Buffelgrass Pasture Research Articles

Can legume seeds establish after land degradation by buffelgrass? Evidence to initiate restoration in Central Sonora, Mexico

AbstractBuffelgrass (Pennisetum ciliare) has been introduced in many localities of northwestern Mexico for cattle grazing. Recent studies have documented how the conversion of natural vegetation to buffelgrass pastures affects several ecological processes that result in high levels of desertification and the subsequent abandonment of lands. However, no previous study has documented successful restoration in these habitats. In this paper we report the results of several experiments focused on the restoration of these areas using native legume species of the region. We selected a degraded buffelgrass pasture considered unproductive by local ranchers in central Sonora. We carried out experiments to evaluate seed removal, seedling emergence, and seedling establishment of native legumes species (Prosopis glandulosa, Parkinsonia microphylla and P. praecox). Our results showed that P. microphylla had greater emergence (10%) than the other two species despite the high seed removal recorded. In addition, P. microphylla was the species with the highest survival (1.4%). Thus, our results show that ecological recovery using native species is possible in desertified buffelgrass pastures. Considering the ecological benefits of P. microphylla in the Sonoran Desert (i.e., nurse plant, positive associations, plant‐growth promoting), this species could be considered highly valuable in restoration procedures.

Habitat thermal quality for Gopherus evgoodei in tropical deciduous forest and consequences of habitat modification by buffelgrass

Tortoises of the genus Gopherus evolved in North America and have survived major environmental challenges in the past 40 million years. However, this genus now faces multiple anthropogenic threats, such as the introduction of invasive plant species. Buffelgrass (Cenchrus ciliaris) is considered one of the greatest threats to arid and tropical ecosystems, where gopher tortoises inhabit, because the grass displaces native flora and fauna. Modification of the environment as a result of this invasive plant portends an alteration of the available thermal landscape. The aim of this paper is twofold: 1) to evaluate the thermal quality of the primary habitat of Gopherus evgoodei (tropical deciduous forest [TDF], and 2) determine the potential thermal changes due to habitat modification by buffelgrass. First, we obtained data on body temperature of active tortoises in semi-captivity. Second, we measured the operative environmental temperature during 5 years at three sites south of Sonora, Mexico that support G. evgoodei: a) a pristine TDF (Conserved-TDF); b) a forest patch surrounded by introduced buffelgrass pasture (Partial-TDF); and c) an introduced buffelgrass pasture area (Buffel-Pasture). Our results demonstrate that the intact microhabitats within the TDF provide G. evgoodei with high thermal quality at both spatial and temporal scales. However modified habitat by buffelgrass had higher operative temperatures for G. evgoodei than TDF. The thermal quality of the sites disturbed with buffelgrass can exceed the thermal requirements of G. evgoodei by up to 25 °C. Finally, we discussed potential collateral effects of habitat modification by invasion by buffelgrass.

Emissões de gases do efeito estufa do solo em sistema de produção de caprinos no semiárido brasileiro

ABSTRACT In the climate change scenario, studying greenhouse gases (GHG) emissions and measures of mitigation in the Caatinga biome are strategic and may provide a basis for mitigation plans. This study aimed to evaluate the soil CO2, CH4 and N2O fluxes, as well as determining an annual baseline for GHG emissions, in a reference site of silvopastoral production system in the Brazilian semiarid region, in order to provide subsidies for future studies on GHG emissions mitigation. The GHG fluxes were monitored over one year, in a buffel grass pasture and in grazed and native Caatinga areas, which are components of a long-term silvopastoral system. The CO2 fluxes ranged from -19.98 to 179.12 mg m-2 h-1 of CO2-C, CH4 fluxes from -76.21 to 113.87 µg m-2 h-1 of CH4-C, N2O fluxes from -1,043.12 to 471.37 µg m-2 h-1 of N2O-N and the soil moisture was the main factor limiting the GHG fluxes. The total emissions converted to CO2-equivalent in the anthropized areas were lower than in the native area (65 % for the buffel grass pasture and 741 % for the grazed Caatinga). Therefore, it is possible to afrm that the GHG soil emissions from grazed areas in the Caatinga biome are not as high as in the native Caatinga, what is an important indication of the environmental sustainability of the evaluated silvopastoral system.

Growth Performance and Plasma Metabolites of Grazing Beef Cattle Backgrounded on Buffel or Buffel-Desmanthus Mixed Pastures.

