INVASÃO POR GRAMÍNEAS EXÓTICAS EM CAMPOS SOBRE PALEODUNAS: EFEITOS NA DIVERSIDADE FLORÍSTICA

O Refúgio de Vida Silvestre Banhado dos Pachecos localiza-se sobre a Coxilha das Lombas, Viamão/RS, e encontra-se em processo de invasão biológica por gramíneas exóticas na área de campo seco. Este fragmento de vegetação campestre sobre paleodunas é habitat da espécie endêmica Ctenomys lami (Rodentia, Ctenomydae) e apresenta composição florística peculiar em relação a maioria das áreas naturais dos Campos Sulinos, com espécies de Asteraceae sendo dominantes em comparação às espécies de Poaceae. Com o objetivo de caracterizar a composição florística e avaliar o grau e efeitos da invasão biológica sobre a comunidade de campo seco foi realizado um levantamento quantitativo. Foram amostradas 31 parcelas de 1 x 1 m e levantados dados de cobertura e altura da vegetação, solo descoberto e serrapilheira. Foram calculados parâmetros fitossociológicos para cada espécie. As parcelas foram classificadas quanto ao nível de invasão por gramíneas exóticas. O efeito da invasão sobre a composição e estrutura da vegetação foi avaliado a partir de Análise de Coordenadas Principais, regressão linear e análise de variância. As gramíneas exóticas invasoras Urochloa decumbens e Digitaria eriantha subsp. pentzii foram dominantes em grande parte da vegetação campestre, modificando a estrutura e composição vegetal conforme o nível de invasão. Cerca de um terço da área encontra-se altamente invadida. Ações de remoção e controle de invasoras se fazem urgentes, considerando que este é um dos poucos fragmentos de ecossistemas naturais abertos na Coxilha das Lombas e abriga espécies ameaçadas de extinção. INVASION BY EXOTIC GRASSES IN GRASSLAND ON PALAEODUNES: EFFECTS ON FLORISTIC DIVERSITY. The Banhado dos Pachecos Wildlife Refuge, located in the Coxilha das Lombas, in Viamão/RS, Brazil, is under a process of invasion by alien grasses in its areas of dry grassland. The grassland on palaeo-dunes is the habitat of the endemic species Ctenomys lami (Rodentia, Ctenomydae) and presents a peculiar floristic composition in relation to most natural grasslands in southern Brazil, with species of the Asteraceae dominating in comparison to grasses. In order to characterize the floristic composition and to evaluate the degree and effects of biological invasion on the grassland community, a quantitative vegetation survey was carried out. In 31 plots of 1 x 1 m, data on cover and height of vegetation, bare soil and litter were collected. Phytosociological parameters were calculated for each species. The plots were classified according to the level of invasion by exotic grasses and Principal Coordinate Analysis, linear regression and Analysis of Variance were performed to observe the species distribution in the community and the effects of the invasion on the richness and structure of the vegetation. The invasive exotic grasses Urochloa decumbens and Digitaria eriantha subsp.pentzii were dominant in grassland vegetation, modifying plant structure and composition according to the level of invasion. About a third of the area is heavily invaded. Invasive removal and control actions are urgent as this is one of the few fragments of natural grasslands in the Coxilha das Lombas and is habitat to species threatened with extinction.

Foraging behaviour and dry matter intake by lambs in a silvopastoral system

Dry matter intake, nutritional contribution of forage to the diet and Lamb foraging behavior were assessed in a silvopastoral system. Twelve Pelibuey female lambs (6.3 months of age, 23.74 ± 3.5 kg live weight), were randomly assigned to two treatments: pastures of Digitaria eriantha (monoculture) or pastures of D. eriantha and Guazuma ulmifolia (silvopastoral). During a 15 day period, lambs foraged individually in 20.14 m2 paddocks each day; time spent grazing and browsing were assessed by scan sampling; dry matter intake was estimated (day 11-15), using the chromic oxide (Cr2O3) method, and metabolizable energy (ME) and protein (CP) ingested by the lambs were estimated. Data analyses were performed using a complete randomized design (dry matter intake) and a repeated-measure design (ME and CP, foraging time) with factorial treatment structure of season (windy and dry) and pasture (monoculture and silvopastoral). Voluntary intake (season*treatment interaction, p = 0.015) was lower in the windy-silvopastoral treatment (448.5±38.2 g day-1) than in the other treatments (625.8±38.2 to 680.5±38.2 g day-1). The contribution of ME (719.7-1190.2 kcal·day-1) and CP (53.7-100.7 g day-1) was low to cover the lamb requirements in all treatments, because forage availability and dry matter intake were low. Lambs dedicated from 6.65±0.26 to 7.50 ± 0.26 h to foraging; time spent grazing was longer that browsing in the silvopastoral system (p < 0.0001). The time dedicated to foraging, intake, and nutritive quality of forage from in both pasture types did not provide nutrients and energy during any season for maintenance of the lambs.

