Competitive and facilitative interactions within and between two species of coastal dune perennials

2003 ◽  
Vol 81 (4) ◽  
pp. 330-337 ◽  
Author(s):  
Steven J Franks
Keyword(s):  
Environmental Gradient ◽  
Coastal Dune ◽  
Positive Interactions ◽  
Substantial Evidence ◽  
Species Identity ◽  
Uniola Paniculata ◽  
Disturbed Zone ◽  
As Stress ◽  
Facilitative Interactions ◽  
Target Plant

While there is substantial evidence for facilitation, the effects of such factors as stress and species identity on positive interactions remain controversial. At two coastal dune sites, I tested the hypotheses that facilitative interactions increase with increasing stress and disturbance along an environmental gradient and that facilitative interactions are stronger among heterospecific than among conspecific individuals. I transplanted Uniola paniculata and Iva imbricata plants into plots along with four conspecific neighbors, four heterospecific neighbors, or no neighbors across an environmental gradient. Neighbors increased target plant survival, suggesting facilitation, but biomass of targets was reduced by the presence of neighbors, suggesting competition. Unexpectedly, competition was greatest in the purportedly most stressful and disturbed zone. In this study, the outcome of neighbor interactions differed for biomass and survival and depended on position along the environmental gradient, but was independent of neighbor identity.Key words: competition, disturbance, facilitation, Iva imbricata, stress, Uniola paniculata.

scholarly journals Beech cupules as keystone structures for soil fauna

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e2562 ◽  
Author(s):  
Nereida Melguizo-Ruiz ◽  
Gerardo Jiménez-Navarro ◽  
Jordi Moya-Laraño
Keyword(s):  
Leaf Litter ◽  
Soil Fauna ◽  
Habitat Modification ◽  
Positive Interactions ◽  
Ecological Communities ◽  
Soil Animals ◽  
Soil Community ◽  
Body Sizes ◽  
Facilitative Interactions

Facilitative or positive interactions are ubiquitous in nature and play a fundamental role in the configuration of ecological communities. In particular, habitat modification and niche construction, in which one organism locally modifies abiotic conditions and favours other organisms by buffering the effects of adverse environmental factors, are among the most relevant facilitative interactions. In line with this, ‘keystone structures’, which provide resources, refuge, or advantageous services decisive for other species, may allow the coexistence of various species and thus considerably contribute to diversity maintenance. Beech cupules are woody husks harbouring beech fruits that remain in the forest soil for relatively long periods of time. In this study, we explored the potential role of these cupules in the distribution and maintenance of the soil fauna inhabiting the leaf litter layer. We experimentally manipulated cupule availability and soil moisture in the field to determine if such structures are limiting and can provide moist shelter to soil animals during drought periods, contributing to minimize desiccation risks. We measured invertebrate abundances inside relative to outside the cupules, total abundances in the leaf litter and animal body sizes, in both dry and wet experimental plots. We found that these structures are preferentially used by the most abundant groups of smaller soil animals—springtails, mites and enchytraeids—during droughts. Moreover, beech cupules can be limiting, as an increase in use was found with higher cupule densities, and are important resources for many small soil invertebrates, driving the spatial structure of the soil community and promoting higher densities in the leaf litter, probably through an increase in habitat heterogeneity. We propose that fruit woody structures should be considered ‘keystone structures’ that contribute to soil community maintenance. Therefore, beech trees may indirectly facilitate soil fauna activities through their decaying fruit husks, hence acting as ecosystem engineers.

scholarly journals The Effect of Positive Interactions on Temporal Turnover of Community Composition along an Environmental Gradient

PLoS ONE ◽  
2013 ◽  
Vol 8 (11) ◽  
pp. e78698 ◽  
Author(s):  
Youshi Wang ◽  
Zhiyong Yang ◽  
Shurong Zhou ◽  
Janne Soininen ◽  
Dexiecuo Ai ◽  
...  
Keyword(s):  
Community Composition ◽  
Environmental Gradient ◽  
Positive Interactions ◽  
Temporal Turnover

Ultrasturcture of cerebellar cells and neuropil in rats subjected to partial global cerebral ischemia

1986 ◽  
Vol 44 ◽  
pp. 126-127
Author(s):  
R.V.W. Dimlich ◽  
M.H. Biros
Keyword(s):  
Purkinje Cells ◽  
Glial Cells ◽  
Granule Cells ◽  
Molecular Layer ◽  
Cell Types ◽  
Primary Objective ◽  
Global Cerebral Ischemia ◽  
Forebrain Ischemia ◽  
Substantial Evidence ◽  
Cerebellar Cells

