Papers by Marco Borghetti
Canadian Journal of Forest Research-revue Canadienne De Recherche Forestiere, 1989
ABSTRACT The morphological and physiological response to water stress was studied in 2-year-old p... more ABSTRACT The morphological and physiological response to water stress was studied in 2-year-old potted Italian alder (Alnuscordata Loisel.) seedlings. Leaf area, transpiration, stomatal conductance, and xylem water potential were measured during May 1987 on seedlings from five geographic sources grown (i) with soil water content close to field capacity and (ii) with a severe drought. Significant differences in leaf area were found, at the end of the experiment, between drought-stressed and well-watered plants. As drought progressed, plants displayed a reduction of xylem water potentials and a decrease in stomatal conductance. However, transpiration did not stop completely, and seedlings were not able to maintain a favourable internal water status. Osmotic potentials for the undiluted cell sap, estimated from pressure–volume curves, were between −0.9 and −1.3 MPa. In June 1988, a similar experiment was carried out using seedlings from only one geographic source. A simultaneous decrease of transpiration, xylem potential, and net photosynthesis was observed in seedlings subjected to the drought treatment. During both experiments, a recovery of physiological parameters was observed, after rewatering. Some differences between provenances were detected. The provenance from Corsica showed the greatest sensitivity to water stress; a seed source from the province of Avellino (Campania, south Italy) was able to maintain a more favourable internal water status, as drought progressed.
Canadian Journal of Forest Research-revue Canadienne De Recherche Forestiere, 1996
Using isoenzymes as gene markers and spatial autocorrelation analysis as a tool to detect spatial... more Using isoenzymes as gene markers and spatial autocorrelation analysis as a tool to detect spatial patterns, we studied the spatial distribution of genotypes in a naturally regenerated uneven-aged Norway spruce (Picea abies (L.) Karst.) stand on the eastern Italian Alps. In ...
Atmospheric Environment, 2009
The importance that nitrogen (N) deposition has in driving the carbon (C) sequestration of forest... more The importance that nitrogen (N) deposition has in driving the carbon (C) sequestration of forests has recently been investigated using both experimental and modeling approaches. Whether increased N deposition has positive or negative effects on such ecosystems depends on the status of the N and the duration of the deposition. By combining d 13 C, d 18 O, d 15 N and dendrochronological approaches, we analyzed the impact of two different sources of NO x emissions on two tree species, namely: a broadleaved species (Quercus cerris) that was located close to an oil refinery in Southern Italy, and a coniferous species (Picea abies) located close to a freeway in Switzerland. Variations in the c i /c a ratio and the distinction between stomatal and photosynthetic responses to NO x emissions in trees were assessed using a conceptual model, which combines d 13 C and d 18 O. d 15 N in leaves, needles and tree rings was found to be a bioindicator of N input from anthropogenic emissions, especially at the oil refinery site. We observed that N fertilization had a stimulatory effect on tree growth near the oil refinery, while the opposite effect was found for trees at the freeway site. Changes in the c i /c a ratio were mostly related to variations in d 13 C at the freeway site and, thus, were driven by photosynthesis. At the oil refinery site they were mainly related to stomatal conductance, as assessed using d 18 O. This study demonstrates that a single method approach does not always provide a complete picture of which physiological traits are more affected by N emissions. The triple isotope approach combined with dendrochronological analyses proved to be a very promising tool for monitoring the ecophysiological responses of trees to long-term N deposition.
Physiologia Plantarum, 1997
Trees-structure and Function, 1998
Effects of changing light conditions on the ecophysiological condition behind survival were exami... more Effects of changing light conditions on the ecophysiological condition behind survival were examined on beech from two different populations. Plants were grown in a greenhouse under simulated understorey and canopy gap light conditions. Upon exposure to high light maximum photosynthesis of shade-acclimated leaves increased followed by a reduction over several days to between high-and low-light control rates. In the reciprocal transfer, the decrease in maximum photosynthesis was rapid during the first 2-3 days and then levelled off to values comparable to low-light controls.
