Top PDF Effect of woodland patch size on rodent seed predation in a fragmented landscape

Effect of woodland patch size on rodent seed predation in a fragmented landscape

Effect of woodland patch size on rodent seed predation in a fragmented landscape

Why were food conditions favourable in the present small patches? An obvious possibility, the availability of large seed trees and bushes, does not seem to be the explanation. However, other alternative food could be found in the sur- rounding fields, at least for wood mice. Previous work in this and other areas has shown that wood mice are abun- dant also in the cropped fields surrounding the habitat patches (Green 1979, Loman 1991, Díaz et al. 1999). Wood mice hoard waste grain that are found in abundance after harvest in these fields (personal data). Thus, the re- sults give some support the hypothesis that individual wood mice forage both in woodlots and in the surround- ing fields (Díaz et al. 1999). However, bank voles and yel- low-necked mice rarely venture out into these fields. Also, the border zone, the part of the patch immediately adja- cent to the fields, may be especially productive with respect to such rodent food, e.g. various herb species that were not recorded in this study.
Mostrar mais

6 Ler mais

Experimental assessment of Heliconia acuminata growth in a fragmented Amazonian landscape

Experimental assessment of Heliconia acuminata growth in a fragmented Amazonian landscape

Changes in shoot number may be particularly criti- cal demographically (Bruna 2001). Plants in fragments failed to recuperate fully from initial dry season losses before the onset of subsequent dry season (Fig. 3b), and these losses continued during the following year of the experiment (Fig. 3c). The compounding loss of shoots over the course of multiple dry seasons could explain why the H. acuminata populations in habitat fragments are more skewed towards smaller demo- graphic size classes than those in continuous forest (Bruna & Kress 2002). Furthermore, while the pre- dicted shifts in the abundance of flowering H. acumi- nata in fragments and continuous forest were only marginally significant, they closely mirror the dispari- ties documented in permanent demographic plots (Bruna & Kress 2002). Previous efforts to quantify the consequences of fragmentation for plant reproduction have focused almost entirely on changes in plant– animal interactions, particularly pollination and seed predation (Aizen & Feinsinger 1994; Jules & Rathcke 1999; Cunningham 2000; Dick 2001). Our results suggest a new way that plant fitness can be reduced in
Mostrar mais

11 Ler mais

Patch size and isolation predict plant species density in a naturally fragmented forest.

Patch size and isolation predict plant species density in a naturally fragmented forest.

Naturally fragmented forests offer an excellent opportunity for testing the effects of patch size, isolation and other spatial variables on biodiversity because they have been fragmented for thousands or millions of years [25,26], and consequently can be assumed to have reached equilibrium. The main goal of this study was to assess whether plant species density is explained by patch size and isolation in a naturally fragmented forest on the Yucatan Peninsula. We used species density (number of species in equal- sized samples) as a response variable, as it is a measure of biodiversity that is less influenced by sample area effects than species richness [27,28]. This forest is characterized by the presence of several forest patches (locally known as Petenes, singular Pete´n) that are roughly circular, variable in size [25,29,30,31] and grow on Quaternary geological formations ca. 1.7 My old [26,32]. Scattered near the coast in a wetland matrix [29,30,31], the Petenes are landscape units that aptly reflect the habitat patch concept as their spatial boundaries naturally contain or delimit populations and communities of plants [12,25]. Therefore, the study area allowed us to test the effect of patch area and isolation while controlling for important confounding factors such as patch shape and matrix. In addition to the effects of patch size and isolation we tested the effect of elevation and patch perimeter. Patch elevation is negatively related to the level of salt water during the rainy season and this affects plant distribution [31,33], while patch perimeter is positively correlated with edge effects [34]. We predicted that plant species density would be positively correlated with patch size and negatively correlated with patch isolation. Patch perimeter would be negatively correlated with plant species density and elevation, positively correlated.
Mostrar mais

7 Ler mais

Investigating The Use Of Mobile Computing In Zimbabwe Polytechnics Case Of A Polytechnic In Zimbabwe

Investigating The Use Of Mobile Computing In Zimbabwe Polytechnics Case Of A Polytechnic In Zimbabwe

