Perennial Grassland Research Articles

Soil climate underpins year effects driving divergent outcomes in semi‐arid cropland‐to‐grassland restoration

AbstractConverting croplands to grasslands can restore ecosystem functions and services, but there is uncertainty about why some restoration treatments succeed and others do not. One likely explanation for variation in restoration outcomes is that interannual variation in the drivers of community assembly, or “year effects,” is often overlooked in restoration planning. Existing restoration strategies tailor species compositions of seed mixes according to long‐term climate means and hardiness zones. However, individual years typically deviate from average climate norms such that restoration activities may be better informed by recent conditions than by climate averages. We monitored a 109‐ha field in northeastern Colorado that was converted from a winter wheat‐fallow rotation to native perennial grassland via seeding. The same seed mix was used to seed 6 of 12,120‐m strips in 2013 (drier) and 6 in 2014 (wetter). In the strips seeded in 2013, only one native grass and one shrub species from the seed mix established widely, whereas in 2014, all native grasses established. Higher soil moisture preceding seed application was positively associated with perennial grasses, while rhizomatous grasses, shrubs, and introduced annuals were associated with other variables. After seeding, high summer soil moisture was positively associated with a rhizomatous C3 grass, while the planted C4 bunchgrasses were negatively associated with high summer soil moisture and positively associated with high fall soil temperatures. We found evidence of facilitatory interactions between grasses and forbs, as well as antagonistic interactions between native perennial grasses and non‐native annuals. Our results suggest that the conditions immediately before and after planting govern community assembly and leave a lasting legacy and should be considered in planning treatments. We suggest composing seed mixes that are tailored to commonly encountered extremes of temperature and moisture availability. Land managers can also use split‐seeding or repeated seeding approaches, within or between years as bet‐hedging strategies. The development of more flexible funding mechanisms could allow for regional go/no‐go climate thresholds to avoid wasting resources.

Mixed cropping of Medicago ruthenica-Bromus inermis exhibits higher yield and quality advantages in the Longxi loess plateau region of Northwest China

Medicago ruthenica is a promising leguminous forage crop due to its lack of saponins, which prevents bloat in livestock from excessive consumption. Legume/grass mixed cropping is an effective forage planting method widely used in agricultural and pastoral regions. However, there is a lack of research on using legume-grass mixed cropping to establish perennial, high-yield, and high-quality cultivated grasslands in the Longxi Loess Plateau. This study conducted a legume/grass intercropping experiment in the Longxi Loess Plateau region of northwestern China, using Medicago ruthenica and Bromus inermis. Experimental plots were established in 2021, with field sampling and laboratory analysis starting in 2022 and 2023, respectively. The research aimed to investigate the effects of intercropping Medicago ruthenica with Bromus inermis on forage yield and quality, and to determine the optimal intercropping ratios. The experiment tested various intercropping ratios of Medicago ruthenica and Bromus inermis in the fall (2:8, 3:7, 4:6, 5:5, 6:4, 7:3, 8:2), with sole crops of each species serving as controls. Results showed that, in the second and third years of mixed cropping, the forage yield under mixed cropping treatments was significantly higher than that of Medicago ruthenica and Bromus inermis monoculture, with increases of 40.89–70.88% and 13.97–38.22% in the second year, and 131.91–199.13% and 44.06–85.82% in the third year. When the legume proportion in the mixed cropping system was around 30%, competition between the two forages reached equilibrium, demonstrating the benefits of mixed cropping. The crude protein and ether extract content of mixed forage were significantly higher than those of monoculture, while the neutral detergent fiber and acid detergent fiber contents were significantly lower, indicating a higher feeding value for the mixed forage. The legume proportion was a key factor influencing the yield of mixed forage. In conclusion, a mixed planting ratio of Medicago ruthenica and Bromus inermis at 3:7 resulted in higher yield and nutritional quality, making it an optimal ratio for establishing cultivated forage fields in the Longxi Loess Plateau.

Species interactions amplify functional group responses to elevated CO2 and N enrichment in a 24-year grassland experiment.