Global Change Biology, 2006
To assess the variation of soil respiration at different forest stages we measured it in a coppic... more To assess the variation of soil respiration at different forest stages we measured it in a coppiced oak (Quercus cerris L.) chronosequence in central Italy during two campaigns, spanning 2 successive years, in four stands at different stages of the rotation: 1 year (S1), 5 years (S5), 10 years (S10) and 17 years (S17) after coppicing. The contribution of the different components of soil respiration flux (aboveground litter, belowground decomposition soil organic matter and root respiration) was estimated by a paired comparison of manipulative experiments between the recently coppiced stand (S1) and mature stand (S17).Ninety percent of soil respiration values were between 1.7 and 7.8 μmol m−2 s−1, with an overall mean (±SD) of 4.0±2.7 μmol m−2 s−1. Spatial variation of soil respiration was high (CV=44.9%), with a mean range (i.e. patch size) of 4.8±2.7 m, as estimated from a semivariance analysis.In the absence of limitation by soil moisture, soil respiration was related to soil temperature with the exponential Q10 model (average Q10=2.25). During summer, soil moisture constrained soil respiration and masked its dependence on soil temperature. Soil respiration declined over the years after coppicing. Assuming a linear decline with stand age, we estimated a reduction of 24% over a 20-year-rotation cycle. The response of soil respiration to temperature also changed with age of the stands: the Q10 was estimated to decrease from 2.90 in S1 to 2.42 in S17, suggesting that different components or processes may be involved at different developmental stages. The contribution of heterotrophic respiration to total soil respiration flux was relatively larger in the young S1 stand than in the mature S17 stand.
Tellus Series B-chemical and Physical Meteorology, 2009
Leakage (spillover) refers to the unintended negative (positive) consequences of forest carbon (C... more Leakage (spillover) refers to the unintended negative (positive) consequences of forest carbon (C) management in one area on C storage elsewhere. For example, the local C storage benefit of less intensive harvesting in one area may be offset, partly or completely, by intensified harvesting elsewhere in order to meet global timber demand. We present the results of a theoretical study aimed at identifying the key factors determining leakage and spillover, as a prerequisite for more realistic numerical studies. We use a simple model of C storage in managed forest ecosystems and their wood products to derive approximate analytical expressions for the leakage induced by decreasing the harvesting frequency of existing forest, and the spillover induced by establishing new plantations, assuming a fixed total wood production from local and remote (non-local) forests combined. We find that leakage and spillover depend crucially on the growth rates, wood product lifetimes and woody litter decomposition rates of local and remote forests. In particular, our results reveal critical thresholds for leakage and spillover, beyond which effects of forest management on remote C storage exceed local effects. Order of magnitude estimates of leakage indicate its potential importance at global scales.
Plant Cell and Environment, 1998
The transpiration of a mature beech (Fagus sylvatica L.) forest was measured over a whole season ... more The transpiration of a mature beech (Fagus sylvatica L.) forest was measured over a whole season by the heat pulse velocity technique and the results analysed in terms of a new analytical canopy conductance model, which takes into account the effects of partial decoupling from the atmosphere on the local humidity environment experienced by the canopy. Stand daily transpiration ranged from 0·62 to 2·97 mm d -1 , with a seasonal mean value of 1·97 mm d -1 . Maximum canopy conductance was 18·5 mm s -1 , with a mean estimated value of 5·0 mm s -1 ; computed values were little affected by the assumption of neutral atmospheric conditions. The decoupling coefficient Ω varied greatly on a daily and seasonal basis, with an average value of 0·28. As a result of partial decoupling, the estimated vapour pressure deficit at the notional canopy surface exceeded the values measured above the canopy by 380 Pa on average. When correctly expressed in terms of humidity at the canopy surface, the model explained 80% of the variance in half-hourly transpiration measurements. Upon cross-validation it still explained 72% of the variance, as compared to only 40% when correction for partial decoupling was not introduced. A baseline canopy conductance of 0·7 mm s -1 , not modulated by the environment, was estimated. The implications of the model are discussed for the representation of canopy conductance and transpiration of broad-leaf forests.