Zimmerman (1999) in his article titled ―Mobile Computing: Characteristics, Benefits, and the Mobile fra mework‖ defined mobile computing as ―the use of computing devices, which usually interact in some way with a centralised information system while away from the normal fixed workplace‖. He went on to say that, Mobile computing technology enables the mobile person to create, access, process, store and communicate information without being constrained to a single location. It is on the above basis that this researcher views mobile computing as embracing a host of portable technologies the can access internet using wireless fidelity (WIFI). These range from notebook computers to tablets, to smartphones and e-book readers. Such devices have brought about Mobile learning (m-Learning) in Zimbabwe Polytechnics, enabling staff and students to share academic resources, be able to research and develop applications from wherever they are. Zimmerman (1999) went on to identify mobile computing hardware, software and communications in use then. He identified hardware as palmtops, clamshells, handheld Pen Keys, pen slates, and laptops. The characteristics of such devices in terms of screen size was small, processing capability was limited and supported a few mobile applications. Over the years mobile devices have improved in such characteristics to make mobile computing easy, fast and user friendly. Great improvements also came with the associated systems software, with the modern devices now running on Android, Symbian and windows 8 mobile, as compared to then when MS DOS, Windows 3.1, Pen DOS were used. In communications Zimmerman talked of internet speeds in kilobytes per second (Kbps), while today’s communications devices have speeds of gigabytes per second (Gbps
Mostrar mais

5 Ler mais

Composition and structure of bird communities in vegetational gradients of Bodoquena Mountains, western Brazil

Composition and structure of bird communities in vegetational gradients of Bodoquena Mountains, western Brazil

The dominance of insectivorous birds could be related to the great abundance of arthropods and the relatively regular supply of these resources. Thus, maintaining a diet of arthropods may be a safer strategy for the birds than the consumption of fruits, which usually have more irregular availability in space and time, especially in vegetational mosaics of forests and grasslands with seasonal precipitation regime, like in Bodoquena Mountains (Reys et al. 2005), as well as throughout the Cerrado domain (Batalha and Mantovani 2000, Batalha and Martins 2004). The adoption of an omnivorous diet, with a regular consumption of fruits, arthropods and vertebrates, often makes the species less sensitive to habitat degradation and fragmentation, since a varied diet allows the birds to forage in different vegetation types and grants them regular food supply throughout the year. Because of this, some omnivorous birds become abundant in disturbed habitats at the same time more specialized birds, both insectivorous and frugivorous, become rare in these areas (Willis 1979).
Mostrar mais

15 Ler mais

Crop damage of Eriotheca gracilipes (Bombacaceae) by the Blue-Fronted Amazon (Amazona aestiva, Psittacidae), in the Brazilian Cerrado

Crop damage of Eriotheca gracilipes (Bombacaceae) by the Blue-Fronted Amazon (Amazona aestiva, Psittacidae), in the Brazilian Cerrado

Field procedures. To sample trees to evaluate fruit production and crop damage by Amazons, I used six 4– Km–long permanent access trails, in which I marked with aluminum numbered tags all individuals of E. gracilipes located within a 3.0 m margin on either sides of the trails, and with a diameter at the base equal or greater than 4 cm (mature trees). This sample included 90 individuals (9–23 per trail), which I monitored for fruit production and crop damage from early June to late September 2004. At every two weeks I checked fruit crop size by counting fruits present at every crown and assessed crop damage by inspecting the ground under the trees to count both fallen damaged and undamaged fruits (the rigid capsules/ exocarps lasts 3–5 months to completely decay). I also checked fallen fruits for the presence of pierce marks caused by insect seed predators, because total seed damage might be underestimated if only parrot seed predation was sampled (Villaseñor-Sanchez et al., 2010). The inspection of a given tree finished when all of the fruits were destroyed or matured to the point they open to expose seeds. In this respect, as I thorough checked the ground under fruiting trees several times, I am confident that no fallen fruit was missed. Then, I measure the distance to the nearest conspecific which also exhibited depredated fruits. Amazons were the putative seed predators because locals often observed then feeding on E. gracilipes fruits. Also, while parakeets foraged on fruits without to remove them from the peduncle (Francisco et al., 2008 ), Amazons detached them to eat seeds. After that they drop the fruit remains under the tree crown. To confirm my observation, from July to September, I sampled parrots feeding on E. gracilipes trees by direct observations (monthly 12 h, from 06:00 to 09:00 h), while walking the permanent access trails mentioned above. Whenever at least a parrot was detected feeding on E. gracilipes fruits I recorded the species, number of individuals, and the time and date. From 5 trees, I collected fruits with different number of seeds to measure both fruit and seed size.
Mostrar mais

