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To combat the decline in North American grasslands and prairies, innovative strategies to establish new native grass and forb plantings must be considered. Integrated vegetation management entails the use of many practices to cultivate desirable vegetation along roadsides, including mowing, applying herbicides, burning, and replanting. Currently, only a limited selection of postemergence herbicides are available to improve native plant establishment along roadsides. A greenhouse herbicide screen that included four postemergence herbicides registered for use on Conservation Reserve Program (CRP) acres and rights-of-way was conducted to test their safety for use on four native grasses (big bluestem, buffalograss, sideoats grama, and switchgrass) and seven forb species (ashy sunflower, black-eyed Susan, butterfly milkweed, desert false indigo, Illinois bundleflower, Mexican hat plant, and purple coneflower). Clopyralid (689 g ae ha–1), metsulfuron (4.18 g ai ha–1), and quinclorac (418 g ai ha–1) applied at labeled rates caused no injury to the native grass species or butterfly milkweed. However, florpyrauxifen-benzyl (38.4 g ai ha–1) caused significant injury to buffalograss and switchgrass. None of the herbicides tested were universally safe to use on all forb species evaluated in this trial, with each herbicide causing unacceptable injury (≥25%) to one or more forb species. None of the herbicides studied here would be completely safe for use on mixed stands of native grasses and native forbs at the seedling growth stage, indicating that prairie establishment must use alternative chemistries, plant mixes with fewer species, or avoid postemergence applications shortly after emergence of native forbs. Nomenclature: Clopyralid; florpyrauxifen-benzyl; metsulfuron; quinclorac; ashy sunflower, Helianthus mollis Lam.; big bluestem, Andropogon gerardii Vitman; black-eyed Susan, Rudbeckia hirta L.; buffalograss, Buchloe dactyloides [Nutt.] J.T. Columbus; butterfly milkweed, Asclepias tuberosa L.; desert false indigo, Amorpha fruticosa L.; Illinois bundleflower, Desmanthus illinoensis (Michx.) MacMill. ex B.L. Rob. & Fernald; Mexican hat plant, Ratibida columnifera (Nutt.) Wooton & Standl.; purple coneflower, Echinacea purpurea (L.) Moench; sideoats grama, Bouteloua curtipendula [Michx.] Torr.; switchgrass, Panicum virgatum L.

1. Temporal changes in semi-arid ecosystems can include transitions between alternative stable states, involving thresholds and multiple domains of attraction, but can also include relatively continuous, symmetric and reversible shifts within a single stable state. Conceptual state-and-transition models (STMs) describe both types of ecosystem dynamics by including state transitions (plant community changes difficult-to-reverse without substantial input or effort) and phase shifts (easily reversible community changes) as consequences of management practices and environmental variability. Grazing management is purported to be the primary driver of state transitions in current STMs for North American grasslands, but there is limited empirical evidence from these grasslands showing that grazing can cause difficult-toreverse transitions between alternate stable states. 2. In a northern mixed-grass prairie in Wyoming, USA, we examined plant community responses to (i) long-term (33-year) grazing intensity treatments (none, light, moderate and heavy stocking rates) and (ii) 8 years of light or no grazing in pastures that were grazed heavily for the previous 25 years. 3. Long-term grazing treatments were associated with distinct, but not stable, plant communities. From year 22 to 33, heavier stocking rates decreased cover of dominant C₃ grasses and increased cover of the dominant C₄ grass Bouteloua gracilis. 4. Reversing stocking rates from heavy to light or no grazing resulted in reversal of changes induced by prior heavy stocking for dominant C₃ grasses, but not for B. gracilis. For both groups, rates of change following grazing treatment reversals were consistent with rates of change during the initial years of the experiment (1982-1990). 5. Synthesis and applications. In a semi-arid rangeland with a long evolutionary history of grazing, different long-term grazing intensity treatments caused slow, continuous and directional changes with important management implications, but did not appear to induce alternative stable states. For this and similar ecosystems, quantifying the time-scales and compositional gradients associated with key phase shifts may be more important than identifying thresholds between alternative stable states.

