Grass Stage Research Articles

Optimization of High-Pressure Processing for Microbial Inactivation in Pigmented Rice Grass Juice and Quality Impact Assessment during Refrigerated Storage.

Pigmented rice grass juice (RGJ) is a good source of bioactive compounds, but fresh juice has a relatively short shelf life of only 7 days at 4 °C. The objectives of this study were to determine the optimal growth stage of pigmented rice grass, investigate the optimal condition of high-pressure processing (HPP) for bacterial inactivation in inoculated RGJ using response surface methodology (RSM), and evaluate quality changes in uninoculated HPP-treated juice during storage at 4 °C compared with heat-treated (85 °C/10 min) and untreated samples. Results revealed that the optimal growth stage of rice grass was 9 days with the highest total anthocyanin content of 158.92 mg/L. The optimal condition of HPP was determined to be 612 MPa, 11 min, and 36 °C, and inactivated Escherichia coli K12 and Listeria innocua with 6.43 and 5.02 log reductions, respectively, meeting FDA regulations. The lethality of bacteria after HPP treatment can be explained by damage to the cell membrane and the leakage of intracellular constituents such as protein and nucleic acid. During 12 weeks of storage at 4 °C, total plate counts and yeast and mold counts in uninoculated HPP-treated juice were not detected. Moreover, HPP did not significantly change phytochemical properties (p < 0.05), caused a minor impact on physicochemical properties of RGJ, and maintained the durability of juice samples during storage. Analysis of the phytochemical profile revealed that HPP treatment could preserve most of the phenolic compounds in RGJ and especially increase the contents of protocatechuic acid, 4-hydroxybenzoic acid, syringic acid, transcinnamic acid, isorhamnetin-3-o-glucoside, quercetin, and cyanidin-3-glucoside (p < 0.05). Overall, HPP is a potential pasteurization technique for microbial inactivation and nutritional preservation for rice grass juice.

The variation in climate conditions and fire-related traits across Pinus (Pinaceae) species

Fire has long been recognized as a significant evolutionary factor for the genus Pinus (family Pinaceae). Many pine species have developed specific fire-adaptations, such as self-pruning, resprouting, and serotiny, to persist under various fire regimes. Fire-related traits, such as needle length, bark thickness, and plant height, also can affect the survival of pines in fire-prone environments. Investigating the climate conditions of pines and analyzing the variation in fire-adaptations and fire-related traits across pines can provide insights into the evolutionary process of the genus Pinus affected by fire. However, such studies are rare, particularly those focusing on the relationship among environmental conditions, fire-adaptations, and fire-related traits with a large number of pine species. In this study, we explored the variation in climate conditions and fire-related traits (including tree height, bark thickness, and leaf length) between fire-adapted and non-fire-adapted pines, as well as among three fire survival strategies (fire-tolerators, fire-embracers, fire avoiders). We also investigated the relationships between climatic conditions and fire-related traits/fire-adaptations (including resprouting, self-pruning, the grass stage, and serotiny) across the genus Pinus. Sixty-one out of 101 pine species were found to possess one or more fire adaptations and were classified as fire-adapted pines. We found that fire-adapted pines occupy warmer and more fire-prone habitats, and exhibit longer leaves, thicker bark, and taller habits than non-fire-adapted species. Our analysis did not indicate a significant difference between fire tolerators and embracers regarding traits and climate conditions, except that fire-tolerators have thicker bark and are more associated with wildfire-prone areas. Climate conditions appeared to significantly affect fire-related traits/fire-adaptations across the genus Pinus. These findings will facilitate our understanding the evolutionary process of fire adaptations/fire-related traits in the genus Pinus and will guide sustainable fire management in different pine forests.

Oaks enhance early life stage longleaf pine growth and density in a subtropical xeric savanna.