7 Ler mais

Assemblages of terrestrial isopods (Isopoda, Oniscidea) in a fragmented forest landscape in Central Europe

Assemblages of terrestrial isopods (Isopoda, Oniscidea) in a fragmented forest landscape in Central Europe

Terrestrial isopods were collected in 13 forest fragments difering in area (within the range of 0.1 and 254.5 ha), shape and composition of forest vegetation (thermophilous oak, mesophilous oak-hornbeam, thermophilous oak-hornbeam, acidophilous oak, basiphilous oak, beech oak-hornbeam, moist mixed de- ciduous forest, plantations of deciduous and coniferous trees), all situated in the Český kras Protected Landscape Area, Czech Republic, Central Europe. Number of sites sampled in each fragment of forest depended on its size and ranged from 1 to 7. Altogether 30 sites were sampled. Soil samples (5 per site col- lected twice a year) and pitfall trapping (5 traps per site in continuous operation throughout a year) during 2008–2009 yielded a total of 14 species of terrestrial isopods. he highest densities and highest epigeic ac- tivities of terrestrial isopods were recorded in the smallest fragments of woodland. Although a wider range of habitats were sampled in the larger fragments of woodland there was not a greater diversity of species there and the population densities and epigeic activities recorded there were lower. Porcellium collicola was most abundant in small fragments of woodland regardless the vegetation there. Armadillidium vulgare and Protracheoniscus politus were statistically more abundant in the larger fragments of woodland. he results indicate that forest fragmentation does not necessarily result in a decrease in the species richness of the isopod assemblages in such habitats.
Mostrar mais

10 Ler mais

Effect of the seed coat on dormancy and germination in

Effect of the seed coat on dormancy and germination in

A wide range of factors that may potentially disrupt seed- coat imposed dormancy under natural conditions have been identified, with differing implications for seed bank dynamics and seedling emergence patterns (Van Klinken et al., 2006; Gama-Arachchige et al., 2012). For example, high temperatures promoted dormancy overcome in impermeable seeds of S. humilis and S. hamata during the hot, dry season in northern Australia (McKeon and Mott, 1982). Mechanical abrasion by soil particle, decomposition of the seed coat by microbial action as well as smoke or heat shock from fire are the others possible environment factors affecting physical dormancy of seeds in nature (Briggs and Morris, 2008). A strong positive relationship between acidic solutions (low pH) and overcome of physiological dormancy has been found in scarified seeds of S. humilis (Pelacani et al., 2005a,b; Ribeiro et al., 2010). However, the importance of low pH for dormancy overcome in intact seeds of S. humilis has been poorly explored. Thus, the aim of the present study was to analyse the consequence of seed-coat-imposed dormancy on the physiological dormancy and germination of S. humilis seeds.
Mostrar mais

9 Ler mais

Variation in seed germination of 134 common species on the eastern Tibetan Plateau: phylogenetic, life history and environmental correlates.

Variation in seed germination of 134 common species on the eastern Tibetan Plateau: phylogenetic, life history and environmental correlates.