Plant functional groups (FGs) differ in their response to global changes, although species within those groups also vary in such responses. Both species and FG responses to global change are likely influenced by species interactions such as inter-specific competition and facilitation, which are prevalent in species mixtures but not monocultures. As most studies focus on responses of plants growing in either monocultures or mixtures, but rarely both, it remains unclear how interspecific interactions in diverse ecological communities, especially among species in different FGs, modify FG responses to global changes. To address these issues, we leveraged data from a 16-species, 24-year perennial grassland experiment to examine plant FG biomass responses to atmospheric CO2, and N inputs at different planted diversity. FGs differed in their responses to N and CO2 treatments in monocultures. Such differences were amplified in mixtures, where N enrichment strongly increased C3 grass success at ambient CO2 and C4 grass success at elevated CO2. Legumes declined with N enrichment in mixtures at both CO2 levels and increased with elevated CO2 in the initial years of the experiment. Our results suggest that previous studies that considered responses to global changes in monocultures may underestimate biomass changes in diverse communities where interspecific interactions can amplify responses. Such effects of interspecific interactions on responses of FGs to global change may impact community composition over time and consequently influence ecosystem functions.

Successional stages in Mediterranean grasslands differ in the quality of ecosystem services in urban greenspaces

Urban habitats represent new opportunities to study natural processes such as ecological succession. Our work focused for the first time on the changes in ecosystem services occurring in the ecological succession from annual to perennial grasslands in Mediterranean peri-urban greenspaces. Student’s t test was used to analyse the influence of the grassland type on plant and soil features, and showed that soil under perennial grassland had a significantly higher C content and arylamidase and arylsulfatase activity than annual grasslands. In contrast, annual grasslands showed a significantly higher plant-species richness, and their soils had higher bulk density and phenoloxidase and arylamidase activity compared to perennial grasslands. Neither the labile nor recalcitrant fractions of the organic matter showed any significant difference between communities. When all the soil factors were included together, Redundancy Analysis revealed a significant gradient in soil phenoloxidase activity and organic matter distinguishing perennial from annual grasslands. We conclude that when annual grasslands give way to perennial grasslands through natural succession in Mediterranean greenspaces, certain ecosystem services such as soil carbon storage and water regulation improve, while biodiversity maintenance declines. Thus, Mediterranean urban greenspaces where natural succession occurs should be handled in such a way as to preserve both type of habitats in order to improve a wider range of ecosystem services.

Soil carbon maintained by perennial grasslands over 30 years but lost in field crop systems in a temperate Mollisol

To mitigate climate change, some seek to store carbon from the atmosphere in agricultural soils. However, our understanding about how agriculture affects soil organic carbon is muddied by studies (1) lacking longitudinal data, (2) ignoring bulk density changes, or (3) sampling only surface soils. To better understand soil organic carbon trends, here we measured changes over 30 years in density-corrected, full-soil-depth (90 cm) soil organic carbon stocks under 6 cropping systems and a restored prairie in a Mollisol of southern Wisconsin, USA. Cash-grain systems and alfalfa-based systems lost soil organic carbon. Prairie and rotationally-grazed pasture maintained soil organic carbon. Average soil organic carbon losses for cash-grain and alfalfa-based systems were −0.82 (±0.12) and −0.64 (±0.17) Mg C ha−1 yr−1, respectively. Sensitivity analysis showed that incomplete methodologies overestimated soil organic carbon improvements. Our findings using more comprehensive methods demonstrate the inadequacy of row-crop systems and the need for well-managed grasslands to protect soil organic carbon in productive agricultural soils of the Upper Midwest USA.

Effects of Different Forms of Nitrogen Addition on Soil Physical and Chemical Properties and Microbial Community Structure of Perennial Alpine Cultivated Grassland

This study aimed to investigate the impact of different nitrogen forms on soil physicochemical properties and microbial community structure in perennial alpine cultivated grasslands, in order to provide scientific basis for developing nitrogen addition strategies for perennial alpine cultivated grasslands. In June 2022, a 4-year-old Qinghai grassland mixed with Poa pratensis Qinghai and Festuca sinensis Qinghai was established at the Bakatai Farm in Gonghe County, Hainan Tibetan Autonomous Prefecture, Qinghai Province. The study was conducted without fertilization as a control (CK), and three different forms of nitrogen treatments were set up, namely, U:urea (amide nitrogen), A:ammonium sulfate (ammonium nitrogen), and N:calcium nitrate (nitrate nitrogen); the nitrogen application rate for each treatment was 67.5 kg·(hm2·a)-1, and the composition and diversity of soil nutrients and microbial communities under different treatments were analyzed. The results showed that the input of exogenous ammonium nitrogen significantly increased NH4+-N content, AP content, and EC; amide nitrogen input significantly increased SOC content and TN content; and nitrate nitrogen input significantly increased NO3--N content, AN content, and TC content. Exogenous nitrogen input changed the structure of soil bacterial and fungal communities, as well as the relative abundance of dominant phyla and genera, but it did not significantly affect the alpha diversity of bacterial and fungal communities. Principal coordinate analysis (PCoA) showed that different forms of nitrogen addition had a significant impact on the Beta diversity of bacterial communities, whereas the impact on fungal communities was not significant. Redundancy analysis (RDA) indicated that nitrogen addition mainly changed the composition and structure of microbial communities through soil ammonium nitrogen. Overall, ammonium nitrogen fertilizer should be given priority in the soil remediation process of perennial cultivated grasslands in the Qinghai Tibet Plateau.

