Changes In Basal Area Research Articles

Stream temperature responses to forest harvesting with different riparian buffer prescriptions in northern California, USA

Forested riparian zones adjacent to headwater streams provide unique habitat attributes and influence water quantity and quality. Forest harvesting adjacent to and within these zones has led to changes in stream temperature (Ts) and impacts on aquatic ecosystems. As such, policies and regulations have sought to limit forest management activities in riparian zones; however, water temperature responses have been variable, necessitating additional research to improve our understanding of the effectiveness of contemporary riparian harvesting prescriptions in limiting water temperature increases after harvest. We sought to quantify the effects of three different riparian buffer prescriptions with increasing intensity of basal area removal (2–43% area harvested) on Ts in forested headwaters in northern California, USA. We measured Ts in 18 headwater catchments (12 harvested, 6 six unharvested references) during a pre-harvest year and two post-harvest years using 12 thermistors distributed longitudinally down each stream (i.e., 216 total sensors). We analyzed the Ts data to assess (1) the seasonal variability of seven-day moving average of daily maximum stream temperature (T7-day-max) and (2) the relative importance of the different harvesting prescriptions and catchment physiographic characteristics in influencing the T7-day-max. Our analysis indicated substantial changes in basal area and shade in the riparian areas with the most intensive harvesting treatment (i.e., 50% reduction in canopy cover). However, these changes in riparian canopy were poorly related to stream temperature. Results indicated a median T7-day-max increase of ∼ 2 °C in the sites with the most intensive harvesting treatment. The greatest changes in seasonal T7-day-max occurred during the summer and fall but only during the first year after harvesting. There was no evidence of increases in T7-day-max during the second post-harvest year. While air temperatures in the riparian areas increased by 1–5 °C after harvesting, this warming did not directly transfer to strong warming in stream temperatures. Rather, random forest models revealed that T7-day-max was more strongly related to topography (i.e., elevation) and climatic variability (i.e., changes in precipitation and stream stage) than to the riparian harvesting prescription or the harvesting period. Our study further highlights the challenges in understanding the thermal regimes of headwater streams and their responses to forest disturbances. Predictions of stream temperature responses to forest disturbances are complicated by the heterogeneity of the factors that influence this important physical water quality parameter. However, with global climate change and increasing pressures on water resources and aquatic ecosystems it is increasingly important to continue to provide insights into the relationships between forest management activities and the thermal regimes of headwater streams.

Role of Speckle Tracking Echocardiography in Assessment of Right Ventricular Function in Heart Failure with Preserved Ejection Fraction

Background: Patients who exhibit signs and indicators of heart failure (HF) but usual or near to ordinary left ventricular ejection fraction are said to have HFpEF, which is an abbreviation for heart failure with preserved ejection fraction. Our goal was to assess the role that 2D-STE plays in the identification of RV dysfunction in HFpEF patients. Methods: Benha Teaching and Benha University Hospitals were both involved in the research for this study. It was carried out on a total of 100 individuals, each of whom was randomly assigned to one of two groups: group I involving 50 patients diagnosed with HFpEF. The patients who acted as control group were compared to another set of fifty healthy individuals who were the same age and gender. Result: No substantial changes were reported between both groups concerning Tricuspid annular plane systolic excursion (TAPSE), right ventricular diameter (RVD) (mid, basal, longitudinal) (P = 0.473), and right ventricular fractional area change (RVFAC) (P = 0.12). Conclusion: Patients with HFpEF who have features that are detected by 2D-STE have a much higher risk of experiencing a negative outcome. This is in contrast to the results of traditional 2D echocardiography. These results provide credence to the idea that RV 2D-STE might be used to identify individuals with HFpEF who are at a greater risk for unfavorable cardiac events.

Dynamics of litterfall production in a forest damaged by oak wilt disease: a case study in a warm-temperate secondary forest

ABSTRACT Quantification of litterfall production is crucial for evaluating net primary productivity and nutrient cycling in forest ecosystems. High mortality among trees in the family Fagaceae due to Japanese oak wilt disease (JOW) might affect litterfall production in secondary forests; however, few studies have quantified these effects. We investigated litterfall production and forest structure in warm-temperate secondary forests in the Kaisho Forest over 6 and 12 years, respectively, and compared the dynamics among different phases of a JOW outbreak to assess the impacts of JOW on litterfall production. We found that total annual litterfall and leaf fall showed little change in peak to post-JOW periods and that changes in basal area were unrelated to total litterfall and leaf fall. The observed fluctuation in BA in the Kaisho Forest may not have been large enough to clearly reveal the effect of JOW during these periods. Canopy gaps formed by JOW may enhance the recruitment and growth rates of sub-canopy and understory trees. Our results may only be applicable to warm secondary forests where evergreen trees are replacing deciduous trees. Additional information on litterfall production in JOW-disturbed secondary forests is needed.

