Changes
On February 18, 2023 at 4:54:43 AM UTC, Anita Risch:
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Updated description of Drivers of the microbial metabolic quotient across global grasslands from
This dataset contains all data on which the following publication below is based. Paper Citation: Risch Anita C., Zimmermann, Stefan, Moser, Martin, Borer, Elizabeth T., Broadbent, Arthur A.D., Caldeira, Maria C., Davies, Kendi F., Eisenhauer, Nico, Eskelinen, Anu, Fay, Philip A., Hagedorn, Frank, Knops, Johannes M.H., Lembrechts, Jonas, J., MacDougall, Andrew S., McCulley, Rebecca L., Melbourne, Brett A., Moore, Joslin L., Power, Sally A., Seabloom, Eric W., Siebert, Julia, Silveira, Maria L., Virtanen, Risto, Yahdjian, Laura, Ochoa-Hueso, Raul (accepted). Drivers of the microbial metabolic quotient across global grasslands. Global Ecology and Biogeography Please cite this paper together with the citation for the datafile. The microbial metabolic quotient (MMQ; mg CO2-C mg MBC-1 h-1), defined as the amount of microbial CO2 respired (MR; mg CO2-C kg soil-1 h-1) per unit of microbial biomass C (MBC; mg C kg soil-1), is a key parameter for understanding the microbial regulation of the carbon (C) cycle, including soil C sequestration. Here, we experimentally tested hypotheses about the individual and interactive effects of multiple nutrient addition (NPK+micronutrients) and herbivore exclusion on MR, MBC, and MMQ across 23 sites (5 continents). Our sites encompassed a wide range of edaphoclimatic conditions, thus we assessed which edaphoclimatic variables affected MMQ the most and how they interacted with our treatments. Soils were collected in plots with established experimental treatments. MR was assessed in a five-week laboratory incubation without glucose addition, MBC via substrate-induced respiration. MMQ was calculated as MR/MBC and corrected for soil temperatures (MMQsoil). Using LMMs and SEMs, we analysed how edaphoclimatic characteristics and treatments interactively affected MMQsoil. MMQsoil was higher in locations with higher mean annual temperature, lower water holding capacity, and soil organic C concentration, but did not respond to our treatments across sites as neither MR nor MBC changed. We attributed this relative homeostasis to our treatments to the modulating influence of edaphoclimatic variables. For example, herbivore exclusion, regardless of fertilization, led to greater MMQsoil only at sites with lower soil organic C (<1.7%). Our results pinpoint the main variables related to MMQsoil across grasslands and emphasize the importance of the local edaphoclimatic conditions in controlling the response of the C cycle to anthropogenic stressors. By testing hypotheses about MMQsoil across global edaphoclimatic gradients, this work also helps to align the conflicting results of prior studies.
toThis dataset contains all data on which the following publication below is based. Paper Citation: Risch Anita C., Zimmermann, Stefan, Schütz, Martin, Borer, Elizabeth T., Broadbent, Arthur A.D., Caldeira, Maria C., Davies, Kendi F., Eisenhauer, Nico, Eskelinen, Anu, Fay, Philip A., Hagedorn, Frank, Knops, Johannes M.H., Lembrechts, Jonas, J., MacDougall, Andrew S., McCulley, Rebecca L., Melbourne, Brett A., Moore, Joslin L., Power, Sally A., Seabloom, Eric W., Silveira, Maria L., Virtanen, Risto, Yahdjian, Laura, Ochoa-Hueso, Raul (accepted). Drivers of the microbial metabolic quotient across global grasslands. Global Ecology and Biogeography Please cite this paper together with the citation for the datafile. The microbial metabolic quotient (MMQ; mg CO2-C mg MBC-1 h-1), defined as the amount of microbial CO2 respired (MR; mg CO2-C kg soil-1 h-1) per unit of microbial biomass C (MBC; mg C kg soil-1), is a key parameter for understanding the microbial regulation of the carbon (C) cycle, including soil C sequestration. Here, we experimentally tested hypotheses about the individual and interactive effects of multiple nutrient addition (NPK+micronutrients) and herbivore exclusion on MR, MBC, and MMQ across 23 sites (5 continents). Our sites encompassed a wide range of edaphoclimatic conditions, thus we assessed which edaphoclimatic variables affected MMQ the most and how they interacted with our treatments. Soils were collected in plots with established experimental treatments. MR was assessed in a five-week laboratory incubation without glucose addition, MBC via substrate-induced respiration. MMQ was calculated as MR/MBC and corrected for soil temperatures (MMQsoil). Using LMMs and SEMs, we analysed how edaphoclimatic characteristics and treatments interactively affected MMQsoil. MMQsoil was higher in locations with higher mean annual temperature, lower water holding capacity, and soil organic C concentration, but did not respond to our treatments across sites as neither MR nor MBC changed. We attributed this relative homeostasis to our treatments to the modulating influence of edaphoclimatic variables. For example, herbivore exclusion, regardless of fertilization, led to greater MMQsoil only at sites with lower soil organic C (<1.7%). Our results pinpoint the main variables related to MMQsoil across grasslands and emphasize the importance of the local edaphoclimatic conditions in controlling the response of the C cycle to anthropogenic stressors. By testing hypotheses about MMQsoil across global edaphoclimatic gradients, this work also helps to align the conflicting results of prior studies.