... A questa metodologia se ne sono affiancate altre più complesse e di tipo geostatistico ([19],... more ... A questa metodologia se ne sono affiancate altre più complesse e di tipo geostatistico ([19], [24], [21]). Nella presente area di studio questa relazione non è stata rinvenuta per cui i metodi sopra citati non sono stati tenuti in considerazione. ... CIMMYT NRG. :: Google Scholar :: 21. ...
Plant Cell and Environment, 1995
The annual course of xylem embolism in twigs of adult beech trees was monitored, and compared to ... more The annual course of xylem embolism in twigs of adult beech trees was monitored, and compared to concurrent changes of tree water status and hydraulic resistances. Xylem embolism was quantified in 1-year-old apical twigs by the hydraulic conductivity as a percentage of the maximum measured after removal of air emboli. Tree and root hydraulic resistances were estimated from water potential differences and sap flux measurements. The considerable degree of twig embolism found in winter (up to 90% loss of hydraulic conductivity) may be attributed to the effect of freeze-thaw cycles in the xylem. A partial recovery from winter embolism occurred in spring, probably because of the production of new functional xylem. Xylem embolism fluctuated around 50% throughout the summer, without significant changes. Almost complete refilling of apical twigs was observed early in autumn. A significant negative correlation was found between xylem embolism and precipitation; thus, an active role of rainfall in embolism reversion is hypothesized. Tree and root hydraulic resistances were found to change throughout the growing period. A marked decrease of hydraulic resistance preceded the refilling of apical twigs in the autumn. Most of the decrease in total tree resistance was estimated to be located in the root compartment.
Canadian Journal of Forest Research-revue Canadienne De Recherche Forestiere, 2009
In this study we assessed carbon sequestration by Italian forest ecosystems at a regional level. ... more In this study we assessed carbon sequestration by Italian forest ecosystems at a regional level. We applied a monthly time-step process-based model (3-PGS), coupled with a modified soil respiration model, to predict both gross primary production (GPP3-PGS) and net ecosystem production (NEP3-PGS). To evaluate the general reliability of model estimates, we compared, at five different forest sites, monthly and annual GPP3-PGS, NEP3-PGS, and predicted total ecosystem respiration (TER3-PGS) with averages of monthly and annual eddy covariance (EC) measures of GPPEC, NEPEC, and TEREC. A strong correlation was found between annual GPP3-PGS and annual GPPEC (r 2 = 0.77, RMSE = 1.28 Mg CÁha -1 Áyear -1 ), and monthly (r 2 = 0.85, RMSE = 35 g CÁm -2 Ámonth -1 ), as well as between NEP3-PGS and annual NEPEC (r 2 = 0.76, RMSE = 0.21 Mg CÁha -1 Áyear -1 ), and monthly (r 2 = 0.78, RMSE = 18 g CÁm -2 Ámonth -1 ). The TER3-PGS also showed a high correlation with annual TEREC (r 2 = 0.93). Furthermore, a sensitivity analysis showed that GPP3-PGS was highly sensitive to the satellite greenness index (normalized difference of vegetation index) and to the vapor pressure deficit. With general confidence in the models, we established a 30 year average meteorological grid of 8 km  8 km resolution across Italy and created a map representing annual NEP3-PGS across Italian forests, based on the remotely sensed CORINE Land Cover forest classification.
Plant Ecology, 1997
Seed density, seed colour and the number of seed damaged by birds were monitored for several mont... more Seed density, seed colour and the number of seed damaged by birds were monitored for several months, after a late-spring fire, in two Aleppo pine (Pinus halepensis Miller) stands growing in South Italy. In one stand (S(1)) the trees were completely burned ('charred’), in the other one (S(2)) the trees were only ‘scorched’, with a crown in part still alive after fire. 37% and 61% of seeds were released during the first month, respectively in S(1) and S(2). Damaged seeds accounted for 43% and 23% of seeds collected in the whole period, respectively in the charred and in the scorched stand. In both stands the percentage of empty seeds increased in late-dispersed seed lots. The colour of released seeds changed with time: dark grey-brown seeds were released at first, whereas late-dispersed seeds showed a yellowish colour. The principal component analysis performed on the categorical colour variables produced a good discrimination between seed lots collected at different dates. Seed dispersal and the characteristics of released seeds have been discussed in relation to the post-fire recruitment process and, in particular, to the possibility that the predation risk by granivorous birds may be reduced by a mimicry effect of seeds to the underlying soil.