Effects of past and present microclimates on northern and southern plant species in a managed forest landscape

AbstractQuestionsNear‐ground temperatures can vary substantially over relatively short distances, enabling species with different temperature preferences and geographical distributions to co‐exist within a small area. In a forest landscape, the near‐ground temperatures may change due to management activities that alter forest density. As a result of such management activities, current species distributions and performances might not only be affected by current microclimates, but also by past conditions due to time‐lagged responses.LocationSweden.MethodsWe examined the effects of past and current microclimates on the distributions and performances of two northern, cold‐favoured, and two southern, warm‐favoured, plant species in 53 managed forest sites. Each pair was represented by one vascular plant and one bryophyte species. We used temperature logger data and predictions from microclimate models based on changes in basal area to relate patterns of occurrence, abundance, and reproduction to current and past microclimate.ResultsThe two northern species were generally favoured by microclimates that were currently cold, characterised by later snowmelt and low accumulated heat over the growing season. In contrast, the two southern species were generally favoured by currently warm microclimates, characterised by high accumulated heat over the growing season. Species generally had higher abundance in sites with a preferred microclimate both in the past and present, and lower abundance than expected from current conditions, if the past microclimate had changed from warm to cold or vice versa, indicating time‐lags in abundance patterns of the species.ConclusionsOur results show a potential importance of past and present microclimate heterogeneity for the co‐existence of species with different temperature preferences in the same landscape and highlight the possibility to manage microclimates to mitigate climate change impacts on forest biodiversity.

MEDFATE 2.9.3: a trait-enabled model to simulate Mediterranean forest function and dynamics at regional scales

Abstract. Regional-level applications of dynamic vegetation models are challenging because they need to accommodate the variation in plant functional diversity, which requires moving away from broadly defined functional types. Different approaches have been adopted in the last years to incorporate a trait-based perspective into modeling exercises. A common parametrization strategy involves using trait data to represent functional variation between individuals while discarding taxonomic identity. However, this strategy ignores the phylogenetic signal of trait variation and cannot be employed when predictions for specific taxa are needed, such as in applications to inform forest management planning. An alternative strategy involves adapting the taxonomic resolution of model entities to that of the data source employed for large-scale initialization and estimating functional parameters from available plant trait databases, adopting diverse solutions for missing data and non-observable parameters. Here we report the advantages and limitations of this second strategy according to our experience in the development of MEDFATE (version 2.9.3), a novel cohort-based and trait-enabled model of forest dynamics, for its application over a region in the western Mediterranean Basin. First, 217 taxonomic entities were defined according to woody species codes of the Spanish National Forest Inventory. While forest inventory records were used to obtain some empirical parameter estimates, a large proportion of physiological, morphological, and anatomical parameters were matched to measured plant traits, with estimates extracted from multiple databases and averaged at the required taxonomic level. Estimates for non-observable key parameters were obtained using meta-modeling and calibration exercises. Missing values were addressed using imputation procedures based on trait covariation, taxonomic averages or both. The model properly simulated observed historical changes in basal area, with a performance similar to an empirical model trained for the same region. While strong efforts are still required to parameterize trait-enabled models for multiple taxa, and to incorporate intra-specific trait variability, estimation procedures such as those presented here can be progressively refined, transferred to other regions or models and iterated following data source changes by employing automated workflows. We advocate for the adoption of trait-enabled and population-structured models for regional-level projections of forest function and dynamics.

How have wildfires affected forest basal area in Northern and Southern California during the 21st century?

Wildfires are unplanned and dynamic fires that occur in areas of combustible vegetation. They can be natural or human-induced and play a vital role in ecosystem health. The severity and intensity of wildfires can change over time based on the weather, available fuel and topography. California is continuously experiencing longer wildfire seasons as a direct result of climate change, affecting the forest structure of the state’s forest. Forest basal area is used to determine forest stand density and is an indicator of annual growth potential (Nix, 2020). It is often used as the basis for making important forest management decisions. My research will determine how wildfire frequency and extent have affected the basal area of Northern and Southern California’s forests in 2000 and 2017. Fire perimeter and frequency data obtained from the United States Forest Service regional datasets website will be used to define fire characteristics in the regions. Tree basal area data obtained from the United States Forest Service regional-level datasets website will be used to quantify the basal area of critical forest types. Percent change in basal area, fire frequency and acres burned each year will be determined to compare the burn regimes of the two regions during the two years to see how that has impacted the forest’s basal area. The findings will give an idea of how the rate of wildfires has changed in the last two decades and its subsequent impacts, which can help us better prepare for the future of forests in an ongoing climate crisis.