The interplay of positive and negative species interactions controls species assembly in communities. Dryland plant communities, such as savannas, are important to global biodiversity and ecosystem functioning. Sandhill oaks in xeric savannas of the southeastern United States can facilitate longleaf pine by enhancing seedling survival, but the effects of oaks on recruitment and growth of longleaf pine have not been examined. We censused, mapped, and monitored nine contiguous hectares of longleaf pine in a xeric savanna to quantify oak-pine facilitation, and to examine other factors impacting recruitment, such as vegetation cover and longleaf pine tree density.We found that newly recruited seedlings and grass stage longleaf pines were more abundant in oak-dominated areas where densities were 230% (newly recruited seedlings) and 360% (grass stage) greater from lowest to highest oak neighborhood densities. Longleaf pine also grew faster under higher oak density. Longleaf pine recruitment was lowest under longleaf pine canopies. Mortality of grass stage and bolt stage longleaf pine was low (~1.0%yr-1) in the census interval without fire. Overall, our findings highlight the complex interactions between pines and oaks-two economically and ecologically important genera globally. Xeric oaks should be incorporated as a management option for conservation and restoration of longleaf pine ecosystems.

Nitrogen acquisition and retention pathways in sustainable perennial bioenergy grass cropping systems

AbstractPerennial tall grasses show promise as bioenergy crops due to high productivity and efficient nutrient use. Ongoing research on bioenergy grasses seeks to reduce their reliance on synthetic nitrogen (N) fertilizer, the manufacture of which relies on fossil fuel combustion. Excessive use of fertilizers also causes adverse environmental consequences and leads to the evolutionary loss of plant traits beneficial to sustainable N cycle. Notably, perennial tall grasses have exhibited the potential to maintain high biomass yield without the need for N fertilizer or causing soil N depletion. Perennial grasses can be adept at interacting with their microbial partners to facilitate N acquisition and retention via mechanisms such as biological N fixation and nitrification inhibition. These inherent N management traits should be preserved and optimized at the this early stage of bioenergy grass breeding programs. This review examines the impact of external N on bioenergy grass production and explores the potential of leveraging advantageous N‐cycling attributes of perennial tall grasses, laying groundwork for future management and research efforts. With minimized dependency on external N input, the cultivation of perennial energy grasses will pave the way toward more resilient agricultural systems and play a significant role in addressing key global energy and environmental challenges.

Radical Hope

In this article, Yizhou Huang considers the transnational transmission of devised theater, focusing on the Shanghai-based performance group Grass Stage (Caotaiban) led by Zhao Chuan. She discusses the group’s devising process from two symbiotic aspects, the corporeal and the political. Attending to Grass Stage’s eclectic inspirations and international collaborations, Huang compares the collective to world renowned ensembles such as Théâtre du Soleil and parses out the unequal transactions between Asian performance traditions and devised theater techniques. She warns against a neo-Orientalism that positions non-Western artists and their works solely into an epistemological framework that applauds liberal democracy and argues for devised theater as a site of minor interventions, world making, as well as radical hope.

Tumble windmill grass (Chloris verticillata Nutt.) control with POST herbicides

AbstractTumble windmill grass (Chloris verticillata Nutt.) is a problematic perennial grass weed in the semiarid Central Great Plains (CGP). Greenhouse and fallow field experiments were conducted during 2021 and 2022 at Kansas State University Agricultural Research Center near Hays, KS, to determine the effectiveness of various POST herbicides for tumble windmill grass control. All selected POST herbicides were applied at field‐recommended rates at the seedling growth stage (3‐to 4‐inches tall) of tumble windmill grass in greenhouse study. Tumble windmill grass was at the heading growth stage (10‐to‐12‐inches tall) in fallow fields when POST herbicides were tested. Results from greenhouse study indicated that quizalofop‐P‐ethyl (QPE) and clethodim provided ≥ 95% control and shoot biomass reduction of tumble windmill grass at 28 days after treatment. Glyphosate provided 89% control and 93% shoot biomass reduction of tumble windmill grass. Imazamox and nicosulfuron had the least control (41 to 51%) and shoot biomass reduction (43 to 66%) of tumble windmill grass in greenhouse study. In contrast, all tested POST herbicides were comparatively less effective on tumble windmill grass (≤68% control and ≤ 50% shoot biomass reduction) except glyphosate (85% control and 54% shoot biomass reduction) in field study. These results conclude that clethodim, QPE, and glyphosate applied at early growth stages can provide effective control of tumble windmill grass in the CGP region.

