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121.
José Ramón Arévalo Guacimara González-Delgado Beatriz Mora José María Fernández-Palacios 《Journal of Forest Research》2012,17(2):184-192
The laurel forest of Anaga is the most emblematic community of the Canarian Archipelago. Restoration programs are being developed
to increase laurel forest area on the island of Tenerife. Structural and spatial characteristics determine many aspects of
the community, including regeneration patterns, disturbance level, stand history. In spite of the importance of this information
for restoration, few quantitative studies have been conducted on laurel forest dynamics. We analyzed two stands of the Anaga
laurel forest of different aspect. The main difference between the two sites was the wind exposure, one leeward and the other
windward. Regeneration, spatial distribution of regeneration, tree species composition, asexual regeneration and environmental
parameters were analyzed in three 50 × 50 m plots at each site. Both sites differ in important aspects such as species richness,
species composition, asexual regeneration and dead tree composition, while they are not different in basal area, density,
density of regeneration and density of dead trees. Both sites have had similar management in the last century. Asexual regeneration
is able to maintain the present species composition, while sexual regeneration is able to offer future changes in the canopy
composition. Regeneration strategies and the effect of some environmental characteristics should be considered in restoration
programs. 相似文献
122.
Wibke Himmelsbach Eduardo J. Treviño-Garza Humberto González-Rodríguez Marco A. González-Tagle Marco V. Gómez Meza Oscar A. Aguirre Calderón A. Eduardo Estrada Castillón Ralph Mitlöhner 《European Journal of Forest Research》2012,131(2):355-367
Water availability and salt excess are limiting factors in Mexican mixed pine-oak forest. In order to characterise the acclimatation
of native species to these stresses, leaf water (Ψw) and osmotic potentials (Ψs) of Juniperus flaccida, Pinus pseudostrobus and Quercus canbyi were measured under natural drought and non-drought conditions under two different aspects in the Sierra Madre Oriental.
Factorial ANOVA revealed significant differences in Ψw and Ψs between two aspects, species and sampling dates. In general, all species showed high predawn and low midday values that declined
progressively with increasing drought and soil–water loss. Seasonal and diurnal fluctuation of Ψw and Ψs were higher for J. flaccida and Q. canbyi than for P. pseudostrobus. Leaf Ψw and Ψs were mainly correlated with soil water content, while Ψs of P. pseudostrobus were hardly correlated with environmental variables. Thus, species have different strategies to withstand drought.
P. pseudostrobus was identified as a species with isohydric water status regulation, while J. flaccida and Q. canbyi presented water potential patterns typical for anisohydric species. The type of water status regulation may be a critical
factor for plant survival and mortality in the context of climate change. Nevertheless, for precise conclusions about the
advantages and disadvantages of each type, further long-term investigations are required. 相似文献
123.
The characterization of plant genetic resources is the first step towards improving their use. The Spanish Plant Genetic Resources
Centre, which belongs to the National Institute for Agricultural and Food Technology Research (CRF-INIA), conserves accessions
of wild underground vetches collected in Spain. In the present work, 26 underground vetch accessions were characterized in
terms of their seed storage proteins (separated by SDS-PAGE) as a means of assessing the genetic variation of these plants
and their agronomic value. Vicia sativa cv. Vereda was used as control. A total of 54 bands were detected, of which 49 were polymorphic. Fifty eight different electrophoretic
patterns were observed in total. Protein bands were scored in terms of their presence (1) or absence (0) for all the seeds
studied, and two matrices constructed, one with all the bands present in each accession, the other with the different patterns
for each accession. Dendrograms based on the Jaccard similarity index and the UPGMA clustering method were produced from these
matrices, and the degree of genetic variation between and within accessions was calculated. The groups obtained were compared
with the chromosome number for each accession. The results reflect the great diversity of underground vetch seed storage proteins.
The aerial and underground seeds of 16 accessions were then analysed separately. In some cases, the aerial and underground
flowers of the same plant produced different proteins. 相似文献
124.
Artemio CARRILLO Rahim FOROUGHBACHK Verónica BUSTAMANTE Christian WEHENKEL Humberto GONZáLEZ 《中国林学(英文版)》2013,15(2):160-166
Thorn scrub vegetation in Mexico is distributed over 50 million ha, where native tree species are the source of forage, timber, firewood and charcoal. Research describing wood durability of species from this vegetation type has not been fully determined, nor classified according to international standards. Thus, the aim of this study was to determine and classify the natural durability of ten woody species. Their natural durability was determined according to the European Pre-Norm 807, the loss of dynamic modulus of elasticity (MOEdyn) (MPa) was determined and wood mass loss (g) after being exposed to Trametes versicolor and Coniophora puteana fungi. Wood durability was classified according to the European Norm 350-1. Highly significant differences (p<0.001) were found between the durability of woody species. The more durable species with lower MOEdyn lost were Condalia hookeri (57.5%±0.6%), Havardia pallens (58.2%±0.4%) and Acacia schaffneri (58.9%±6.3%). Species with lower mass loss after exposed to Coniophora puteana were Ebenopsis ebano (6.3%±1.9%), Condalia hookeri (8.6%±2.3%) and Cordia boissieri (11.8%±2.3%). E. ebano (7.1%±2.4%), Condalia hookeri (8.2%±2.5%) and Cordia boissieri (11.5%±3.1%) showed the lower mass lost after exposed to T. versicolor. According to European Norm 350-1, three woody species were classified as very durable and durable species. 相似文献
125.