New Phytologist, 2006
Intra-annual radial growth rates and durations in trees are reported to differ greatly in relatio... more Intra-annual radial growth rates and durations in trees are reported to differ greatly in relation to species, site and environmental conditions. However, very similar dynamics of cambial activity and wood formation are observed in temperate and boreal zones. • Here, we compared weekly xylem cell production and variation in stem circumference in the main northern hemisphere conifer species (genera Picea , Pinus , Abies and Larix ) from 1996 to 2003. Dynamics of radial growth were modeled with a Gompertz function, defining the upper asymptote ( A ), x -axis placement ( β ) and rate of change ( κ ). • A strong linear relationship was found between the constants β and κ for both types of analysis. The slope of the linear regression, which corresponds to the time at which maximum growth rate occurred, appeared to converge towards the summer solstice. • The maximum growth rate occurred around the time of maximum day length, and not during the warmest period of the year as previously suggested. The achievements of photoperiod could act as a growth constraint or a limit after which the rate of tree-ring formation tends to decrease, thus allowing plants to safely complete secondary cell wall lignification before winter.
Forest Ecology and Management, 2004
The process-based model HYDRALL has been applied to simulate growth patterns and carbon balance o... more The process-based model HYDRALL has been applied to simulate growth patterns and carbon balance of three Pinus radiata and one Pseudotsuga menziesii plantations growing in different sites in Italy, under current climate and climate change scenarios. In three out of four cases, growth patterns simulated by the model under current climatic conditions showed good convergence with measured growth patterns, as provided by stem analysis. Climatic variables for the period 1990-2100 have been obtained from the General Circulation Model (GCM) projections of the HadCM2 model. At all sites simulations predicted an increase of both temperature and precipitation. The effects of climate change on forest growth was explored by simulating 50year stand rotations starting from different dates in the 1960-2100 period. Climate change had a positive effect on stand growth patterns, with the largest effect found for P. menziesii (73 and 55% increase for stand volume and height at the age of 40). Mean annual increment (MAI) was also stimulated by climate change, whereas no change in MAI temporal patterns was observed. In three out of four cases the model predicted an increase in the allocation of carbon to the foliage compartment. A positive effect of climate change on net ecosystem exchange (NEE) was observed only for the P. menziesii stand; in contrast, water-use efficiency, estimated as the ratio between net primary production and stand transpiration, increased in all sites. #
Trees-structure and Function, 1998
Effects of changing light conditions on the ecophysiological condition behind survival were exam... more Effects of changing light conditions on the ecophysiological condition behind survival were examined on beech from two different populations. Plants were grown in a greenhouse under simulated understorey and canopy gap light conditions. Upon exposure to high light maximum photosynthesis of shade-acclimated leaves increased followed by a reduction over several days to between high- and low-light control rates. In the reciprocal transfer, the decrease in maximum photosynthesis was rapid during the first 2–3 days and then levelled off to values comparable to low-light controls. Seedlings from Sicily (Madonie) showed generally higher maximum photosynthetic rates than those from Abetone. Leaf conductance varied in the same direction as photosynthesis in high- to low-light seedlings but to a lesser degree. Leaves grown under low light and exposed to high light experienced photoinhibition. The Abetone population was more susceptible to photoinhibitory damage than the seedlings from Sicily. Exposure to high light of shade-acclimated seedlings resulted in intermediate chlorophyll concentrations between levels of the high-light and low-light seedlings. Carotenoid concentration was unaffected by treatments. Seedlings grew more in high light, but had a lower leaf area ratio. Light-limited seedlings showed a shift in carbon allocation to foliage. Leaves formed in the new light regime maintained the same anatomy that had been developed before transfer. Seedlings from Sicily had thicker leaves than those of seedlings from Abetone. Seedlings from Abetone were found to be more susceptible to changing light conditions than seedlings from Sicily. We conclude that small forest gaps may represent a favorable environment for photosynthesis and growth of beech regeneration as a result of the limited ability of seedlings to acclimate to sudden increases in high irradiance and because of the moderate levels of light stress in small gaps.
