Impacts of targeted grazing, controlled burning, and strip seeding on soil microbial communities
Data files
Apr 15, 2026 version files 37.15 KB
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README.md
9.13 KB
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Stripseed_CNRatio020124.xlsx
12.49 KB
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StripSeed_pH_010924.csv
5.26 KB
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Stripseed_PlantData2023.csv
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Abstract
Increased vegetation management efforts are crucial due to the magnitude of global land degradation. Most modern land management projects focus on either controlling undesirable plant species or attempting to reconstruct the historical plant community. While most strategies are generally expected to enhance native vegetation establishment and diversity, there may be unintended impacts on vital soil microbial communities. Soil microbial communities play a crucial role in biogeochemical processes like nutrient cycling, organic matter decomposition, and the development of soil structure, all of which influence plant productivity, nutrient acquisition, and the regulation of plant diversity and composition. We sought to investigate the consequences of different combinations of vegetation management strategies used to restore a former cropland to a perennial grassland in Davis, California, USA. Specifically, we assessed soil microbial community diversity, composition and putative functional group abundances across different combinations of 1) targeted sheep grazing, 2) low and high frequency controlled burning, and 3) native plant strip seeding. We found that microbial taxonomic diversity was largely unchanged across vegetation management practices, but grazing, burning, and seeding led to shifts in soil microbial community composition. Microbial community shifts were primarily associated with changes in plant community composition; however, indirect modifications to carbon:nitrogen and pH were also differentially associated with compositional shifts in bacteria and fungi, respectively. Overall, our findings highlight that soil bacterial communities are resilient to increasing management intensities. Future studies should investigate how changes in soil microbial communities within managed ecosystems impact ecosystem processes, and whether these processes align with land management objectives.
https://doi.org/10.5061/dryad.nk98sf82z
Description of the data and file structure
In an effort to assess whether isolated or combined vegetation management strategies enhance desired vegetation communities, we leveraged an ongoing restoration project transforming former cropland into perennial-dominated grassland in northern California, USA. We assessed soil microbial community diversity, composition and putative functional group abundance across different combinations of 1) targeted sheep grazing; 2) low and high frequency-controlled burning; and 3) native plant strip seeding.
In November 2011, a mixture of seven native grasses was drill seeded in six different strip seed treatments in replicated 25 m × 44 m macroplots using a drill seeder at a bulk seeding rate of 2.02 g/m2 (20,000 g/ha; seeded area). Strip seed treatments were applied at six seed coverage rates (0%, 33%, 50% narrow, 50% wide, 66%, 100% of area seeded) to create differentially sized areas of native grassland patches and unseeded patches. Strip widths ranged from 2.4 m–7.2 m. Treatments included for this investigation were (1) 0% seeded (2) 50% wide seeded (“50%W”) with 7.2 m seeded and unseeded strips; and (3) 100% seeded. Each treatment was replicated four times in a randomized block design, resulting in 12 total 25 m × 44 m macroplots enrolled in this study. The seeded species were Poa secunda (Sandberg bluegrass), Festuca microstachys (small fescue), Elymus multisetus (big squirreltail), Melica californica (California melic), Stipa (Nassella) pulchra (purple needlegrass), Elymus glaucus (blue wildrye), and Hordeum brachyantherum ssp. californicum (California meadow barley). All seeded species except for F. microstachys (an annual grass) are perennial grasses.
Since the initial establishment of the strip seeding project, there has been re-establishment of weedy non-native grasses and forbs (i.e., Bromus hordeaceus, Avena Fatua, Bromus diandrus, and Lactuca serriola). In an effort to preserve the planted native species, multiple control strategies have been implemented in a subset of the seeded macroplots, which include annual targeted sheep grazing and low and high frequency-controlled burns. Of the 24 total macroplots, 12 have been seasonally grazed by sheep (approximately 180 sheep throughout, none of which were actively treated with antibiotics) for a oneweek duration during peak aboveground plant production (mid-April) every year since 2017 with a grazing target of 50% forage utilization and/or loss. Furthermore, six 1 m x 1 m plots have been established within each macroplot (specifically the unseeded strips of the 50%W macroplot), with two “high frequency” burn plots having undergone controlled burning over the course of three years (2017, 2018, and 2021), two “low frequency” burn plots having been burned once in 2021, and two unburned controls. As a result, 72 plots were assessed across 4 blocks.