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Changed value of field
related_publications
toRisch Anita C., Zimmermann, Stefan, Schütz, Martin, Borer, Elizabeth T., Broadbent, Arthur A.D., Caldeira, Maria C., Davies, Kendi F., Eisenhauer, Nico, Eskelinen, Anu, Fay, Philip A., Hagedorn, Frank, Knops, Johannes M.H., Lembrechts, Jonas, J., MacDougall, Andrew S., McCulley, Rebecca L., Melbourne, Brett A., Moore, Joslin L., Power, Sally A., Seabloom, Eric W., Silveira, Maria L., Virtanen, Risto, Yahdjian, Laura, Ochoa-Hueso, Raul (accepted). Drivers of the microbial metabolic quotient across global grasslands. Global Ecology and Biogeography
in Drivers of the microbial metabolic quotient across global grasslands
f | 1 | { | f | 1 | { |
2 | "author": "[{\"affiliation\": \"Swiss Federal Institute for Forest, | 2 | "author": "[{\"affiliation\": \"Swiss Federal Institute for Forest, | ||
3 | Snow and Landscape Research WSL\", \"affiliation_02\": \"\", | 3 | Snow and Landscape Research WSL\", \"affiliation_02\": \"\", | ||
4 | \"affiliation_03\": \"\", \"data_credit\": [\"collection\", | 4 | \"affiliation_03\": \"\", \"data_credit\": [\"collection\", | ||
5 | \"validation\", \"curation\", \"publication\"], \"email\": | 5 | \"validation\", \"curation\", \"publication\"], \"email\": | ||
6 | \"anita.risch@wsl.ch\", \"given_name\": \"Anita C.\", \"identifier\": | 6 | \"anita.risch@wsl.ch\", \"given_name\": \"Anita C.\", \"identifier\": | ||
7 | \"\", \"name\": \"Risch\"}]", | 7 | \"\", \"name\": \"Risch\"}]", | ||
8 | "author_email": null, | 8 | "author_email": null, | ||
9 | "creator_user_id": "d30dde41-6b11-44de-9191-23cdd5bda0e9", | 9 | "creator_user_id": "d30dde41-6b11-44de-9191-23cdd5bda0e9", | ||
10 | "date": "[{\"date\": \"2015-04-01\", \"date_type\": \"collected\", | 10 | "date": "[{\"date\": \"2015-04-01\", \"date_type\": \"collected\", | ||
11 | \"end_date\": \"2016-12-31\"}]", | 11 | \"end_date\": \"2016-12-31\"}]", | ||
12 | "doi": "10.16904/envidat.379", | 12 | "doi": "10.16904/envidat.379", | ||
13 | "funding": "[{\"grant_number\": \"\", \"institution\": \"WSL | 13 | "funding": "[{\"grant_number\": \"\", \"institution\": \"WSL | ||
14 | internal competitive grant\", \"institution_url\": \"\"}, | 14 | internal competitive grant\", \"institution_url\": \"\"}, | ||
15 | {\"grant_number\": \"NSF-DEB-1042132\", \"institution\": \"National | 15 | {\"grant_number\": \"NSF-DEB-1042132\", \"institution\": \"National | ||
16 | Science Foundation Research Coordination Network\", | 16 | Science Foundation Research Coordination Network\", | ||
17 | \"institution_url\": \"\"}, {\"grant_number\": \"NSF-DEB-1234162 to | 17 | \"institution_url\": \"\"}, {\"grant_number\": \"NSF-DEB-1234162 to | ||
18 | Cedar Creek LTER\", \"institution\": \"Long Term Ecological Research | 18 | Cedar Creek LTER\", \"institution\": \"Long Term Ecological Research | ||
19 | \", \"institution_url\": \"\"}, {\"grant_number\": \"DG-0001-13\", | 19 | \", \"institution_url\": \"\"}, {\"grant_number\": \"DG-0001-13\", | ||
20 | \"institution\": \"Institute on the Environment\", | 20 | \"institution\": \"Institute on the Environment\", | ||
21 | \"institution_url\": \"\"}, {\"grant_number\": \"UID/AGR/00239/2019\", | 21 | \"institution_url\": \"\"}, {\"grant_number\": \"UID/AGR/00239/2019\", | ||
22 | \"institution\": \"CEF, a research unit funded by FCT, Portugal\", | 22 | \"institution\": \"CEF, a research unit funded by FCT, Portugal\", | ||
23 | \"institution_url\": \"\"}, {\"grant_number\": \"FZT 118, 202548816\", | 23 | \"institution_url\": \"\"}, {\"grant_number\": \"FZT 118, 202548816\", | ||
24 | \"institution\": \"German Research Foundation\", \"institution_url\": | 24 | \"institution\": \"German Research Foundation\", \"institution_url\": | ||
25 | \"\"}]", | 25 | \"\"}]", | ||
26 | "groups": [], | 26 | "groups": [], | ||
27 | "id": "679bdff7-9fb3-4704-be93-8add5cb206ba", | 27 | "id": "679bdff7-9fb3-4704-be93-8add5cb206ba", | ||
28 | "isopen": true, | 28 | "isopen": true, | ||
29 | "language": "en", | 29 | "language": "en", | ||
30 | "license_id": "odc-odbl", | 30 | "license_id": "odc-odbl", | ||
31 | "license_title": "ODbL with Database Contents License (DbCL)", | 31 | "license_title": "ODbL with Database Contents License (DbCL)", | ||
32 | "license_url": "https://opendefinition.org/licenses/odc-odbl", | 32 | "license_url": "https://opendefinition.org/licenses/odc-odbl", | ||
33 | "maintainer": "{\"affiliation\": \"Swiss Federal Institute for | 33 | "maintainer": "{\"affiliation\": \"Swiss Federal Institute for | ||
34 | Forest, Snow and Landscape Research WSL\", \"email\": | 34 | Forest, Snow and Landscape Research WSL\", \"email\": | ||
35 | \"anita.risch@wsl.ch\", \"given_name\": \"Anita C\", \"identifier\": | 35 | \"anita.risch@wsl.ch\", \"given_name\": \"Anita C\", \"identifier\": | ||
36 | \"\", \"name\": \"Risch\"}", | 36 | \"\", \"name\": \"Risch\"}", | ||
37 | "maintainer_email": null, | 37 | "maintainer_email": null, | ||
38 | "metadata_created": "2023-02-18T03:38:29.406811", | 38 | "metadata_created": "2023-02-18T03:38:29.406811", | ||
n | 39 | "metadata_modified": "2023-02-18T03:43:08.266873", | n | 39 | "metadata_modified": "2023-02-18T04:54:43.151766", |
40 | "name": | 40 | "name": | ||
41 | drivers-of-the-microbial-metabolic-quotient-across-global-grasslands", | 41 | drivers-of-the-microbial-metabolic-quotient-across-global-grasslands", | ||
42 | "notes": "This dataset contains all data on which the following | 42 | "notes": "This dataset contains all data on which the following | ||
43 | publication below is based.\r\n\r\nPaper Citation:\r\n\r\nRisch Anita | 43 | publication below is based.\r\n\r\nPaper Citation:\r\n\r\nRisch Anita | ||
n | 44 | C., Zimmermann, Stefan, Moser, Martin, Borer, Elizabeth T., Broadbent, | n | 44 | C., Zimmermann, Stefan, Sch\u00fctz, Martin, Borer, Elizabeth T., |
45 | Arthur A.D., Caldeira, Maria C., Davies, Kendi F., Eisenhauer, Nico, | 45 | Broadbent, Arthur A.D., Caldeira, Maria C., Davies, Kendi F., | ||
46 | Eskelinen, Anu, Fay, Philip A., Hagedorn, Frank, Knops, Johannes M.H., | 46 | Eisenhauer, Nico, Eskelinen, Anu, Fay, Philip A., Hagedorn, Frank, | ||
47 | Lembrechts, Jonas, J., MacDougall, Andrew S., McCulley, Rebecca L., | 47 | Knops, Johannes M.H., Lembrechts, Jonas, J., MacDougall, Andrew S., | ||
48 | Melbourne, Brett A., Moore, Joslin L., Power, Sally A., Seabloom, Eric | 48 | McCulley, Rebecca L., Melbourne, Brett A., Moore, Joslin L., Power, | ||
49 | W., Siebert, Julia, Silveira, Maria L., Virtanen, Risto, Yahdjian, | 49 | Sally A., Seabloom, Eric W., Silveira, Maria L., Virtanen, Risto, | ||
50 | Laura, Ochoa-Hueso, Raul (accepted). Drivers of the microbial | 50 | Yahdjian, Laura, Ochoa-Hueso, Raul (accepted). Drivers of the | ||
51 | metabolic quotient across global grasslands. Global Ecology and | 51 | microbial metabolic quotient across global grasslands. Global Ecology | ||
52 | Biogeography\r\n\r\nPlease cite this paper together with the citation | 52 | and Biogeography\r\n\r\nPlease cite this paper together with the | ||
53 | for the datafile.\r\n\r\nThe microbial metabolic quotient (MMQ; mg | 53 | citation for the datafile.\r\n\r\nThe microbial metabolic quotient | ||
54 | CO2-C mg MBC-1 h-1), defined as the amount of microbial CO2 respired | 54 | (MMQ; mg CO2-C mg MBC-1 h-1), defined as the amount of microbial CO2 | ||