Potential gains in soil carbon and nitrogen as a result of systems perenniality: Insights from on‐farm experiments and soil organic matter fractions

AbstractUnderstanding soil organic matter (SOM) dynamics along gradients of land intensification is critical to guide conservation goals towards improvements in soil carbon (C) and nitrogen (N) storage. In this study, we clarified (a) how the C and N concentrations within SOM fractions of distinct ecological relevance responded to soil management representing a cropland‐grassland gradient and (b) how these operationally defined fractions affected soil physicochemical and biological properties. We compared sites with annual row crop rotations with and without cover crops (i.e. cropland soils) with perennial grassland sites (i.e. reference soil) by sampling near‐surface soils from statewide on‐farm cover crop experiments replicated across four agro‐ecoregions in Midwest USA. Soil management had a significant main effect on C and N content in SOM fractions, but responses were site‐ and fraction‐specific. We found that C content of free particulate organic matter and water‐extractable organic matter (WEOM) of reference soils were 58%–76% and 31%–59% greater than those of the cropland soils in two of the four sites. Differences in N content of WEOM because of soil management were observed in two of the four sites. These reference soils had between 40% and 60% greater N than cropland soils. Additionally, the N content of aggregate occluded POM (o‐POM) of reference soils was three times greater than those of the cropland soils in one of the four sites. Broadly across bulk and SOM fractions, high declines in cropland C and N relative to reference soils were observed in non‐irrigated and strip‐till sites and coarse‐texture soils. Free and o‐POM C and N were strongly associated with aggregate stability, water infiltration and enzyme activity, whereas C and N contents of WEOM and MAOM were correlated with soil's ability to hold onto essential nutrients (e.g. calcium, magnesium, potassium and sodium). Although the potential of cover crops to drive changes on ecologically meaningful SOM fractions is less pronounced in the short (3 year) term, the findings demonstrate the potential of continuous living cover as an approach to agroecosystem design to improve soil functions closely related to SOM characteristics.

Climate and habitat type interact to influence contemporary dispersal potential in Prairie Smoke (Geum triflorum).

Understanding dispersal potential, or the probability a species will move a given distance, under different environmental conditions is essential to predicting species' ability to move across the landscape and track shifting ecological niches. Two important drivers of dispersal ability are climatic differences and variations in local habitat type. Despite the likelihood these global drivers act simultaneously on plant populations, and thus dispersal potential is likely to change as a result, their combined effects on dispersal are rarely examined. To understand the effect of climate and varying habitat types on dispersal potential, we studied Geum triflorum-a perennial grassland species that spans a wide range of environments, including both prairie and alvar habitats. We explored how the climate of the growing season and habitat type (prairie vs. alvar) interact to alter dispersal potential. We found a consistent interactive effect of climate and habitat type on dispersal potential. Across prairie populations, an increased number of growing degree days favored traits that increase dispersal potential or the probability of dispersing farther distances. However, for alvar populations, dispersal potential tended to decrease as the number of growing degree days increased. Our findings suggest that under continued warming, populations in prairie habitats will benefit from increased gene flow, while alvar populations will become increasingly segregated, with reduced potential to track shifting fitness optima.