On the other hand, there is no accordant relationship between seed size and germination strategies in the previous studies. For example, many studies have indicated that there is a significant negative relationship between seed size and dormancy [11]. However, Wang et al. reported that germination percentages among species had a significant negative correlation with seed size [17]. Some other authors reported that seed size did not have a general effect on germination [39]. In this study, we proved that seed size had significant effects on both GP and GT (but not linear relation between germination and seed size). These different results may stem from the following reasons. Firstly, the important factors co-varying with seed size and/or seed dormancy may have been left out of consideration [11]. For example, Rees (1996) found a significant positive relationship between seed size and germination in species with specialization for dispersal but no such relationship for unspecialized seeds [15]. Secondly, seed size varies greatly among different floras and the distribution of seed size in alpine/subalpine meadows on the Tibetan Plateau is skewed to small size compared with other communities. For example, seed size of Wang’s study ranged from 0.06 mg to 63.50 mg, with a mean of 10.54 mg, and 70% of the seeds were heavier than 1 mg, whereas seed size of our study ranged from 0.03 mg to 6.61 mg, with a mean of 0.98 mg, only 33% of the seeds were heavier than 1 mg. Thirdly, the environment of plants to be a better predictor of dormancy than are plant longevity and seed size combined [11]. Therefore, the differences among habitats should be considered, especially the special condition of alpine/subalpine meadow in the Tibetan Plateau.
Mostrar mais

13 Ler mais

Modeling the effects of size on patch dynamics of an inert tracer

Modeling the effects of size on patch dynamics of an inert tracer

For patches of all sizes, both the surface area and total volume of the patch generally increases with time at first due to the high IT concentration inside the patch. Then, after reaching its peak, it starts to decrease gradually until it disappears (Fig. 2a, b). This trend is hard to obtain from in-situ measurements and most of the field experiments only focus on the expanding period of the patch due to the limited time of observation

22 Ler mais

Coupled local facilitation and global hydrologic inhibition drive landscape geometry in a patterned peatland

Coupled local facilitation and global hydrologic inhibition drive landscape geometry in a patterned peatland

reference landscapes deviate from the linear function indicating their a non-fractal na- ture Although a linear–scaling relationship seemed to hold acceptably within a certain patch-size range (Fig. 5b), Casey et al. (2015) found that the perimeter-area scaling in real ridge-slough landscapes was better explained by a quadratic function over the entire size range (i.e., without any cutoffs). This indicates that the larger patches in real

31 Ler mais

Fabrication of in situ composite layer on cast steel

Fabrication of in situ composite layer on cast steel

The study describes the technology of fabrication of composite layers in cast steel reinforced with titanium carbides. In the process under discussion, the reinforcing TiC phase is formed in situ from the substrates deposited on mould cavity, where the said substrates under the effect of heat supplied by molten metal poured into mould (1823K) undergo a synthesis in the SHS reaction. An outcome of this process is the formation, within the casting surface, of a layer from 550 to 1200µm thick. Carbides produced in this synthesis have the size from 0,5 to 20µm and a non-typical spheroidal shape. The hardness of the produced layer examined in function of the distance from the casting surface is from 700 to 1134 HV, and is determined by volume fraction of the reinforcing TiC phase. To better document the type of microstructure obtained in the produced material, metallographic and structural examinations were carried out using the method of scanning electron microscopy (SEM), X-ray microanalysis (EDS/EDX), and phase analysis (XRD). To check the mechanical properties of the examined material, hardness was measured by the Vickers test.
Mostrar mais

6 Ler mais

Estimation of plant diversity in a forested mosaic landscape: the role of landscape, habitat and patch features

Estimation of plant diversity in a forested mosaic landscape: the role of landscape, habitat and patch features

The fragmented ownership pattern in areas with non-industrial private forest ownership NIPF, in combination with these forestry practices, have created fragmented forests with relatively low proportions of habitat types important to many species, such as the native broadleaved species and, at the same time, large areas of other species such as pine stands. Thus, changes in species composition and structure of Portuguese forests are assumed to affect the overall biodiversity value of forest areas. Landscape analysis has been used to access the overall effect of landscape change in forests biodiversity. However, landscape studies have been developed for areas with homogenous ownership patterns and not for areas with fragmented ownership. The objective of this study was to investigate: (1) how quantitative indicators of spatial heterogeneity of the landscapes (metrics) behave in this kind of landscape; (2) the relationships between landscape patterns of forest types and plant diversity estimates. This idea is based on the suggestion of several studies that spatial patterns may be important determinant of species distribution at landscape level (Honnay et al., 1999b, Jeanneret et al., 2003).
Mostrar mais

9 Ler mais

Effect of GA3 treatment on seed development and seed-related gene expression in grape.

