Flooding tolerance of native and nonnative grasses: Variation in photosynthesis, transpiration, respiration, and carbon isotope discrimination
Notice bibliographique
Résumé
Invasion by nonnative plants is particularly prevalent in wetlands. While the ecological patterns in wetland plants are well known, it is less well known how flooding-related soil conditions influence the physiological success of introduced species in wetlands. In chapter 1, effects of flooding were measured in invasive common reed (Phragmites australis), reed canary grass (Phalaris arundinacea), Johnson grass (Sorghum halepense), and native prairie cordgrass (Spartina pectinata). The four species were kept at four levels of flooding (deep flooding, medium flooding, low flooding, and dry conditions), and their responses were measured after 7 and 28 days of treatment using by a Li-Cor LI-6400 photosynthesis and fluorescence system. Measurements included light harvesting abilities, CO2 fixation rates, leaf carbon isotope ratios, and root anaerobic enzyme activities. CO2 fixation and light harvesting abilities in Phragmites were maximized at deep flooding conditions whereas they were maximized in Phalaris at medium flooding conditions. Light harvesting abilities in Sorghum were maximized at deep flooding conditions after 7 days. However, at 28 days most of the Sorghum had died. Native Spartina had the lowest light harvesting and CO2 fixation abilities after 7 days of flooding. After 28 days of flooding, light harvesting abilities of Spartina were maximized at deep flooding levels, but the rates were lower than Phragmites. In chapter 2, flooding-sensitive Sorghum halepense and flooding-tolerant Phragmites australis (n=5) were flooded to 8 cm depth or kept dry for 7 days. Transpiration, stomatal conductance, boundary layer conductance, and vapor conductance were measured for each. Transpiration was significantly higher in drained treatments compared to flooded treatments for Sorghum. However, transpiration was significantly higher in flooded treatments compared to drained treatments for Phragmites. Thus, there was a significant species x treatment interaction in transpiration. A similar interaction was detected in both stomatal and vapor conductances. Phragmites had increased stomatal conductance when flooded, which indicated a high physiological tolerance to waterlogged soils. This allowed Phragmites to photosynthesize under waterlogged conditions and to be successful as wetland invaders. Further information on the conditions that maximize stomatal opening for Phragmites can help management efforts. By contrast, stomatal conductance in Sorghum was decreased under flooding, indicating a greater sensitivity to flooding. The sampled population of Sorghum is therefore not a threat to invade chronically flooded soils based on these results. Additional work will be needed to test the ability of Sorghum to acclimate to wet environments. Increased photosynthesis rates under flooded conditions, especially in short-term flooding, might help invasive grasses to invade wetland settings.
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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 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 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 ».