Mattia Terzaghi

Fine-root seasonal pattern, production and turnover rate of European beech (Fagus sylvatica L.) stands in Italy Prealps: Possible implications of coppice conversion to high forest

Abstract The aim of this study was to investigate the possible effects of coppice conversion to high forest on the beech fine-root systems. We compared the seasonal pattern of live and dead fine-root mass (d < 2 mm), production and turnover in three beech stands that differed in management practices. Tree density was higher in the 40-year-old coppice stand than in the stands that were converted from coppice to high forest in 1994 and 2004, respectively. We found that a reduction in tree density reduced the total fine-root biomass (Coppice stand, 353.8 g m−2; Conversion 1994 stand, 203.6 g m−2; Conversion 2004 stand, 176.2 g m−2) which continued to be characterised by a bimodal pattern with two major peaks, one in spring and one in early fall. Conversion to high forest may also affect the fine-root soil depth distribution. Both fine-root production and turnover rate were sensitive to management practices. They were lower in the Coppice stand (production 131.5 g m−2 year−1; turnover rate 0.41 year−1) than in the converted stands (1994 Conversion stand: production 232 g m−2 year−1, turnover rate 1.06 year−1; 2004 Conversion stand: production 164.2 g m−2 year−1, turnover rate 0.79 year−1).

Fine-root carbon and nitrogen concentration of European beech (Fagus sylvatica L.) in Italy Prealps: possible implications of coppice conversion to high forest

Fine-root systems represent a very sensitive plant compartment to environmental changes. Gaining further knowledge about their dynamics would improve soil carbon input understanding. This paper investigates C and N concentrations in fine roots in relation to different stand characteristics resulting from conversion of coppiced forests to high forests. In order to evaluate possible interferences due to different vegetative stages of vegetation, fine-root sampling was repeated six times in each stand during the same 2008 growing season. Fine-root sampling was conducted within three different soil depths (0–10; 10–20; and 20–30 cm). Fine-root traits were measured by means of WinRHIZO software which enable us to separate them into three different diameter classes (0–0.5, 0.5–1.0 and 1.0–2.0 mm). The data collected indicate that N concentration was higher in converted stands than in the coppiced stand whereas C concentration was higher in the coppiced stand than in converted stands. Consequently the fine-root C:N ratio was significantly higher in coppiced than in converted stands and showed an inverse relationship with fine-root turnover rate, confirming a significant change of fine-root status after the conversion of a coppice to high forest.

Drought and fire stress influence seedling competition in oak forests: fine-root dynamics as indicator of adaptation strategies to climate change

Increased summer drought and wildfires as a consequence of continuing climate change are expected to lead to disturbance of Mediterranean ecosystems. Seedlings recruitment is sensitive to both stresses and, therefore, any adaptation and restoration strategy devised to protect these forests should take into account a careful study on their effects on seedling development. As a substantial fraction of net primary productivity of forested ecosystems is channelled in the belowground compartments, the knowledge of how roots behave under stressful conditions becomes of primary importance to select the right management strategy to be implemented. This work tries to enlighten the events occurring in the fine root portion of the root system in young seedlings of three co-existing oak species (Quercus ilex, Quercus trojana and Quercus virgiliana) under controlled conditions. We have made a comparative analysis of the effect of these two stresses, alone or in combination, with the aim to evaluate the tolerance level of these seedlings and, therefore, to obtain an indication of their recruitment potential in the field. The parameters investigated were biomass and a number of morphological traits. Data obtained suggest that a decrease in diameter could be part of a tolerance strategy in all three oaks tested together with a reduction of root length. In addition, tolerance to water shortage could require a reduction of carbon allocated belowground, in particular in the very fine roots, which leads to an overall reduction of the root system dimension. Q. trojana seedlings seem to be the fastest in resuming growth after stress interruption but a good recovery was also found for the remaining two oak species. Although our study provides interesting information regarding a possible tolerance strategy taking place in the fine root compartment when seedlings of these three oak species undergo water stress and fire treatment, more information is needed before any suggestion can be made as to which species would be best suited to make these forests more resistant to global changes.

Interspecific variation in functional traits of oak seedlings (Quercus ilex, Quercus trojana, Quercus virgiliana) grown under artificial drought and fire conditions.

To face summer drought and wildfire in Mediterranean-type ecosystems, plants adopt different strategies that involve considerable rearrangements of biomass allocation and physiological activity. This paper analyses morphological and physiological traits in seedlings of three oak species (Quercus ilex, Quercus trojana and Quercus virgiliana) co-occurring under natural conditions. The aim of this study was to evaluate species-specific characteristics and the response of these oak seedlings to drought stress and fire treatment. Seedlings were kept in a growth chamber that mimicked natural environmental conditions. All three species showed a good degree of tolerance to drought and fire treatments. Differences in specific biomass allocation patterns and physiological traits resulted in phenotypic differences between species. In Q. ilex, drought tolerance depended upon adjustment of the allocation pattern. Q. trojana seedlings undergoing mild to severe drought presented a higher photosystem II (PSII) efficiency than control seedlings. Moreover, Q. trojana showed a very large root system, which corresponded to higher soil area exploitation, and bigger leaf midrib vascular bundles than the other two species. Morphological and physiological performances indicated Q. trojana as the most tolerant to drought and fire. These characteristics contribute to a high recruitment potential of Q. trojana seedlings, which might be the reason for the dominance of this species under natural conditions. Drought increase as a result of climate change is expected to favour Q. trojana, leading to an increase in its spatial distribution.