Tropical forest loss impoverishes arboreal mammal assemblages by increasing tree canopy openness.

Landscape-scale deforestation poses a major threat to global biodiversity, not only because it limits habitat availability, but also because it can drive the degradation of the remaining habitat. However, the multiple pathways by which deforestation directly and indirectly affects wildlife remain poorly understood, especially for elusive forest-dependent species such as arboreal mammals. Using structural equation models, we assessed the direct and indirect effects of landscape forest loss on arboreal mammal assemblages in the Lacandona rainforest, Mexico. We placed camera traps in 100 canopy trees, and assessed the direct effect of forest cover and their indirect effects via changes in tree basal area and canopy openness on the abundance and diversity (i.e., species richness and exponential of Shannon entropy) of arboreal mammals. We found that forest loss had negative indirect effects on mammal richness through the increase of tree canopy openness. This could be related to the fact that canopy openness is usually inversely related to resource availability and canopy connectivity for arboreal mammals. Furthermore, independently of forest loss, the abundance and richness of arboreal mammals was positively related to tree basal area, which is typically higher in old-growth forests. Thus, our findings suggest that arboreal mammals generally prefer old-growth vegetation with relatively low canopy openness and high tree basal area. However, unexpectedly, forest loss was directly and positively related to the abundance and richness of mammals, probably due to a crowding effect, a reasonable possibility given the relatively short history (~40years) of deforestation in the study region. Conversely, the Shannon diversity was not affected by the predictors we evaluated, suggesting that rare mammals (not the common species) are the ones most affected by these changes. All in all, our findings emphasize that conservation measures ought to focus on increasing forest cover in the landscape, and preventing the loss of large trees in the remaining forest patches.

Modelling temporal change in inventory attributes from a LiDAR-derived inventory for the United Counties of Prescott and Russell, Ontario: A comparison of random forest and linear regression methods

This study assessed the feasibility of updating a forest inventory derived from 2014 Light Detection and Ranging (LiDAR) data using ground plot data collected in 2021 to model change in basal area, volume, and average stand height. These attributes were determined for a subset (n=32) of stands from the original 2014 inventory. Both 2nd order polynomial regression and random forest learning methods were used to model annual growth increments for these attributes and results were compared. Except for height, the variance explained using random forest regression was greater than that explained using linear regression. As well, root mean square error was lower using random forest as opposed to linear regression for all three attributes, suggesting random forest produced more accurate results overall. Although the random forest results could not be extrapolated to the landscape with confidence due to limitations associated with that approach. Rather, the quadratic equations from the linear regression models were used to predict 2021 landscape values. The results at the landscape scale were deemed to be reasonable in terms of ecological expectations despite recognized model weaknesses. Increasing sample size to capture a greater diversity of stand types and allow for species-specific modeling would no doubt result in much better predictions.

Increasing liana biomass and carbon stocks in tropical dry evergreen forests of southern India

Tropical forests act as a great carbon reservoir covering about 30% of the global carbon content, however, structural alteration of these forests caused by forest disturbances adversely affects the carbon cycle. One such structural change happening in these tropical forests is the increasing dominance of lianas (woody climbers). Among various tropical forest types, lianas are an integral constituent of the tropical dry evergreen forests (TDEFs) found in peninsular India. A re-inventory of lianas was carried out to observe temporal changes in basal area and carbon stock in two 1-ha permanent plots of two disturbed tropical dry evergreen forest sites (TDEF; Oorani -OR and Puthupet - PP) over a 19-year interval (2001-2020). The total basal area in OR and PP increased respectively by 2.26 m2 ha-1 and 0.93 m2 ha-1. The total biomass and the carbon stock in OR and PP increased by 82% and 51% respectively. The dominant species Strychnos lenticellata showed an increase in its basal area by three-fold in OR, whereas, in PP, a marginal increase of 4% was observed. The lower diameter class (1-6 cm) showed an increase in basal area in OR and PP by 101% and 16% respectively. The mid-diameter class (6-11 cm) was the top contributor of the total biomass/carbon in both OR and PP in the latest re-inventory (2020). The present results show that lianas, although known to negatively affect the forest biomass/carbon stock, play an important role in carbon sequestration, thus providing insights into their ecological importance which will certainly be useful in proposing strategies for the conservation of this forest type dominated by lianas.

