistence, light preference and moisture requirements. For each ecological group, we found out its best diversity indicator from subplot location, micro-environmental factors (soil moisture and compaction, light) and stand attributes (stand type, basal area), then assessed the magnitude and negligibility of the effect of the best indicator. (1) Higher soil compaction compared to controls was detected on the tracks of skid trails in the 50- and 63-year-old stands. Neither soil moisture nor light varied with subplot location whatever the stand type. (2) The best diversity indicator that showed non-negligible effects included subplot location, and soil moisture or soil compaction. Compared to controls, skid trails in the 50- and 63-year-old stands were richer in tree and short-term seed bank species, while skid trails in the 30-year-old plots had no effect on ground flora. The abundance of tree and shade-tolerant species was also higher on skid trails. Soil moisture was positively correlated with the richness of low- and high-humidity species, shade-tolerant species and transient seed bank species as well as with the abundance of short-term seed bank species. Bulk density positively affected heliophilous species richness, while penetration resistance was positively related to shrub abundance. Skid trails and soil compaction in our research area had either no impact or a positive impact on ground flora diversity. Longer-term studies of skid trail effects are needed to validate these main findings.
Mots clés
BIODIVERSITY
FORESTS
PLAINS
FOREST STANDS
STAND STRUCTURE
FLORA
UNDERGROWTH
FOREST EXPLOITATION
SOIL WATER CONTENT
SOIL COMPACTION
LIGHT
SOIL DENSITY
MECHANIZATION
MODELS
MODELE
MECANISATION
DENSITE DU SOL
TYPE DE PEUPLEMENT
PERTURBATION ANTHROPIQUE
CLOISONNEMENT D'EXPLOITATION
LUMIERE
COMPACTAGE DU SOL
HUMIDITE DU SOL
BIODIVERSITE
FORET
PLAINE
PEUPLEMENT FORESTIER
CLOISONNEMENT
STRUCTURE DU PEUPLEMENT
FLORE
SOUS BOIS
EXPLOITATION FORESTIERE
RICHESSE FLORISTIQUE
ABONDANCE FLORISTIQUE
Domaines
Sciences de l'environnement
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no2015-pub00043118.pdf (1.56 Mo)
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NO2015-PUB00043118_s1.pdf (318.12 Ko)
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