Although a previous study in this laboratory determined that Purkinje cells of the rat cerebellum did not appear to be damaged following 30 min of forebrain ischemia followed by 30 min of reperfusion, it was suggested that an increase in rough endoplasmic reticulum (RER) and/or polysomes had occurred in these cells. The primary objective of the present study was to morphometrically determine whether or not this increase had occurred. In addition, since there is substantial evidence that glial cells may be affected by ischemia earlier than other cell types, glial cells also were examined. To ascertain possible effects on other cerebellar components, granule cells and neuropil near Purkinje cells as well as neuropil in the molecular layer also were evaluated in this investigation.

Communication/Interaction Development at Mealtimes for the Multiply Handicapped Child

1981 ◽  
Vol 12 (4) ◽  
pp. 216-232 ◽  
Author(s):  
Suzanne Evans Morris
Keyword(s):  
Handicapped Child ◽  
Positive Interactions ◽  
Speech Language Pathologist ◽  
Specific Program ◽  
Communication Interaction

The mealtime setting can be creatively used by the speech-language pathologist to increase the positive interactions between the child and caregiver and to establish the basic prerequisites for the development of communication. Specific program suggestions are provided to enable the speech-language pathologist to utilize the mealtime setting to integrate both vocal and nonvocal communicative objectives. The roots of interaction and communication which underly both vocal and nonvocal systems are described.

Social Psychology and Noninvasive Electrical Stimulation

2016 ◽  
Vol 21 (1) ◽  
pp. 30-40 ◽  
Author(s):  
Paulo S. Boggio ◽  
Gabriel G. Rêgo ◽  
Lucas M. Marques ◽  
Thiago L. Costa
Keyword(s):  
Social Psychology ◽  
Social Neuroscience ◽  
Special Focus ◽  
Social Pain ◽  
Substantial Evidence ◽  
Social Decision ◽  
Correlational Research ◽  
Neuroscience Research ◽  
Social Decision Making ◽  
Brain Behavior

Abstract. Social neuroscience and psychology have made substantial advances in the last few decades. Nonetheless, the field has relied mostly on behavioral, imaging, and other correlational research methods. Here we argue that transcranial direct current stimulation (tDCS) is an effective and relevant technique to be used in this field of research, allowing for the establishment of more causal brain-behavior relationships than can be achieved with most of the techniques used in this field. We review relevant brain stimulation-aided research in the fields of social pain, social interaction, prejudice, and social decision-making, with a special focus on tDCS. Despite the fact that the use of tDCS in Social Neuroscience and Psychology studies is still in its early days, results are promising. As better understanding of the processes behind social cognition becomes increasingly necessary due to political, clinical, and even philosophical demands, the fact that tDCS is arguably rare in Social Neuroscience research is very noteworthy. This review aims at inspiring researchers to employ tDCS in the investigation of issues within Social Neuroscience. We present substantial evidence that tDCS is indeed an appropriate tool for this purpose.

Cytocompatibility and Material Properties of Poly-carbonate Urethane/Carbon Nanofiber Composites for Neural Applications

2003 ◽  
Vol 774 ◽  
Author(s):  
Janice L. McKenzie ◽  
Michael C. Waid ◽  
Riyi Shi ◽  
Thomas J. Webster
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanofibers ◽  
Material Properties ◽  
Carbon Nanofiber ◽  
Scar Tissue ◽  
Tissue Response ◽  
Positive Interactions ◽  
Weight Percentage ◽  
Poly Carbonate

AbstractCarbon nanofibers possess excellent conductivity properties, which may be beneficial in the design of more effective neural prostheses, however, limited evidence on their cytocompatibility properties exists. The objective of the present in vitro study was to determine cytocompatibility and material properties of formulations containing carbon nanofibers to predict the gliotic scar tissue response. Poly-carbonate urethane was combined with carbon nanofibers in varying weight percentages to provide a supportive matrix with beneficial bulk electrical and mechanical properties. The substrates were tested for mechanical properties and conductivity. Astrocytes (glial scar tissue-forming cells) were seeded onto the substrates for adhesion. Results provided the first evidence that astrocytes preferentially adhered to the composite material that contained the lowest weight percentage of carbon nanofibers. Positive interactions with neurons, and, at the same time, limited astrocyte functions leading to decreased gliotic scar tissue formation are essential for increased neuronal implant efficacy.

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