Simple SummaryPasture quality and digestibility decline during the dry season resulting in weight loss or marginal weight gains of grazing cattle in the seasonally dry subtropics of northern Australia. Oversowing grass with legume pastures has shown potential to improve pasture quality and cattle weight gain. This study aimed to evaluate the change in steers’ weight gain and plasma metabolites in response to grazing buffel grass pastures oversown with Desmanthus spp. (Desmanthus), a tropical legume adapted to cracking clay soils, compared to buffel-grass-only pastures. Results showed that Desmanthus at a low botanical composition had no effect on weight gain and plasma metabolites, although pasture yield and stocking rate were 443 kg/ha and 9.5% higher, respectively. Since the productivity of grazing systems depends on cattle annual weight gain and stocking rate, the practical implication of this study is that Desmanthus may improve the profitability of beef production in the dry tropics of northern Australia by improving pasture-carrying capacity with no adverse effect on cattle health status and growth performance.Dietary crude protein and dry matter digestibility are among the major factors limiting feed intake and weight gain of cattle grazing native and improved pastures in the subtropics of Northern Australia during the dry season. Incorporating a suitable legume into grasses improves pasture quality and cattle weight gain, but only a limited number of legume pastures can establish and persist in cracking clay soils. This study aimed to evaluate the effect of Desmanthus inclusion in buffel grass (Cenchrus ciliaris) pastures on the plasma metabolite profile and growth performance of grazing beef cattle during the dry season. We hypothesised that backgrounding steers on buffel grass-Desmanthus mixed pastures would elicit significant changes in plasma glucose, bilirubin, creatinine, non-esterified fatty acids and β-hydroxybutyrate, resulting in higher liveweight gains than in steers on buffel grass only pastures. Four hundred tropical composite steers were assigned to buffel grass only (n = 200) or buffel grass oversown with Desmanthus (11.5% initial sward dry matter) pastures (n = 200) and grazed for 147 days during the dry season. Desmanthus accounted for 6.2% sward dry matter at the end of grazing period. Plasma metabolites results showed that changes in β-hydroxybutyrate, creatinine, bilirubin, glucose and non-esterified fatty acids were within the expected normal range for all the steers, indicating that with or without Desmanthus inclusion in the diet of grazing steers, animal health status was not compromised. It was also evident that Desmanthus inclusion in buffel grass pastures had no impact on the plasma metabolite profile, liveweight and daily weight gain of grazing steers. Therefore, our tested hypothesis of higher changes in plasma metabolite profile and higher liveweight gains due to backgrounding on low-level buffel grass-Desmanthus mixed pastures does not hold.

Heavy grazing of buffel grass pasture in the Brigalow Belt bioregion of Queensland, Australia, more than tripled runoff and exports of total suspended solids compared to conservative grazing

Loss of sediment and particulate nutrients in runoff from the extensive grazing lands of the Fitzroy Basin, central Queensland, continue to contribute to the declining health of the Great Barrier Reef. This study measured differences in hydrology and water quality from conservative and heavy grazing pressures on rundown improved grass pastures in the Fitzroy Basin. Conservative grazing pressure was defined as the safe long-term carrying capacity for rundown buffel grass pasture, whereas heavy grazing pressure was defined as the recommended stocking rate for newly established buffel grass pasture. Heavy grazing of rundown pasture resulted in 2.5 times more bare ground and only 8% of the pasture biomass compared to conservative grazing. Heavy grazing also resulted in 3.6 times more total runoff and 3.3 times the peak runoff rate compared to conservative grazing. Loads of total suspended solids, nitrogen and phosphorus in runoff were also greater from heavy than conservative grazing.

Diets selected and growth of steers grazing buffel grass (Cenchrus ciliaris cv. Gayndah)–Centro (Centrosema brasilianum cv. Oolloo) pastures in a seasonally dry tropical environment