Impact of Fire on Secondary Forest Succession in a Sub-Tropical Landscape

In Hong Kong, as in many tropical areas, grasslands are maintained by fire on disturbed and abandoned land. However, Hong Kong’s native forests are regenerating in many areas, alongside frequent burning of the hillsides, and are in different stages of structural succession to closed canopy forest patches. Understanding the major determinants of secondary succession is a vital input to forest management policies. Given the importance of forests for biodiversity conservation, watershed protection and carbon cycling. This study examines the relationship between burning regimes and structural forest succession over 42 years from 1973 to 2015, using an archive of satellite images, aerial photographs and field plot data. Overlay of a fire frequency map with maps of forest structural classes at different dates indicates the number of fires undergone by each successional class as well as the time taken to progress from one class to another under different fire regimes. Results indicate that the native sub-tropical evergreen forests, which are naturally fire intolerant, can regenerate alongside moderate burning, and once the shrub stage is reached, succession to closed forest is relatively rapid and can occur within 13 years. More than one burn, however, is more destructive, and twice-burnt areas were seen to have only one-third of the woody biomass of once-burnt plots. The most frequent fires occurred in areas where mono-cultural plantations had been destroyed by disease in the 1960s and were subsequently invaded by grasslands. These former plantation areas remained in early successional stages of grass and open shrubland by 2015. Other plantations from the 1970s and 1980s remain as plantations today and have acted as a barrier to natural forest succession, attesting to the greater effectiveness of fire control over re-afforestation measures.

Assessing the Effect of Slope Position on the Community Assemblage of Soil Diazotrophs and Root Arbuscular Mycorrhizal Fungi.

Considering the crucial role of soil diazotrophs and root arbuscular mycorrhizal fungi (AMF) in soil nutrient cycling during ecosystem restoration, diazotroph and AMF communities may be determined by slope position. However, the effect of slope position on diazotroph and AMF abundance, diversity, and community composition of karst ecosystems remains unknown. In this study, soil diazotrophs and root AMF characteristics on varying slope positions were assessed in a karst shrub ecosystem. The results displayed that the abundance of soil diazotrophs and root AMF diversity were significantly affected by slope position. Diazotroph abundance accompanied by soil nutrient and plant richness was higher on the lower slopes than the upper slopes, whereas root AMF diversity displayed the opposite trend. The soil diazotroph and root AMF community composition differed among the upper, middle, and lower slopes. The dominant taxa of soil diazotrophs and root AMF at the order level were Rhizobiales and Glomerales, respectively. Moreover, the diazotroph order of Nostocales and the AMF order of Paraglomerales were richer on the upper slopes than on the lower slopes. The slope position directly affected the plant diversity and soil nutrient distribution, indirectly affecting the diazotroph and AMF communities. Increased available nitrogen on the lower slope caused great diazotroph abundance by stimulating plant growth with sufficient carbohydrates. However, low soil nutrients and plant diversity but high plant root biomass induced more root AMF diversity on the upper slope than on the lower slope. Therefore, this study expands the knowledge of soil diazotroph and root AMF ecological functions along different slope positions during vegetation recovery for the successive stages of grass and shrub in the karst region.

Grass Stage as a Method: (Un)Doing Cultural Studies in China

Abstract The article argues that the practice of the grassroots theatre group Grass Stage provides an inspiring method for (un)doing Cultural Studies in China, in view of the challenges brought by the institutionalisation of mainland Chinese Cultural Studies and its theoretical impasse. This method, we argue, includes four key aspects: firstly, it positions itself from the margins, developing a critical relation with the centre; secondly, it transforms the urban space dominated by the state and the market into public and political space; thirdly, it uses the body as a point to connect the individual and society; lastly, it places the audience at the centre of the social construction of meaning through post-performance dialogue. The method proposed is a metaphor, in S. Hall’s terms, for developing possible counter-hegemonic elements, which open up the horizons of the possible. It offers a way to dislocate culture through reflections on the powers currently operating in Chinese society.