Effect of GA3 treatment on seed development and seed-related gene expression in grape.

replicates were harvested in each case. Following fixation in Carnoy’s fluid (3:1 anhydrous alcohol/glacial acetic acid) for 12–24 h at room temperature, the samples were dehydrated through an ethanol series (30%, 50% and 70%) and stored in 70% ethanol at 4°C until further use [51]. Samples stored at 4°C were further dehydrated with a graded ethanol series (85%, 95% and 100%), infiltrated with xylene, and embedded in paraffin (Taiva, Hubei, China). Sections 8-10 μm in thickness were transferred onto poly-L-Lys-coated glass slides (WHB, Shanghai, China), deparaffinized with xylene, and re-hydrated through an ethanol series (100%, 95%, 85%, 70%, 50% and 30%). The resulting sections were stained with Ehrlich’s haematoxylin (Saichi, Shanghai, China) for 30 minutes at room temperature, dehydrated with an ethanol series, infiltrated with xylene, sealed with resinene (XT, Shanxi, China), and finally mounted beneath a coverslip. Slides were observed using an optical microscope (OLYMPUS BH-2, Japan) and photos were obtained using an attached digital camera (OLYMPUS DP72, Japan).
Mostrar mais

14 Ler mais

Group dynamics of zebra and wildebeest in a woodland savanna: effects of predation risk and habitat density.

Group dynamics of zebra and wildebeest in a woodland savanna: effects of predation risk and habitat density.

Factors explaining the composition of groups for these ungulate species differed from those explaining group sizes. This was expected given the seasonal and sex differences in predation risk for these species. In Kruger National Park, South Africa, predation risk from lion was highest for male wildebeest during the early dry season but for females, it was highest in the early wet season [12]. Despite differences between the sexes in vulnerability across seasons, we found no difference in group composition as a function of lion activity or season in wildebeest. By contrast, zebra groups in KGR comprised of more females during the rainy season, which corresponded to the calving period, a time when vulnerability to predation risk is highest. Females of zebra are also more vulnerable than males to predation by lions in general [12,20]. Thus, it was not surprising that groups of zebra with higher proportions of females were more risk averse, by avoiding areas with high lion activity and avoiding open scrub habitats where they would be more conspicuous. Wildebeest groups with proportionally more females also avoided certain habitat types, but this response was likely a combination of both risk aversion (open scrub) and resource selection (open riverine and closed woodland).
Mostrar mais

6 Ler mais

ИССЛЕДОВАНИЕ СТЕПЕНИ ЗАГРЯЗНЕНИЯ СНЕЖНОГО ПОКРОВА САМОТЛОРСКОГО МЕСТОРОЖДЕНИЯ

ИССЛЕДОВАНИЕ СТЕПЕНИ ЗАГРЯЗНЕНИЯ СНЕЖНОГО ПОКРОВА САМОТЛОРСКОГО МЕСТОРОЖДЕНИЯ

Abstract In the Northern Elbrus Greater Caucasus submeridional river network dissecting sublatitudinal ridges into separate segmenty. Such geomorphology modern topography creates conditions for an extremely uneven distribution of summer rainfall. For the identify the conditions of localized flash floods used landscape-hydrological approach. Comparative study of the river basins 1-4 orders are located in different morfostrukture. Such factors as geological structure, morphology and other channels do not affect the formation of river drain. It is established that are most favorable for heavy rainfall river basins, confined to the northern windward slopes of the individual segments ranges of 10 km in length and over. Local flooding occurred at high intensity rainfall, much higher than the intensity of the rain, caused by regional flooding in June 2002. Potentially flood pools should first stop the automatic water, measuring devices.
Mostrar mais

