The effect of forest fragmentation on aboveground carbon stocks and tree diversity: a case study of the Montérégie, Québec
Notice bibliographique
Résumé
Habitat fragmentation is ubiquitous in temperate forests, and affects ecosystem functions and services through decreased area, increased isolation, and greater exposure to forest edges. While fragmentation has been extensively studied, the effect of fragmentation on the relationship between biodiversity and ecosystem services is not well documented or understood. Alterations to forest fragment size and connectivity are increasingly linked to changes in ecosystem function via changes to dispersal patterns and other spatial processes. However, whether or not these functional implications of fragmentation extend to carbon storage, and thus the ability of a forested landscape to regulate climate, is uncertain, especially in temperate systems. In this thesis, I investigated the effects of forest fragment size, isolation, and management intensity on the relationship between aboveground carbon (AGC) stocks and tree biodiversity in 24 small forest fragments in the Montérégie, QC. I also examined whether forest edge effects influenced AGC stocks and tree species composition. I found that forest fragments in the Montérégie differed with respect to AGC stocks, and that these differences were mediated by functional diversity, forest management, and connectivity. Unmanaged fragments stored less carbon on average than managed, but demonstrated a significant positive relationship between functional diversity and AGC stocks, with the slope of the relationship significantly greater in connected fragments than isolated. Small (10ha) fragments performed on par with their larger (100ha) counterparts. Managed stands exhibited a negative relationship between functional diversity and AGC stocks, demonstrating that anthropogenic influence can alter the link between biodiversity and AGC stocks in forested systems. Contrary to observations in tropical forests, proximity to the forest edge did not alter AGC stocks; rather, AGC stocks remained constant across a 100m edge to interior gradient in forest fragments of all types, despite changes in tree community composition and relative abundance consistent with expectations of forest edge effects. My results suggest that taking into account aspects of forest heterogeneity, such as structural connectivity, and gradients in diversity and management intensity may increase accuracy in estimating landscape level carbon stocks. Additionally, these results have implications for conservation. Like many other peri-urban, agricultural areas in North America, the Montérégie contains a high number of small forest fragments, likely to increase as fragmentation becomes more prevalent with development. The ecological importance of small fragments is often questioned. Here, I show that small forest fragments are likely to demonstrate "win-win" conservation scenarios with respect to AGC stocks and tree biodiversity, and that AGC stocks are constant across even very small and irregularly shaped fragments. If we consider the number of small forest fragments throughout this region, combined with their contributions to regional biodiversity and service provision, it is clear that the continued loss of small forest fragments in the Montérégie would be to the detriment of conservation efforts.
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,001 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,001 |
| Études des sciences et des technologies | 0,002 | 0,001 |
| Communication savante | 0,001 | 0,000 |
| Science ouverte | 0,001 | 0,001 |
| Intégrité de la recherche | 0,000 | 0,001 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».