Xerophytic hardwood retention promotes competition over facilitation in longleaf pine woodlands in the absence of fire

Recent reports of xerophytic hardwood facilitation of longleaf pine seedlings challenge the traditional paradigm that co-occurring hardwood tree species constrain longleaf pine (Pinus palustris Mill.) regeneration. To better understand this dynamic, we established an experiment examining the effects of hardwood retention duration (no retention, one-year retention, four-year retention), overstory basal area (2-to-41 m2 ha−1), and understory vegetation cover on microclimatic conditions and longleaf pine seedling survival, development, physiological performance, and brownspot needle blight (Mycosphaerella dearnessii) infection in the Sandhills Ecoregion of North Carolina, USA. Light availability (μmol m−2 s−1) at the forest floor (∼20 cm) was reduced by 27% in the four-year retention treatment which significantly exceeded reductions found in the one-year (<1%) and no retention (<1%) treatments, respectively, post midstory removal. However, midstory treatment had little effect on soil moisture and temperature at 15 and 30 cm depth. Longleaf pine seedling survival (85%), aboveground biomass (7.51 g dry weight), and root collar size (1.53 cm) were significantly highest in the no retention treatment compared to the four-year retention treatment. Between treatments with midstory retention (one-year vs. four-year retention), longleaf pine seedlings were statistically larger in the one-year retention treatment (5.37 g dry weight) compared to the four-year retention treatment (4.84 g dry weight). Seedling brownspot infection did not statistically vary among midstory retention treatments. Across all midstory treatments, overstory basal area had a stronger negative effect on longleaf pine seedling aboveground biomass development, root collar development and brownspot infection compared to midstory hardwood stem density or understory vegetation cover. Moreover, for most measured metrics, overstory basal area had a stronger negative effect on longleaf pine physiological performance compared to midstory hardwood stem density. Collectively, these results indicate that hardwood retention did not facilitate longleaf pine survival and development in the grass stage and that asymmetric competition from the overstory represents a stronger impediment to longleaf pine sapling recruitment than midstory hardwoods.

Helium Atmospheric Pressure Plasma Jet Effects on Two Cultivars of Triticum aestivum L.

The use of cold plasma in the treatment of seeds before sowing presents a promising technique for sustainable agriculture. The objective of this study is to evaluate the effect of cold plasma treatment on the morphology of wheat seeds (Triticum aestivum L. 'Dacic' and 'Otilia'), their germination, biochemical composition, and the nutritional quality of wheat grass. Wheat seeds were morphologically and elementally characterized by atomic force microscopy (AFM), scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDX), X-ray computer tomography (CT), and particle-induced X-ray emission (PIXE). Helium was used as a working gas for plasma generation and the analysis of the species produced showed the presence of NOγ, OH, N2 and N2+ and O. Evaluation of germination and plant growth for 10 days (wheat grass stage) highlighted a specific trend for each cultivar. The biochemical analysis of wheat grass highlighted an increase in the chlorophyll content in the plasma-treated variants, an increase in the flavonoid and polyphenol content in 'Dacic'-treated variant, while the soluble protein content, antioxidant activity, and color were not affected. The analysis of the nutritional quality of wheat grass by the FT-NIR analytical technique highlighted an increase in the ash content in the plasma-treated wheat cultivars, while the humidity, proteins, neutral detergent fiber (NDF), acid detergent fiber (ADF), and energy values were not affected.

