Tree Age Effects on Fine Root Biomass and Morphology over Chronosequences of <i>Fagus sylvatica</i>, <i>Quercus robur</i> and <i>Alnus glutinosa</i> Stands

<div><p>There are few data on fine root biomass and morphology change in relation to stand age. Based on chronosequences for beech (9–140 years old), oak (11–140 years) and alder (4–76 years old) we aimed to examine how stand age affects fine root biomass and morphology. Soil cores from depths of 0–15 cm and 16–30 cm were used for the study. In contrast to previously published studies that suggested that maximum fine root biomass is reached at the canopy closure stage of stand development, we found almost linear increases of fine root biomass over stand age within the chronosequences. We did not observe any fine root biomass peak in the canopy closure stage. However, we found statistically significant increases of mean fine root biomass for the average individual tree in each chronosequence. Mean fine root biomass (0–30 cm) differed significantly among tree species chronosequences studied and was 4.32 Mg ha^-1, 3.71 Mg ha^-1 and 1.53 Mg ha^-1, for beech, oak and alder stands, respectively. The highest fine root length, surface area, volume and number of fine root tips (0–30 cm soil depth), expressed on a stand area basis, occurred in beech stands, with medium values for oak stands and the lowest for alder stands. In the alder chronosequence all these values increased with stand age, in the beech chronosequence they decreased and in the oak chronosequence they increased until ca. 50 year old stands and then reached steady-state. Our study has proved statistically significant negative relationships between stand age and specific root length (SRL) in 0–30 cm soil depth for beech and oak chronosequences. Mean SRLs for each chronosequence were not significantly different among species for either soil depth studied. The results of this study indicate high fine root plasticity. Although only limited datasets are currently available, these data have provided valuable insight into fine root biomass and morphology of beech, oak and alder stands.</p></div

Relationships between stand age and fine root biomass for the average individual tree in each stand (kg tree^-1) for 0–30 cm soil depth for beech, oak and alder chronosequences, modeled by Generalized Additive Models (GAM).

<p>The mean individual tree root biomass was calculated by dividing the respective fine root biomass for each stand per ha (shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0148668#pone.0148668.s004" target="_blank">S1 Table</a>) by the number of trees in the stand per ha (shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0148668#pone.0148668.t001" target="_blank">Table 1</a>). Shaded area represents the confidence interval of GAM. Points represent mean values for each tree stand, raw datapoints are available in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0148668#pone.0148668.s003" target="_blank">S1 File</a>.</p

The Aedileship in the Roman Republic

The search for origins of the republican aedileship presents a difficult task. At first sight the story about foundation and evolution of this magistracy lies in ancient sources. On the closer look it may be discerned, that the same sources have their own present intentions. They search for a tradition in oral based history to legitimise the current status of the aedileship and present it in historical context. Yet another question raises ambiguity. The twin character of the magistracy blurs our perceptions and makes it challenging to distinguish whether plebeian and curule aedileships are evolving intertwined or apart of each other. Nevertheless, delving upon the wide variety of ancient sources it is still possible to reconstruct the basic functions and duties of the aediles. Furthermore, the aedileship has to be looked upon in broader picture, in order to figure out, how it is situated in the system of republican magistracies and why the roman aristocrats strived to serve as aediles. The main purpose of this paper is to bring the aedileship out of the shadows and present it as full pledged research topic. Starting with aedileship it may embark us on questioning our knowledge of the republican magistracies. Powered by TCPDF (www.tcpdf.org

Mean fine root biomass (±SE) from 0–30 cm soil depth for beech, oak and alder stand chronosequences.

<p>Analysis of variance was performed to show significance of differences among stand chronosequences for total fine root biomass. Same letters in Tukey’s test show lack of differences among mean values of fine root biomass of beech, oak and alder stands.</p

Relationships between stand age and fine root biomass expressed on a stand area basis (g m^-2) for 0–30 cm soil depth for beech, oak and alder chronosequences.

<p>Relationships were modeled using Generalized Additive Models. Shaded area represents the confidence interval of GAM. Points represent mean values for each tree stand, raw datapoints are available in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0148668#pone.0148668.s003" target="_blank">S1 File</a>.</p

Relationships between stand age and fine root length, surface area, volume and number of root tips for the average individual tree in each stand for 0–30 cm soil depth for beech, oak and alder chronosequences modeled by Generalized Additive Models (GAM).

<p>The mean individual fine root indices were calculated by dividing the particular root traits values for each stand per ha (shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0148668#pone.0148668.s005" target="_blank">S2</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0148668#pone.0148668.s006" target="_blank">S3</a> and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0148668#pone.0148668.s007" target="_blank">S4</a> Tables) by the number of trees in the stand per ha (shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0148668#pone.0148668.t001" target="_blank">Table 1</a>). Shaded area represents the confidence interval of GAM. Points represent mean values for each tree stand, raw datapoints are available in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0148668#pone.0148668.s003" target="_blank">S1 File</a>.</p

Interaction of mitochondria with the endoplasmic reticulum and plasma membrane in calcium homeostasis, lipid trafficking and mitochondrial structure

Studying organelles in isolation has been proven to be indispensable for deciphering the underlying mechanisms of molecular cell biology. However, observing organelles in intact cells with the use of microscopic techniques reveals a new set of different junctions and contact sites between them that contribute to the control and regulation of various cellular processes, such as calcium and lipid exchange or structural reorganization of the mitochondrial network. In recent years, many studies focused their attention on the structure and function of contacts between mitochondria and other organelles. From these studies, findings emerged showing that these contacts are involved in various processes, such as lipid synthesis and trafficking, modulation of mitochondrial morphology, endoplasmic reticulum (ER) stress, apoptosis, autophagy, inflammation and Ca2+handling. In this review, we focused on the physical interactions of mitochondria with the endoplasmic reticulum and plasma membrane and summarized present knowledge regarding the role of mitochondria-associated membranes in calcium homeostasis and lipid metabolism