Context Liveweight (LW) gain of grazing cattle in the seasonally dry tropics is usually moderate during the wet season (WS) and declines to slow growth or LW loss during the dry season (DS). Cattle growth can often be improved by inclusion of herbaceous legumes into pastures to improve their nutritional quality. Aims A study examined the quality of the diet selected and the growth of young cattle grazing a buffel grass (Cenchrus ciliaris)–Centro (Centrosema brasilianum) pasture in a high-rainfall, seasonally dry, tropical environment in northern Australia to relate the diet selected to cattle growth. Methods During three annual cycles, young steers grazed a grass–Centro legume pasture at moderate stocking rate. LW was measured monthly, and diet attributes (legume content, DM digestibility (DMD) and crude protein concentration) were measured fortnightly by near-infrared reflectance spectroscopy analyses of faeces. Pasture available and species were measured twice annually. Key results The annual LW gain and diet attributes followed a consistent profile through the annual cycles. Following the seasonal break, the diet DMD and crude protein concentration increased abruptly to maxima (means 732 and 184 g/kg respectively), and then declined approximately linearly during the remainder of the WS and the wet–dry transition season (TS); DMD decreased by 0.49, 0.74 and 0.88 g/kg units per day. DMD and crude protein averaged 561 and 61 g/kg respectively during the DS. Centro comprised 86–291 g/kg of the pasture on offer, and averaged 283 and 205 g/kg of the diet during the TS and DS, respectively, but only 58 g/kg during the WS. Cattle selected for Centro during the TS and the DS, but not during the WS. Cattle LW gain reflected diet quality averaging 0.86, 0.59 and 0.12 kg/day during the WS, TS and DS respectively. Conclusions The Centro legume contributed substantially to the diet of growing cattle during the TS and DS, but not during the WS. The LW gains of cattle were moderate during the WS and TS, and low during the DS. Implications Centro in a buffel grass pasture contributed substantially to the diet, but nevertheless annual LW gain was only modest (mean 179, range 159–209 kg/annum).

Preliminary assessment of rearing male buffalo calves on <i>Leucaena leucocephala</i>-buffel grass pasture in Maharashtra State, India

Poster presented at the International Leucaena Conference, 1‒3 November 2018, Brisbane, Queensland, Australia.

Shading and intercropping with buffelgrass pasture affect soil biological properties in the Brazilian semi-arid region

The objective of this work was to evaluate the changes caused by shading and intercropping with a legume (Clitoria ternatea L.) in a grass (Cenchrus ciliaris L.) pasture on the microbiological and biochemical attributes of the soil. Microbial biomass carbon (MB-C), soil respiration, the activities of soil enzymes (β‑glucosidase, acid phosphatase and urease) and total soil fungal and bacterial were evaluated. Soil samples were collected at four periods: before intercropping (BI), at 120, 165 and 210 days of cultivation and under four shading levels 0 (full sun), 26, 39 and 55%. Before intercropping (BI), shading affected biological and biochemical parameters by increasing the MB-C but reducing soil respiration, resulting in a reduction of qCO2. There was an increase in MB-C and β‑glucosidase in the intercropping treatment and 39% shading, while under monoculture an increment in MB-C was reached only under 55% shading at 120 days of cultivation. The highest CO2 fluxes by soil respiration were observed in the intercropping areas and in the shaded areas at 0, 26 and 39% at 120 days of cultivation. The intercropping system and the higher levels of shading reduced the qCO2 at all sampling time. The highest soil urease activity occurred in the intercropping areas and in full sunlight, regardless of the sampling time, while acid phosphatase presented greater activity in the intercropped areas at 165 days of cultivation. From the multivariate analysis, it was possible to verify that the effects of intercropping are evident at 165 days of cultivation with the formation of two distinct groups and an increase in the biological quality in the intercropped areas. For qPCR it was verified that only shading affected the amounts of total soil fungi and bacteria; the use of shading reduced the amount of fungi only at 120 days, while for bacteria, the use of 26% shading in the BI period and full sun at 165 days increased the amount of bacteria. This variation of shading effect over time on the amount of fungi and bacteria may indicate changes in the composition of fungal and bacterial species. It is concluded that shading and intercropping with C. ternatea into C. ciliaris pasture promotes improvements in soil quality indicators under semi-arid conditions.

