COMPARISON OF SOIL RESPIRATION IN BROAD-LEAVED KOREAN PINE FOREST AND RECLAIMED CROPLAND IN CHANGBAI MOUNTAINS, CHINA
Notice bibliographique
Résumé
Background and Aims Soil respiration is a major flux in the global carbon cycle. A small change in soil respiration may result in a large increase of atmospheric CO_2. Land conversion has the greatest impact on the terrestrial ecosystems among the components of global change, but the effects on soil respiration are inadequately understood. Our objective was to examine the response of soil respiration to conversion from forests to agricultural lands, using broad_leaved Korean pine forest and reclaimed cropland in the Changbai Mountains. Methods We used an Infra_red Gas Analyser (IGA) linked to a 50 cm×50 cm×15 cm chamber without a bottom. Three 50 cm×50 cm steel frames were inserted to a soil depth of 3-5 cm in randomly selected plots one day prior to measurement. When measuring, the chamber was put on the steel frame to make a closed container capturing CO_2 from the soil surface and piping the gas of chamber through the IGA. We repeated measurements every 15 days during the growing seasons from 2003 to 2005. Key Results Diurnal and seasonal variations of soil respiration were mainly affected by soil temperatures. Soil respiration rate reached a maximum around noon in cropland plots, about six hours earlier than that in forest plots. Minimum rates occurred at 5∶00 am in cropland plots and 7∶00-8∶00 am in forest plots. Diurnal variations were driven mostly by temperature. During the growing season, soil respiration had a statistically significant exponential relationship with soil temperatures at 5 cm depth, but was weakly correlated with soil volumetric water contents at 10 cm depth. Although soil temperatures in cropland plots were higher than those in forest plots, soil CO_2 efflux in forest was about twice that in cropland during the growing season (May to September). During the period of measurement, soil respiration rate of cropland ranged from 23.4% to 76.3% that of forest. Therefore, vegetation types were another factor affecting soil respiration due to the change of land_use. Q_ 10 values of soil respiration averaged 2.92 for forest plots and 3.07 for cropland plots, which may be overestimated. Conclusions Differences in soil respiration rates and patterns between forests and croplands result from changes in abiotic and biotic factors, including soil physicochemical properties, due to land_use change.
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Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| 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 | 0,001 |
| 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 tête enseignante, 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 ».