Teresa Valor Míriam Piqué Bernat C. López José Ramón González-Olabarria 《Annals of Forest Science》2013,70(5):503-513
Context
After wildfire, surviving trees are of major ecological importance as they can help in the post-fire regeneration process. Although these trees may be damaged, they may also benefit from reduced fuel hazard and competition. However, little is known about the long-term growth response of surviving trees.Aims
This study aims to explain short- to long-term variations in the postfire growth of surviving black pines in an area burnt in 1994, focusing on levels of fire severity and tree sizes.Methods
Relative basal area increments were used to detect time-course variations in postfire radial tree growth depending on fire severity. Linear mixed-effects models were used to describe the factors affecting postfire ring growth.Results
In the short term, fire caused stronger reduction in growth in small trees with increasing bole char height. However, as time since fire increased, a positive effect of fire on growth due to reduced competition counteracted the short-term fire impacts. Indeed, small surviving trees demonstrated a surge in growth 15 years after the fire.Conclusion
It was concluded that reduced competition might offset the short-term negative effects of fire in surviving black pines. 相似文献126.
María Llarena-Reino Carmen Piñeiro José Antonio Luis Outeriño Carlos Vello Ángel F. González Santiago Pascual 《Veterinary parasitology》2013,191(3-4):276-283
During the last 50 years human anisakiasis has been rising while parasites have increased their prevalence at determined fisheries becoming an emergent major public health problem. Although artificial enzymatic digestion procedure by CODEX (STAN 244-2004: standard for salted Atlantic herring and salted sprat) is the recommended protocol for anisakids inspection, no international agreement has been achieved in veterinary and scientific digestion protocols to regulate this growing source of biological hazard in fish products. The aim of this work was to optimize the current artificial digestion protocol by CODEX with the purpose of offering a faster, more useful and safer procedure for factories workers, than the current one for anisakids detection. To achieve these objectives, the existing pepsin chemicals and the conditions of the digestion method were evaluated and assayed in fresh and frozen samples, both in lean and fatty fish species. Results showed that the new digestion procedure considerably reduces the assay time, and it is more handy and efficient (the quantity of the resulting residue was considerably lower after less time) than the widely used CODEX procedure. In conclusion, the new digestion method herein proposed based on liquid pepsin format is an accurate reproducible and user-friendly off-site tool, that can be useful in the implementation of screening programs for the prevention of human anisakiasis (and associated gastroallergic disorders) due to the consumption of raw or undercooked contaminated seafood products. 相似文献
127.
Mikel González Sergio López Bradley A. Mullens Thierry Baldet Arturo Goldarazena 《Veterinary parasitology》2013,191(1-2):81-93
Culicoides species (Diptera: Ceratopogonidae) belonging to the Obsoletus and Pulicaris groups are considered to be the main vectors of bluetongue virus (BTV) in non Mediterranean Europe. Selected terrestrial microhabitats (n = 17) on a farm in northern Spain were sampled repeatedly over a year-long period and characterized for use by Culicoides species for immature development. Concurrent use of CDC light traps showed the presence of 37 species and 66,575 specimens of adult Culicoides. A total of 28 species and 11,396 individuals emerged from laboratory-maintained soil samples. Culicoides obsoletus and Culicoides scoticus (pooled as Obsoletus complex) were particularly abundant (comprising 58.6% and 74.5% of the total collections in light traps and emergence traps respectively). Potential key vectors of animal viruses (such as BTV) were found in two main terrestrial types of microhabitats. In the case of C. obsoletus, different types of manure (old and composted manure, manure mixed with organic matter, and fresh manure) produced most of the specimens. In contrast, larvae of C. scoticus and Culicoides lupicaris were associated with soil substantially comprised of rotting leaf litter that included the parasitic plant Lathraea clandestina. Several species, Culicoides festivipennis, Culicoides punctatus and Culicoides brunnicans, were very common in mud at pond margins. Indeed, pond microhabitats and runoff below barn rooflines supported the greatest species richness. In the pond habitat, 49.4% of Culicoides specimens emerged from mud at the water edge, as opposed to 50 cm above (32.4%) and 1 meter above waterline (18%). Similar species richness, but statistically significant differences in abundance, were observed among the four pond microhabitats. Overall, the majority of the specimens were found in the upper layer (0–3 cm), except in manure, where they preferred deeper layers (>6 cm). Maximum peaks of abundance occurred in both light traps and soil samples in summer months, whereas increased captures in autumn were noticed only in light traps. Both trapping systems failed to collect adult Culicoides midges in the coldest months of December, January and February. The literature on immature habitats of species suspected in BTV transmission in Europe, the Pulicaris group and particularly the Obsoletus group, is briefly reviewed. 相似文献
128.