Productivity and profitability of alternative steer growth paths resulting from accessing high-quality forage systems in the subtropics of northern Australia: a modelling approach

Beef producers have to determine the best allocation of a limited resource of high-quality forage. This analysis assessed the most profitable way of incorporating high-quality forages into the whole-of-life steer growth path on forage systems in central Queensland, using property-level, regionally relevant herd models that determine whole-of-business productivity and profitability over a 30-year investment period. Twenty-two growth paths (liveweight change over time) from weaning to marketing were investigated for steers grazing buffel grass (Cenchrus ciliaris) pastures with and without access to leucaena–grass pastures (Leucaena leucocephala spp. glabrata + perennial, tropical grass (C4) species) or forage oats (Avena sativa) for varying intervals throughout their growth path. The production, economic and financial effect of each growth path was assessed by comparison to a base scenario that produced finished, slaughter steers (605 kg) from buffel grass pastures. The relative profitability of marketing steers at feedlot entry (feed-on) weight (474 kg) instead of slaughter weights was also assessed. The growth paths were applied within two beef enterprises, namely (1) steer turnover and (2) breeding and finishing. For both enterprises, grazing steers on leucaena-grass pastures from weaning until they achieved feedlot entry weight (474 kg) was substantially more profitable than any other growth path. Compared with the base scenario, this optimal growth path improved profitability by 121% and 37% for the steer turnover and the breeding and finishing enterprises respectively. The purchase of additional breeders for the latter enterprise was required to optimise utilisation of the leucaena–grass pastures immediately. Incorporating leucaena–grass pastures at any steer age improved the profitability of the steer turnover enterprise (AU$7368–AU$106508 extra profit/annum), and similarly for the breeding and finishing enterprise (AU$1754–AU$31383 extra profit/annum) except for two scenarios where leucaena–grass pastures were provided to older steers targeted at the feed-on market (AU$4816 and AU$23886 less profit/annum). However, incorporation of leucaena–grass into steer growth paths also resulted in increased peak deficit levels and financial risk to the business compared with buffel grass-only production systems, with payback periods for the most profitable growth path of 8 and 14 years for the steer turnover and the breeding and finishing enterprise respectively. All growth paths that incorporated forage oats and leucaena–grass resulted in lower economic and financial performance than did comparable growth paths that incorporated leucaena–grass only. Furthermore, incorporating oats into buffel grass-only growth paths always reduced the enterprise profitability. There was no relationship, across scenarios within an enterprise, between change in profit and the number of extra weaners produced or the amount of extra beef produced per hectare.

Grazing pressure, land condition, productivity and profitability of beef cattle grazing buffel grass pastures in the subtropics of Australia: a modelling approach

There is widespread evidence that beef cattle land managers in Queensland are using stocking rates for perennial pastures that are substantially higher than recommended guidelines, and some indication that these decisions are motivated by perceived financial and economic benefits. Considerable effort has been, and is currently being, applied by public-sector organisations to encourage producers to reduce grazing pressure from beef cattle across Queensland’s pastoral lands. A better understanding of the relationships among stocking rate, land condition and profitability of beef-grazing enterprises is imperative to better inform cattle producers and policy makers. The present study assessed the effect of grazing pressure and land condition on the productivity and profitability of a steer-turnover enterprise utilising buffel grass (Cenchrus ciliaris) pastures in central Queensland. A property-level, regionally relevant herd model was used to determine whole-of-business productivity and profitability over a 30-year investment period. Growth paths for steers from weaning to marketing were developed for 16 scenarios encompassing a range of pasture-utilisation rates (30%, 35% and 50% of annual biomass growth), land condition (A, B and C) and market targets (feedlot entry at 474 kg or slaughter at 605 kg). The economic effect of each scenario was assessed by comparison to a base scenario of 30% pasture utilisation and turn-off of slaughter steers. Our analyses demonstrated a large economic advantage from increasing grazing pressure above 30% utilisation for buffel grass pastures, even with assumptions of declining land condition and animal performance. For instance, producing slaughter steers under a 50% pasture-utilisation regime with a continuous decline in land condition from A to C (and, hence, productivity) over Years 10–30 was AU$21 772/annum more profitable than was a 30% pasture-utilisation strategy, which is widely recommended as closer to a long-term, safe utilisation rate. The present research has provided insights into the relationship between grazing pressure and economic returns of beef producers over the medium term. However, it should be considered as a scoping study due to the paucity of data for effects of utilisation rate on the productivity of buffel grass pastures and, hence, on land-condition rating. Further research is required to better understand the effects of utilisation rate of buffel grass, and other sown pasture grass and legume species, on plant biomass production, plant-diet quality for cattle, land-condition decline and cattle productivity.