55 | (MR; mg CO2-C kg soil-1 h-1) per unit of microbial biomass C (MBC; mg | 55 | respired (MR; mg CO2-C kg soil-1 h-1) per unit of microbial biomass C | ||
56 | C kg soil-1), is a key parameter for understanding the microbial | 56 | (MBC; mg C kg soil-1), is a key parameter for understanding the | ||
57 | regulation of the carbon (C) cycle, including soil C sequestration. | 57 | microbial regulation of the carbon (C) cycle, including soil C | ||
58 | Here, we experimentally tested hypotheses about the individual and | 58 | sequestration. Here, we experimentally tested hypotheses about the | ||
59 | interactive effects of multiple nutrient addition (NPK+micronutrients) | 59 | individual and interactive effects of multiple nutrient addition | ||
60 | and herbivore exclusion on MR, MBC, and MMQ across 23 sites (5 | 60 | (NPK+micronutrients) and herbivore exclusion on MR, MBC, and MMQ | ||
61 | continents). Our sites encompassed a wide range of edaphoclimatic | 61 | across 23 sites (5 continents). Our sites encompassed a wide range of | ||
62 | conditions, thus we assessed which edaphoclimatic variables affected | 62 | edaphoclimatic conditions, thus we assessed which edaphoclimatic | ||
63 | MMQ the most and how they interacted with our treatments. Soils were | 63 | variables affected MMQ the most and how they interacted with our | ||
64 | collected in plots with established experimental treatments. MR was | 64 | treatments. Soils were collected in plots with established | ||
65 | assessed in a five-week laboratory incubation without glucose | 65 | experimental treatments. MR was assessed in a five-week laboratory | ||
66 | addition, MBC via substrate-induced respiration. MMQ was calculated as | 66 | incubation without glucose addition, MBC via substrate-induced | ||
67 | MR/MBC and corrected for soil temperatures (MMQsoil). Using LMMs and | 67 | respiration. MMQ was calculated as MR/MBC and corrected for soil | ||
68 | SEMs, we analysed how edaphoclimatic characteristics and treatments | 68 | temperatures (MMQsoil). Using LMMs and SEMs, we analysed how | ||
69 | interactively affected MMQsoil. MMQsoil was higher in locations with | 69 | edaphoclimatic characteristics and treatments interactively affected | ||
70 | MMQsoil. MMQsoil was higher in locations with higher mean annual | ||||
70 | higher mean annual temperature, lower water holding capacity, and soil | 71 | temperature, lower water holding capacity, and soil organic C | ||
71 | organic C concentration, but did not respond to our treatments across | 72 | concentration, but did not respond to our treatments across sites as | ||
72 | sites as neither MR nor MBC changed. We attributed this relative | 73 | neither MR nor MBC changed. We attributed this relative homeostasis to | ||
73 | homeostasis to our treatments to the modulating influence of | 74 | our treatments to the modulating influence of edaphoclimatic | ||
74 | edaphoclimatic variables. For example, herbivore exclusion, regardless | 75 | variables. For example, herbivore exclusion, regardless of | ||
75 | of fertilization, led to greater MMQsoil only at sites with lower soil | 76 | fertilization, led to greater MMQsoil only at sites with lower soil | ||
76 | organic C (<1.7%). Our results pinpoint the main variables related to | 77 | organic C (<1.7%). Our results pinpoint the main variables related to | ||
77 | MMQsoil across grasslands and emphasize the importance of the local | 78 | MMQsoil across grasslands and emphasize the importance of the local | ||
78 | edaphoclimatic conditions in controlling the response of the C cycle | 79 | edaphoclimatic conditions in controlling the response of the C cycle | ||
79 | to anthropogenic stressors. By testing hypotheses about MMQsoil across | 80 | to anthropogenic stressors. By testing hypotheses about MMQsoil across | ||
80 | global edaphoclimatic gradients, this work also helps to align the | 81 | global edaphoclimatic gradients, this work also helps to align the | ||
81 | conflicting results of prior studies. \r\n", | 82 | conflicting results of prior studies. \r\n", | ||
82 | "num_resources": 1, | 83 | "num_resources": 1, | ||
83 | "num_tags": 7, | 84 | "num_tags": 7, | ||
84 | "organization": { | 85 | "organization": { | ||
85 | "approval_status": "approved", | 86 | "approval_status": "approved", | ||
86 | "created": "2018-04-20T09:51:26.756810", | 87 | "created": "2018-04-20T09:51:26.756810", | ||
87 | "description": "We are studying the distribution of and | 88 | "description": "We are studying the distribution of and | ||
88 | interactions among producers, consumers as well as decomposers and | 89 | interactions among producers, consumers as well as decomposers and | ||
89 | between these communities and their environment. We focus on food webs | 90 | between these communities and their environment. We focus on food webs | ||
90 | in real world ecosystems and thus mainly sample our data during | 91 | in real world ecosystems and thus mainly sample our data during | ||
91 | experimental field campaigns. Data collection under controlled | 92 | experimental field campaigns. Data collection under controlled | ||
92 | conditions in the greenhouse or experimental garden are, however, | 93 | conditions in the greenhouse or experimental garden are, however, | ||
93 | common add-ons hereby. We are mainly interested in the functioning of | 94 | common add-ons hereby. We are mainly interested in the functioning of | ||
94 | natural ecosystems and often conduct research in National Parks around | 95 | natural ecosystems and often conduct research in National Parks around | ||
95 | the world. Our main study area is, however, the Swiss National Park. | 96 | the world. Our main study area is, however, the Swiss National Park. | ||
96 | While working on basic research questions, we regularly consider | 97 | While working on basic research questions, we regularly consider | ||
97 | applied aspects that are related to protecting or conserving | 98 | applied aspects that are related to protecting or conserving | ||
98 | endangered ecosystems.\r\n\r\nExamples of research question of our | 99 | endangered ecosystems.\r\n\r\nExamples of research question of our | ||
99 | research group assesses are:\r\n\r\nHow is species loss related to | 100 | research group assesses are:\r\n\r\nHow is species loss related to | ||
100 | ecosystem processes and functions? Which species or species groups are | 101 | ecosystem processes and functions? Which species or species groups are | ||
101 | particularly relevant for ecosystem functioning? Which effects are | 102 | particularly relevant for ecosystem functioning? Which effects are | ||
102 | expected with the loss of such important species groups? How are | 103 | expected with the loss of such important species groups? How are | ||
103 | aboveground organisms interacting with belowground organisms? Which | 104 | aboveground organisms interacting with belowground organisms? Which | ||
104 | abiotic and biotic conditions favor diverse ecosystems? Is global | 105 | abiotic and biotic conditions favor diverse ecosystems? Is global | ||
105 | change (for example eutrophication, habitat fragmentation, climate) a | 106 | change (for example eutrophication, habitat fragmentation, climate) a | ||
106 | thread for diverse ecosystems? How can diverse ecosystems be | 107 | thread for diverse ecosystems? How can diverse ecosystems be | ||
