Differential forage use between large native and domestic herbivores in Southern Patagonian Nothofagus forests

Plant—animal interactions at the landscape level become particularly relevant when land use is diversified. Nothofagus forests in southern Patagonia have been used for timber and cattle grazing purposes during the last century, causing livestock to increase (Bos taurus and Ovis aries) and large native herbivores, such as guanaco (Lama guanicoe), either maintained or decreased their populations. Within this scenario, feeding interactions between guanaco and domestic herbivores were analysed in a mosaic of open habitats and different Nothofagus forest types and management histories, whereby a total of six habitat types were identified through satellite image analysis. A total of 205 floristic surveys were conducted to characterize the plant species composition at the landscape level. Diet composition of herbivores was assessed once each season during a year, using microhistological analysis of feces. Results showed higher plant richness in open lands and lower in closed, unmanaged forests. Overall, 43 plant taxa were detected in herbivore feces, which represent 56% of plant richness detected in the field. Both guanacos and domestic herbivores included mainly grasses in their diet, which were found predominantly in open lands. Tree seedlings and saplings were consumed by all herbivores, as well, except during winter. Differential forage use between guanaco and domestic herbivores in southern Patagonian Nothofagus forests did exist. However, competition for available resources among theses herbivores resulted in an alternation of feeding sites, which varied throughout the year. Management plans in southern Southern Patagonia (livestock, silvopastoral plans and timber harvesting) do not consider the direct or indirect consequences on guanaco populations. The challenge, therefore, is to generate management decisions to avoid either guanacos or domestic herbivores from becoming detrimental to the sustainability of managed forested ecosystems.     

Identifying plant DNA in the sponging–feeding insect pest <Emphasis Type="Italic">Drosophila suzukii</Emphasis>

Drosophila suzukii (Diptera: Drosophilidae) is a highly polyphagous invasive pest threatening fruit production in the Americas and Europe. The current knowledge of its host plants is mainly based on oviposition and larval development in fruits, while little is known on the diet of the adult flies. This information is important for developing effective control strategies. Here, we examine DNA-based techniques to determine food plants of D. suzukii. Adult flies were fed with raspberries (Rubus idaeus) and allowed to digest up to 72 h after feeding. Raspberry DNA was detected by diagnostic PCR for up to 48 h post-feeding with a significant negative effect of time on DNA detection success but no significant differences between male and female flies in detection probabilities. As D. suzukii walks on plants, its body surface can get contaminated with DNA. With a bleaching experiment, we succeeded to remove contaminating external plant DNA, while the DNA in the gut content stayed unaffected. Finally, field-collected flies were subjected to a next-generation sequencing approach, demonstrating that plant DNA from different host plants can be efficiently detected in both bleached and non-bleached specimens. In order to safeguard against erroneous host plant detections, we recommend bleaching flies before they are subjected to DNA extraction. The current findings encourage the use of DNA-based gut content analysis in D. suzukii to obtain a better understanding of its feeding ecology which is a prerequisite for developing successful control strategies.     

Cattle in the Patagonian forests: Feeding ecology in Los Alerces National Reserve

Cattle (Bos taurus) are the largest exotic ungulates introduced in Patagonian forest, and the most widely distributed. Although detrimental effects of cattle grazing on these forests have been documented, cattle-plant interaction has never been studied from the perspective of the feeding ecology of this ungulate. We assessed cattle diet on a seasonal basis by microhistological analysis of fecal samples in Los Alerces National Reserve, Argentina. We found that: (1) the annual diet was largely dominated by graminoids and shrubs; (2) the percentage of shrubs, forbs, and other species in the diet changed significantly across seasons; (3) cattle predominantly fed on Nothofagus spp., Berberis spp., Maytenus spp., Chusquea culeou, and Hierocloe sp.; and (4) selected more forbs than other vegetation types in warm-growing season, while highly selected graminoids and avoided shrubs during the cold-dormant season. Although these general selection patterns of plant types were observed seasonally, selection or avoidance at the species level was also recorded. Cattle have been described as grazers, suggesting that the composition of their diet should be dominated by graminoids. However, we found that cattle include significant proportions of woody plants in their diet. These results offer the first data available on diet composition and selection in a protected area in Patagonian forests, a first step towards understanding detrimental effects of cattle grazing on native forest from the perspective of their feeding ecology. Our evidence that cattle positively select Nothofagus spp. and Austrocedrus chilensis suggests that they can negatively affect the establishment and growth of these species. Given that livestock ranching is an important form of subsistence for economically disadvantaged settlers of Los Alerces National Reserve, alternatives to current ranching activities must be considered to improve their livelihood and reduce the negative effects of cattle on forests.     