Spatiotemporal trends of black walnut forest stocking under climate change

Basal area is a key measure of forest stocking and an important proxy of forest productivity in the face of climate change. Black walnut (Juglans nigra) is one of the most valuable timber species in North America. However, little is known about how the stocking of black walnut would change with differed bioclimatic conditions under climate change. In this study, we projected the current and future basal area of black walnut. We trained different machine learning models using more than 1.4 million tree records from 10,162 Forest Inventory and Analysis (FIA) sample plots and 42 spatially explicit bioclimate and other environmental attributes. We selected random forests (RF) as the final model to estimate the basal area of black walnut under climate change because RF had a higher coefficient of determination (R2), lower root mean square error (RMSE), and lower mean absolute error (MAE) than the other two models (XGBoost and linear regression). The most important variables to predict basal area were the mean annual temperature and precipitation, potential evapotranspiration, topology, and human footprint. Under two emission scenarios (Representative Concentration Pathway 4.5 and 8.5), the RF model projected that black walnut stocking would increase in the northern part of the current range in the USA by 2080, with a potential shift of species distribution range although uncertainty still exists due to unpredictable events, including extreme abiotic (heat, drought) and biotic (pests, disease) occurrences. Our models can be adapted to other hardwood tree species to predict tree changes in basal area based on future climate scenarios.

Long-term changes in floristic diversity, composition and stand structure in Acacia auriculiformis plantation in Mount Makiling Forest Reserve, Philippines

Abstract. Hernandez JO, Ata JP, Combalicer MS. 2022. Long-term changes in floristic diversity, composition and stand structure in Acacia auriculiformis plantation in Mount Makiling Forest Reserve, Philippines. Biodiversitas 23: 3631-3638. There have been continuous debates about whether exotic tree plantation facilitates vegetation succession. In the Philippines, the potential for the re-establishment of native plant communities and improvement of the plant community structure under exotic tree plantations has not yet been evaluated adequately. Thus, the study investigated the dynamics in floristic diversity, composition and stand structure of a reforested area using Acacia auriculiformis Benth. in Sitio Kay Inglesia, Mount Makiling Forest Reserve (MMFR), Philippines. The changes in basal area, stem density, biomass growth, species diversity, species evenness and richness, and canopy closure were determined between two study periods, i.e., 1993-2008 and 2009-2019. Results revealed significant changes in stem density (i.e., 1324 to 2135 trees ha-1) and canopy closure (i.e., 18% to 10%) for mature trees and seedlings/saplings in 2009-2019. The changes in basal area and aboveground biomass were not significant between the two study periods. The species richness was significantly higher in 2009-2019 (i.e., 55 species) than in 1993-2008 (i.e., 22 species). The species diversity also significantly increased from low (i.e., H' = 1.99, S = 23) to moderate (i.e., H' = 2.88, S = 55). Moreover, the number of exotics decreased (i.e., 60 to 40% or 15 to 9 species) as the number of native ones increased (i.e., 27 to 72% or 15 to 40 species). Therefore, the findings of the present study show that re-establishment of native species is possible when restoring degraded land with A. auriculiformis plantation. However, monitoring studies on other key ecosystem attributes (e.g., ecosystem functionality, external exchanges, structural diversity) of the plantation are recommended to enhance our understanding of the species' potential for restoration.

Functional traits and propagule pressure explain changes in the distribution and demography of non‐native trees in Spain

AbstractQuestionsNon‐native tree species (NNT) may bring about economic benefits, but also threats to ecosystems, mostly if they show expansive trends.LocationA set of 12,000 permanent plots of the second (1986–1996), third (1997–2007) and fourth (2008–2017) Spanish Forest Inventory.MethodsWe quantified changes over time (1986–2017) of the NNT present in forests of peninsular Spain and we assessed how NNT’s traits, propagule pressure and human perception of NNT explain changes in distribution and demography of NNT. We quantified changes in four demographic parameters of every NNT: changes in the occupancy of species (number of plots where the species are present), annual changes in tree density and basal area, and tree growth. To explain the observed species trends, we selected functional traits related to the resource acquisition strategy, and key human drivers.ResultsMost of the NNT expanded their occupancy in the study area and increased their density, basal area, and tree growth through time. Increases in tree density and growth were greater in NNT with greater tolerance for low water potentials, with low specific leaf area, and with high propagule pressure. Increases in basal area were greater with high height of the NNT.ConclusionsThe overall increase in occupancy suggests that there is room for expansion of NNT in Spain. This knowledge will help to predict the dynamics of NNT already present in Spain and identify risks for forest biodiversity.