107 | protected?", | 108 | protected?", | ||
108 | "id": "60e92a46-5f9b-4a06-a32e-6a5e04869486", | 109 | "id": "60e92a46-5f9b-4a06-a32e-6a5e04869486", | ||
109 | "image_url": "2018-07-10-090227.680797LogoWSL.svg", | 110 | "image_url": "2018-07-10-090227.680797LogoWSL.svg", | ||
110 | "is_organization": true, | 111 | "is_organization": true, | ||
111 | "name": "plant-animal-interactions", | 112 | "name": "plant-animal-interactions", | ||
112 | "state": "active", | 113 | "state": "active", | ||
113 | "title": "Plant-Animal Interactions", | 114 | "title": "Plant-Animal Interactions", | ||
114 | "type": "organization" | 115 | "type": "organization" | ||
115 | }, | 116 | }, | ||
116 | "owner_org": "60e92a46-5f9b-4a06-a32e-6a5e04869486", | 117 | "owner_org": "60e92a46-5f9b-4a06-a32e-6a5e04869486", | ||
117 | "private": false, | 118 | "private": false, | ||
118 | "publication": "{\"publication_year\": \"2023\", \"publisher\": | 119 | "publication": "{\"publication_year\": \"2023\", \"publisher\": | ||
119 | \"EnviDat\"}", | 120 | \"EnviDat\"}", | ||
120 | "publication_state": "pub_pending", | 121 | "publication_state": "pub_pending", | ||
121 | "related_datasets": "", | 122 | "related_datasets": "", | ||
t | 122 | "related_publications": "Risch Anita C., Zimmermann, Stefan, Moser, | t | 123 | "related_publications": "Risch Anita C., Zimmermann, Stefan, |
123 | Martin, Borer, Elizabeth T., Broadbent, Arthur A.D., Caldeira, Maria | 124 | Sch\u00fctz, Martin, Borer, Elizabeth T., Broadbent, Arthur A.D., | ||
124 | C., Davies, Kendi F., Eisenhauer, Nico, Eskelinen, Anu, Fay, Philip | 125 | Caldeira, Maria C., Davies, Kendi F., Eisenhauer, Nico, Eskelinen, | ||
125 | A., Hagedorn, Frank, Knops, Johannes M.H., Lembrechts, Jonas, J., | 126 | Anu, Fay, Philip A., Hagedorn, Frank, Knops, Johannes M.H., | ||
126 | MacDougall, Andrew S., McCulley, Rebecca L., Melbourne, Brett A., | 127 | Lembrechts, Jonas, J., MacDougall, Andrew S., McCulley, Rebecca L., | ||
127 | Moore, Joslin L., Power, Sally A., Seabloom, Eric W., Siebert, Julia, | 128 | Melbourne, Brett A., Moore, Joslin L., Power, Sally A., Seabloom, Eric | ||
128 | Silveira, Maria L., Virtanen, Risto, Yahdjian, Laura, Ochoa-Hueso, | 129 | W., Silveira, Maria L., Virtanen, Risto, Yahdjian, Laura, Ochoa-Hueso, | ||
129 | Raul (accepted). Drivers of the microbial metabolic quotient across | 130 | Raul (accepted). Drivers of the microbial metabolic quotient across | ||
130 | global grasslands. Global Ecology and Biogeography", | 131 | global grasslands. Global Ecology and Biogeography", | ||
131 | "relationships_as_object": [], | 132 | "relationships_as_object": [], | ||
132 | "relationships_as_subject": [], | 133 | "relationships_as_subject": [], | ||
133 | "resource_type": "datapaper", | 134 | "resource_type": "datapaper", | ||
134 | "resource_type_general": "datapaper", | 135 | "resource_type_general": "datapaper", | ||
135 | "resources": [ | 136 | "resources": [ | ||
136 | { | 137 | { | ||
137 | "cache_last_updated": null, | 138 | "cache_last_updated": null, | ||
138 | "cache_url": null, | 139 | "cache_url": null, | ||
139 | "created": "2023-02-18T03:43:03.643074", | 140 | "created": "2023-02-18T03:43:03.643074", | ||
140 | "description": "Study sites and experimental design\r\nWe | 141 | "description": "Study sites and experimental design\r\nWe | ||
141 | collected data from 23 sites that are part of the Nutrient Network | 142 | collected data from 23 sites that are part of the Nutrient Network | ||
142 | Global Research Cooperative (NutNet, https://nutnet.umn.edu/). The | 143 | Global Research Cooperative (NutNet, https://nutnet.umn.edu/). The | ||
143 | mean annual air temperature (MAT) across these sites ranged from -4 to | 144 | mean annual air temperature (MAT) across these sites ranged from -4 to | ||
144 | 22\u00b0C, mean annual precipitation (MAP) from 252 to 1592 mm, and | 145 | 22\u00b0C, mean annual precipitation (MAP) from 252 to 1592 mm, and | ||
145 | elevations from 6 to 4261 m above sea level (Fig 1a, Supplementary | 146 | elevations from 6 to 4261 m above sea level (Fig 1a, Supplementary | ||
146 | Table S1), hence cover a wide range of climatic conditions under which | 147 | Table S1), hence cover a wide range of climatic conditions under which | ||
147 | grasslands occur (Fig 1b). Soil organic C concentrations ranged | 148 | grasslands occur (Fig 1b). Soil organic C concentrations ranged | ||
148 | between 0.8 to 7.8%, soil total N concentrations between 0.1 and 0.6%, | 149 | between 0.8 to 7.8%, soil total N concentrations between 0.1 and 0.6%, | ||
149 | and the soil C:N ratio between 9.1 and 21.5. Soil clay content spanned | 150 | and the soil C:N ratio between 9.1 and 21.5. Soil clay content spanned | ||
150 | from 3.0 to 35%, and soil pH from 3.4 to 7.6 (Supplementary Table S2). | 151 | from 3.0 to 35%, and soil pH from 3.4 to 7.6 (Supplementary Table S2). | ||
151 | \r\nAt each site, the effects of nutrient addition and herbivore | 152 | \r\nAt each site, the effects of nutrient addition and herbivore | ||
152 | exclusion were tested via a randomized-block design (Borer et al., | 153 | exclusion were tested via a randomized-block design (Borer et al., | ||
153 | 2014). Three blocks with 10 treatment plots each were established at | 154 | 2014). Three blocks with 10 treatment plots each were established at | ||
154 | each site, except for the site at bldr.us (only two blocks). Each of | 155 | each site, except for the site at bldr.us (only two blocks). Each of | ||
155 | these 10 plots was randomly assigned to a nutrient or fencing | 156 | these 10 plots was randomly assigned to a nutrient or fencing | ||
156 | treatment. An individual plot was 5 x 5 m, divided into four 2.5 x 2.5 | 157 | treatment. An individual plot was 5 x 5 m, divided into four 2.5 x 2.5 | ||
157 | m subplots. Each subplot was further divided into four 1 x 1 m square | 158 | m subplots. Each subplot was further divided into four 1 x 1 m square | ||
158 | sampling plots, one of which was set aside for soil sampling (Borer et | 159 | sampling plots, one of which was set aside for soil sampling (Borer et | ||
159 | al., 2014). Plots were separated by at least 1 m wide walkways. We | 160 | al., 2014). Plots were separated by at least 1 m wide walkways. We | ||
160 | collected soil samples from four different treatments for this study: | 161 | collected soil samples from four different treatments for this study: | ||
161 | (i) untreated control plots (Control), (ii) herbivore exclusion plots | 162 | (i) untreated control plots (Control), (ii) herbivore exclusion plots | ||
162 | (Fence), (iii) plots fertilized with N, P, K, plus nine essential | 163 | (Fence), (iii) plots fertilized with N, P, K, plus nine essential | ||
163 | macro and micronutrients (NPK), and (iv) plots with simultaneous | 164 | macro and micronutrients (NPK), and (iv) plots with simultaneous | ||
164 | fertilizer addition and herbivore exclusion (NPK+Fence). The | 165 | fertilizer addition and herbivore exclusion (NPK+Fence). The | ||
165 | experiments were established at different times in the past, with | 166 | experiments were established at different times in the past, with | ||
166 | years of treatment different among sites (2 \u2013 9 years since start | 167 | years of treatment different among sites (2 \u2013 9 years since start | ||