Productive performance and parasitological control of kids supplemented with umbu fruits (Spondias tuberosa Arruda)

Summary Native fruits from Caatinga vegetation can be an important alternative to improve the productive performance of kids in the semi-arid region of Brazil. This work aimed to evaluate the effect of supplementation with Umbuzeiro fruits in natura over the weight gain and anthelmintic control of kids kept in Buffel grass pasture in the semi-arid zone of Pernambuco, Brazil. Twenty-four castrated, crossbreed kids were allocated into three treatments: 1) Control (n = 8) fed exclusively with Buffel grass; 2) Umbu 1x (n = 8) fed with fruits once a week and 3) Umbu 3x (n = 8) fed with fruits for three times a week. The following parameters were evaluated: variation of body weight, faecal egg counts (FEC) and coproculture. Overall, the average consumption of Umbu fruits in natura was 1.48 kg/animal/day, which corresponded to 133.5 g daily dry matter intake (DMI/animal/day). There were no significant difference (P>0.05) for any parameters evaluated. During the experimental period, the overall daily weight gain was variable between 108.75 to 116.70 g/animal/day and the average FEC was 436 eggs. In the present study, the goat kids supplemented with fresh umbu fruits showed a good productive performance, however the supplementation with umbu did not control the infestation of gastrointestinal nematodes in kids.

Desempenho produtivo e características de carcaça de ovinos mantidos em pastos de duas cultivares de capim-bufel manejados em três ofertas de forragem

RESUMO Objetivou-se com este estudo avaliar o consumo de forragem, o desempenho produtivo (ganho médio diário, ganho de peso total e peso corporal final), os parâmetros de carcaça (peso de carcaça quente e rendimento de carcaça quente), além da taxa de lotação e do ganho de peso por unidade de área de pastos de capim-bufel (Cenchrus ciliaris L.) pastejados por ovinos. O trabalho foi realizado no período de setembro de 2009 a agosto de 2010, com o pasto manejado em lotação contínua. Os tratamentos constituíram-se de combinações de duas cultivares de capim-bufel (Biloela e Cpatsa 7754) e três ofertas de forragem (4, 8 e 12kg de matéria seca/100kg de peso corporal ou 4, 8 e 12%) em arranjo fatorial 3 x 2 e delineamento em blocos completos casualizados com três repetições. As variáveis relacionadas com o consumo de forragem, desempenho produtivo do animal, características da carcaça, taxa de lotação e ganho de peso por unidade de área não foram afetadas pelas cultivares, ofertas de forragem e interação entre ofertas de forragem e cultivares. Em média os ovinos apresentaram 452,14g/animal/dia de consumo de forragem, 59,77g/animal/dia de ganho médio diário, 41,51% de rendimento de carcaça quente, enquanto os pastos permitiram em média 11,78 ovinos/ha com a obtenção de 205,64kg/ha/ano de ganho de peso.

Organic carbon transport under simulated rainfall conditions for different land uses

La demanda de información sobre el transporte de carbono motivó la generación de datos sobre la salida de carbono orgánico en partículas de suelo en suspensión. Se consideraron diferentes usos de suelo: praderas de zacate buffel (PZB), parcelas de cultivo abandonadas (PCA) y el pastizal nativo (PN). Se utilizó la técnica de simulación de lluvia para generar escurrimiento sobre parcelas de escurrimiento (3 x 1 m) para obtener en cada uso de suelo una alícuota de 0.5 L, de la cual se separaron los sedimentos sólidos (suelo y material orgánico) y mediante un análisis por el método de Walkley y Black se determinó el porcentaje de carbono. Se utilizó un diseño experimental de bloques al azar con tres repeticiones para determinar las diferencias en el contenido de carbono (%). Los resultados obtenidos muestran que en el pastizal nativo y en condiciones de humedad inicial se registraron los valores promedio más altos de carbono en los sedimentos en suspensión (3.79 %); mientras que las condiciones de mejor cobertura del suelo en las praderas de zacate buffel y en las parcelas de cultivo abandonadas (1.20 y 1.18 % respectivamente) fueron menores que las pérdidas de carbono ocurridas en el pastizal nativo (3.11 %).

