The influence of cattle activity on tree regeneration in wood-pastures

Wood-pastures are semi-natural, highly biodiverse systems maintained by traditional extensive agriculture. They are used for grazing and timber. The shifting mosaics of grassland, shrub thickets and woodland patches in these systems are driven by large herbivores. Current changes in agricultural practices are leading to either intensification or abandonment and they result in a segregation of grassland and forest. This presents a complex conservation problem for these endangered ecosystems. Large herbivores have been identified as an important factor preventing the establishment of trees and the regeneration of woodland. However, successful management is severely hindered by the lack of ecological knowledge about the effects of large herbivores on woody species. This research focussed on the quantification of the impact of cattle activity on the early stages of tree establishment for four tree species (Abies alba, Picea abies, Acer pseudoplatanus and Fagus sylvatica) common in the wood-pastures of the Swiss Jura Mountains. Cattle can have both direct and indirect effects on tree establishment, and the interaction between cattle activity and both competition and facilitation by surrounding vegetation was studied. Experimental field studies (involving seed sowing and sapling planting) were carried out. Both cattle activity and competition from neighbours reduced first-year tree seedling recruitment in wood-pastures. Seedling establishment decreased with increasing cattle grazing intensity. The effects of gaps in the vegetation on seedling emergence were complex, as a result of biotic (i.e. competition, facilitation and predation from rodents, invertebrates and large herbivores) and abiotic (e.g. moisture, temperature and light) interactions, leading to different results in different years. Although overall the chances for tree seeds to make it to seedlings were low, seedling establishment was relatively high for Picea, intermediate for Abies and Acer and low for Fagus. The probability of a sapling of being browsed increased with sapling size and decreased with the height of surrounding vegetation and in the presence of nurse shrubs. It was similar for the four species and under low and high grazing intensities. Saplings had species- and size-specific responses in survival and growth to cattle browsing. Under both low and high grazing intensity, small coniferous saplings (36 %) had a lower survival rate than small deciduous saplings (53 %), which we hypothesize is due to the larger biomass losses stemming from a more vulnerable plant architecture. Under low grazing intensities, large Picea (80 %) and Fagus (67 %) saplings had a higher survival than large Acer (50 %) and Abies (33 %) saplings. This was likely due to differences in sapling tolerances to loss of biomass. Simulated browsing damage resulted in relatively smaller growth losses when small saplings were growing slowly in the presence of neighbours. Shade increased this effect. At least in the short term, the degree of small sapling tolerance was not related to plant performance as saplings that compensated almost for biomass losses still had lower survival and growth rates than less tolerant saplings. Picea was the only species not negatively affected by strong irradiance as found in an open pasture. For all tree species, the facilitative effect of nurse shrubs on small saplings was highest at intermediate levels of grazing intensity. Shrubs were more heavily damaged at high intensity than low intensity. Consequently, escaping browsing, sapling survival and growth was significantly increased by shrubs under low grazing intensity but not under high grazing intensity. Moreover, the positive effects of shrubs tended to be higher for coniferous species, and in particular Picea which was more sensitive to both competition from neighbours and browsing. In conclusion, the resistance of trees to cattle activity varies among the early stages of tree establishment and is affected by tree species, grazing intensities and environmental conditions. Both competitive and facilitative interactions found between young trees and surrounding vegetation illustrate the complex nature of plant-plant and plant-animal interactions during the tree establishment phase in wood-pastures. The insight provided into the interactions between cattle grazing and tree establishment in wood-pastures will contribute to improve ecological theory and models, in addition to informing the management and conservation of wood-pasture systems

Nurse plants, tree saplings and grazing pressure: changes in facilitation along a biotic environmental gradient