167 | of treatment; Supplementary Table S1). For the nutrient additions, all | 168 | of treatment; Supplementary Table S1). For the nutrient additions, all | ||
168 | sites applied 10 g N m-2 each year as time-release urea; 10 g P m-2 | 169 | sites applied 10 g N m-2 each year as time-release urea; 10 g P m-2 | ||
169 | yr-1 as triple-super phosphate; 10 g K m-2 yr-1 as potassium sulfate. | 170 | yr-1 as triple-super phosphate; 10 g K m-2 yr-1 as potassium sulfate. | ||
170 | A micro-nutrient mix (Fe, S, Mg, Mn, Cu, Zn, B, Mo, Ca) was applied at | 171 | A micro-nutrient mix (Fe, S, Mg, Mn, Cu, Zn, B, Mo, Ca) was applied at | ||
171 | 100 g m-2 together with K in the first year of treatments but not | 172 | 100 g m-2 together with K in the first year of treatments but not | ||
172 | thereafter. \r\nWe excluded large vertebrate herbivores (Fence) by | 173 | thereafter. \r\nWe excluded large vertebrate herbivores (Fence) by | ||
173 | fencing two plots, one with and one without NPK additions, within each | 174 | fencing two plots, one with and one without NPK additions, within each | ||
174 | block. The fences excluded all aboveground mammalian herbivores with a | 175 | block. The fences excluded all aboveground mammalian herbivores with a | ||
175 | body mass of over 50 g (Borer et al., 2014). At most sites, the fences | 176 | body mass of over 50 g (Borer et al., 2014). At most sites, the fences | ||
176 | were 180 cm high, and the fence contained a wire mesh (1 cm holes) for | 177 | were 180 cm high, and the fence contained a wire mesh (1 cm holes) for | ||
177 | the bottom 90 cm with a 30 cm outward-facing flange stapled to the | 178 | the bottom 90 cm with a 30 cm outward-facing flange stapled to the | ||
178 | ground to exclude burrowing animals. Climbing and subterranean animals | 179 | ground to exclude burrowing animals. Climbing and subterranean animals | ||
179 | may potentially still access these plots (Borer et al., 2014). For | 180 | may potentially still access these plots (Borer et al., 2014). For | ||
180 | slight modifications in fence design at a few sites see Supplementary | 181 | slight modifications in fence design at a few sites see Supplementary | ||
181 | Table S3. Most sites only had wild herbivores, although four sites | 182 | Table S3. Most sites only had wild herbivores, although four sites | ||
182 | were also grazed by domestic animals (Supplementary Table | 183 | were also grazed by domestic animals (Supplementary Table | ||
183 | S1).\r\n\r\nCollection of soil samples, soil microbial respiration, | 184 | S1).\r\n\r\nCollection of soil samples, soil microbial respiration, | ||
184 | microbial biomass, and other soil properties\r\nEach of the 23 sites | 185 | microbial biomass, and other soil properties\r\nEach of the 23 sites | ||
185 | received a package containing identical material from the Swiss | 186 | received a package containing identical material from the Swiss | ||
186 | Federal Institute for Forest, Snow and Landscape Research WSL, | 187 | Federal Institute for Forest, Snow and Landscape Research WSL, | ||
187 | Switzerland to be used for sampling (Risch et al., 2015; Risch et al., | 188 | Switzerland to be used for sampling (Risch et al., 2015; Risch et al., | ||
188 | 2019). We collected two soil cores of 5 cm diameter and 12 cm depth in | 189 | 2019). We collected two soil cores of 5 cm diameter and 12 cm depth in | ||
189 | each sampling plot and composited them to measure MR, MBC, and soil | 190 | each sampling plot and composited them to measure MR, MBC, and soil | ||
190 | chemical properties (see below). An additional sample (5 x 12 cm) was | 191 | chemical properties (see below). An additional sample (5 x 12 cm) was | ||
191 | collected to assess soil physical properties. This sample remained | 192 | collected to assess soil physical properties. This sample remained | ||
192 | within a steel sampling core after collection and both ends were | 193 | within a steel sampling core after collection and both ends were | ||
193 | tightly closed with plastic caps to avoid disturbance. All soils were | 194 | tightly closed with plastic caps to avoid disturbance. All soils were | ||
194 | shipped cooled to the laboratory at (Location will be disclosed after | 195 | shipped cooled to the laboratory at (Location will be disclosed after | ||
195 | manuscript acceptance) within a few days after collection. Soils were | 196 | manuscript acceptance) within a few days after collection. Soils were | ||
196 | sampled roughly 6 weeks prior to peak biomass at each site during 2015 | 197 | sampled roughly 6 weeks prior to peak biomass at each site during 2015 | ||
197 | and 2016.\r\nTo assess MR (CO2 production) in a laboratory incubation | 198 | and 2016.\r\nTo assess MR (CO2 production) in a laboratory incubation | ||
198 | experiment we weighed duplicate soil samples (8 g dry soil equivalent) | 199 | experiment we weighed duplicate soil samples (8 g dry soil equivalent) | ||
199 | into 50-ml Falcon tubes. No additional substrate (glucose, sugar) was | 200 | into 50-ml Falcon tubes. No additional substrate (glucose, sugar) was | ||
200 | added to these samples. We adjusted the soil moisture of each sample | 201 | added to these samples. We adjusted the soil moisture of each sample | ||
201 | to 60% field capacity. We then placed a 15 ml plastic test tube | 202 | to 60% field capacity. We then placed a 15 ml plastic test tube | ||
202 | (Semadeni 1701A) containing 7.25 ml 0.05 M NaOH over each soil sample. | 203 | (Semadeni 1701A) containing 7.25 ml 0.05 M NaOH over each soil sample. | ||
203 | The test tube was fixed with a plastic rod so that it was not in | 204 | The test tube was fixed with a plastic rod so that it was not in | ||
204 | contact with the soil sample. The Falcon tubes were then sealed with a | 205 | contact with the soil sample. The Falcon tubes were then sealed with a | ||
205 | screw cap and placed in an incubator under completely dark conditions | 206 | screw cap and placed in an incubator under completely dark conditions | ||
206 | at 20\u00b0C. The CO2 produced by microbial respiration was absorbed | 207 | at 20\u00b0C. The CO2 produced by microbial respiration was absorbed | ||
207 | by the 0.05 M NaOH. For five weeks we measured the decrease in | 208 | by the 0.05 M NaOH. For five weeks we measured the decrease in | ||
208 | conductivity within the 0.05 M NaOH solution on a weekly basis with a | 209 | conductivity within the 0.05 M NaOH solution on a weekly basis with a | ||
209 | Multimeter WTW Multi 3410 (WTW GmbH, Germany) and replaced the 0.05 M | 210 | Multimeter WTW Multi 3410 (WTW GmbH, Germany) and replaced the 0.05 M | ||
210 | NaOH with fresh solution. We included Falcon tubes without soil | 211 | NaOH with fresh solution. We included Falcon tubes without soil | ||
211 | samples in each incubation run as blanks to test if tubes were tight | 212 | samples in each incubation run as blanks to test if tubes were tight | ||
212 | and no CO2 could enter or escape. We calibrated the relationship | 213 | and no CO2 could enter or escape. We calibrated the relationship | ||
213 | between conductivity reduction and NaOH absorbed as follows: 400 ml | 214 | between conductivity reduction and NaOH absorbed as follows: 400 ml | ||