The role of timber tree species in the nutritional ecology of spider monkeys in a certified logging concession,Bolivia

Selective harvesting of timber can lead to population declines in some primate species. As frugivorous primates are important seed dispersers in tropical forests, the reduction of their populations may affect the ecological sustainability of selectively logged forests. This paper is the first to quantify the importance of timber tree species in the diet and nutritional ecology of a primate species. We studied spider monkeys (Ateles chamek) inhabiting a certified forestry concession in Bolivia where post-logging population declines of this species have been recorded. We show that spider monkeys occupying unlogged areas obtained approximately 50% of their total intake of macro-nutrients from timber tree species and exhibited a distinct preference for foraging within trees that were of harvestable size. Timber tree species dominated the spider monkeys’ diet both during peak fruiting periods and during periods of fruit scarcity. We estimate that under current timber extraction intensities spider monkeys lose significant proportions of their food sources. Our results indicate that further extraction limits could be considered for Ficus boliviana, Spondias mombin and Pouteria nemorosa. We suggest that to ensure long-term ecological sustainability of certified forestry concessions, the importance of timber tree species in the ecology of seed dispersers needs to be taken into account.     

Quercus calliprinos regrowth advantage under grazing in Mediterranean maquis and its management implications

The post disturbance natural succession of the Mediterranean maquis, which turns open and species-rich landscapes into dense, closed stands of sclerophyllous woody vegetation is a principal threat to plant and animal diversity. Therefore, in the absence of traditional agricultural disturbance, active management regimes that include cutting and grazing are proposed to preserve biodiversity. The Mediterranean woody vegetation in Israel is strongly dominated by one species - the evergreen sclerophyllous Quercus calliprinos (Kermes oak). We hypothesized that under cutting and grazing, the evergreen Q. calliprinos has a relative regrowth advantage over other competing tree species. Here we examined the effect of grazing and the effect of tree structural traits on the regrowth after clear cutting of all trees in our study plots at Mt. Meron LTER site, Israel. All trees were removed from five blocks of 2000 m² and each block was divided into two plots, five of which were exposed to grazing livestock while five were wire-fenced and ungrazed. The regrowth rate of Q. calliprinos under grazing was higher than that of all other tree species suggesting that in the long-term, under such a conservation management regime, the dominance of the evergreen sclerophyllous Q. calliprinos over the deciduous tree species will increase and consequently will decrease plant and animal diversity. Therefore, we conclude that to protect landscape and species diversity in Mediterranean ecosystems dominated by evergreen oaks, when cutting and grazing are applied, special care must be paid to trees that are more negatively affected by such treatment.     

Are wild flowers and insect honeydews potential food resources for adults of the olive moth, <Emphasis Type="Italic">Prays oleae</Emphasis>?

The use of non-crop resources by natural enemies and their potentialities to enhance their effectiveness as pest control agents is increasing as a method for conservation biological control. Nevertheless, the effect of consumption of non-crop resources by pests has been generally overlooked being this knowledge crucial to favor natural enemies but not pests. In the present work, insect honeydews and flowers suitability as food resources for the olive tree key-pest Prays oleae were analyzed under laboratory conditions. The selected honeydews were excreted by Saissetia oleae and Euphyllura olivina, two olive pests, and the selected plants were seven abundant species in the olive grove agroecosystem that bloom simultaneously with the flight period of the anthophagous generation of P. oleae. In this work, some of these resources were identified as potential food sources for P. oleae. Despite the general findings, which indicate that honeydews have less nutritional value for insects than nectar, P. oleae reached the best survival and reproduction performance with the insects’ honeydews. Several of the tested flowers were identified as potential food resources for P. oleae, being Malva sylvestris the one that originated the best performance. Moreover, our results suggest that P. oleae females are synovigenic and emerge with nutritional reserves for reproduction. We highly recommend accomplishing further research before establishing these resources in biological control methods in order to confirm their effect on pests in fields.     