Mass feeding event of Turquoise Parrots and Eastern Rosellas on the North-west Slopes of New South Wales

This note describes the detection of two contemporaneous mass feeding events of a total of ~1000 parrots. After a report of large numbers of Turquoise Parrots Neophema pulchella being found on 8 May 2021, the next day we encountered flocks totalling ~300 Turquoise Parrots and ~700 Eastern Rosellas Platycercus eximius feeding on seeding grasses on a cattle property on the North-west Slopes of New South Wales. The two species, which congregated separately from each other, showed a preference for different species of introduced grasses, neither of which had been reported previously in the diets of these parrots: Turquoise Parrots fed on Purple Pigeon Grass Setaria incrassata and Eastern Rosellas fed on Premier Digit Grass Digitaria eriantha. Sometime between 10 and 21 May, the feeding event was over, before the supply of seeds was exhausted; neither before nor after the event has either species been observed in these large numbers in the region.

Pastures and Climate Extremes: Impacts of warming and drought on the productivity and resilience of key pasture species in a field experiment

Shifts in the timing and frequency of climate extremes, such as drought and heatwaves, can generate sustained shifts in ecosystem function with important ecological and economic impacts for rangelands and managed pastures. The Pastures and Climate Extremes experiment (PACE) in southeast Australia used a factorial combination of elevated temperature (ambient +3 °C) and winter/spring extreme drought (60% rainfall reduction) to evaluate the impacts of increased frequency of climate extremes on pasture productivity and subsequent summer/autumn recovery. The experiment included nine species comprising three plant functional groups (C3 grasses, C4 grasses, and legumes) in monoculture and three two-species mixtures. The winter/spring drought resulted in productivity declines of up to 73% (Digitaria eriantha) during the 6-month treatment period, with nine of the twelve plantings exhibiting significant yield reductions. Functional group identity was not an important predictor of yield response to drought. Many species recovered rapidly once the drought ended, although there were carry-over effects on warm season (summer/autumn) growth for four species/mixtures, spanning all functional groups. Cool season drought translated into significant reductions in annual biomass production for four species/mixtures, ranging from 33% (Medicago sativa) to 70% (Festuca arundinacea). Additionally, warming had neutral to negative effects on productivity during both winter/spring and summer/autumn periods, resulting in annual yield declines of up to 58%, driven at least partially by indirect effects on soil water content. The combination of winter/spring drought and year-round warming resulted in net yield reductions that were either additive or less-than-additive, compared to ambient plots. This study demonstrates that predicted extreme climate conditions will have substantial negative impacts on productivity of common pasture and rangeland species.

Digitaria eriantha (pangola grass).

D. eriantha is a perennial grass not considered as a serious weed in some countries, but a competitive and aggressive weed in others (PROTA, 2016; Tropical Forages, 2016; Weeds of Australia, 2016). The species is listed as invasive in Central America (Costa Rica), the Caribbean (Cuba), South America (Colombia, Ecuador) and Oceania (Australia, USA-Hawaii) (Oviedo Prieto et al., 2012; PIER, 2016). Catasús Guerra (2015), however, argues that the species should not be on the list of the invasive species for Cuba, due to lack of spread as it is being over-grazed and not producing viable seeds. It is on the list of the top 200 most invasive species in Queensland, Australia, forming dense populations in riparian areas, open woodlands and on some beaches (Weeds of Australia, 2016).

Efecto de la inoculación de micorrizas arbustivas en la evaluación agronómica de cuatro tipos de pastos en el cantón Pedernales, provincia de Manabí, Ecuador

En el Ecuador la actividad ganadera tiene un rol importante, es conocido que la alimentación del ganado básicamente es en torno a las gramíneas, por ser el alimento natural y de bajo costo que crece en los potreros. Evaluar los datos agronómicos de los pastos con la inoculación de micorrizas arbusculares y contrastar con las gramíneas que no fueron inoculadas, es de importancia ya que se logró obtener información sobre si es conveniente el uso de estos hongos para mejorar los rendimientos agronómicos en los pastos tropicales. Los datos que se evaluaron son altura de planta, diámetro de tallo, largo de hoja, ancho de hoja, peso de planta (g), rendimiento kg/ha, las gramíneas sometidas a esta investigación son: Brizanta, Urochloa brizantha (Hochst. ex A. Rich.) R. D. Webster; Saboya, Panicum maximum Jacq.; Tanzania, Panicum maximum cv. Tanzania) y Pangola, Digitaria eriantha Steud. Todos los taxones con que se experimentó tienen una dependencia de micorrizas de aproximadamente el 80%.