214 | 0.05 M NaOH was placed in a beaker and its conductivity was measured | 215 | 0.05 M NaOH was placed in a beaker and its conductivity was measured | ||
215 | with the multimeter. While stirring, air containing CO2 was blown into | 216 | with the multimeter. While stirring, air containing CO2 was blown into | ||
216 | the solution for approximately one minute, which reacts with NaOH to | 217 | the solution for approximately one minute, which reacts with NaOH to | ||
217 | form Na2CO3. After this process, conductivity was measured again. We | 218 | form Na2CO3. After this process, conductivity was measured again. We | ||
218 | then transferred 7.25 ml of the solution into a smaller beaker and | 219 | then transferred 7.25 ml of the solution into a smaller beaker and | ||
219 | added 1 ml of 0.1 M BaCl2 to precipitate Na2CO3 and then titrated the | 220 | added 1 ml of 0.1 M BaCl2 to precipitate Na2CO3 and then titrated the | ||
220 | solution with 0.05 M HCl to determine the remaining NaOH. We then | 221 | solution with 0.05 M HCl to determine the remaining NaOH. We then | ||
221 | repeated these steps with the remaining solution a total of nine times | 222 | repeated these steps with the remaining solution a total of nine times | ||
222 | and plotted the conductivities (y-axis) against the NaOH consumed | 223 | and plotted the conductivities (y-axis) against the NaOH consumed | ||
223 | (x-axis, Supplementary Fig S1). This regression line was used to infer | 224 | (x-axis, Supplementary Fig S1). This regression line was used to infer | ||
224 | the consumption of NaOH from the conductivity reduction in the | 225 | the consumption of NaOH from the conductivity reduction in the | ||
225 | incubation experiments and to calculate CO2 evolution during | 226 | incubation experiments and to calculate CO2 evolution during | ||
226 | incubation. In addition, we determined the optimum concentration for | 227 | incubation. In addition, we determined the optimum concentration for | ||
227 | the NaOH solution in series of preliminary experiments, so that the | 228 | the NaOH solution in series of preliminary experiments, so that the | ||
228 | concentration was not too high to become insensitive, but also not too | 229 | concentration was not too high to become insensitive, but also not too | ||
229 | low so that not all NaOH reacts during incubation. We then calculated | 230 | low so that not all NaOH reacts during incubation. We then calculated | ||
230 | MR (mg CO2-C kg dry soil-1 h-1) as total amount of CO2 released over | 231 | MR (mg CO2-C kg dry soil-1 h-1) as total amount of CO2 released over | ||
231 | the 5 weeks divided by the duration of the entire incubation in | 232 | the 5 weeks divided by the duration of the entire incubation in | ||
232 | hrs.\r\nSoil microbial biomass carbon (MBC; mg C kg soil-1 ) was | 233 | hrs.\r\nSoil microbial biomass carbon (MBC; mg C kg soil-1 ) was | ||
233 | measured at the beginning of the experiment by measuring the maximal | 234 | measured at the beginning of the experiment by measuring the maximal | ||
234 | respiratory response to the addition of glucose solution (4 mg glucose | 235 | respiratory response to the addition of glucose solution (4 mg glucose | ||
235 | per g soil dry weight dissolved in distilled water; substrate-induced | 236 | per g soil dry weight dissolved in distilled water; substrate-induced | ||
236 | respiration method) on approximately 5.5 g of soil (J. P. E. Anderson | 237 | respiration method) on approximately 5.5 g of soil (J. P. E. Anderson | ||
237 | & Domsch, 1978; Nico Eisenhauer et al., 2018; Scheu, 1992). For this | 238 | & Domsch, 1978; Nico Eisenhauer et al., 2018; Scheu, 1992). For this | ||
238 | purpose we used an O2-micro-compensation apparatus (Scheu, 1992). More | 239 | purpose we used an O2-micro-compensation apparatus (Scheu, 1992). More | ||
239 | specifically, substrate-induced respiration was calculated from the | 240 | specifically, substrate-induced respiration was calculated from the | ||
240 | respiratory response to D-glucose for 10 hr at 20\u00b0C. Glucose was | 241 | respiratory response to D-glucose for 10 hr at 20\u00b0C. Glucose was | ||
241 | added according to preliminary studies to saturate the catabolic | 242 | added according to preliminary studies to saturate the catabolic | ||
242 | enzymes of microorganisms (4 mg g soil-1 dissolved in 400 ml deionized | 243 | enzymes of microorganisms (4 mg g soil-1 dissolved in 400 ml deionized | ||
243 | water). The mean of the lowest three readings within the first 10 hrs | 244 | water). The mean of the lowest three readings within the first 10 hrs | ||
244 | (between the initial peak caused by disturbing the soil and the peak | 245 | (between the initial peak caused by disturbing the soil and the peak | ||
245 | caused by microbial growth) was taken as maximum initial respiratory | 246 | caused by microbial growth) was taken as maximum initial respiratory | ||
246 | response (MIRR; ml O2 kg soil-1 h-1) and microbial biomass (mg C kg | 247 | response (MIRR; ml O2 kg soil-1 h-1) and microbial biomass (mg C kg | ||
247 | soil-1) was calculated as 38 x MIRR (Beck et al., 1997; Cesarz et al., | 248 | soil-1) was calculated as 38 x MIRR (Beck et al., 1997; Cesarz et al., | ||
248 | 2022; Thakur et al., 2015).\r\nThe rest of the composited sample was | 249 | 2022; Thakur et al., 2015).\r\nThe rest of the composited sample was | ||
249 | dried at 65\u00b0C for 48 h, ground and sieved (2 mm mesh) to assess | 250 | dried at 65\u00b0C for 48 h, ground and sieved (2 mm mesh) to assess | ||
250 | the soil pH, mineral soil total C and N and C:N ratio, and mineral | 251 | the soil pH, mineral soil total C and N and C:N ratio, and mineral | ||
251 | soil organic C (Risch et al., 2019). The undisturbed sample was used | 252 | soil organic C (Risch et al., 2019). The undisturbed sample was used | ||
252 | to assess water holding capacity (WHC), bulk density (BD), and soil | 253 | to assess water holding capacity (WHC), bulk density (BD), and soil | ||
253 | texture [sand, silt, clay; methods in (Risch et al., 2019)]. We used | 254 | texture [sand, silt, clay; methods in (Risch et al., 2019)]. We used | ||
254 | the percentage of sand and clay as an indicator of soil texture in | 255 | the percentage of sand and clay as an indicator of soil texture in | ||
255 | this study. MAT (\u00b0C), MAP (mm) and temperature of the wettest | 256 | this study. MAT (\u00b0C), MAP (mm) and temperature of the wettest | ||
256 | quarter (\u00b0C) were obtained from www.worldclim.com (Fick & | 257 | quarter (\u00b0C) were obtained from www.worldclim.com (Fick & | ||
257 | Hijmans, 2017; Hijmans, Cameron, Parra, Jones, & Jarvis, 2005). These | 258 | Hijmans, 2017; Hijmans, Cameron, Parra, Jones, & Jarvis, 2005). These | ||
258 | variables were selected as they were found to be drivers of soil | 259 | variables were selected as they were found to be drivers of soil | ||
259 | nutrient processes across these sites in earlier studies (Risch et | 260 | nutrient processes across these sites in earlier studies (Risch et | ||
260 | al., 2020; Risch et al., 2019). Mean annual soil temperatures (MAST; | 261 | al., 2020; Risch et al., 2019). Mean annual soil temperatures (MAST; | ||
261 | \u00b0C) for the 0 to 5 cm soil layer were obtained for each site from | 262 | \u00b0C) for the 0 to 5 cm soil layer were obtained for each site from | ||