Effect of exclosure ages on woody plant structure,diversity and regeneration potential in the western Tigray region of Ethiopia

Exclosure is a method of rehabilitating degraded lands by protecting them from the interference of animals and from human encroachment, and is used to regenerate native vegetation as a way to reduce soil erosion, increase rain water infiltration and provide fodder and woody biomass in degraded grazing lands. Therefore, we studied woody plant structure, diversity and regeneration potentials in 5- and 10-year grazing exclosures in comparison with open grazed sites in a semi-arid environment. Data on species diversity, abundance, structure, basal area, frequency, density, and regeneration status were collected from 270 sample plots. Forty-one woody species representing 20 families were identified, with 18, 28 and 38 species found in open grazed areas, and in 5- and 10-year grazing exclosures, respectively. The 10-year grazing exclosures had a higher (P < 0.05) species richness and plant densities compared to the 5-year grazing exclosures and the open grazed areas. The population structure and regeneration status of woody species in both grazing exclosures showed an inverted J-shape, indicating a healthy regeneration status, whereas hampered regeneration was observed in open grazed areas. The establishment of grazing exclosures had positive effects in restoring woody plant diversity and improving vegetation structure and regeneration potentials of degraded grazing lands.     

Establishing grazing and grazing-excluded patches increases plant and invertebrate diversity in a Mediterranean oak woodland

Grazing is a global, dominant land use affecting biodiversity and ecosystem processes. In Mediterranean ecosystems grazing is a major ecological and evolutionary driver but, surprisingly, there is little information on the use of grazing as a tool to manage biodiversity in these ecosystems. We conducted an experiment to assess if establishing grazing and small scale grazing-excluded areas would increase plant and invertebrate diversity in a Mediterranean evergreen oak woodland. Plant community traits were different between treatments. Biomass of herbs (176.7 ± 18.3 g m⁻²vs 100.4 ± 10.6 g m⁻²) and litter (291.0 ± 38.3 g m⁻²vs 186.8 ± 26.4 g m⁻²), as well as the total cover of legumes (0.83 ± 0.05 vs 0.91 ± 0.03) were higher, and the proportion of bare ground (0.83 ± 0.05 vs 0.91 ± 0.03) was lower, in ungrazed plots. There were no differences in the number of plant species between treatments. Some plant species and invertebrate taxa were recorded exclusively in grazed or ungrazed plots. Invertebrate detritivores and sap sucking insects were more abundant in ungrazed plots. Ant assemblages were functionally different between treatments: Honeydew-gatherer ants were associated with ungrazed and higher plant biomass plots, and seed-eaters as well as aggressive predator ant species were associated with grazed, open habitat, plots. Management practices that maintain grazing and small scale grazing-excluded areas can increase habitat heterogeneity and promote herbaceous plant and invertebrate diversity at the local level.     

Grazing affects shoot growth,nutrient and water status of Quercus ilex L. in Mediterranean open woodlands

Context

Mediterranean open woodlands (dehesa) have faced a dual process of intensification and abandonment of grazing which has resulted in alteration of the understory vegetation.

Aims

We analysed the effects of land use changes on the physiological status of holm oak in different open woodlands (dehesa) in southern Iberian Peninsula.

Methods

In an area of extensive grazing, we selected six paired plots (one grazed, one abandoned) and grouped them by habitat types according to understory composition (nearly all monospecific Cistus ladanifer L. shrub or mixed shrub). Six plots of moderate and heavy grazing intensity were chosen within a settled area of livestock use. Shoot growth, macronutrient concentrations and water content were assessed in samples of holm oak leaves.

Results

Abandonment of grazing affected some nutrient concentrations and water content of holm oak leaves, but the effects were different according to habitat type. C. ladanifer shrub reduced N and P concentrations and water content while mixed shrub increased P concentration and water content. High grazing intensity improved shoot growth and leaf N and Mg concentrations.

Conclusion

Extensive grazing could be a useful management tool to enhance growth, nutritional and water status of holm oak in a habitat with limited resources such as Mediterranean open woodlands (dehesa).     

我国白刺植物资源及其开发利用

白刺是第三纪孑遗植物,是我国西北荒漠地区重要建群种,具有明显的生态与药用价值。文中总结分析白刺植物分类、分布、主要化学成分及药理学作用等研究现状,探讨白刺植物资源开发利用过程中的问题,提出科学利用白刺植物资源的主要对策是构建白刺植物种质资源库、开展良种选育、逐步建立高质量原料标准化生产与高效利用技术平台等,以期为今后有效开发利用该科植物提供参考。     

Floral resource partitioning by ants and bees in a jambolan Syzygium jambolanum (Myrtaceae) agroforestry system in Brazilian Meridional Amazon