J.C. Bambou W. Cei S. Camous H. Archimède A. Decherf L. Philibert C. Barbier N. Mandonnet E. González-García 《Veterinary parasitology》2013,191(3-4):284-292
The objective of this study was to compare the effects of the type of Haemonchus contortus experimental infection (trickle infection, TI versus single infection, SI) on feed intake, nutrients digestibility, parasitological and haematological measures, and plasma leptin in Creole kids. The animals were infected over 2 periods (challenge 1 and challenge 2) of 6 weeks each, corresponding respectively to the primary and the secondary infection. Periods prior infection (1 week each) were considered as controls. The primary infection was realized with 35 Creole kids (18.40 ± 3.76 kg BW) housed in individual boxes and fed a hay-based diet. The secondary infection continued with 29 kids (21.90 ± 3.40 kg BW) from the initial 35. A total of 6 kids and 8 kids were slaughtered for measuring nematode burden at the end of the primary and the secondary infection, respectively. Measurements of nutrients digestibility were made at 0, 3 and 5 weeks post-infection for both challenges. Faecal egg count (FEC), blood eosinophilia and packed cell volume (PCV) were monitored weekly. Feed intake (dry matter intake, DMI) and nutrients digestibility were negatively affected by H. contortus infection only during the primary infection. Plasma leptin changed significantly over time (P = 0.0002) but was not affected by the infection type. Effect of infection type was observed only on crude protein digestibility during the primary infection, which was lower in the TI group (P < 0.01). The overall level of blood eosinophilia was significantly higher in the TI group (P < 0.0001) during both challenges. The overall FEC mean was significantly higher in the SI compared with the TI groups, during both challenges (P < 0.02). These results were related to the mean female length significantly higher in the SI group compared with the TI group during challenge 1 (P = 0.004), and the number of adult nematode significantly lower in the TI group compared with the SI group during the challenge 2 (P = 0.05). The results showed that the response of Creole kids to H. contortus experimental infection was in part dependent on the type of experimental infection. Our data suggest that plasma leptin would not be involved in the response of Creole kids against H. contortus infection, as no relationship between its plasma level and the transient reduction in voluntary feed intake observed in both groups during the primary infection was observed. 相似文献
129.
Effects of considering the comminution rate (kc) and the correction of microbial contamination (using 15N techniques) of particles in the rumen on estimates of ruminally undegraded fractions and their intestinal digestibility were examined generating composite samples (from rumen‐incubated residues) representative of the undegraded feed rumen outflow. The study used sunflower meal (SFM) and Italian ryegrass hay (RGH) and three rumen and duodenum cannulated wethers fed with a 40:60 RGH to concentrate diet (75 g DM/kgBW0.75). Transit studies up to the duodenum with Yb‐SFM and Eu‐RGH marked samples showed higher kc values (/h) in SFM than in RGH (0.577 vs. 0.0892, p = 0.034), whereas similar values occurred for the rumen passage rate (kp). Estimates of ruminally undegraded and intestinal digestibility of all tested fractions decreased when kc was considered and also applying microbial correction. Thus, microbial uncorrected kp‐based proportions of intestinal digested undegraded crude protein overestimated those corrected and kc?kp‐based by 39% in SFM (0.146 vs. 0.105) and 761% in RGH (0.373 vs. 0.0433). Results show that both kc and microbial contamination correction should be considered to obtain accurate in situ estimates in grasses, whereas in protein concentrates not considering kc is an important source of error. 相似文献
130.
José J Corral-Rivas María Socorro González-Elizondo José E Lujan-Soto 《Southern Forests》2019,81(1):1-10
The Sierra Madre Occidental in the Mexican State of Durango, is home to about 5 million ha of species-rich forest ecosystems. Local communities depend on these forests for their livelihood. The preservation of the species richness and productivity of this unique resource requires improved understanding of the effects of forest structure and density on production. The community structure was analysed for three species groups (all species; 12 species of Pinus; and 16 species of Quercus). Based on data gathered in 580 remeasured observational field plots, the main results of this study were as follows: (1) two distinct clusters were identified in each species group, (a) the dominant species with a smaller range of growth rates, and (b) the remaining species which have a smaller maximum size and a greater variation of growth rates. (2) Density (expressed as basal area per hectare) and the percentage contribution to the total basal area of all pine species have a significant effect on forest production (expressed as volume increment per hectare per year). (3) Potential production is surprisingly high (in excess of 20 m3 ha?1 y?1 for some stands) in these forests, but the high potential cannot be realised in many areas because of reduced basal areas caused by overharvesting. (4) The available evidence does not confirm the findings of a recent study that suggests a continuous increase in production with increasing richness. Our observations show that production attains a potential maximum at intermediate levels of richness (between 7 and 9 species per 0.25 ha) and declines with further increases in species richness. This study represents a comprehensive analysis of the effects of density and structure on the community forests of the Sierra Madre Occidental based on a large set of permanent field plots where all trees have been mapped. 相似文献