262 | the SoilTemp maps (J. Lembrechts et al., 2021; J. J. Lembrechts et | 263 | the SoilTemp maps (J. Lembrechts et al., 2021; J. J. Lembrechts et | ||
263 | al., 2022), global gridded modelled products of soil bioclimatic | 264 | al., 2022), global gridded modelled products of soil bioclimatic | ||
264 | variables for the 1979-2013 period at a 1-km\u00b2 resolution, based | 265 | variables for the 1979-2013 period at a 1-km\u00b2 resolution, based | ||
265 | on CHELSA, ERA5 and in-situ soil temperature | 266 | on CHELSA, ERA5 and in-situ soil temperature | ||
266 | measurements.\r\nNumerical calculations and statistical analyses\r\nWe | 267 | measurements.\r\nNumerical calculations and statistical analyses\r\nWe | ||
267 | calculated MMQ as MR/MBC. We corrected this measure using the average | 268 | calculated MMQ as MR/MBC. We corrected this measure using the average | ||
268 | soil temperature of each site (MMQsoil). This temperature correction | 269 | soil temperature of each site (MMQsoil). This temperature correction | ||
269 | is necessary as incubation temperatures are usually much higher than | 270 | is necessary as incubation temperatures are usually much higher than | ||
270 | site mean annual soil temperatures (see Xu et al. 2017). MMQsoil = MMQ | 271 | site mean annual soil temperatures (see Xu et al. 2017). MMQsoil = MMQ | ||
271 | x Q10(MAST \u2013 20)/10, where Q10 was assumed to be 2 (Xu et al. | 272 | x Q10(MAST \u2013 20)/10, where Q10 was assumed to be 2 (Xu et al. | ||
272 | 2017). See Supplementary Fig S2 for comparison of air and soil | 273 | 2017). See Supplementary Fig S2 for comparison of air and soil | ||
273 | temperatures across the 23 sites as well as the incubation | 274 | temperatures across the 23 sites as well as the incubation | ||
274 | temperature. \r\nSome of the explanatory variables (clay, soil organic | 275 | temperature. \r\nSome of the explanatory variables (clay, soil organic | ||
275 | C, C:N ratio) were skewed and were thus log-transformed prior to | 276 | C, C:N ratio) were skewed and were thus log-transformed prior to | ||
276 | analyses. All continuous explanatory variables were centred and scaled | 277 | analyses. All continuous explanatory variables were centred and scaled | ||
277 | to have a mean of zero and variance of one. To avoid collinearity | 278 | to have a mean of zero and variance of one. To avoid collinearity | ||
278 | between them we filtered them using correlation analysis | 279 | between them we filtered them using correlation analysis | ||
279 | (Supplementary Fig S3). From the variables that were strongly | 280 | (Supplementary Fig S3). From the variables that were strongly | ||
280 | correlated (Pearson\u2019s |r| > 0.70) (Dormann et al., 2013), we | 281 | correlated (Pearson\u2019s |r| > 0.70) (Dormann et al., 2013), we | ||
281 | selected the ones that allowed us to minimize the number of variables | 282 | selected the ones that allowed us to minimize the number of variables | ||
282 | (Supplementary Fig S3). Specifically, soil total N concentration, soil | 283 | (Supplementary Fig S3). Specifically, soil total N concentration, soil | ||
283 | total C concentration, soil sand content and soil bulk density were | 284 | total C concentration, soil sand content and soil bulk density were | ||
284 | dropped from the dataset. We then assessed how these edaphoclimatic | 285 | dropped from the dataset. We then assessed how these edaphoclimatic | ||
285 | variables are related to MMQ across our global grasslands.\r\nFor | 286 | variables are related to MMQ across our global grasslands.\r\nFor | ||
286 | this, we used linear mixed effects models (LMMs) fitted by maximum | 287 | this, we used linear mixed effects models (LMMs) fitted by maximum | ||
287 | likelihood with the lme function in the nlme package (version 3.1-153) | 288 | likelihood with the lme function in the nlme package (version 3.1-153) | ||
288 | (Pinheiro, Bates, DebRoy, & Sarkar, 2021) in R version 3.6.3. (R Core | 289 | (Pinheiro, Bates, DebRoy, & Sarkar, 2021) in R version 3.6.3. (R Core | ||
289 | Team, 2019). We used treatment as a fixed effect and plot nested in | 290 | Team, 2019). We used treatment as a fixed effect and plot nested in | ||
290 | site as random effects to assess treatment differences in MMQsoil, as | 291 | site as random effects to assess treatment differences in MMQsoil, as | ||
291 | well as MR, and MBC. The number of years since the treatment started | 292 | well as MR, and MBC. The number of years since the treatment started | ||
292 | was included as a fixed effect in all the initial models but was not | 293 | was included as a fixed effect in all the initial models but was not | ||
293 | significant and therefore not retained in the models. To assess how | 294 | significant and therefore not retained in the models. To assess how | ||
294 | differences in MMQsoil were affected by environmental factors (soil, | 295 | differences in MMQsoil were affected by environmental factors (soil, | ||
295 | climatic properties) we again used LMMs. Soil and climatic properties | 296 | climatic properties) we again used LMMs. Soil and climatic properties | ||
296 | were included as fixed effects and plot nested in site as random | 297 | were included as fixed effects and plot nested in site as random | ||
297 | effects. We did not include interactions between environmental | 298 | effects. We did not include interactions between environmental | ||
298 | variables. We then used the MuMin package (Barton, 2018) (version | 299 | variables. We then used the MuMin package (Barton, 2018) (version | ||
299 | 1.42.1) to select the best models that explained the most variation | 300 | 1.42.1) to select the best models that explained the most variation | ||
300 | based on Akaike\u2019s information criterion (AIC; model.avg | 301 | based on Akaike\u2019s information criterion (AIC; model.avg | ||
301 | function). We used the corrected AIC (AICc) to account for our small | 302 | function). We used the corrected AIC (AICc) to account for our small | ||
302 | sample size and selected the top models that fell within 4 AICc units | 303 | sample size and selected the top models that fell within 4 AICc units | ||
303 | (delta AICc < 4) (Burnham & Anderson, 2002; Johnson & Omland, 2004). | 304 | (delta AICc < 4) (Burnham & Anderson, 2002; Johnson & Omland, 2004). | ||
304 | We present all our top models rather than model averages. Conditional | 305 | We present all our top models rather than model averages. Conditional | ||
305 | averages are provided in the Supplementary material. \r\nBased on | 306 | averages are provided in the Supplementary material. \r\nBased on | ||
306 | findings from analyses described above and the literature, we | 307 | findings from analyses described above and the literature, we | ||
307 | developed a conceptual model of direct and indirect relationships | 308 | developed a conceptual model of direct and indirect relationships | ||
308 | between both edaphoclimatic variables and experimental treatments | 309 | between both edaphoclimatic variables and experimental treatments | ||
309 | (Supplement Figure S4) to obtain a more holistic approach in | 310 | (Supplement Figure S4) to obtain a more holistic approach in | ||