The fruit production of flowering plants critically depends on the pollination services provided by animals that compete for flower resources. The output of competitive interactions between ants and bees for inflorescences of jambolan Syzygium jambolanum (Myrtaceae) in an agroforestry system in Brazilian Meridional Amazonian are an interesting system of investigation due the possibility to control variables experimentally. In 20 S. jambolanum individuals we performed 300 treatments in different inflorescences of two strata (upper and lower) as follows: (1) ants exclusion, (2) bees exclusion, and (3) control group where ants and bees could access the inflorescences. There was no difference in the number of inflorescences, volume of nectar and sugar concentration between the strata. Also the visitors considered are distributed equally in the tree??s stratum. When bees were prevented from access the inflorescences, ants dominated more inflorescences only in the lower stratum. On the contrary, when ants were excluded, bees visited more inflorescences only in the upper stratum. We conclude that ants prevent the access to bees and vice versa as the result of different ability of resource utilization and foraging strategies. Thus, preventing the access of ants to the floral nectar could increase the level of nectar available to pollinators of S. jambolanum, thereby increasing productivity and reducing economic losses.     

Diversity of non-timber forest products in Cachar District,Assam, India

We identified 67 and 21 NTFP-yielding plant and animal species, respectively, in a reserve forest in Cachar district of Assam. We recorded globally threatened species listed by IUCN as Critically Endangered （plant species Dipterocarpus turbinatus）, Vulnerable （plant species Aquillaria malaccensis）, Endangered （animal species Hoolock hoolock, Indotestudo elongata and Manis pentadactyla）, and Vulnerable （animal species Nilssonia hurum and Rusa unicolor）. The whole plant or animal and/or their various parts were used as food or medicine, in house construction, magico-religious activities and others. While some NTFPs were harvested throughout the year, others were harvested seasonally. A comprehensive NTFP policy, along with scientific measures for regen- eration, restoration and augmentation of NTFP-yielding plants and animals, would help in addressing the conflicting demands of conservation and livelihood in the forests of this area.     

FORAGING STRATEGY OF RUFOUS-BACKED SHRIKE DURING BREEDING PERIOD

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Effects of nest hoarding on foraging behavior of two species of Apodemus mice,A. speciosus and A. argenteus (Rodentia: Muridae)

Food hoarding is one of the determinant factors of foraging behavior and benefits the hoarder. Two species of Apodemus mice, A. speciosus Temminck and A. argenteus Temminck, hoard acorns for later use. In 1988 and 1989, I conducted laboratory experiments to reveal the effects of food hoarding in the nest on the foraging behavior of these mice. I released a mouse into an indoor arena (2.8 × 2.8m) and recorded the foraging behavior of four female A. speciosus and four female A. argenteus mice in sessions with and without food hoarding in the nest box. Nest hoarding did not affect the time that a mouse allotted to excursions or the number of peanuts that a mouse ate during the night, but decreased the number of peanuts handled and the intensity of food handling (the number of handled peanuts per visit) at the food stations. The decrease in food handling outside the nest box, which seemed to be beneficial to the survival and reproduction of the hoarder in the field, was more apparent in A. speciosus than in A. argenteus. The different behavioral responses in foraging behavior to nest hoarding between two Apodemus mice may be related to their different microhabitat preferences.     

Trillium grandiflorum height is an indicator of white-tailed deer density at local and regional scales

High densities of white-tailed deer (Odocoileus virginianus) in the U.S.A. and Canada are reducing or preventing forest regeneration, and as a result, deer function as a keystone species in some sites. Management decisions about deer require reliable population density data, which are challenging to obtain at both regional and local scales. We tested the broad-scale applicability of the indicator species approach in which forage plant height was used to estimate deer density. The maximum heights of marked and unmarked plants of the widely distributed, spring-flowering polycarpic herb, white trillium (Trillium grandiflorum) were measured across southern Ontario, Canada, over a 15-year period. A significant negative relationship was found at 10 sites between maximum plant height and estimates of deer population densities, which were derived from counts of live or culled animals and varied from 7 to 40 deers km⁻². Maximum plant height could be reliably measured within a 4-week period. The underlying mechanism driving the negative relationship between plant height and deer density was attributed to deer preferentially selecting taller plants that grew less than ungrazed plants in the subsequent year. In 16 additional sites with locally high deer populations, the mean maximum height of T. grandiflorum appeared to be a more reliable indicator of deer density than estimates based on hunter returns across the broader regional scale of the Wildlife Management Unit. The ability to assess local scale white-tailed deer densities based on measuring heights of an easily identifiable, widespread plant, provides local residents and landowners with a tool for estimating the potential impacts of deer browsing and grazing in local woodlots and forests, improving local knowledge about herbivory pressure.     