Improved soil composition promotes nutrient recovery during vegetation restoration in karst peak-cluster depressions

The relationship between the soil structure and nutrient content during vegetation restoration of karst peak-cluster depression remains uncertain. Via field investigations and laboratory experiments, the changes in soil aggregate composition and nutrient distribution characteristics and their relationship during four stages of vegetation restoration (grassland (GL), shrub grass (SG), bush forest (BF) and secondary forest (SF) stages) in a karst peak-cluster depression were evaluated. The results showed that (1) vegetation restoration enhanced the formation of > 0.25 mm aggregates, while the distribution of aggregates in each stage was dominated by > 2 mm aggregates, constituting>72.18 % of the total aggregates, while the content of the other aggregates decreased with decreasing size. (2) Vegetation restoration gradually increased the soil organic matter (SOM), total potassium (TK) and available phosphorus (AP) contents, which peaked at the SF stage; the total nitrogen (TN), total phosphorus (TP), alkali-hydrolyzable nitrogen (AN), rapidly available potassium (AK) and exchangeable calcium (ExCa2+) and magnesium ions (ExMg2+) contents peaked in the BF stage and then slightly decreased, indicating that soil nutrient storage thresholds existed in the karst area. (3) The TN, AP, and ExMg2+ contents increased with decreasing aggregate size, and the AN and AK contents first increased and then decreased with decreasing aggregate size. (4) Among the soil aggregates, the nutrient contribution rate was dominated by > 2 mm aggregates, accounting for 41.42 %∼89.01 % of the total aggregates, with a coefficient of determination ranging from 0.456 to 0.998 according to stepwise regression analysis, suggesting that soil nutrients are highly correlated with the nutrient contents in the > 2 and 2–1 mm aggregates and that the soil aggregate composition determines the aggregate nutrient contribution. Vegetation restoration improves the soil structure and nutrient retention capacity, and the aggregate composition is the decisive factor of the nutrient distribution.

The effects of fire, climate, and species composition on longleaf pine stand structure and growth rates across diverse natural communities in Florida

The longleaf pine (Pinus palustris) savanna is an endangered ecosystem within a global biodiversity hotspot. However, most studies of longleaf habitats have not considered their distinct structure and function among unique communities, which are critical for developing appropriate management strategies. We aim to assess how differences in climate, fire, and species composition interact and relate to longleaf pine densities and growth rates in distinct communities. We surveyed longleaf pine stand structure (density by size and age classes) and estimated growth rates using 516 tree cores across 5 community types (69 plots, each ≤ 160 m2). Surveys covered the range of longleaf pine in Florida, USA, including the southernmost extent of the species range, and included all communities where longleaf are dominant (sandhill, upland pine, and mesic, wet, and scrubby flatwoods). We used an NMDS ordination to classify communities by species composition. We used linear mixed-effects models to examine the effect of community type on longleaf pine density and growth rates and then used recursive partitioning and regression tree analyses to identify how climate, fire, and species composition affect density and growth rates. We found that stand structure and species composition were different across communities, with upland pine being the most species rich and having the highest density of mature trees, whereas growth rates were not statistically different across communities. Across communities, unique interactions between climate, fire, and species composition, resulted in differences in stand structure and growth rates. In general, tree and grass stage densities were best predicted by species composition and fire rather than by climate, whereas growth rates were best predicted by climate. Having included the southernmost extent of longleafs range we show that longleaf growth rates increased with higher temperatures, but this effect is reversed in dry conditions. Our results suggest that longleaf growth rates across its range will be more sensitive to current and future climate change than longleaf population density. Furthermore, while controlling competition from hardwoods has been a focus of longleaf restoration, our results suggest that species that facilitate longleaf establishment may be equally important in restoring and managing these habitats. Managers should design and apply regional and community specific plans that take into account relationships between fire and associated species composition under a changing climate, which will influence strand structure and tree growth differently in different communities.

