Plantation clearcut size and the persistence of early-successional wildlife populations     

M. Paz Acuña  Cristián F. Estades 《Biological conservation》2011,(5):1577-1584

Plantation clearcuts represent an important habitat for many open-area wildlife species – including conservation-concern species – in landscapes dominated by industrial forests. However, due to the ephemeral nature of clearcuts, species using this type of environment face a “shifting mosaic” in which their ability to successfully relocate to another habitat patch may play a crucial role in the species’ persistence in the landscape. Although several studies have shown a positive effect of patch size on the persistence of open-habitat species, forest clearcutting represents a special case in which, on average, larger patches also tend to be more isolated from each other, likely creating a trade-off between area and isolation effects. We developed an individual-based spatially-explicit model to test the effect of clearcut size (a critical management variable in plantation forestry) on the persistence of generic early-successional wildlife species in a landscape dominated by forest plantations. We simulated a landscape covered with a plantation harvested regularly over a 25-year rotation and different versions of a wildlife population whose habitat was constituted only by 1–4 year-old patches. We observed that when the species could perceive the attributes of the neighboring pixels persistence time was higher at intermediate clearcut sizes agreeing with our prediction. Also, species with a high dispersal capacity were less limited by connectivity and reached their maximum persistence at higher clearcut sizes. Results also showed a positive effect of habitat lifetime on persistence. Our results suggest large clearcuts may be incompatible with the conservation of many early-successional vertebrates that have limited dispersal capacity, unless additional conservation measures, such as the use of corridors or special spatial arrangement of clearcuts, are taken to overcome the lack of connectivity.  相似文献   

Fine temporal resolution satellite sensors with global coverage: an opportunity for landscape ecologists     

Pazúr  Robert  Price  Bronwyn  Atkinson  Peter M. 《Landscape Ecology》2021,36(8):2199-2213

Landscape Ecology - Open data policies and accessible computation platforms allow efficient extraction of information from remote sensing data for landscape research. Landscape ecology is strongly...  相似文献   

Effect of high temperature on physiological parameters of Nelore (Bos taurus indicus) and Caracu (Bos taurus taurus) cattle breeds     

Lima  Sergio B. G. P. N. P.  Stafuzza  Nedenia Bonvino  Pires  Bianca V.  Bonilha  Sarah F. M.  Cyrillo  Joslaine N. S. G.  Negrão  João A.  Paz  Claudia C. P. 《Tropical animal health and production》2020,52(5):2233-2241

The climate-related problems that affect animal production in tropical countries have encouraged seeking solutions to increase herd productivity and one alternative is the use of breeds adapted to high-temperature environments. The objective of this study was to evaluate the effect of temperature on 77 Caracu and Nelore males submitted to three different environments: morning period (8:00 to 10:00 AM), afternoon in the sun, and afternoon in a shaded environment (11:00 AM to 1:00 PM). The following physiological parameters were measured in each treatment: heart and respiration rates, rectal and dorsal surface temperatures, and cortisol level. The data were analyzed with the MIXED procedure (SAS) and the model included the fixed effects of treatment (morning, sun, and shade), breed (Nelore and Caracu), month of measurement (December and February), and the interaction between effects. A higher dorsal surface temperature was observed in animals of both breeds in the sun treatment compared with the shade treatment. Caracu animals had a higher dorsal surface temperature than Nelore animals, which probably caused the higher rectal temperature observed in the sun treatment compared with the shade treatment in both breeds over the 2 months of the study. All physiological parameters measured in this study were efficient to detect the thermal stress in both breeds. Despite the variations in rectal temperature observed during the treatments, the animals of the two breeds exhibited no significant changes in heart rate, respiration rate, and cortisol level for the maintenance of thermal homeostasis. In conclusion, both breeds were considered tolerant to sun exposure, demonstrating adaptation of these animals to high-temperature environments, without evidence of harm to its health and welfare.

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A semi-empirical model to predict the EM38 electromagnetic induction measurements of soils from basic ground properties     

Fernando Visconti  José Miguel De Paz 《European Journal of Soil Science》2021,72(2):720-738

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An anti-inflammatory and immunomodulatory polysaccharide from Orbignya phalerata     

Bernadete Pereira da Silva  Jos Paz Parente 《Fitoterapia》2001,72(8)

A polysaccharide, a glucan with mean M_r of 1.0×10⁶ (MP1), was isolated from the mesocarp of fruits of Orbignya phalerata. Chemical and spectroscopic studies indicated that MP1 has a highly branched glucan type structure composed of α-(1→4) linked -glucopyranose residues with (3→4), (4→6), and with (3→6) branching points. MP1 enhanced phagocytosis in vivo and exhibited anti-inflammatory activity.  相似文献   

Crop Residue Effects on Total and Dissolved Losses of Fe,Mn, Cu,and Zn by Runoff     

José Manuel Mirás-Avalos  Ildegardis Bertol  Cleide A. de Abreu  Eva Vidal Vázquez  Antonio Paz González 《Communications in Soil Science and Plant Analysis》2015,46(4):272-282