Current conceptual models predict that an increase in stress shifts interactions between plants from competitive to facilitative; hence, facilitation is expected to gain in ecological importance with increasing stress. Little is known about how facilitative interactions between plants change with increasing biotic stress, such as that incurred by consumer pressure or herbivory (i.e. disturbance sensu Grime). In grazed ecosystems, the presence of unpalatable plants is reported to protect tree saplings against cattle grazing and enhance tree establishment. In accordance with current conceptual facilitation-stress models, we hypothesised a positive relationship between facilitation and grazing pressure. We tested this hypothesis in a field experiment in which tree saplings of four different species (deciduous Fagus sylvatica, Acer pseudoplatanus and coniferous Abies alba, Picea abies) were planted either inside or outside of the canopy of the spiny nurse shrub Rosa rubiginosa in enclosures differing in grazing pressure (low and high) and in exclosures. During one grazing season we followed the survival of the different tree saplings and the level of browsing on these; we also estimated browsing damage to the nurse shrubs. Shrub damage was highest at the higher grazing pressure. Correspondingly, browsing increased and survival decreased in saplings located inside the canopy of the shrubs at the high grazing pressure compared to the low grazing pressure. Saplings of both deciduous species showed a higher survival than the evergreens, while sapling browsing did not differ between species. The relative facilitation of sapling browsing and sapling survival - i.e. the difference between saplings inside and outside the shrub canopy - decreased at high grazing pressure as the facilitative species became less protective. Interestingly, these findings do not agree with current conceptual facilitation-stress models predicting increasing facilitation with abiotic stress. We used our results to design a conceptual model of facilitation along a biotic environmental gradient. Empirical studies are needed to test the applicability of this model. In conclusion, we suggest that current conceptual facilitation models should at least consider the possibility of decreasing facilitation at high levels of stres

Use of hatch date for broiler breeder production planning

Data on 109 batches of broiler breeders belonging to six strains and bred in conventional sheds were analyzed to determine the possible influence of natural day length cycle phase on age at start of laying, at sexual maturity, and at peak egg production. The dependence of these variables on date of hatching was characterized by polynomial regression analysis. The resulting equations constitute simple, novel empirical models that are in keeping with current theory on the effects of photoperiod on sexual maturation, and should facilitate production planning in broiler breeder farmsS

Short-Term Effects of Cattle Browsing on Tree Sapling Growth in Mountain Wooded Pastures

Browsing by livestock has been identified as an important factor preventing tree regeneration in wooded pastures. Two field experiments were performed to investigate the effects of cattle browsing on tree sapling growth in a mountain-wooded pasture. Two size classes (ca.12-17cm and 41-59cm) of each of 4 species (Picea abies, Abies alba, Acer pseudoplatanus and Fagus sylvatica) were exposed to zero, low and high grazing intensities. We measured the proportion of saplings browsed and the effect of browsing on growth. A mowing treatment within the zero grazing intensity treatment showed no significant effect on sapling growth. One percent of the large saplings but 25% of the small saplings escaped browsing. Saplings were better protected when surrounded by taller vegetation. The proportion of saplings browsed was not significantly different among species although evergreen tree saplings lost a larger proportion of biomass than deciduous species when browsed. Under grazing, average current-year shoot production and total aboveground biomass of all species were significantly reduced. Browsing effects tended to be smaller at the lower grazing intensity. Because the deciduous species were least reduced in aboveground growth, especially under the low grazing intensity, we conclude that at least in short-term, deciduous species are less affected by cattle browsin

Tenogenically induced allogeneic mesenchymal stem cells for the treatment of proximal suspensory ligament desmitis in a horse

Suspensory ligament injuries are a common injury in sport horses, especially in competing dressage horses. Because of the poor healing of chronic recalcitrant tendon injuries, this represents a major problem in the rehabilitation of sport horses and often compromises the return to the initial performance level. Stem cells are considered as a novel treatment for different pathologies in horses and humans. Autologous mesenchymal stem cells (MSCs) are well known for their use in the treatment of tendinopathies; however, recent studies report a safe use of allogeneic MSCs for different orthopedic applications in horses. Moreover, it has been reported that pre-differentiation of MSCs prior to injection might result in improved clinical outcomes. For all these reasons, the present case report describes the use of allogeneic tenogenically induced peripheral blood-derived MSCs for the treatment of a proximal suspensory ligament injury. During conservative management for 4 months, the horse demonstrated no improvement of a right front lameness with a Grade 2/5 on the American Association of Equine Practitioners (AAEP) scale and a clear hypo-echoic area detectable in 30% of the cross sectional area. From 4 weeks after treatment, the lameness reduced to an AAEP Grade 1/5 and a clear filling of the lesion could be noticed on ultrasound. At 12 weeks (T-4) after the first injection, a second intra-lesional injection with allogeneic tenogenically induced MSCs and platelet rich plasma was given and at 4 weeks after the second injection (T-5), the horse trotted sound under all circumstances with a close to total fiber alignment. The horse went back to previous performance level at 32 weeks after the first regenerative therapy and is currently still doing so (i.e., 20 weeks later or 1 year after the first stem cell treatment). In conclusion, the present case report demonstrated a positive evolution of proximal suspensory ligament desmitis after treatment with allogeneic tenogenically induced MSCs

Influence of livestock grazing on meadow pipit foraging behaviour in upland grassland