Tree growth response to drought partially explains regional-scale growth and mortality patterns in Iberian forests.

Tree-ring data has been widely used to inform about tree growth responses to drought at the individual scale, but less is known about how tree growth sensitivity to drought scales up driving changes in forest dynamics. Here, we related tree-ring growth chronologies and stand-level forest changes in basal area from two independent data sets to test if tree-ring responses to drought match stand forest dynamics (stand basal area growth, ingrowth, and mortality). We assessed if tree growth and changes in forest basal area covary as a function of spatial scale and tree taxa (gymnosperm or angiosperm). To this end, we compared a tree-ring network with stand data from the Spanish National Forest Inventory. We focused on the cumulative impact of drought on tree growth and demography in the period 1981-2005. Drought years were identified by the Standardized Precipitation Evapotranspiration Index, and their impacts on tree growth by quantifying tree-ring width reductions. We hypothesized that forests with greater drought impacts on tree growth will also show reduced stand basal area growth and ingrowth and enhanced mortality. This is expected to occur in forests dominated by gymnosperms on drought-prone regions. Cumulative growth reductions during dry years were higher in forests dominated by gymnosperms and presented a greater magnitude and spatial autocorrelation than for angiosperms. Cumulative drought-induced tree growth reductions and changes in forest basal area were related, but initial stand density and basal area were the main factors driving changes in basal area. In drought-prone gymnosperm forests, we observed that sites with greater growth reductions had lower stand basal area growth and greater mortality. Consequently, stand basal area, forest growth, and ingrowth in regions with large drought impacts was significantly lower than in regions less impacted by drought. Tree growth sensitivity to drought can be used as a predictor of gymnosperm demographic rates in terms of stand basal area growth and ingrowth at regional scales, but further studies may try to disentangle how initial stand density modulates such relationships. Drought-induced growth reductions and their cumulative impacts have strong potential to be used as early-warning indicators of regional forest vulnerability.

Biotic, abiotic, and anthropogenic drivers of demographic performance of non-native Eucalyptus and Pinus species in forested areas of Spain

Non-native trees enhance services that are fundamental for human well-being. Yet, the extensive use of non-native trees has the potential of causing environmental and socio-economic harm. Eucalyptus and Pinus are the most widely distributed and extensively planted tree genera worldwide, because their rapid growth allows profitable production of timber and pulp. Their naturalization is causing severe effects on the environment, but the relative importance of underlying factors determining their demographic performance is not well known. Thus, our aim was to evaluate the relative importance of biotic, abiotic, and anthropogenic factors driving demographic changes of Eucalyptus and Pinus at the regional scale. We compiled environmental variables and demographic data for Eucalyptus globulus, Eucalyptus camaldulensis, and Pinus radiata across 6388 permanent forestland plots surveyed in the Spanish Forest Inventory (SFI). We used the second (1986–1996), third (1997–2007), and fourth (2008–2017) SFI datasets to quantify annual changes in basal area per plot between consecutive inventories (ΔBA; m2 ha−1 year−1). We also quantified the components of ΔBA: tree ingrowth (transitions from juvenile to adult trees), growth, and mortality. We evaluated juvenile recruitment with in-situ regeneration (No. juvenile trees ha−1) within plots already occupied by the focal species in the previous inventory, and with natural colonization of plots where the focal species was absent at the beginning of the time interval. We found that the structure of the biotic community was especially important to explain demographic performance of non-native trees growing in benign environments (E. globulus and P. radiata), whereas abiotic factors were particularly important regulating basal area increments of E. camaldulensis, which occurs in harsher environments. Basal area increments decreased with species and functional richness, heterospecific density, mean annual temperature, and increased with soil capacity to retain nutrients and water. Colonization of new plots increased with propagule availability in the surrounding landscape. Tree cutting was beneficial for P. radiata. Collectively, our results suggest that non-native trees perform better in forests with high propagule pressure, low biotic resistance, favourable abiotic conditions, and human management.