We evaluated the plant community during the late Spring, when above ground biomass production was near peak levels. We also conducted a follow up survey in the early summer to measure late flowering invasive annual species. Utilizing a 1 m x 1 m square frame, we ocularly estimated canopy cover of each plant species present, exposed surface plant litter and bare soil on a scale of 0-1;1-100%. For soil physicochemical analysis, we first sieved soil samples to 2 mm and air dried them overnight. We measured soil pH with 1:1 (weight/volume) soil to deionized water using a FiveEasy Plus pH meter (Mettler Toledo, Columbus, OH, USA). For total carbon (C) and nitrogen (N), we oven-dried the samples at 105 °C overnight, manually grinded the samples using a mortar, and then weighed them at 1 g for thermal combustion analysis (Vario MAX Cube, Elementar, Langenselbold, DE).
Files and variables
File: Stripseed_CNRatio020124.xlsx
Description: The total carbon and nitrogen present in the collected soil samples across the observed sites.
Variables
- carbon, nitrogen, and carbon:nitrogen ratio
File: StripSeed_pH_010924.csv
Description: Soil pH identified from the collected soil samples across the observed sites.
Variables
- pH
File: Stripseed_PlantData2023.csv
Description: Plant community cover across the observed sites, including plant identification codes.
Variables
- Plant cover
Plant Codes
| Code | Species | Notes |
| AMSP | Amsinckia_sp | NA |
| AVENA | Avena_sp | NA |
| Bare | NA | Bareground |
| BigWildRadish | Raphanus raphanistrum | maybe hybrid with Raphnus sativus |
| BRDI | Bromus_diandrus | NA |
| BRHO2 | Bromus_hordeaceus | NA |
| CabbagePatch | Kickxia_sp | Fluvellin- either likely Kickxia spurria or maybe Kickxia eltain |
| catsear | Hypochaeris glabra | NA |
| COAR | Convolvulus_arvensis | NA |
| Cutleafgeranium | Geranium dissectum | NA |
| ELGL | Elymus_glaucus | NA |
| ERBO | Erodium_botrys | NA |
| FEMY | Vulpia_myuros | NA |
| HOBR? | Hordeum_brachyantherum | likely |
| HOMA | Hordium_marinum | NA |
| HorseWeed | Erigeron_bonariensis | NA |
| LASE | Lactuca_serriola | NA |
| Litter | NA | Dead plant biomass |
| MALO | Malva_parviflora | NA |
| MECA2 | Melica_californica | NA |
| MEPO | Medicago polymorpha | NA |
| MinersLettuce | Claytonia perfoliata | NA |
| Moss | NA | unknown moss |
| oxtongue | Picris echioides | NA |
| POAN | Poa_annua | NA |
| POSE | Poa_secunda | NA |
| PurpleSpoon | Sonchus_arvensis | NA |
| RedMaids | Calandrinia ciliata | NA |
| RoseClover | Trifolium hirtum | NA |
| SEVU | Senecio_vulgaris | NA |
| SOAR | Sonchus_arvensis | NA |
| STME2 | Stellaria_media | NA |
| STPU | Stipa_pulchra | NA |
| TinyForb | Claytonia perfoliata | Baby miners lettuce |
| TRAE | Triticum_aestivum | NA |
| VUMI | Vulpia microstachys | NA |
| YST | Centaurea solstitialis | yellow starthistle |
Code/software
Excel
Plant community sampling
We evaluated the plant community during the late Spring, when above ground biomass production was near peak levels. We also conducted a follow up survey in the early summer to measure late flowering invasive annual species. Utilizing a 1 m x 1 m square frame, we ocularly estimated canopy cover of each plant species present, exposed surface plant litter and bare soil on a scale of 0-1;1-100%.
Soil sampling
For soil physicochemical analysis, we first sieved soil samples to 2 mm and air dried them overnight. We measured soil pH with 1:1 (weight/volume) soil to deionized water using a FiveEasy Plus pH meter (Mettler Toledo, Columbus, OH, USA). For total carbon (C) and nitrogen (N), we oven-dried the samples at 105 °C overnight, manually grinded the samples using a mortar, and then weighed them at 1 g for thermal combustion analysis (Vario MAX Cube, Elementar, Langenselbold, DE).