World Political Theatre and Performance: Theories, Histories, Practices ed. by Mireia Aragay, Paola Botham, and José Ramón Prado-Pérez

Reviewed by: World Political Theatre and Performance: Theories, Histories, Practices ed. by Mireia Aragay, Paola Botham, and José Ramón Prado-Pérez Kevin J. Wetmore Jr. WORLD POLITICAL THEATRE AND PERFORMANCE: THEORIES, HISTORIES, PRACTICES. Edited by Mireia Aragay, Paola Botham, and José Ramón Prado-Pérez. Leiden: Brill Rodopi, 2020. Cloth, €105.00/ $126.00; ebook, €105.00/ $126.00. This volume arose out of the Political Performances Working Group of IFTR, offering fourteen essays concerning political performances in Finland, the United Kingdom, Malta, Turkey, Belarus, Poland, Estonia, South Africa, India, and China. It is the last two that would be of interest to readers of this journal, although the entire volume is interesting and readable. At heart, by "political theatre" the editors here refer to theatre in response to political oppression and social injustice. The volume is divided into two sections. The first considers "the relationship between performance and activism" and the second concerns "current debates in and around political theatre" (p. 4). In part one the Asianist will find two essays of particular interest. The first, Pujya Ghosh's "From Revolution to Dissent: A Case Study of the Changing Role of Theatre and Activism in Bengal," offers an historical analysis of playwrights Utpal Dutt and Debesh Chattopadhyay and the Naxalbari movement in the 1960s in Bengal. Ghosh posits that both artists emerged in the sixties as performers, activists, and intellectuals, using theatre to challenge the political and social status quo. They created a Bengali theatre that was "a component of civil society, a space in which political battles and future dreams would be reflected" (p. 40). However, as the seventies drew on, progressive [End Page 403] politics began to lose their cultural heft. Ghosh then asks, "to what extent can an intellectual/artist with a left political ideology perform his/her 'political' role under the growing pervasiveness of the capitalist order?" (p. 41). The answer, of course, is "it's complicated," but she concludes that "the parameters of theatre and activism have indeed shifted from revolution to dissent," a paradigm that reflects much theatre in the world since the sixties (p. 51). Revolution seems no longer possible and merely pointing out a different path than the status quo is now the aim of political theatre, which ultimately requires us to rethink what the term "left" means in a political sense. As historical analysis, the essay is interesting and informative, as a critique of the history of political performance in Bengal; it offers a means by which to understand the ultimate lack of efficacy in theatre as a force for social change on the macro level. A second essay from the first section, Julia Boll's "Making the Audience Cry: Witnessing Violence and the Ethics of Compelled Empathy" offers a fascinating exploration of two separate plays that each attempt to make an audience cry in response to atrocity. Boll compares the Belarus Free Theatre's 2012 production of Trash Cuisine (a play about state-sponsored violence and genocide) with Yael Farber's 2013 Nirbhaya, a play devised in response to the gang rape of a young woman on a bus in Delhi. The latter piece was devised and workshopped in India under the direction of Farber, a South African playwright best known for her post-apartheid works that engage and deconstruct that nation's historic racial and gender traumas and explore the politics of witnessing and restorative justice. The play was subsequently toured to Edinburgh, Mumbai, Delhi, and Bangalore. An example of verbatim theatre, using the words and stories of witnesses, the play attempts to evoke empathy, horror, and ultimately tears from the audience. Boll's essay effectively explores the ethics of doing so, and Farber's role as an outsider engaging with an Indian atrocity; Boll then compares it with Free Theatre's show in one of the strongest essays in the volume about the role and purpose of the artist in dealing with political violence, making it as personal as possible, especially for those who have not suffered from it. Lastly, one essay in the second section engages Chinese political theatre. Wei Zheyu's "The Touring Grass Stage: Staging the Site-Specific Dilemma of Globalization...