Arbuscular mycorrhizal fungal communities in buffelgrass pasture under intercropping and shading systems in Brazilian semiarid conditions

The intercropping of grasses and legumes has been suggested as an alternative for ensuring pasture sustainability. However, few studies have focused on the impact of intercropping and shading on the soil microbiota in semi-arid regions. The goal of this study was to evaluate the effects of intercropping a grass, Cenchrus ciliaris, with a legume, Clitoria ternatea, under different levels of shading, on the C. ciliaris carbohydrate concentration and the arbuscular mycorrhizal fungal (AMF) community over time. Soil samples were collected at four sampling times: before intercropping (BI) and after 120, 165 and 210days cultivation. Four levels of shading were tested: 0 (full sunlight), 26, 39 and 55%. In the intercropped system, mycorrhizal colonization was higher under lower shading levels after 120 and 165days cultivation, but the number of glomerospores was higher under higher shading levels. After 165days cultivation, the carbohydrate concentrations were higher under full sunlight. After 210days cultivation, the reducing carbohydrate concentrations were higher in the intercropped system. Thirty-one AMF species were detected; Acaulospora and Glomus species were predominant compared with the remaining genera. This study showed that AMF community composition was relatively similar between shading and intercropping by multidimensional scaling (MDS) and PERMANOVA analysis, and it was observed only sampling time effect on the AMF community. The Shannon diversity index showed a reduction in AMF diversity from 210days of cultivation and an increase in the AMF species richness over time. It was concluded that pastures of C. ciliaris under shading and intercropping with C. ternatea did not modify the AMF community composition. However, the results suggest that intercropping of these plant species may result in AMF species selection over time.

Conversion of thornscrub to buffelgrass pasture in northwestern Mexico: Microclimatic consequences

Buffelgrass (Pennisetum ciliare) have been planted in large areas of northwestern Mexico for cattle grazing. Previous studies have documented how buffelgrass conversion affects several ecological processes; however, very few studies have documented how conversion affects local microclimate. We used data on soil temperature and moisture to document seasonal changes in microclimate as a consequence of land conversion. We describe soil and air temperature and soil moisture content in a thornscrub and an adjacent buffelgrass pasture, in open spaces and under trees, during one year. Air temperature in the pasture exceeded ∼1 °C the value in the thornscrub during the colder months. Mean soil temperatures were slightly greater in the thornscrub during the dry season but during the wet season, mean temperatures were greater in the pasture reaching differences of ∼2 °C. Maximum monthly soil temperatures were greater in the pasture after the wet season with values that reached 6 °C above the thornscrub. Soil moisture showed significant greater values in the thornscrub than in the pasture. Our data suggest that conversion of thornscrub to buffelgrass pasture modify the local microclimate, which in turn could influence the process of regeneration of native species persisting in pastures.

Impacto hidrológico del cambio de uso del suelo de un pastizal nativo a praderas de zacate buffel (Pennisetum ciliare L.)

El objetivo de este trabajo es documentar el impacto del establecimiento de praderas de zacate buffel (Pennisetum ciliare L.) en terrenos de pastizal, sobre la tasa de infiltración del suelo. El estudio se estableció en el área de San Luis del Cordero, Dgo. Para determinar el impacto se realizaron pruebas de infiltración con un simulador de lluvia en praderas de zacate buffel y en terrenos de pastizal nativo. Las simulaciones se realizaron en condiciones secas y húmedas (24 horas después de las simulaciones en seco) para tres repeticiones en cada uso del suelo y condición de humedad. La base de datos hidrológica, lámina precipitada (mm) y volumen escurrido (l) fueron medidos cada 5 minutos durante la prueba, la cual tuvo una duración de 50 minutos. Los resultados indican que para las dos condiciones de uso del suelo la tasa de infiltración final se puede clasificar como moderada (entre 2.0 a 6.6 cm·h-1). Para las tasas de infiltración, la evaluación del cambio en el uso del suelo de un pastizal nativo al establecimiento de una pradera de zacate buffel en la región de estudio no representó diferencias estadísticamente significativas (P ≤ 0.05) entre usos de suelo. Para el sitio experimental, en la condición de la pradera con zacate buffel y la de pastizal nativo, en promedio la tasa de infiltración final fue de 5.04 y 3.88 cm·h-1, respectivamente.