Efficacy of Multiseason Sentinel-2 Imagery for Classifying and Mapping Grassland Condition

Assessing the condition of ecosystems is imperative for understanding their degree of degradation and managing their conservation. The increasing availability of remote sensing products offers unprecedented opportunities for mapping vegetation with high detail and accuracy. However, mapping complex ecosystems, like grasslands, remains challenging due to their heterogeneity in vegetation composition and structure. Furthermore, degraded ecosystems affected by invasive vegetation present different condition levels within vegetation classes, limiting the accuracy of classifications and condition assessment. Here, we evaluated the capacity of Sentinel-2 multispectral time series imagery as an input for classifying different levels of cover within a vegetation class to detect the subtle differences needed to assess the condition of degraded ecosystems. Our study was conducted in the iron-grasslands of South Australia, a perennial tussock grassland dominated by iron-grasses (Lomandra spp.) and severely affected by invasive annual grasses. We developed random forest models to discriminate classes defined by the cover of iron-grasses, wild oats (Avena barbata), and woodland (training points = 250). We tested the importance of data seasonality, spatial resolution, spectral bands, and vegetation indices. The combination of spatial, temporal, and spectral detail produced the best classification results. Random forest classifications performed best at 10 m resolution, suggesting that detailed resolution outweighs spectral detail for discriminating vegetation patterns in systems with high spatial heterogeneity. The model at 10 m resolution combining all periods and all variables (spectral bands and vegetation indices) produced a mean kappa coefficient of 56% and a mean overall accuracy of 67%. The dry season imagery and vegetation indices emerged as the most informative, suggesting that vegetation classes presented different phenological properties critical for their discrimination. Our study contributes to mapping complex ecosystems, facilitating the discrimination of different levels of condition in grasslands degraded by invasive species, and thus benefits the conservation of native grasslands and other ecosystems.

Effect of Long-Term Different Land Uses on Improving Stable Humic Compounds in Arenosol

There has not been enough research conducted on the effect of land use on the composition of humus in Arenosols. This long-term study (1995–2022) aimed to determine the differences in the formation of humic compounds in the natural and agricultural ecosystems of Arenosols. Soil samples were collected from six plots at two soil depths (0–15 and 15–25 cm), with four replicates. Conclusions were reached based on the results of the accumulation of humic substances (HSs) and their qualitative fractional composition, C/N ratio, humification degree (HD), and the optical properties of the humus substances. Afforestation, after 27 years, significantly increased (+6.7 g kg−1) the soil organic carbon (SOC) and influenced the qualitative composition of HS: HA + FA 79.3% of the SOC. Grassland cultivation showed faster (+3.8 g kg−1) SOC sequestration, a higher HA/FA ratio, and an increased HD. Arenosols may be used in crop rotation with approximately 40% leguminous plants to maintain a stable humus balance. Additionally, the effects of mineral fertilisers on the humification processes and humus quality of +2.59 g kg−1 SOC, +1.27 g kg−1 humin in crop rotation, +3.26 g kg−1 SOC, and 2.82 g kg−1 humin in a grass cultivation field were established. For SOC accumulation and a larger humus amount of a better quality, it is recommended that an Arenosol is used, as it is suitable for use in perennial cut grasslands, natural grasslands, and pine afforestation.

Mechanical soil disturbance in a pine savanna has multiyear effects on plant species composition

AbstractSoil disturbance threatens native perennial grasslands and savannas worldwide, including pine savannas of the North American Coastal Plain. Disk harrows are used in the region to plow linear features for firebreaks to contain prescribed fires, to manage game and other wildlife, and to reduce wildfire hazard to protect forest resources. However, the long‐term response of vegetation to these disturbances has not been well investigated. Our aim was to compare vegetation changes over time (0–9 years) following repeated disturbance by disking and a single disturbance by disking for firebreaks with undisturbed vegetation within a native pine savanna. We hypothesized that (1) a single disking event has multiyear effects on plant species composition and abundance because of the loss of perennial, dispersal‐limited species, but that partial survival of propagules allows the recovery to be more complete than following repeated disturbance, and (2) post‐disturbance changes are determined by species' life‐history characteristics resulting in a successional trajectory toward the undisturbed community. We established 10 plots within a repeated‐disturbance firebreak and a single‐disturbance firebreak, and in undisturbed vegetation (n = 30). We identified plant species within the plots six times over nine years, categorized plant species by life span, seed bank persistence, and dispersal mechanism, and assessed changes in the plant community using ordination. Changes in species composition in both repeated and single disturbance treatments showed a pattern consistent with succession toward the undisturbed plant community, but vegetation in neither disturbance treatment matched undisturbed treatment conditions within the nine years of study. Repeated‐disturbance plots progressed from a high occurrence of annuals to species with persistent seed banks and wind‐dispersed species. Single‐disturbance plots were more strongly associated with perennials, species lacking a persistent seed bank, and species dispersed by vertebrate consumption, but not to the same degree as undisturbed plots, although differences decreased slightly over time. Our results relating to narrow mechanical soil disturbances in pine savanna vegetation are consistent with studies concluding that similar but larger scale disturbances have long‐term degradational effects on the plant community. Therefore, conservation management plans should consider the possible negative long‐term effects of soil disturbance on native perennial herbaceous plant communities.