167 Ler mais

Effect of endosperm mutants on maize seed germination

Effect of endosperm mutants on maize seed germination

The expression of genetic potential of yielding and quality of a certain genotype depends among other factors on seed quality. Seed is very important not only for the reproduction of the particular plant spe- cies, but also, for the contemporary plant production. Each part of maize seed (pericarp, endosperm and germ) has a specific function in the com- plex process of germination and emergence. The following three geno- types of different endosperm types were observed: ZPSC 42A (standard grain quality dent hybrid), ZPSC 504 su (sweet maize hybrid with a sug- ary gene) and ZPSyn.II sh2 (synthetic population with a shrunken2 gene). Seed viability of the stated genotypes was determined by the accepted ISTA methods: standard method, accelerating age and cold test. Obtained results point out to differences in the germination capacity of the observed genotypes. The greatest reduction of the germination capacity and the emergence rate was expressed by the application of the accelerating age- ing method. Appeared differences are probably a result of the endosperm texture (type), grain weight, sugar content and pericarp thickens and composition.
Mostrar mais

6 Ler mais

Seed dormancy, seedling establishment and dynamics of the soil seed bank of Stipa bungeana (Poaceae) on the Loess Plateau of northwestern China.

Seed dormancy, seedling establishment and dynamics of the soil seed bank of Stipa bungeana (Poaceae) on the Loess Plateau of northwestern China.

To determine the effect of burial depth and burial duration on seed survival and seed dormancy of S. bungeana, seeds collected on 23 June 2012 were put into 96 15 cm610 cm nylon mesh bags and buried at the Yuzhong Campus of Lanzhou University on 5 July 2012. The permeable nylon fabrics allowed movement of water, air and microbes between inside and outside of bags. The burial site is about 300 m from the seed collection site and has a sparse vegetation cover. The vegetation within and surrounding burial site was removed before burial. Forty-eight bags with 50 seeds each were placed on the soil surface (0 cm) and 48 at a soil depth of 5 cm. They were arranged in a randomized complete block design. For 0 cm burial depth, the bags were fixed to the ground by iron nails so that each bag was in contact with the soil and won’t move to the other soil profile. Physical removal of weeds within burial site was applied every week during experimental period. Six bags each were retrieved from 0 cm and 5 cm burial depths on 28 July, 30 August, 30 September, 31 October and 30 December 2012 and on 2 March, 9 May and 5 July 2013. For each of these dates, the seeds in each of 12 bags were put into one 11-cm-diameter Petri dish with two layers of filter paper moistened with 8 mL of distilled water and incubated in darkness at 20 uC. Thus, there were six replications each for the 0 cm and 5 cm
Mostrar mais

10 Ler mais

Effect of some environmental factors on seed germination of

Effect of some environmental factors on seed germination of

The genus Eryngium of the family Apiaceae includes about 250 species distributed throughout Eurasia, North Africa, North and South America and Australia. The genus Eryngium is considered to be the most species-rich genus of Apiaceae (Pimenov & Leonov 1993). Species of Eryngium are distributed among a wide range of environmental conditions in Iran, from semi-arid to temperate regions (Karimi 2001). Eryngium caeruleum is a perennial herbaceous plant that is native to northern Iran (Ghahreman 1997). This plants life cycle begins in mid October from permanent roots in the soil and/or seed, and reaches maturity late in July (Karimi 2001). Eryngium caeruleum is used in folk medicinal and as a spice plant in different regions of Iran. Root, leaf, stem and inflorescence of the plant have medicinal properties. The fresh leaves of the plant have a good taste and are aromatic, and so it is used in traditional cooking (Khoshbakht et al. 2006; Daneshfar et al. 2014). Species of Eryngium are propagated by seed production, transplanted plantlets or by cuttings (Armitage 1993). The growth rate of Eryngium is very slow, so their ability to respond to habitat disruption is weak (Everett 1960). Seeds of species of Apiaceae are often morphologically or morphophysiologically dormant (Finch-Savage & Leubner-Metzger 2006).
Mostrar mais

9 Ler mais

Effect of water glass modification with nanoparticles of zinc oxide on selected physical and chemical properties of binder and mechanical properties of sand mixture

Effect of water glass modification with nanoparticles of zinc oxide on selected physical and chemical properties of binder and mechanical properties of sand mixture

The unmodified water glass shows inadequate wetting of the surface of the quartz grains (Fig. 3). Changes of contact angle in time are characterised by high values of both the initial contact angle θ 0 (about 45 deg.) a nd the equilibrium angle θ r (about 33

4 Ler mais

Show all 10000 documents...