Changes in grazing management are believed to be responsible for declines in populations of birds breeding in grassland over the last decades. The relationships between grazing management regimes, vegetation structure and composition and the availability of invertebrate food resources to passerine birds remain poorly understood. In this Study, we investigated the foraging site selection of meadow pipits (Anthus pratensis L.) breeding in high intensity sheep-grazed plots or low intensity mixed (i.e. sheep and cattle)-grazed plots. We sampled above-ground invertebrates, measured vegetation height and density and conducted a vegetation survey in areas where meadow pipits were observed to forage and areas that were randomly selected. Birds foraged in areas with a lower vegetation height and density and in areas containing a lower proportion of the dominant, tussock-forming grass species Molinia caerulea. They did not forage in areas with a total higher invertebrate biomass but at areas with preferred vegetation characteristics invertebrate biomass tended to be higher in foraging sites than random sites. The foraging distance of meadow pipits was higher in the intensively grazed plots. Our findings support the hypothesis that resource-independent factors such as food accessibility and forager mobility may determine patch selection and are of more importance as selection criteria than food abundance per se. Food accessibility seems to become an even more important selection criterion under high grazing intensity, where prey abundance and size decrease. In our upland grazing system, a low intensity, mixed grazing regime seems to provide a more suitable combination of sward height, plant diversity, structural heterogeneity and food supply for meadow pipit foraging activity compared to a more intensive grazing regime dominated by sheep. (c) 2009 Gesellschaft fur Okologie. Published by Elsevier GmbH. All rights reserved

Nurse plants, tree saplings and grazing pressure: decreasing facilitation along a biotic environmental gradient

Current conceptual models predict that an increase in stress shifts interactions between plants from competitive to facilitative; hence, facilitation is expected to gain in ecological importance with increasing stress. Little is known about how facilitative interactions between plants change with increasing biotic stress, such as that incurred by consumer pressure or herbivory (i.e. disturbance sensu Grime). In grazed ecosystems, the presence of unpalatable plants is reported to protect tree saplings against cattle grazing and enhance tree establishment. In accordance with current conceptual facilitation-stress models, we hypothesised a positive relationship between facilitation and grazing pressure. We tested this hypothesis in a Weld experiment in which tree saplings of four diVerent species (deciduous Fagus sylvatica, Acer pseudoplatanus and coniferous Abies alba, Picea abies) were planted either inside or outside of the canopy of the spiny nurse shrub Rosa rubiginosa in enclosures diVering in grazing pressure (low and high) and in exclosures. During one grazing season we followed the survival of the diVerent tree saplings and the level of browsing on these; we also estimated browsing damage to the nurse shrubs. Shrub damage was highest at the higher grazing pressure. Correspondingly, browsing increased and survival decreased in saplings located inside the canopy of the shrubs at the high grazing pressure compared to the low grazing pressure. Saplings of both deciduous species showed a higher survival than the evergreens, while sapling browsing did not diVer between species. The relative facilitation of sapling browsing and sapling survival – i.e. the diVerence between saplings inside and outside the shrub canopy – decreased at high grazing pressure as the facilitative species became less protective. Interestingly, these Wndings do not agree with current conceptual facilitationstress models predicting increasing facilitation with abiotic stress. We used our results to design a conceptual model of facilitation along a biotic environmental gradient. Empirical studies are needed to test the applicability of this model. In conclusion, we suggest that current conceptual facilitation models should at least consider the possibility of decreasing facilitation at high levels of stress

Short-term effects of cattle browsing on tree sapling growth in mountain wooded pastures

Browsing by livestock has been identified as an important factor preventing tree regeneration in wooded pastures. Two field experiments were performed to investigate the effects of cattle browsing on tree sapling growth in a mountainwooded pasture. Two size classes (ca. 12–17 cm and 41–59 cm) of each of 4 species (Picea abies, Abies alba, Acer pseudoplatanus and Fagus sylvatica) were exposed to zero, low and high grazing intensities. We measured the proportion of saplings browsed and the effect of browsing on growth. A mowing treatment within the zero grazing intensity treatment showed no significant effect on sapling growth. One percent of the large saplings but 25% of the small saplings escaped browsing. Saplings were better protected when surrounded by taller vegetation. The proportion of saplings browsed was not significantly different among species although evergreen tree saplings lost a larger proportion of biomass than deciduous species when browsed. Under grazing, average current-year shoot production and total aboveground biomass of all species were significantly reduced. Browsing effects tended to be smaller at the lower grazing intensity. Because the deciduous species were least reduced in aboveground growth, especially under the low grazing intensity, we conclude that at least in short-term, deciduous species are less affected by cattle browsing