Diversification of crop rotations and soil carbon balance: impact assessment based on national-scale monitoring data

A successful crop rotation choice is key to the profitability and sustainability of farm management and may simultaneously have an impact on soil organic carbon (SOC) content. In this study, we estimated how changes in crop rotations affected SOC balance in Finland between 2009 and 2018, using geospatial data and Bayesian modeling. The area designated for perennial-dominated and diverse cereal rotations increased over the study period. Perennial grassland rotation was found to have a positive impact on SOC balance, while rotations dominated by annual crops did not differ in their impacts on SOC content. At the national scale, changes in Finnish crop rotations resulted in an estimated annual mitigation of the loss of SOC content by 1336 Mg C year−1 in mineral soils and reduced the carbon dioxide emissions of organic soils by 10,475 Mg C year−1. The combined effect of these two contributions is 11,811 Mg C year−1, with an 80% probability interval of (−6600; 30,300) Mg C year−1. While the overall impact of changes in crop rotations on SOC is relatively small, a continued change to more diverse and perennial-dominated crop rotations may have other agronomic and environmental benefits, e.g. on resilience and biodiversity.

Total Soil CO2 Efflux from Drained Terric Histosols.

Histosols cover about 8-10% of Lithuania's territory and most of this area is covered with nutrient-rich organic soils (Terric Histosols). Greenhouse gas (GHG) emissions from drained Histosols contribute more than 25% of emissions from the Land Use, Land Use Change and Forestry (LULUCF) sector. In this study, as the first step of examining the carbon dioxide (CO2) fluxes in these soils, total soil CO2 efflux and several environmental parameters (temperature of air and topsoil, soil chemical composition, soil moisture, and water table level) were measured in drained Terric Histosols under three native forest stands and perennial grasslands in the growing seasons of 2020 and 2021. The drained nutrient-rich organic soils differed in terms of concentrations of soil organic carbon and total nitrogen, as well as soil organic carbon and total nitrogen ratio. The highest rate of total soil CO2 efflux was found in the summer months. Overall, the rate was statistically significant and strongly correlated only with soil and air temperature. A trend emerged that total soil CO2 efflux was 30% higher in perennial grassland than in forested land. Additional work is still needed to estimate the net CO2 balance of these soils.

Evaluation of an autonomous acoustic surveying technique for grassland bird communities in Nebraska.

Monitoring trends in wildlife communities is integral to making informed land management decisions and applying conservation strategies. Birds inhabit most niches in every environment and because of this they are widely accepted as an indicator species for environmental health. Traditionally, point counts are the common method to survey bird populations, however, passive acoustic monitoring approaches using autonomous recording units have been shown to be cost-effective alternatives to point count surveys. Advancements in automatic acoustic classification technologies, such as BirdNET, can aid in these efforts by quickly processing large volumes of acoustic recordings to identify bird species. While the utility of BirdNET has been demonstrated in several applications, there is little understanding of its effectiveness in surveying declining grassland birds. We conducted a study to evaluate the performance of BirdNET to survey grassland bird communities in Nebraska by comparing this automated approach to point count surveys. We deployed ten autonomous recording units from March through September 2022: five recorders in row-crop fields and five recorders in perennial grassland fields. During this study period, we visited each site three times to conduct point count surveys. We compared focal grassland bird species richness between point count surveys and the autonomous recording units at two different temporal scales and at six different confidence thresholds. Total species richness (focal and non-focal) for both methods was also compared at five different confidence thresholds using species accumulation curves. The results from this study demonstrate the usefulness of BirdNET at estimating long-term grassland bird species richness at default confidence scores, however, obtaining accurate abundance estimates for uncommon bird species may require validation with traditional methods.