310 | understanding how these properties affect MMQsoil. We had data from 23 | 311 | understanding how these properties affect MMQsoil. We had data from 23 | ||
311 | sites with 272 observations. We tested this model using structural | 312 | sites with 272 observations. We tested this model using structural | ||
312 | equation modelling based on a d-sep approach (Lefcheck, 2016; Shipley, | 313 | equation modelling based on a d-sep approach (Lefcheck, 2016; Shipley, | ||
313 | 2009). We considered those environmental drivers that were included in | 314 | 2009). We considered those environmental drivers that were included in | ||
314 | our top LMMs, namely temperature of the wettest quarter (T.q.wet), | 315 | our top LMMs, namely temperature of the wettest quarter (T.q.wet), | ||
315 | soil pH, water holding capacity (WHC) and soil organic C (organic C; | 316 | soil pH, water holding capacity (WHC) and soil organic C (organic C; | ||
316 | Supplementary Figure S4). These factors were allowed to directly | 317 | Supplementary Figure S4). These factors were allowed to directly | ||
317 | affect MMQsoil, and via their interactions with treatments. In | 318 | affect MMQsoil, and via their interactions with treatments. In | ||
318 | addition, treatments were allowed to directly affect MMQsoil. | 319 | addition, treatments were allowed to directly affect MMQsoil. | ||
319 | Treatments were included as dummy variables in the model. We tested | 320 | Treatments were included as dummy variables in the model. We tested | ||
320 | our conceptual model (Supplementary Fig S4) using the piecewiseSEM | 321 | our conceptual model (Supplementary Fig S4) using the piecewiseSEM | ||
321 | package (version 2.0.2; Lefcheck, 2016) in R 3.4.0, in which a | 322 | package (version 2.0.2; Lefcheck, 2016) in R 3.4.0, in which a | ||
322 | structured set of linear models are fitted individually. This approach | 323 | structured set of linear models are fitted individually. This approach | ||
323 | allowed us to account for the nested experimental design, and overcome | 324 | allowed us to account for the nested experimental design, and overcome | ||
324 | some of the limitations of standard structural equation models, such | 325 | some of the limitations of standard structural equation models, such | ||
325 | as small sample sizes (Lefcheck, 2016; Shipley, 2009). We used the lme | 326 | as small sample sizes (Lefcheck, 2016; Shipley, 2009). We used the lme | ||
326 | function of the nlme package to model response variables, including | 327 | function of the nlme package to model response variables, including | ||
327 | site as a random factor. Good fit of the SEM was assumed when | 328 | site as a random factor. Good fit of the SEM was assumed when | ||
328 | Fisher\u2019s C values were non-significant (p > 0.05). For all | 329 | Fisher\u2019s C values were non-significant (p > 0.05). For all | ||
329 | significant interactions between soil or climate variables and | 330 | significant interactions between soil or climate variables and | ||
330 | treatments detected in the SEMs, we calculated treatment effect sizes, | 331 | treatments detected in the SEMs, we calculated treatment effect sizes, | ||
331 | i.e., the differences in MMQsoil between Control and treatments as log | 332 | i.e., the differences in MMQsoil between Control and treatments as log | ||
332 | response ratios (LRR) and plotted these values against the climate or | 333 | response ratios (LRR) and plotted these values against the climate or | ||
333 | soil factors. The LRR were defined as log(Control/Treatment), where | 334 | soil factors. The LRR were defined as log(Control/Treatment), where | ||
334 | treatment was either Fence, NPK or NPK+Fence. To assess which of the | 335 | treatment was either Fence, NPK or NPK+Fence. To assess which of the | ||
335 | LRR-climate or soil property relationships were significant we again | 336 | LRR-climate or soil property relationships were significant we again | ||
336 | used LMMs, in which soil and climatic properties were included as | 337 | used LMMs, in which soil and climatic properties were included as | ||
337 | fixed effects and plot nested in site as random effects. \r\n", | 338 | fixed effects and plot nested in site as random effects. \r\n", | ||
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375 | { | 376 | { | ||
376 | "display_name": "CLIMATE", | 377 | "display_name": "CLIMATE", | ||
377 | "id": "5a33b7dc-dca1-42c3-8651-9d00b5428823", | 378 | "id": "5a33b7dc-dca1-42c3-8651-9d00b5428823", | ||
378 | "name": "CLIMATE", | 379 | "name": "CLIMATE", | ||
379 | "state": "active", | 380 | "state": "active", | ||
380 | "vocabulary_id": null | 381 | "vocabulary_id": null | ||
381 | }, | 382 | }, | ||
382 | { | 383 | { | ||
383 | "display_name": "HERBIVORE EXCLUSION", | 384 | "display_name": "HERBIVORE EXCLUSION", | ||
384 | "id": "f2021f0d-d563-4f9c-a24f-1acebac60b92", | 385 | "id": "f2021f0d-d563-4f9c-a24f-1acebac60b92", | ||
385 | "name": "HERBIVORE EXCLUSION", | 386 | "name": "HERBIVORE EXCLUSION", | ||
386 | "state": "active", | 387 | "state": "active", | ||
387 | "vocabulary_id": null | 388 | "vocabulary_id": null | ||
388 | }, | 389 | }, | ||
389 | { | 390 | { | ||
390 | "display_name": "MICROBIAL BIOMASS CARBON", | 391 | "display_name": "MICROBIAL BIOMASS CARBON", | ||
391 | "id": "edd64a11-276e-4acf-b063-0370c63ee135", | 392 | "id": "edd64a11-276e-4acf-b063-0370c63ee135", | ||
392 | "name": "MICROBIAL BIOMASS CARBON", | 393 | "name": "MICROBIAL BIOMASS CARBON", | ||
393 | "state": "active", | 394 | "state": "active", | ||
394 | "vocabulary_id": null | 395 | "vocabulary_id": null | ||
395 | }, | 396 | }, | ||
396 | { | 397 | { | ||
397 | "display_name": "MICROBIAL RESPIRATION", | 398 | "display_name": "MICROBIAL RESPIRATION", | ||
398 | "id": "4d759529-e01f-4c61-a5a9-debb88d681d1", | 399 | "id": "4d759529-e01f-4c61-a5a9-debb88d681d1", | ||
399 | "name": "MICROBIAL RESPIRATION", | 400 | "name": "MICROBIAL RESPIRATION", | ||
400 | "state": "active", | 401 | "state": "active", | ||
401 | "vocabulary_id": null | 402 | "vocabulary_id": null | ||
402 | }, | 403 | }, | ||
403 | { | 404 | { | ||
404 | "display_name": "NUTRIENT ADDITION", | 405 | "display_name": "NUTRIENT ADDITION", | ||
405 | "id": "3e6bed69-a2b3-4036-b6d8-e5592f7cef4a", | 406 | "id": "3e6bed69-a2b3-4036-b6d8-e5592f7cef4a", | ||
406 | "name": "NUTRIENT ADDITION", | 407 | "name": "NUTRIENT ADDITION", | ||
407 | "state": "active", | 408 | "state": "active", | ||
408 | "vocabulary_id": null | 409 | "vocabulary_id": null | ||
409 | }, | 410 | }, | ||
410 | { | 411 | { | ||
411 | "display_name": "SOIL PROPERTIES", | 412 | "display_name": "SOIL PROPERTIES", | ||
412 | "id": "4730ad8f-dea2-4b33-b551-85acf1ebaac4", | 413 | "id": "4730ad8f-dea2-4b33-b551-85acf1ebaac4", | ||
413 | "name": "SOIL PROPERTIES", | 414 | "name": "SOIL PROPERTIES", | ||
414 | "state": "active", | 415 | "state": "active", | ||
415 | "vocabulary_id": null | 416 | "vocabulary_id": null | ||
416 | } | 417 | } | ||
417 | ], | 418 | ], | ||
418 | "title": "Drivers of the microbial metabolic quotient across global | 419 | "title": "Drivers of the microbial metabolic quotient across global | ||
419 | grasslands", | 420 | grasslands", | ||
420 | "type": "dataset", | 421 | "type": "dataset", | ||
421 | "url": null, | 422 | "url": null, | ||
422 | "version": "1.0" | 423 | "version": "1.0" | ||
423 | } | 424 | } |