The effects of grazing management in montado fragmentation and heterogeneity

The Portuguese silvo-pastoral system montado is broadly classified as a High Nature Value (HNV) system since it corresponds to farmland hosting high biodiversity levels, and such biodiversity depends on specific land use practices. However, in recent decades a decline both in the total montado area and in the tree cover density within the montado has been observed, driven mainly by management changes. This decline may result in biodiversity loss. Grazing is a central aspect determining the long-term sustainability of the montado system and it has implications also on the montado structural diversity, particularly on connectivity and heterogeneity, which is crucial for the maintenance of montado HNV. The aim of this paper is to demonstrate how variations in montado structural diversity are correlated with grazing management and its implications on the value of the system for conservation. The empirical data derives from a case study composed of 41 montado farms in two municipalities of the Alentejo region. Data on grazing management, biophysical and spatial factors were collected and several metrics were calculated to assess montado fragmentation and heterogeneity. A multivariate analysis was performed using generalized additive models. Results show that different grazing patterns, depending on stocking density and grazing animal type, are correlated with variations in montado fragmentation and heterogeneity. Particularly, cattle’s grazing is shown to have adverse effects on the montado fragmentation, while sheep grazing is shown to have stronger impacts on the heterogeneity within the montado patches.     

Antifeedent and toxic activity of endophytic Alternaria alternata against tobacco caterpillar Spodoptera litura

Fungal endophytes play a significant role in plant resistance to insects by altering the nutritional quality of plants or by production of various alkaloid-based defensive compounds. Ethyl acetate extract of endophytic Alternaria alternata isolated from Azadirachta indica A. Juss was tested for its bioactivity against Spodoptera litura (Fab.). Effect of different concentrations of ethyl acetate extract of A. alternata was assessed on growth and development of S. litura larvae. The results indicate higher larval mortality on diet supplemented with the fungal extract than control. Adverse effects of A. alternata were also observed on development of the insect. Ethyl acetate extract of the fungus also significantly reduced the adult emergence, longevity and reproductive potential of S. litura. Larvae feeding on diet supplemented with fungal extract showed significant reduction in relative growth and consumption rate, as well as efficiency of ingested and digested food. The antifeedant and toxic effects of A. alternata may be due to production of bioactive molecules by this fungus.     

Effects of management options on mammal richness in a Mediterranean agro-silvo-pastoral system

Non-flying mammal richness and distribution were studied in a landscape matrix consisting of a highly managed agro-silvo-pastoral system dominated by a cork oak woodland (montado) to test the predictions of the Intermediate Disturbance Hypothesis (IDH). Sampling consisted on detection of mammalian signs of presence, along with the use of scent stations and small mammal live-trapping. Results were analyzed using generalized linear models, considering land uses, landscape metrics and grazing intensity and gave support to the predictions of the IDH. Pure forestry and intensive agricultural uses showed lower species richness than the silvopastoral system, whilst landscape heterogeneity and riparian corridors were shown to be most beneficial to mammal species richness, with small mammals being directly and negatively affected by grazing intensity. The increasing use of the montado for raising cattle has led to landscape homogenization by means of grazing and shrub clearance for pasture cultivation and this, combined with incremented stocking rates, constrains species richness. In this landscape context, watercourses assume a relevant role as patches of suitable habitat providing shelter, food, movement corridors and dispersion routes for mammals. Recent options of fencing forest patches with good forest natural regeneration or with a high diversity/density of Mediterranean maquis, and restoring degraded watercourses, both to improve landscape heterogeneity, appear to positively affect the mammal community. This is a current challenge in terms of monitoring and research.     

Effect of Rhabdias pseudosphaerocephala on prey consumption of free-ranging cane toads (Rhinella marina) during Australian tropical wet seasons

The development of biological control measures to reduce the impact of invasive species is a desired goal. Rhabdias species have recently been advocated as biological control agents for invasive anurans. This study describes a field-based approach to support laboratory results on the potential impact of the lung nematode Rhabdias pseudosphaerocephala on the prey consumption of its host, the invasive cane toad (Rhinella marina, Bufonidae). Toads were sampled from various populations in the Wet Tropics of Australia during the wet seasons of 2010 and 2012. Consumed prey items were counted in 212 cane toads and identified to class and order levels and the number of lung nematodes was counted for each toad. The number of R. pseudosphaerocephala in free-ranging cane toads affected negatively the diversity of prey items consumed, but was not related to the number of prey items or the number of ants consumed. The results suggest that infection of free-ranging cane toads by the lung nematode reduces their range of prey items. Possible reasons could be a reduced locomotor activity resulting in changes of foraging modes of infected toads which was reported from some laboratory trials. Infection of cane toads by R. pseudosphaerocephala may therefore have the potential to alter the impact of cane toads on invertebrate communities and their competition for food resources with native Australian anurans.