Background. Martial arts, characterized by intermittent high-intensity efforts, generate specific cardiovascular constraints. Few studies have examined post-exercise cardio-electrical and hemodynamic responses in this context, particularly during the recovery phase. Objective. This study aimed to analyze variations in heart rate (HR), blood pressure (systolic: SYS, diastolic: DIAS), oxygen saturation (SpO₂), and electrocardiographic parameters (PR, QT, QRS, QTc, RV5, SV1) in martial arts practitioners before, immediately after, and up to 30 minutes following an intense bout of exercise. Methods. Twenty-four male athletes performed a high-intensity session simulating competition (≥85% HRmax). Physiological measurements were collected at four time points (rest, end of exercise, and 15- and 30-minute recovery). A repeated-measures ANOVA and a factorial analysis were performed. Results. Significant post-exercise hypotension was observed (SYS: −11.33% at 30 min; DIAS: −14.63% at end of exercise). HR doubled at the end of effort (138 bpm), with partial recovery by 30 minutes. QT interval shortened and then progressively normalized. SpO₂ showed a slight decrease (−1.28%) before rising again. Factorial analysis identified clusters of interrelated variables. Conclusion. Martial arts induce specific transient cardio-electrical responses. These findings highlight the importance of individualized recovery monitoring for both performance optimization and cardiovascular prevention. Antecedentes. Las artes marciales, caracterizadas por esfuerzos intermitentes de alta intensidad, generan restricciones cardiovasculares específicas. Pocos estudios han examinado las respuestas cardioeléctricas y hemodinámicas post-ejercicio en este contexto, particularmente durante la fase de recuperación. Objetivo. Este estudio tuvo como objetivo analizar las variaciones en la frecuencia cardíaca (FC), la presión arterial (sistólica: PAS, diastólica: PAD), la saturación de oxígeno (SpO₂) y los parámetros electrocardiográficos (PR, QT, QRS, QTc, RV5, SV1) en practicantes de artes marciales antes, inmediatamente después y hasta 30 minutos tras un esfuerzo intenso. Métodos. Veinticuatro atletas masculinos realizaron una sesión de alta intensidad que simulaba una competición (≥85% de la FC máxima). Se recogieron mediciones fisiológicas en cuatro momentos temporales (reposo, final del ejercicio, y recuperación a 15 y 30 minutos). Se realizó un ANOVA de medidas repetidas y un análisis factorial. Resultados. Se observó una hipotensión post-ejercicio significativa (PAS: −11,33 % a los 30 min; PAD: −14,63 % al final del ejercicio). La FC se duplicó al final del esfuerzo (138 lpm), con una recuperación parcial a los 30 minutos. El intervalo QT se acortó y luego se normalizó progresivamente. La SpO₂ mostró una ligera disminución (−1,28 %) antes de volver a aumentar. El análisis factorial identificó grupos de variables interrelacionadas. Conclusión. Las artes marciales inducen respuestas cardioeléctricas transitorias específicas. Estos hallazgos resaltan la importancia de un monitoreo individualizado de la recuperación tanto para la optimización del rendimiento como para la prevención cardiovascular. Contexto. As artes marciais, caracterizadas por esforços intermitentes de alta intensidade, geram restrições cardiovasculares específicas. Poucos estudos examinaram as respostas cardioelétricas e hemodinâmicas pós-exercício neste contexto, particularmente durante a fase de recuperação. Objetivo. Este estudo teve como objetivo analisar as variações da frequência cardíaca (FC), pressão arterial (sistólica: PAS, diastólica: PAD), saturação de oxigénio (SpO₂) e parâmetros eletrocardiográficos (PR, QT, QRS, QTc, RV5, SV1) em praticantes de artes marciais antes, imediatamente após e até 30 minutos após o exercício intenso. Métodos. Vinte e quatro atletas do sexo masculino realizaram uma sessão de alta intensidade simulando competição (≥85% da FC máxima). As medidas fisiológicas foram recolhidas em quatro momentos (repouso, final do exercício e recuperação de 15 e 30 minutos). Foram realizadas ANOVA de medidas repetidas e análise fatorial. Resultados. Observou-se hipotensão significativa após o exercício (PAS: −11,33% aos 30 min; PAD: −14,63% no final do exercício). A frequência cardíaca duplicou no final do esforço (138 bpm), com recuperação parcial aos 30 minutos. O intervalo QT encurtou e depois normalizou gradualmente. A SpO₂ apresentou uma ligeira queda (−1,28%) antes de voltar a aumentar. A análise fatorial identificou agrupamentos de variáveis ​​inter-relacionadas. Conclusão: As artes marciais induzem respostas cardioelétricas transitórias específicas. Estes achados realçam a importância da monitorização individualizada da recuperação tanto para a otimização do desempenho como para a prevenção cardiovascular.