NUTRITIVE VALUE OF GUATEMALA GRASS (Tripsacum andersonii) HARVESTED AT THREE STAGES OF MATURITY IN GEDEO AGROFORESTRY SYSTEMS, SOUTHERN ETHIOPIA

&lt;div class="WordSection1"&gt;&lt;p&gt;&lt;strong&gt;Background:&lt;/strong&gt; Gedeo agroforestry is characterized as the integration of trees, crops and livestock on the same unit of land. Land scarcity is a common characteristic in the Gedeo agroforestry system. Hence integrating forage crops with the agroforestry system is one of the options to alleviate feed scarcity in the area. &lt;strong&gt;Objectives:&lt;/strong&gt; To evaluate the biomass yield and nutritional value of Guatemala grass harvested at three stages of maturity: Early (120days), Mid (150days) and Late (180 days) cultivated at three different altitudes (high, medium and low). &lt;strong&gt;Methodology:&lt;/strong&gt; A randomized complete block design with three replications was employed. Morphological parameters and chemical composition were measured at each stage of maturity and altitude. &lt;strong&gt;Result:&lt;/strong&gt; The results showed that the number of leaves per plant (NL), plant height (PH), leaf length (LL) and dry matter yield (DMY) exhibited (p&amp;lt;0.05) an increasing trend as harvesting days were delayed. Contrarily the number of tillers (NT) showed (p&amp;lt;0.05) decreasing trend as harvesting dates advanced. The highest (p&amp;lt;0.05) CP (12.6±0.25%DM) was recorded at 120 days. The highest (p&amp;lt;0.05) NDF (61.27±0.07%DM) and ADF (42.3±0.91%DM) were recorded at 180 days of harvesting. The highest (p&amp;lt;0.05) IVDMD (56.7±1.97%) was recorded at 120 days of harvesting, whereas the least (p&amp;lt;0.05) (48.0±2.06) was at 180 days of harvesting. Generally, as the harvesting date advanced, CP and IVDMD showed a decreasing trend, whereas the fiber content (ADF, NDF and ADL) showed an increasing trend. &lt;strong&gt;Implication:&lt;/strong&gt; Based on the morphological characteristics and dry matter yield, the best harvesting stage of Guatemala grass was at the late (180days) stage of maturity. On the other hand, considering the chemical composition and IVDMD, the best harvest stage was at the early (120days) stage of maturity. &lt;strong&gt;Conclusion:&lt;/strong&gt; Cutting Guatemala grass at the proper growth stage is crucial for forage management. However, to fully utilize the potential of Guatemala grass, further studies on live animal experiments should be carried out.&lt;/p&gt;&lt;/div&gt;

Life Stage and Neighborhood-Dependent Survival of Longleaf Pine after Prescribed Fire

Determining mechanisms of plant establishment in ecological communities can be particularly difficult in disturbance-dominated ecosystems. Longleaf pine (Pinus palustris Mill.) and its associated plant community exemplify systems that evolved with disturbances, where frequent, widespread fires alter the population dynamics of longleaf pine within distinct life stages. We identified the primary biotic and environmental conditions that influence the survival of longleaf pine in this disturbance-dominated ecosystem. We combined data from recruitment surveys, tree censuses, dense lidar point clouds, and a forest-wide prescribed fire to examine the response of longleaf pine individuals to fire and biotic neighborhoods. We found that fire temperatures increased with increasing longleaf pine neighborhood basal area and decreased with higher oak densities. There was considerable variation in longleaf pine survival across life stages, with lowest survival probabilities occurring during the bolt stage and not in the earlier, more fire-resistant grass stage. Survival of grass-stage, bolt-stage, and sapling longleaf pines was negatively associated with basal area of neighboring longleaf pine and positively related to neighboring heterospecific tree density, primarily oaks (Quercus spp.). Our findings highlight the vulnerability of longleaf pine across life stages, which suggests optimal fire management strategies for controlling longleaf pine density, and—more broadly—emphasize the importance of fire in mediating species interactions.

Changes in soil aggregate stability and aggregate-associated organic carbon during old-field succession in karst valley.