2012–2016年三江源垂穗披碱草人工草地碳水热通量观测数据集

In the Sanjiangyuan Area known as the “Chinese Water Tower”, planting perennial artificial grassland has become an important measure for the restoration of degraded grassland in this area. The spatial-temporal pattern of the carbon, water, and heat fluxes of Elymus nutans artificial grasslands are crucial for comprehending the ecological service functions of the Elymus nutans artificial grasslands in the Sanjiangyuan Area. Sanjiangyuan Grassland Ecosystem National Observation and Research Station (referred to as Sanjiangyuan Sation) has used the eddy covariance technique to monitor the carbon, water, and heat fluxes over an Elymus nutans artificial grassland for 5 years since 2009. In order to advance the research on carbon, water, and heat fluxes and other related researches in the Sanjiangyuan Area and the broader Qinghai-Tibetan Plateau alpine ecosystems, we plan to publish the routine meteorological data of carbon, water and heat fluxes over an Elymus nutans artificial grassland observed from 2012 to 2016. This dataset includes routine meteorological data (i.e. air temperature, air relative humidity, water vapor pressure, soil temperature, soil moisture, photosynthetically active radiation, and precipitation) and carbon, water, and heat fluxes data (net ecosystem CO2 exchange, ecosystem CO2 respiration, gross ecosystem CO2 exchange, latent heat flux, and sensible heat flux) on half-hourly, daily, monthly, and yearly scales. The dataset used the flux data processing method recommended by ChinaFLUX. It is expected to provide field observational data support for scientific understanding, remote sensing retrieval processes, and model validation efforts in exploring the spatiotemporal patterns of carbon, water, and heat exchanges in artificial Elymus nutans grasslands.

Soil Seed Banks and Their Relation to Soil Properties in Hilly Landscapes.

For the prevention of hilly soils from erosion, a smart selection of crop rotations is very important. The aim of this study was to investigate the influence of different agrophytocenoses on seed numbers in the soil runoff sediments and soil seed banks' relations to soil properties in hilly landscapes. This study analyzes long-term monitoring data from three different agrophytocenoses (permanent grassland, cereal-grass crop rotation and crop rotation with a row crop) set up on slopes of 9-11° steepness with collectors for soil and water installed. The soil of the southern exposition slope was a slightly eroded Eutric Retisol. In the soil of permanent grassland, the number of seeds was 4036 seeds m-2, 6.0 and 3.2 times smaller compared to cereal-grass crop rotation and crop rotation with a row crop. The seeds found in the soil runoff sediments composed, on average, 0.9% of the soil seed bank, and the number of seeds depended on the number of days with heavy precipitation during the plant vegetation period, as well as on the plant communities grown in a particular rotation. Correlation analysis showed the seed numbers' dependence on the soil's chemical and physical properties. Hill slopes were not affected by water erosion, when agrophytocenoses were based on perennial grassland and also cereal-grass crop rotation, where reduced soil tillage was applied.

Establishment from seed is more important for exotic than for native plant species.

Climate change has initiated movement of both native and non-native (exotic) species across the landscape. Exotic species are hypothesized to establish from seed more readily than comparable native species. We tested the hypothesis that seed limitation is more important for exotic species than native grassland species. We compared seed limitation and invasion resistance over three growing seasons between 18 native and 18 exotic species, grown in both monocultures and mixtures in a field experiment. Half of the plots received a seed mix of the contrasting treatment (i.e., exotic species were seeded into native plots, and native species were seeded into exotic plots), and half served as controls. We found that (1) establishment in this perennial grassland is seed limited, (2) establishment from seed is greater in exotic than native species, and (3) community resistance to seedling establishment was positively related to diversity of extant species, but only in native communities. Native-exotic species diversity and composition differences did not converge over time. Our results imply that native to exotic transformations occur when diversity declines in native vegetation and exotic seeds arrive from adjacent sites, suggesting that managing for high diversity will reduce transformations to exotic dominance.

Restoring historical grasslands in a desert national park: Resilience or unrecoverable states in an emerging climate?