Large areas of desert grasslands in the southwestern United States have shifted to sparse shrublands dominated by drought-tolerant woody species over the last 150 yr, accompanied by accelerated soil erosion. An important step toward the understanding of patterns in species dominance and vegetation change at desert grassland-shrubland transitions is the study of environmental limitations imposed by the shrub-encroachment phenomenon on plant establishment. Here, we analyze the structure of soil seed banks, environmental limitations for seed germination (i.e., soil-water availability and temperature), and simulated seedling emergence and early establishment of dominant species (black grama, Bouteloua eriopoda, and creosotebush, Larrea tridentata) across a Chihuahuan grassland-shrubland ecotone (Sevilleta National Wildlife Refuge, New Mexico, USA). Average viable seed density in soils across the ecotone is generally low (200-400 seeds/m²), although is largely concentrated in densely vegetated areas (with peaks up to 800-1,200 seeds/m² in vegetated patches). Species composition in the seed bank is strongly affected by shrub encroachment, with seed densities of grass species sharply decreasing in shrubdominated sites. Environmental conditions for seed germination and seedling emergence are synchronized with the summer monsoon. Soil-moisture conditions for seedling establishment of B. eriopoda take place with a recurrence interval ranging between 5 and 8 yr for grassland and shrubland sites, respectively, and are favored by strong monsoonal precipitation. Limited L. tridentata seed dispersal and a narrow range of rainfall conditions for early seedling establishment (50-100 mm for five to six consecutive weeks) constrain shrub-recruitment pulses to localized and episodic decadal events (9-25 yr recurrence intervals) generally associated with late-summer rainfall. Re-establishment of B. eriopoda in areas now dominated by L. tridentata is strongly limited by the lack of seeds and decreased plant-available soil moisture for seedling establishment.

In the tropical Atlantic, the ichthyofauna between the coast of Brazil and the Caribbean regions, divided by the Amazon barrier, is very similar presenting several geminate species, including Gramma brasiliensis, endemic in Brazil, and its Caribbean counterpart Gramma loreto. Morphological and molecular studies have helped establish evolutionary patterns that sister-species of these two marine habitats are subjected to. However, their chromosomal characteristics are only beginning to be better characterized. Accordingly, a comparative cytogenetic analysis was carried out in G. brasiliensis and G. loreto, seeking evidence of cytotaxonomic markers implicated in the karyotypic diversification of these species and likely associated with speciation events. Heterochromatic regions and their affinity to fluorochromes GC- or AT-specific were identified, as well as the distribution of ribosomal DNA sites in chromosomes, either by silver nitrate impregnation (Ag-NORs) or dual-color FISH mapping with 18S and 5S rDNA probes. While displaying the same diploid number, 2n = 48 chromosomes, considered basal for Perciformes, the two species differed in karyotype structure, showing karyotypic formulas and species-specific heterochromatin pattern. The cytological characters found support the differentiating status of these species, possibly achieved under the conditions of allopatry due to the Amazon/Orinoco barrier, showing chromosomal peculiarities in Grammatidae species when compared to other groups of Perciformes.