Identification and characterization of lactic acid bacteria associated with tropical grass silage produced in Okinawa

In Okinawa, rate of increase in gross agricultural production during 2011‒2016 was the highest in Japan and sales of calves ranked fourth throughout Japan. Raising cattle by feeding high quality silage is beneficial both nutritionally and economically. However, little is known about lactic acid bacteria (LAB) present in silages made from tropical grass in Okinawa. To improve understanding of fermentation processes in silages, the LAB present in a range of silages (Digitaria eriantha, Megathyrsus maximus, Chloris gayana, Urochloa mutica, Sorghum sp. and Zea mays) were identified. All isolates were Gram-positive and mainly catalase-negative bacteria. According to morphological and biochemical characters, 37 isolates were divided into 16 groups and on the basis of 16S rDNA sequence analysis, 7 were identified as Lactobacillus plantarum, 3 as L. paraplantarum, 1 as L. brevis, 1 as L. acidipiscis, 3 as L. casei, 1 as L. fermentum, 9 as Weissella paramesenteroides, 1 as W. kimchii, 5 as Lactococcus lactis subsp. lactis, 2 as Lactococcus garvieae and 4 as Pediococcus pentosaceus. Some of this wide variety of LAB in Okinawan silage could be beneficial for improving quality of silages and further studies are planned to determine benefits of inoculating forage with particular strains at ensiling.

Population dynamics and structural characteristics of 'Survenola' digit grass subjected to intermittent defoliation strategies

The objective of this work was to evaluate the effect of defoliation strategies and insolation periods on the population dynamics and structural characteristics of Digitaria eriantha 'Survenola'. The following four defoliation strategies (DSs) were evaluated: 40/10, 40/20, 50/10, and 50/20 cm (that is, 40 and 50 cm pre-defoliation height, and 10 and 20 cm post-defoliation height), under high- (September to March) and low- (April to August) insolation periods. An experimental randomized complete block design was carried out with five replicates. The accumulation of forage and leaf blade was higher when using the DS 40/20 cm in the higher insolation period. DSs 40/10, 50/10, and 50/20 cm resulted in a higher stem accumulation than DS 40/20 cm. 'Survenola' grass showed a higher appearance rate for basal and aerial tillers using the 40/10 and 40/20 cm strategies, respectively, during the lower insolation period. Greater tiller densities (basal, aerial, and total) were observed in the DS 40/20 cm in the higher insolation period. DS 40/20 cm resulted in a greater tiller renewal. In the DS 40/20 cm, 'Survenola' grass shows the greatest number of defoliation cycles, the highest density of tillers, and the greatest accumulation of forage and leaf blade.

Growth-promoting thermophilic microorganisms in self-heating pasteurized substrate improve Agaricus bisporus mycelial growth

Background: Certain microorganisms during the preparation of substrate for growing Agaricus bisporus are of great interest for the conversion of organic material and for the excretion of a wide range of metabolites with growth regulation activities that may affect the mycelial growth processes and mushroom yield. Adding beneficial microorganisms in the substrate may be a biotechnological alternative to optimize A. bisporus cultivation. Objective: Isolate and evaluate thermophilic microorganisms from self-heating pasteurized substrate with growth-promoting effects on A. bisporus cultivation. Methods: Different microorganisms were isolated and selected at 45 and 55 °C. They were tested for siderophore production, 1-octen-3-ol consumption, and phosphate solubilization in coculture with A. bisporus to determine their growth effects on potato dextrose agar (PDA) and on sterile pangola grass (Digitaria eriantha). Results: Of the 106 microorganisms isolated, 88 % were able to grow in the presence of 1-octen-3-ol, while 1 % had the capacity to produce siderophores, and 55 % had the ability to solubilize phosphate. The strains Bacillus hisashii ECS-B-65, B. licheniformis ECS-B-78, Rhizomucor pusillus ECS-710 and ECS-712, Aspergillus fumigatus ECS-709, and Thermomyces sp. ECS-711 were found to have a positive effect on A. bisporus mycelial growth.