Ecosystems that supported multiple biological communities during the Holocene and that form alternative stable states pose challenges for identifying appropriate and feasible target communities for ecological restoration and conservation strategies for climate adaptation. In the Chihuahuan Desert, shrubland and perennial grassland alternatively dominated for millennia. However, grassland declined beginning 100–150 years ago during concomitant change in both climate and anthropogenic land use, making it unclear whether restoring grassland is appropriate or feasible in the emerging climate. In Guadalupe Mountains National Park, Texas, USA, we characterized remnant grasslands and performed experiments including outplanting and shrub reduction to assess feasibility and techniques for restoring desert grassland. In remnant patches, grass cover was more temporally variable than shrub cover, as grass cover varied 1.5× between years. Survival of outplanted grasses, either under Larrea tridentata shrubs or in the open with or without woody material encircling outplants for protection, was high (95 %) after seven months but declined to 2 % after 19 months. Response of perennial grass cover was variable after shrub and litter removal on soil surfaces varying in stoniness. Results suggest that 1) restoration can increase native desert grasses but gains may be intermittent; 2) reducing shrubs to facilitate natural expansion of remnant grasses and propagules may be more effective than outplanting grasses; and 3) restoring native grassland by reducing shrubs appears feasible even in dry conditions projected for the emerging climate. Findings that native grasses can increase at least intermittently suggest that practitioners have multiple candidate communities for conservation management and climate change adaptation as grassland, shrubland, and mixed communities each provide unique habitat.

Soil health and root‐zone enrichment characteristics between paired grassland and cropland fields in the southeastern United States

AbstractBackgroundSoil organic C and N data from privately managed pastures in the southeastern United States are relatively scant.MethodsA paired‐farm approach was deployed to determine how a variety of soil health parameters related to nutrient and water cycling might be altered under grazed, botanically diverse perennial pastures compared with annual monoculture croplands in three Major Land Resource Areas of the southeastern United States.ResultsSoil stability index averaged 0.64 and 0.91 mm mm−1 under cropland and grazed pasture, respectively, suggesting that pastures had a more stable soil surface that was resistant to erosion and allowed rapid water infiltration. Surface‐soil organic C and N fractions (i.e., total, particulate, and mineralizable fractions at 0–10 cm depth) were greater under pasture than under cropland. Across locations, root‐zone enrichments (0–30 cm depth) of organic C and N fractions were greater under pasture than under cropland. Within locations, root‐zone enrichment of total soil N was greater (p < 0.05) under pasture than under cropland in the Blue Ridge (2.87 vs. 1.10 Mg N ha−1, respectively) and the Piedmont (2.80 vs. 2.10 Mg N ha−1), but not in the Blackland Prairie (2.40 vs. 2.12 Mg N ha−1).ConclusionsThis study provides evidence that rotationally grazed, perennial grasslands can store more soil organic C and N and improve soil surface stability conditions compared with neighboring croplands producing commodity feed grains for feedlot finishing.

Evaluation of Soil Organic Carbon Stability in Different Land Uses in Lithuania

The effective management of soil organic carbon (SOC) is highlighted as one of the strategies and cost-effective options for mitigating climate change, while soil nitrogen (N) often is specified as an essential element for plant growth. This study was conducted to evaluate basic soil physical, chemical, and microbial indicators in three major soil types dominated in Lithuania—Arenosols, Retisols, and Cambisols—under forest land, perennial grassland, and arable land. Furthermore, soil microbial biomass carbon (SMBC) and nitrogen (SMBN), their ratio, and soil microbial respiration (microbial CO2) next to SOC and total N were hypothesized to be important measures for assessing SOC stability under different land uses. Therefore, selected soil indicators were evaluated in the surface 0–10 and 10–20 cm mineral soil layers. The study results showed higher concentrations of SOC, N, SMBC, and SMBN, and soil microbial CO2 in forest land and perennial grasslands than in arable land. The higher SMBC/SOC and SNBN/TN ratios indicated a higher ability to accumulate SOC and N in forest land and grasslands. Higher SOC immobilization in forest land and higher N immobilization in arable land were both specified by the obtained SMBC:SMBN ratio. This study identified forest land followed by grassland as the best land management practice that addresses soil C sequestration through higher C immobilisation. Assessing soil in forest land as a control land use next to the agricultural land could be a reasonable soil management practice to evaluate C sequestration in the region. Additionally, it was assumed that evaluation of the SMBC and SMBN concentrations together with soil physical and chemical indicators allow for a more effective assessment of SOC stability. Taken together, these findings support recommendation to develop grassland (and especially forest land systems) through afforestation or within agroforestry system, without reducing the importance of the agricultural sector.