The reliance on imported seeds for grassland rehabilitation in Mexico has led to increased costs and other difficulties in implementing grassland rehabilitation programs. Varieties need to be generated from local ecotypes that are outstanding in forage production and their response to rehabilitation programs. However, the scarcity of occurrence records is often a deterrent to niche and distribution modeling, hence the need for an approach that overcomes such limitations. The objectives of this study were (1) to develop a geographic information system (GIS)-based approach to determining the population distribution of a promising ecotype of Bouteloua curtipendula (Michx.) Torr. for grassland rehabilitation in the Chihuahuan Desert, Mexico; (2) to identify the edaphoclimatic variables that define the ecotype’s distribution; and (3) to develop models to determine the potential area for the use of the ecotype in grassland rehabilitation. The challenge for the present study was that only one georeferenced collection site of the ecotype in Chihuahua was available for use in the construction and calibration of the models. GIS software 10.3 was used to develop two potential distribution models: Model A, with variables obtained directly from a vector climate dataset, and Model B, with derived variables. A field work methodology was developed for the validation process using a georeferenced digital mesh and the nested sampling method modified by Whittaker. The information was analyzed with 10 non-parametric statistical tests. The two models had an overall accuracy and sensitivity level greater than 70% and a positive predictive power greater than 80%. The predicted population distribution areas in Chihuahua (18,158 ha) in the form of discontinuous patches cohered with those in previous reports on the distribution form of B. curtipendula. The edaphoclimatic variables influencing ecotype distribution were soil type, average minimum and maximum temperature in January, average maximum temperature in June, average minimum temperature in July, and average precipitation in August. The sensitivity analysis showed soil type as an important variable in defining the ecotype’s distribution. Considering soil as the main predictor variable, the potential rehabilitation area where the ecotype may be used was estimated at 7,181,735 ha in the Chihuahuan Desert region. The study developed and validated an approach to modeling the ecological niche of an ecotype of commercial interest, despite severe limitations in the number of georeferenced sites available for modeling. Further study is needed to explore its applicability to grassland rehabilitation in the Chihuahuan Desert and the study of rare and understudied ecotypes or species in other settings.

Global climate change is expected to result in increased temperatures and variation in precipitation. In the Desert Southwest region of the United States, climate change may result in drier conditions. Eragrostis lehmanniana (Lehmann lovegrass) is an invasive species that has extensively colonized the southwestern United States, including Bouteloua eriopoda (black grama) grasslands. While both E. lehmanniana and B. eriopoda evolved in arid conditions, drier conditions may influence this invader–native system in unforeseen ways. Using a combination of precipitation pivot point (PPP) and drought sensitivity (DS) analysis, we compared responses of B. eriopoda and E. lehmanniana to altered precipitation regimes including long‐term drought treatments in the northern Chihuahuan Desert, New Mexico. We defined PPP as the critical point in precipitation amount below which plant percent cover decreased and above which it increased. We used DS, defined as the square millimeters of cover lost when precipitation decreased by 1 mm, to elucidate the direct response of biomass to drought on either side of the PPP. We estimated mean monsoon PPPs of 62.5 and 63.7 mm for B. eriopoda and E. lehmanniana, respectively. We estimated mean annual (1 October–30 September) PPPs of 108.6 and 108.5 mm for B. eriopoda and E. lehmanniana, respectively. Bouteloua eriopoda mean DS was 4.71 mm2/mm. Eragrostis lehmanniana mean DS was 1.56 mm2/mm. Results suggest that it is unlikely that extended drought will benefit E. lehmanniana over B. eriopoda and both species may decline under extreme drought.

Plant soil feedback (PSF) occurs when a plant modifies soil biotic properties and those changes in turn influence plant growth, survival or reproduction. These feedback effects are not well understood as mechanisms for invasive plant species. Eragrostis lehmanniana is an invasive species that has extensively colonized the southwest US. To address how PSFs may affect E. lehmanniana invasion and native Bouteloua gracilis growth, soil inoculant from four sites of known invasion age at the Appleton-Whittell Audubon Research Ranch in Sonoita, AZ were used in a PSF greenhouse study, incorporating a replacement series design. The purpose of this research was to evaluate PSF conspecific and heterospecific effects and competition outcomes between the invasive E. lehmanniana and a native forage grass, Bouteloua gracilis . Eragrostis lehmanniana PSFs were beneficial to B. gracilis if developed in previously invaded soil. Plant-soil feedback contributed to competitive suppression of B. gracilis only in the highest ratio of E. lehmanniana to B. gracilis . Plant-soil feedback did not provide an advantage to E. lehmanniana in competitive interactions with B. gracilis at low competition levels but were advantageous to E. lehmanniana at the highest competition ratio, indicating a possible density-dependent effect. Despite being beneficial to B. gracilis under many conditions, E. lehmanniana was the superior competitor.