Functional Ecology, 2002
1. The hypothesis is tested that functional limitations, possibly related to the risk of disrupti... more 1. The hypothesis is tested that functional limitations, possibly related to the risk of disruptive xylem embolism, maintain the leaf water potential of trees within a safety range. This strategy would particularly apply to conifers. 2. It is also hypothesized that homeostasis in water transport is achieved by a combination of short-term stomatal regulation and the optimal allocation of resources between transpiring foliage, conductive sapwood and absorbing roots. 3. The implications of this hypothesis for responses of plant structure to the environment are explored from a theoretical viewpoint, focusing in particular on the effects of temperature, vapour pressure deficit and soil water availability and texture. 4. A comparison with published data sets confirms model predictions of greater allocation to transpiring foliage with increasing temperature, and lower allocation with increasing vapour pressure deficit and soil drought. Allocation to fine roots would respond more strongly to drought, and the effect would be magnified by coarse soil textures.
Global Change Biology, 2004
The effects of harvest on European forest net ecosystem exchange (NEE) of carbon and its photosyn... more The effects of harvest on European forest net ecosystem exchange (NEE) of carbon and its photosynthetic and respiratory components (GPP (gross primary production) and TER (total ecosystem respiration)) were examined by comparing four pairs of mature/ harvested sites in Europe via a combination of eddy covariance measurements and empirical modeling. Three of the comparisons represented high coniferous forestry (spruce in Britain, and pines in Finland and France), while a coppice-with-standard oak plantation was examined in Italy.
Trees-structure and Function, 1998
The present study was carried out to elucidate the response mechanisms of 50-year-old Pinus hale... more The present study was carried out to elucidate the response mechanisms of 50-year-old Pinus halepensis Mill. trees to a long-term and severe drought. The amount of water available to trees was artificially restricted for 12 months by covering the soil with a plastic roof. Over the short term a direct and rapid impact of drought was evident on the water relations and gas exchanges of trees: as the soil dried out in the Spring, there was a concurrent decrease of predawn water potential; transpiration was strongly reduced by stomatal closure. Seasonal changes in the water volume fractions of twig and stem xylem were observed and interpreted as the result of cavitation and refilling in the xylem. When droughted trees recovered to a more favourable water status, refilling of embolized xylem was observed; twig predawn water potentials were still negative in the period when the embolism was reversed in the twig xylem. A few months after the removal of the covering, no differences in whole plant hydraulic resistance were observed between droughted and control trees. Needle and shoot elongation and stem radial growth were considerably reduced in droughted trees; no strategy of trees to allocate carbon preferentially to the stem conducting tissues was apparent throughout the experiment. An after-effect of the drought on growth was observed.
Plant Physiology, 2007
The oxygen isotope enrichment of bulk leaf water (D b ) was measured in cotton (Gossypium hirsutu... more The oxygen isotope enrichment of bulk leaf water (D b ) was measured in cotton (Gossypium hirsutum) leaves to test the Craig-Gordon and Farquhar-Gan models under different environmental conditions. D b increased with increasing leaf-to-air vapor pressure difference (VPd) as an overall result of the responses to the ratio of ambient to intercellular vapor pressures (e a /e i ) and to stomatal conductance (g s ). The oxygen isotope enrichment of lamina water relative to source water ð D 1 Þ; which increased with increasing VPd, was estimated by mass balance between less enriched water in primary veins and enriched water in the leaf. The Craig-Gordon model overestimated D b (and D 1 Þ; as expected. Such discrepancies increased with increase in transpiration rate (E), supporting the Farquhar-Gan model, which gave reasonable predictions of D b and D 1 with an L of 7.9 mm, much less than the total radial effective length L r of 43 mm. The fitted values of L for D 1 of individual leaves showed little dependence on VPd and temperature, supporting the assumption that the Farquhar-Gan formulation is relevant and useful in describing leaf water isotopic enrichment.
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Papers by Marco Borghetti