Poplar woody root proteome during the transition dormancy-active growth

Woody plants living in temperate climates finely regulate their growth and development in relation to seasonal changes; their transition from vegetative to dormancy phase represents an adaptation to their environment. Events occurring in the shoot during onset/release from dormancy have been largely investigated, whereas in woody roots they remain completely unknown. In recent years, we have been interested in understanding the molecular and physiological events occurring in poplar woody root during release from dormancy. Here, we propose the results of a comparative analysis of the proteome of poplar woody root sampled at different time points: T0 (dormancy condition), T1 (release from dormancy), and T2 (full vegetative condition). This study identified proteins that may be involved in the long-term survival of a dormant root or landmarking a specific time point.

Non-destructive Phenotypic Analysis of Early Stage Tree Seedling Growth Using an Automated Stereovision Imaging Method

A plant phenotyping approach was applied to evaluate growth rate of containerized tree seedlings during the precultivation phase following seed germination. A simple and affordable stereo optical system was used to collect stereoscopic red–green–blue (RGB) images of seedlings at regular intervals of time. Comparative analysis of these images by means of a newly developed software enabled us to calculate (a) the increments of seedlings height and (b) the percentage greenness of seedling leaves. Comparison of these parameters with destructive biomass measurements showed that the height traits can be used to estimate seedling growth for needle-leaved plant species whereas the greenness trait can be used for broad-leaved plant species. Despite the need to adjust for plant type, growth stage and light conditions this new, cheap, rapid, and sustainable phenotyping approach can be used to study large-scale phenome variations due to genome variability and interaction with environmental factors.

Tree seedling response to LED spectra: Implications for forest restoration

Abstract We found that different spectra, provided by light-emitting diodes or a fluorescent lamp, caused different photomorphological responses depending on tree seedling type (coniferous or broad-leaved), species, seedling development stage, and seedling fraction (shoot or root). For two conifers (Picea abies and Pinus sylvestris) soon after germination (≤40 days), more seedling growth was related to a lower ratio of red-to-far-red (R:FR) light. As growth continued to 120 days, spectra with a greater complement of blue light yielded more growth. Roots showed more plasticity to light spectra than shoots. In general for the evergreen broad-leaved Quercus ilex, spectra with additional R:FR than for conifers yielded more growth in the first 57 days. Subsequently as seedlings grew, shoot growth appeared to be influenced less by light source than roots, with root length showing the greatest responses. Our results suggest that manipulating light spectra to foster desired seedling traits may be another tool for use in the production of high-quality seedlings as defined through the Target Plant Concept. Such seedlings are needed for restoration of the two billion hectares of degraded forestland, especially on harsh sites such as those found in the Mediterranean region, and to sequester carbon to mitigate climate change.

Conversion from coppice to high stand increase soil erosion in steep forestland of European beech

In forestlands on steep slopes, where the shallow soil can be considered a non-renewable resource, erosion is of special concern. The vegetation covers, at both soil and canopy level, provides essential protection to the soil against the rainfall erosivity and reduces considerably the water erosion rate. Consequently vegetation management may affect soil erosion. We focused our attention on old coppice beech forest growing on a steep slope (28-32°) and subjected to conversion to high stand. With the aim of obtaining information on surface water flow and the mineral soil loss, three runoff-erosion plots (10 m long ´ 3 m wide) were installed in catchments in Lombardy Alps (Intelvi Valley, Como) at three stands: a coppice 40 years old (CpS 1968) and two conversions from coppice to high forest respectively cut in 1994 (CvS 1994) and 2004 (CvS 2004). Water run-off and sediment losses were collected from June to October 2008 and from May to October 2009 together with stand characteristics, LAI, soil surface cover, canopy cover and fine-root traits. Our results showed that the conversion practices significantly affect the water runoff and soil erosion with the younger conversion CvS 2004 showing the highest erosivity. This was due to the lower values of tree density, canopy cover, soil surface cover and fine-root biomass and length. The old coppice stand (CpS 1968) together with the older conversion stand (CvS 1994) showed comparable values of soil erosion. Therefore, the major role in protecting soil from erosion played by old coppice stand is recovered by the conversion stand after a number of years since harvesting. Our study highlights that abandoned old coppice stand plays an important role in protecting soil from erosion and claims consideration in forest management of steep forestland stands.

Tissue-specific hormone profiles from woody poplar roots under bending stress

Mechanical forces induced by bending are able to trigger an asymmetrical response in Populus nigra L. woody taproots. This response includes the recruitment of new lateral roots on the convex side and the deposition of reaction wood (RW) on the opposite concave side. Since these responses seem to be induced by asymmetric activity and differentiation of cambium cells, in the present work, we investigated how mechanical forces could influence the activation of specific phytohormone signaling pathways on the two sides of the vascular cambium. Thus, distinctive tissues were isolated from convex and concave sides of bent poplar root using cryosectioning. Successively, the isolated tissues, represented by the cambial zone, and the developing phloem and xylem, were analyzed using liquid chromatography coupled to tandem mass spectrometry to profile auxins, abscisic acid (ABA), cytokinins (CKs) and their metabolites. The auxin gradient on the concave side, with the IAA maximum localized in the cambium and decreasing level toward the developing phloem and xylem, suggests a pivotal role of IAA in the control of cambial growth rate, xylem differentiation and RW production. The IAA differences between the two bent root sides could be at the basis of the strictly unidirectional RW production. The higher levels of ABA and all CKs metabolites on the concave side support their involvement in RW production, whereby ABA could mediate the adaptation to the deforming conditions generated by bending, while CKs could act in synergy with IAA in controlling cell differentiation and meristem size. This article is protected by copyright. All rights reserved.