With the increasing frequency of large‐scale restoration efforts, the need to understand the adaptive genetic structure of natural plant populations and their relation to heavily utilized cultivars is critical. Bouteloua gracilis (blue grama) is a wind‐dispersed, perennial grass consisting of several cytotypes (2n = 2×–6×) with a widespread distribution in western North America. The species is locally dominant and used regularly in restoration treatments. Using amplified fragment length polymorphism (AFLP) and cpDNA analyses, we assessed the genetic variability and adaptive genetic structure of blue grama within and among 44 sampling sites that are representative of the species’ environmental and habitat diversity in the southwestern United States. Five cultivars were also included to investigate genetic diversity and differentiation in natural versus cultivated populations. Three main findings resulted from this study: (a) Ninety‐four polymorphic AFLP markers distinguished two population clusters defined largely by samples on and off the Colorado Plateau; (b) substructure of samples on the Colorado Plateau was indicated by genetic divergence between boundary and interior regions, and was supported by cytotype distribution and cpDNA analysis; and (c) six AFLP markers were identified as “outliers,” consistent with being under selection. These loci were significantly correlated to mean annual temperature, mean annual precipitation, precipitation of driest quarter, and precipitation of wettest quarter in natural populations, but not in cultivated samples. Marker × environment relationships were found to be largely influenced by cytotype and cultivar development. Our results demonstrate that blue grama is genetically variable, and exhibits genetic structure, which is shaped, in part, by environmental variability across the Colorado Plateau. Information from our study can be used to guide the selection of seed source populations for commercial development and long‐term conservation management of B. gracilis, which could include genetic assessments of diversity and the adaptive potential of both natural and cultivated populations for wildland restoration. Blue grama is a naturally occurring and widely distributed species that is often cultivated for use in restoration. We found that natural populations differed significantly in their response to environmental variation relative to cultivated varieties, which showed no response. This suggests that the adaptive potential of cultivated varieties may be compromised, making them less suitable for restoration in the wild.

The importance of competition and predation in structuring ecological communities is typically examined separately such that interactions between these processes are seldom understood. By causing large reductions in native prey, invasive predators may modify native species interactions. I conducted a manipulative field experiment in The Bahamas to investigate the possibility that the invasive Pacific red lionfish (Pterois volitans) alters competition between planktivorous fairy and blackcap basslets (Gramma loreto and Gramma melacara, respectively). Competition between these coral-reef fishes is known to have symmetrical effects on the juveniles of both species, whereby the feeding positions under reef ledges and growth rates of these individuals are hindered. Following baseline censuses of local populations of competing basslets, I simultaneously manipulated the abundance of lionfish on entire reefs, and the abundance of basslets in local populations under isolated ledges within each reef, resulting in three treatments: unmanipulated control populations of both basslets, reduced abundance of fairy basslet, and reduced abundance of blackcap basslet. For eight weeks, I measured the change in biomass and feeding position of 2–5 cm size classes of each basslet species and calculated the growth rates of ∼2 cm individuals using a standard mark-and-recapture method. Experimental populations were filmed at dusk using automated video cameras to quantify the behavior of lionfish overlapping with basslets. Video playback revealed lionfish hunted across all ledge positions, regardless of which basslet species were present, yet lionfish differentially reduced the biomass of only juvenile (2 cm) fairy basslet. Predation reduced the effects of interspecific competition on juvenile blackcap basslet as evidenced by corresponding shifts in feeding position toward coveted front edges of ledges and increases in growth rates that were comparable to the response of these fish in populations where competition was experimentally reduced. Thus, an invasive marine predator altered the outcome of interspecific competition via differential predation, which tipped the balance of competition between native prey species from symmetrical to asymmetrical effects on juveniles. This study reveals a newly demonstrated context in which predation can indirectly facilitate prey, further broadening our understanding of the interactive effects of predation and competition in the context of invasive species.