Soil carbon, nitrogen and phosphorus changes from conversion of thornscrub to buffelgrass pasture in northwestern Mexico

In many regions of the world, land conversion of native plant communities to non-native pastures is usually associated with significant changes in soil nutrient contents. In Mexico, more than one million hectares of drylands have been converted to non-native pastures, with little knowledge on the biogeochemical consequences. We investigated the effects of non-native buffelgrass (Pennisetumciliare) pasture conversion on soil carbon (C), nitrogen (N) and phosphorus (P) dynamics to understand the effects of disturbance on soil nutrient in a region of the state of Sonora. Eleven sites that formed a gradient (1–44 years) of buffelgrass establishment history where buffelgrass establishment has been practiced for at least 50 years, were studied. Soil organic C, total N and P, microbial biomass C, extractable P, and mineral N contents and basal soil respiration, were measured in samples collected during the dry and rainy seasons in buffelgrass pastures and undisturbed thornscrub. Conversion to buffelgrass pastures decreased mineral N content and basal soil respiration. Extractable P decreased in older pastures (>10 years), suggesting a potential P-limitation for the permanence of long-term buffelgrass pastures in Sonora. In contrast, we did not detect a significant reduction of soil organic C, total N and P in older pastures. This study suggests that P limitation may serve as important controls on ecosystem nutrient cycling in natural vegetation and recovery of these thornscrubs after buffelgrass pasture establishment for cattle ranching.

<b>Arbuscular mycorrhizal fungi within agroforestry and traditional land use systems in semi-arid Northeast Brazil</b> - doi: 10.4025/actasciagron.v35i3.16213

The diversity of arbuscular mycorrhizal fungi (AMF) can be a critical factor in enhancing both the productivity and the diversity of plants in ecosystems, and the plants in the ecosystem also strongly influence the occurrence of these fungi. The relationships between different land use systems and AMF communities in the semi-arid region of the State of Paraíba, NE Brazil were evaluated. The experiment followed a split-plot randomized block design, with four replicates. The main plots were defined by the presence or absence of trees (gliricidia and maniçoba), while the split plots were defined by three land use systems: 1) traditional cropping of maize + beans, 2) buffel grass pasture, and 3) prickly pear forage crop. The presence of trees increased sporulation, mycorrhizal colonization and the production of infective propagules of AMF in all three land use systems. Greater production of glomalin-related soil protein (GRSP) occurred in the prickly pear plots regardless of the presence or absence of trees. Species belonging to the Glomus genus predominated regardless of the presence of trees, land use systemor soil sampling period.

Species diversity and regeneration of native species in Pennisetum ciliare (buffelgrass) pastures from the thornscrub of Sonora, México

To examine the influence of buffelgrass land conversion and pasture management on native species diversity and regeneration patterns, we describe community attributes and population structure in four different active pastures in thornscrub vegetation from eastern Sonora, Mexico. We compare a relatively undisturbed thornscrub community with a contiguous five years old active pasture, to identify species able to regenerate under current management practices. Buffelgrass conversion has a significant influence on species diversity and other community attributes. Active pastures have lower species diversity, crown cover and basal area of native species than the studied native thornscrub. An active pasture subjected to heavy grazing and without management of the thorny legume, Acacia cochliacantha, showed the lower species diversity and an almost monospecific stand of this legume. It is likely that the reduction in species diversity is caused by the conversion process, inadequate management and regeneration barriers that limit seedling establishment in active pastures. Our data recorded eight native species (13%) that were able to regenerate in active pastures. However, the great majority of native species were unable to regenerate under pastures. This study shows that under current management, active buffelgrass pastures maintain only a small fraction of native species with regenerating populations in the thornscrub.

Buffelgrass (Pennisetum ciliare) Invades Lands Surrounding Cultivated Pastures in Sonora, Mexico

AbstractWe examined relationships between land disturbance and the extent and abundance of exotic buffelgrass (Pennisetum ciliare) at the interface of cultivated pastures and native desert lands in Sonora, Mexico. Plot and transect surveys of lands inside and outside pasture fences and general linear mixed models revealed complex relationships among buffelgrass, native vegetation, distance from pasture fences, and three categories of land disturbance (undisturbed, moderate, and severe). Results illustrate that buffelgrass invasion is extensive in lands surrounding pastures, and that buffelgrass abundance declines steeply with distance from pasture fences. The role of disturbance is weak but significant in its interaction with distance from the fence. Buffelgrass is more successful at colonizing severely disturbed lands than native vegetation, and its decline in abundance on severely disturbed lands is relatively more gradual than on other disturbance regimes, so landscapes where severely disturbed lands are interspersed with buffelgrass pastures could become centers of extensive buffelgrass invasion. In light of its potential to transform the Sonoran Desert, buffelgrass outside pastures warrants attention in a region-wide control scheme, as well as in future research, which ideally would involve remote sensing.