Soil is the largest carbon pool whose change will have an impact on the terrestrial carbon cycle in the terrestrial ecosystem. Old-field succession on abandoned farmland, which usually has a noticeable effect on soil status, is a common phenomenon in karst valley where human activity alters frequently. In order to understand the changes in the accumulation of organic carbon (OC) in aggregates and bulk soil in different stages of old-field succession on abandoned farmland in the karst valley area, soil samples were collected at 0-10-cm and 10-20-cm depth representing three typical stages of old-field succession, i.e., abandoned farmland, secondary grass, and secondary shrub in Qingmuguan karst valley area, Chongqing City, Southwest China. Results displayed that during old-field succession (1) the mean weight diameter and geometric mean diameter of the aggregates increased and the fractal dimension decreased; (2) OC content within aggregates and bulk soil had no significant change in topsoil (0-10cm); OC content within microaggregates and bulk soil had a significant reduction in subsoil (10-20cm); the OC content within silt and clay fractions was significantly higher than that within the other two kinds of aggregates; (3) bulk-soil OC storage had no significant change but its accumulation relied more on the increase in the number of larger aggregates. It is concluded that the old-field succession in karst valley was beneficial to protect against soil erosion by improving soil aggregate stability, but had a limited effect on soil organic carbon sequestration.

Effects of Sod-culture on Soil Nutrients and Microbial Abundance in Zanthoxylum bungeanum Plantation

In order to study the impacts of sod-culture on soil nutrients and soil microorganisms under Zanthoxylum bungeanum plantation, white clover was planted and natural weeds were cultivated, and the changes of soil nutrients and soil microorganisms were studied with clear tillage as control. The results showed that the effect of grass on soil nutrients and microbial abundance was mainly in 0~20 cm soil layer in Zanthoxylum bungeanum plantation. Grass increased the content of soil organic matter, some nutrient elements, the microbial abundance in soil, and changed the population structure of microorganisms. At the early stage of grass growing, the consumption of soil water and nitrogen fertilizer may be great, so scientific management combined with agricultural measures should be carried out according to the growth characteristics of Zanthoxylum bungeanum.

Grass(stage)root movement to ensure future resilience of longleaf pine ecosystems

Recent interest in restoring longleaf pine ecosystems highlights the need for an improved understanding, appreciation, and consideration of longleaf pine’s unique life history compared to other southern pines. Longleaf pine ecosystems are considered more resilient than other southern pine ecosystems and the attributes that confer this resilience may be related to belowground carbon allocation patterns that occur during the seedling stage of its life history where it exists for years in a grass stage. The long residence time spent in the grass stage has impeded adoption of longleaf pine by landowners for decades, which has resulted in efforts to expedite emergence from the grass stage through silviculture, nursery production, and selection breeding techniques; however, expedited emergence may come at the expense of root and belowground carbohydrate storage reserve development—traits that purportedly enhance longleaf pine tree and ecosystem resilience relative to other southern pine species. Here, I caution that efforts to expedite longleaf pine emergence from the grass stage also consider the potential implications on belowground carbon allocation and identify research priorities to help facilitate the improvement of longleaf pine seedling silviculture, nursery production, and breeding in a way that ensures the maintenance of attributes linked to resilience.

Assessment of natural regeneration of longleaf pine (Pinus palustris) 15 years post-regeneration control

We assessed natural regeneration of longleaf pine (Pinus palustris Mill.) using the data collected from the Escambia Experimental Forest in southern Alabama. Fifteen years after the regeneration control, natural regeneration of longleaf pine remained patchy across a wide range of site and stand conditions; slightly more than half of all plots contained regeneration, but the density of seedlings and saplings varied significantly. The abundance of seedlings ≤1-year-old was positively related to stand age and time since last fire, but negatively related to overstory basal area. The abundance of seedlings and saplings was positively related to stand age, but negatively related to time since last fire and overstory basal area. The probability of achieving at least 15 000 seedlings·ha–1 that are older than 1 year but less than 1 m tall and at least 1250 saplings·ha–1 that are over 1 m tall was, respectively, positively related to the ratio of time since last fire to overstory basal area and the ratio of quadratic mean diameter to site index. A longer fire interval (&gt; 2 to 3 years) should be adopted to naturally regenerate longleaf. We did not find clear zones of exclusion present in natural regeneration even though overstory trees, seedlings, and saplings tended to be repulsive spatially and &gt;80% grass stage seedlings and saplings occurred outside tree crowns.