Runoff may cause losses of micronutrients from soils. This can result in environmental problems such as contaminant transfers to water or a decrease in soil fertility. Appropriate soil management may reduce these micronutrient losses. This study examined the effect of applying crop residues to the soil surface on iron (Fe), manganese (Mn), copper (Cu), and zinc (Zn) losses by runoff. Runoff and sediment yield were measured on 1-m² plots using a rainfall simulator with constant 65 mm h^?1 intensity. Eight successive rainfall applications were performed at 65 mm each. Corn (Zea mays L.) straw was applied to plots at rates ranging from 0 to 8 t ha^?1. Both total and dissolved concentrations of the micronutrients studied were decreased by corn straw applications. After 520 mm cumulative rainfall, total soil losses ranged from 150 to 15354 kg ha^?1 depending on the amount of corn straw applied. Total micronutrient concentrations in runoff were as follows: Fe from 14.98 to 611.12 mg L^?1, Mn from 0.03 to 0.61 mg L^?1, Cu from 0.10 to 1.43 mg L^?1, and Zn from 0.21 to 5.45 mg L^?1. The relative contribution of the dissolved fraction to the total micronutrient content loss was low, but varied depending on the nutrient, being less than 1 percent for Fe and Mn and almost 10 percent for Zn. Total and dissolved concentrations in runoff of the studied elements decreased exponentially as the rate of applied corn straw increased. In conclusion, the addition of corn straw to soil reduced micronutrient losses.  相似文献   

Bipolar Mesoderm Cells in vitro Examined by Scanning Electron Microscopy     

C. A. Chamorro  P. de  Paz  J. G. Fernandez    M. Fernandez  J. M. Villar 《Anatomia, histologia, embryologia》1987,16(1):48-52

Head mesoderm cells from chick embryo at stage 10 were cultured onto coverslips. The mesoderm cells with bipolar aspect were studied by means of scanning electron microscopy. Several features of the filopodia and lamellipodia of these cells, as number, length and width were quantified and the results ire discussed in view of the role proposed for these projections in the cellular locomotion. Moreover, the morphological characterization here carried out permits to have comparison with other cellular types of the same culture or between cultured cells of different stages of chick embryo development.  相似文献   

Exploitation of Marine Molecules to Manage Alzheimer’s Disease     

Marisa Silva  Paula Seijas  Paz Otero 《Marine drugs》2021,19(7)

Neurodegenerative diseases are sociosanitary challenges of today, as a result of increased average life expectancy, with Alzheimer’s disease being one of the most prevalent. This pathology is characterized by brain impairment linked to a neurodegenerative process culminating in cognitive decline and behavioral disorders. Though the etiology of this pathology is still unknown, it is usually associated with the appearance of senile plaques and neurofibrillary tangles. The most used prophylaxis relies on anticholinesterase drugs and NMDA receptor antagonists, whose main action is to relieve symptoms and not to treat or prevent the disease. Currently, the scientific community is gathering efforts to disclose new natural compounds effective against Alzheimer’s disease and other neurodegenerative pathologies. Marine natural products have been shown to be promising candidates, and some have been proven to exert a high neuroprotection effect, constituting a large reservoir of potential drugs and nutraceutical agents. The present article attempts to describe the processes of extraction and isolation of bioactive compounds derived from sponges, algae, marine bacteria, invertebrates, crustaceans, and tunicates as drug candidates against AD, with a focus on the success of pharmacological activity in the process of finding new and effective drug compounds.  相似文献   

Canine normal corneal epithelium bears a large population of CD45-positive cells     

Carvalho AR  Naranjo C  Leiva M  Fondevila D  Iborra A  Martinez P  Peña T 《Veterinary journal (London, England : 1997)》2009,179(3):437-442

This investigation sought to identify the presence of immune cells in normal canine corneal epithelium. A whole-mount immunofluorescence study of normal canine epithelium using monoclonal antibodies against CD45, CD11c, CD1c and MHC class II was performed. CD45-positive cells were located in all epithelial layers throughout the cornea, occurring in greater numbers (51.98 ± 4.1/mm²) at the periphery and decreasing towards the central region (11.8 ± 3.1/mm²). CD11c-positive cells were also observed, but were fewer in number. The findings show that the normal canine cornea carries a significant number of cells of immune origin; these cells seem to be of an inactive phenotype as they do not express MHC class II. Further studies are needed to determine whether these cells can express co-stimulatory molecules and act as antigen presenting cells if stimulated.  相似文献   

Genetic associations between age at first calving and heifer body weight and scrotal circumference in Nelore cattle     

D.A. Grossi  G.C. Venturini  C.C.P. Paz  L.A.F. Bezerra  R.B. Lôbo  J.A. Oliveira  & D.P. Munari 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》2009,126(5):387-393

Age at first calving (AFC) measures the entry of heifers into the beef cattle production system. This trait can be used as a selection criterion for earlier reproductive performance. Using data from Nelore cattle participating in the 'Program for Genetic Improvement of the Nelore Breed' (PMGRN-Nelore Brazil), bi-trait analyses were performed using the restricted maximum likelihood method, based on an AFC animal model and the following traits: female body weight adjusted to 365 (BW365) and 450 (BW450) days of age, and male scrotal circumference adjusted to 365 (SC365), 450 (SC450), 550 (SC550) and 730 (SC730) days of age. The heritability estimates for AFC ranged from 0.02 ± 0.02 to 0.04 ± 0.02. The estimates of additive direct heritabilities (with standard error) for BW365, BW450, SC365, SC450, SC550 and SC730 were 0.36 ± 0.07, 0.38 ± 0.07, 0.48 ± 0.07, 0.65 ± 0.07, 0.64 ± 0.07 and 0.42 ± 0.07, respectively, and the genetic correlations with AFC were −0.38, −0.33, 0.10, −0.13, −0.13 and 0.06, respectively. In the herds studied, selection for SC365, SC450, SC550 or SC730 should not cause genetic changes in AFC. Selection based on BW365 or BW450 would favor smaller AFC breeding values. However, the low magnitude of direct heritability estimates for AFC in these farms indicates that changes in phenotypical expression depend mostly on non-genetic factors.  相似文献