Soil moisture affects microbial decay of SOM and rhizosphere respiration (RR) in temperate forest soils, but isolating the response of soil respiration (SR) to summer drought and subsequent wetting is difficult because moisture changes are often confounded with temperature variation. We distinguished between temperature and moisture effects by simulation of prolonged soil droughts in a mixed deciduous forest at the Harvard Forest, Massachusetts. Roofs constructed over triplicate 5 \uffc3\uff97 5\uffe2\uff80\uff83m2plots excluded throughfall water during the summers of 2001 (168\uffe2\uff80\uff83mm) and 2002 (344\uffe2\uff80\uff83mm), while adjacent control plots received ambient throughfall and the same natural temperature regime. In 2003, throughfall was not excluded to assess the response of SR under natural weather conditions after two prolonged summer droughts. Throughfall exclusion significantly decreased mean SR rate by 53\uffe2\uff80\uff83mg\uffe2\uff80\uff83C\uffe2\uff80\uff83m\uffe2\uff88\uff922\uffe2\uff80\uff83h\uffe2\uff88\uff921over 84 days in 2001, and by 68\uffe2\uff80\uff83mg\uffe2\uff80\uff83C\uffe2\uff80\uff83m\uffe2\uff88\uff922\uffe2\uff80\uff83h\uffe2\uff88\uff921over 126 days in 2002, representing 10\uffe2\uff80\uff9330% of annual SR in this forest and 35\uffe2\uff80\uff9375% of annual net ecosystem exchange (NEE) of C. The differences in SR were best explained by differences in gravimetric water content in the Oi horizon (r2=0.69) and the Oe/Oa horizon (r2=0.60). Volumetric water content of the A horizon was not significantly affected by throughfall exclusion. The radiocarbon signature of soil CO2efflux and of CO2respired during incubations of O horizon, A horizon and living roots allowed partitioning of SR into contributions from young C substrate (including RR) and from decomposition of older SOM. RR (root respiration and microbial respiration of young substrates in the rhizosphere) made up 43\uffe2\uff80\uff9371% of the total C respired in the control plots and 41\uffe2\uff80\uff9380% in the exclusion plots, and tended to increase with drought. An exception to this trend was an interesting increase in CO2efflux of radiocarbon\uffe2\uff80\uff90rich substrates during a period of abundant growth of mushrooms.
Our results suggest that prolonged summer droughts decrease primarily heterotrophic respiration in the O horizon, which could cause increases in the storage of soil organic carbon in this forest. However, the C stored during two summers of simulated drought was only partly released as increased respiration during the following summer of natural throughfall. We do not know if this soil C sink during drought is transient or long lasting. In any case, differential decomposition of the O horizon caused by interannual variation of precipitation probably contributes significantly to observed interannual variation of NEE in temperate forests.
", "keywords": ["Ecology", "04 agricultural and veterinary sciences", "Biological Sciences", "15. Life on land", "soil respiration", "6. Clean water", "soil drought", "heterotrophic respiration", "rhizosphere respiration", "13. Climate action", "soil organic matter", "temperate forest", "radiocarbon", "0401 agriculture", " forestry", " and fisheries", "soil wetting", "soil moisture", "Q(10)", "Environmental Sciences"]}, "links": [{"href": "https://escholarship.org/content/qt3mk9v58k/qt3mk9v58k.pdf"}, {"href": "https://doi.org/10.1111/j.1365-2486.2005.001058.x"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Global%20Change%20Biology", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1111/j.1365-2486.2005.001058.x", "name": "item", "description": "10.1111/j.1365-2486.2005.001058.x", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1111/j.1365-2486.2005.001058.x"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2005-11-28T00:00:00Z"}}, {"id": "10.1111/j.1365-2486.2009.02121.x", "type": "Feature", "geometry": null, "properties": {"updated": "2026-04-13T16:19:34Z", "type": "Journal Article", "created": "2009-12-22", "title": "Functional Changes In The Control Of Carbon Fluxes After 3 Years Of Increased Drought In A Mediterranean Evergreen Forest?", "description": "AbstractOur objective was to test how a long\uffe2\uff80\uff90term increased water limitation affects structural and functional properties of a Mediterranean ecosystem, and how these changes modify the response of the main carbon fluxes to climatic controls. In 2003, a 27% throughfall exclusion experiment was installed in a Quercus ilex L. forest in France. Gross primary production (GPP), ecosystem respiration (RECO) and net ecosystem exchange (NEE) were estimated in a control and a dry treatment. Decreasing throughfall decreased GPP by 14% and had a smaller effect on RECO (\uffe2\uff88\uff9212%), especially soil respiration RS (\uffe2\uff88\uff9211%). Interannual variability of GPP (29%) was higher than for RECO (12%). Error propagation was used to estimates uncertainties in the NEE fluxes, which ranged from 3% to 10% in the control treatment but up to 167% for NEE in the dry treatment because more steps and data types were involved in the scaling. After 3 years of throughfall exclusion, we found no acclimation of RS to climatic drivers. Functional properties of the response of RS to soil water, temperature and rain pulse remained similar in the control and the dry treatments. A diurnal clockwise hysteresis in RS was probably controlled by canopy photosynthesis with a 3\uffe2\uff80\uff83h lag. The proportion of diurnal variation of respiration due to photosynthesis was similar in all treatments (4\uffe2\uff80\uff935%). Because of the characteristic of rain in Mediterranean climates, a continuous decrease of water input in these environments have an effect on topsoil water and consequently on RS only during short periods when rainfall is characterized by infrequent and small events that does not allow the topsoil to reach field capacity and does not allow to dry completely. However, in the longer term, we expect a stronger decrease in RS in the dry treatment driven by the decrease in GPP.
", "keywords": ["0106 biological sciences", "550", "15. Life on land", "gross primary production", "soil respiration", "01 natural sciences", "630", "6. Clean water", "Quercus ilex", "throughfall exclusion", "13. Climate action", "rain pulse", "eddy-covariance", "Q(10)", "error propagation", "0105 earth and related environmental sciences"]}, "links": [{"href": "https://doi.org/10.1111/j.1365-2486.2009.02121.x"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Global%20Change%20Biology", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1111/j.1365-2486.2009.02121.x", "name": "item", "description": "10.1111/j.1365-2486.2009.02121.x", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1111/j.1365-2486.2009.02121.x"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2010-08-01T00:00:00Z"}}], "links": [{"rel": "self", "type": "application/geo+json", "title": "This document as GeoJSON", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items?keywords=Q%2810%29&f=json", "hreflang": "en-US"}, {"rel": "alternate", "type": "text/html", "title": "This document as HTML", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items?keywords=Q%2810%29&f=html", "hreflang": "en-US"}, {"rel": "collection", "type": "application/json", "title": "Collection URL", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main", "hreflang": "en-US"}, {"type": "application/geo+json", "rel": "first", "title": "items (first)", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items?keywords=Q%2810%29&", "hreflang": "en-US"}, {"rel": "last", "type": "application/geo+json", "title": "items (last)", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items?keywords=Q%2810%29&offset=2", "hreflang": "en-US"}], "numberMatched": 2, "numberReturned": 2, "distributedFeatures": [], "timeStamp": "2026-04-14T23:22:21.157530Z"}