A disturbance-induced increase in tree species diversity facilitates forest productivity

Context

Natural disturbances can have a considerable negative impact on the productivity of forest landscapes. Yet, disturbances are also important drivers of diversity, with diversity generally contributing positively to forest productivity. While the direct effects of disturbance have been investigated extensively it remains unclear how disturbance-mediated changes in diversity influence landscape productivity. Considering that disturbances are increasing in many ecosystems a better understanding of disturbance impacts is of growing importance for ecosystem management.

Objectives

Here, our objectives were to study the effect of disturbance on tree species diversity at different spatial scales (α and β diversity), and to analyze how a disturbance-mediated variation in tree species diversity affects forest productivity.

Methods

To account for long-term interactions between disturbance, diversity, and productivity and test a range of disturbance scenarios we used simulation modeling, focusing on a temperate forest landscape in Central Europe.

Results

We found an overall positive effect of disturbance on tree species diversity both with regard to α and β diversity, persisting under elevated disturbance frequencies. Productivity was enhanced by within- and between-stand diversity, with the effect of α diversity decreasing and that of β diversity increasing through the successional development. Positive diversity effects were found to be strongly contingent on the available species pool, with landscapes containing species with different life-history strategies responding most strongly to disturbance-mediated diversity.

Conclusions

We conclude that, rather than homogenizing disturbed areas, forest managers should incorporate the diversity created by disturbances into stand development to capitalize on a positive diversity effect on productivity.

     

A panel of protein candidates for comprehensive study of Caprine Arthritis Encephalitis (CAE) infection

The caprine arthrite encephalite (CAE) is a disease that affects especially dairy goat. The virus shows compartmentalization features, that allows it to hide at certain times during the course of the disease, making it difficult to control. The present study was conducted to identify the major seminal plasma protein profile of goats infected by CAE and its associations with seroconversion using Western blotting. Two groups containing five males each, were used in this experiment. The first group was composed by seropositive animals and the control by seronegative confirmed by Western blotting and PCR. The semen was collected through artificial vagina and after that, two-dimensional electrophoresis and MALDI-TOF MS were used. Seventy-five spots were identified in the goat seminal plasma gels, equivalent to 13 different proteins with more expression. The similar proteins found in both groups and related to reproduction were spermadhesin Z13-like, bodhesin and bodhesin-2, Lipocalin, protein PDC-109-like, and albumin. In infected goats, proteases such as arisulfatase A have been identified, whose function probably is related to metabolism control of sulfatides, involved to virus control. The other ones were bifunctional ATP-dependent dihydroxyacetone kinase/FAD-AMP lyase, cathepsin F isoform X1, disintegrin and metalloproteinase domain-containing protein 2-like isoform X1, clusterin, carbonic anhydrase 2, electron transfer flavoprotein subunit beta, and epididymal secretory glutathione peroxidase. The results of this study show the reaction of the innate immune system against chronic infection of goats by CAE.     

Supplementation of pig diets in the growth and termination phases with different calcium sources

The aim of this study was to evaluate the effect of supplementation of pig diets in the growth and termination phases with different calcium sources. In experiment I, 36 whole males were distributed in randomized blocks in six groups, with six replications. A basal diet was formulated to meet the animals’ nutritional requirements except for calcium (0.09%), and the sources evaluated (calcitic limestone, monodicalcium phosphate, calcinated bone flour, and oyster flour) replaced the basal diet to provide 0.59% of total calcium. To determine the endogenous calcium, a diet containing low calcium (0.019%) was given simultaneously to another group of animals. Feces and urine were collected for determination the coefficients of apparent and true digestibility. In experiment II, 160 piglets were distributed in randomized blocks in four treatments, with five replications and four animals per experimental unit. Carcass and performance parameters, calcium concentration in bone and serum, and bone parameters were evaluated. The data were submitted to analysis of variance and factorial. The calcium source did not influence the digestibility coefficients determined by total collection (P > 0.05). The digestibility of Ca from oyster flour estimated by collection with an indicator was higher than that from the other sources (P < 0.05). Calcium sources did not interfere in the evaluated parameters (P > 0.05). The sources studied in this work can be used to supplement growing pigs’ diets.     

Minor corral changes and adoption of good handling practices can improve the behavior and reduce cortisol release in Nellore cows

Inadequate corral facilities and improper handling are major causes of stress in beef cattle. The purpose of this study was to evaluate the effects of minor changes in the corral and adoption of good handling practices on the behavior, cortisol release, and time spent taking blood samples in Nellore cows. Minor corral changes included obstructing the cow’s vision when the handler walked deep into the animal’s flight zone and the elimination of bright objects, color contrasts, puddles, shadows, and darkness in the corral. Handling was improved by eliminating dogs, electric goads (prods), and yelling, as well as adopting a calm behavior. A total of 141 Nellore cows from two typical extensive livestock farms were studied. The cows were evaluated individually before and after the corral changes. Blood samples were collected in the restraint device for cortisol measurement. The minor corral changes and the adoption of good handling practices result in better results for all variables studied. The results showed differences in the interactions between treatment and ranch for chute score (P = 0.0091) and exit score (P < 0.0001). The cortisol release was lower (P < 0.001) and better for the improved methods, resulting in calmer cows compared to cortisol released before the minor changes (41.03 ± 2.9 vs 60.40 ± 3.8 ng/mL). Minor changes made in the corrals and the adoption of good handling practices were effective in improving cow behavior in the chute and in reducing exit velocity, cortisol released, and the time spent taking blood samples.     

Leptospirosis is strongly associated to estrus repetition on cattle

Tropical Animal Health and Production - Although prevalent, the exact impact of infectious diseases on reproductive failures remains to be determined. Among them, leptospirosis has commonly been...     

Characteristics of Livestock Husbandry and Management Practice in the Central Dry Zone of Myanmar

Tropical Animal Health and Production - The central dry zone of Myanmar is the area with the highest density of small-scale livestock farmers under harsh environmental condition. In this study, we...     

Ovines submitted to diets containing cassava foliage hay and spineless cactus forage: histological changes in the digestive and renal systems

The aim of this study was to evaluate the histological alterations in the digestive and renal systems of 35 male ovines in Paraíba, Brazil, at around 16?± 1.87 kg submitted to the following treatments for 90 days (15 of adaptation +?75 of experimental period): 1- Tifton hay (TH); 2- Cassava foliage hay (CH); 3–35% TH and 35% CH; 4–35% TH and 35% forage palm (FP), and 5–35% CH and 35% FP, based on dry matter (DM). Samples of the liver, kidney, rumen, and small intestine were histomorphometrically evaluated and the data were submitted to ANOVA analysis and Tukey post test at p ≤?0.05. The use of alternative foods in the voluminous fraction (CH?+?FP) in the ovine diets did not compromise the performance of the animals; on the contrary, promoted better gain when compared with TH treatment (18.55 kg vs 9.42 kg). The CH?+?FP diet had a positive effect on papilla height. The papilla width decreased with the diets CH?+?FP and TH?+?FP. The thickness of the ruminal muscular layer were higher in the diets containing TH?+?CH and CH?+?FP. The keratinized layer of the ruminal epithelium was larger in the diet containing CH and FP. The villi of the intestinal crypts were deeper in the diets with FP and the villus/crypt ratio was the same in all diets. Goblet cells decreased with the CH or FP diet. Some renal changes were observed according to the diets, mainly when using FP. It is recommended to use CH and FP as a large fraction of the ovines diet, which will not alter animal performance.