Temperature effect on size distributions in spruce-fir-beech mixed stands across Europe

Forest composed of Picea abiesL., Abies alba Mill. and Fagus sylvatica L. cover a large area in the European mountain regions and have a high ecological and socio-economic importance as they supply many ecosystems services. Because of climate change, these forests are exposed to warming, and this effect increases with elevation, which may impact their delivery of goods and services. Previous studies did not find significant changes in the overall productivity of these species over the last 30 years, but they observed changes in species competitiveness at the species and tree levels.In this study, we aimed to link previous results on tree, species and stand level growth in spruce-fir-beech mixed mountain forests by analysing species size distribution dynamics under different climate conditions and their effect on stand growth. We developed a matrix model based on data from 76 long-term experimental plots distributed throughout Europe. We used the change in stand basal area to explore whether temperature modifies species size dominances and proportions, whether the temperature effects on changes in species basal area depend on species size dominance, and whether the effect of species size dominance on changes in the stand basal area varies with temperature.Our results showed that annual mean temperature is an important climatic driver of species dynamics in spruce-fir-beech mixed mountain forests, such that stand basal area growth was favored by higher temperatures, particularly due to positive responses of silver fir which were greater than negative effects of temperature on European beech. The high temperatures also favored the size-dominance of silver fir, while European beech tended to have smaller diameters, independent of the temperature. We also found that the identity of the size-dominant species also influenced changes in stand basal area, with the highest or the lowest changes when Norway spruce and European beech were the size-dominant species, respectively. Silver fir was less influenced by the identity of the size-dominant species than by temperature.Therefore, although mixed mountain forests of spruce-fir-beech were found to be resilient systems in terms of stand productivity, we conclude that increasing temperatures may modify species dynamics and consequently silvicultural interventions will be needed to control species proportions and dominances.

Phenotyping the right heart according to left ventricular geometry patterns in severe HFrEF

Abstract Background Right ventricular (RV) failure significantly impact on heart failure with reduced ejection fraction (HFrEF) prognosis. How and whether specific functional and geometrical phenotypes of the RV function adapt and combined with left ventricular (LV) geometry is unknown. Purpose To test the RV function across LV geometrical patterns looking at respective prognostic roles. Methods We retrospectively examined a population of patients homogenously diagnosed with chronic HFrEF (defined as LV ejection fraction (EF) less than 35%) and treated with optimal therapy (OT) and all implanted with ICD for primary prevention of sudden cardiac death. Patients were categorized by echocardiography according to remodeling pattern based on left ventricular mass index and relative wall thickness into four groups: normal geometry (NG), concentric remodeling (CR), concentric hypertrophy (CH) and eccentric hypertrophy (EH). RV parameters were: tricuspid annulus plane systolic excursion (TAPSE), TAPSE/pulmonary artery pressures (PAPs), RV basal diameter and fractional area change (FAC). Outcome variable was all-cause mortality, assessed with multivariable Cox proportional hazard (PH) models. Results Among 193 patients (age 66±11 years, 81% men, 74% with ischemic etiology of HF and EF 28±5%) 21% had NG, 3% had CR, 8% had CH, and 68% had EH. Distribution of RV echo parameters across LV remodeling groups is shown in table 1. Over a median follow-up time of 4 (1.9 – 6.1) years, 65 deaths occurred. In multivariable Cox PH models adjusted for age, LVEF, ischemic etiology and LV geometry, TAPSE, TAPSE/PAPs, RV basal diameter and FAC strongly and independently predicted the outcome variable [HR 0.92 (95% C.I. 0.86–0.98), HR 0.08 (95% C.I. 0.01–0.57), HR 1.87 (95% C.I. 1.29–2.71), HR 0.97 (95% C.I. 0.95–1.00), respectively all p-value <0.05]. Conclusion In a homogeneously defined population of severe HFrEF outpatients receiving OT, the majority showed EH remodeling pattern, which did not predict the primary outcome. LV geometry did not further stratify patients in this high risk group. Conversely, RV dysfunction proved to be a strong predictor of mortality, independently of age, LV function and etiology of HF, regardless LV morphology. Funding Acknowledgement Type of funding sources: None.

High growth recovery ability of Eucalyptus grandis trees following a 3-year period of 80% throughfall reduction

Eucalyptus plantations are already planted in - or expanding to - water-limited regions with a high risk of severe drought. In future drier and more variable climate including extreme events, the ability of trees to recover after severe droughts emerges as a crucial for the sustainability of forest plantations.An original experiment involving 80% reduction in throughfall was set up in Brazil to gain insight into the responses of Eucalyptus grandis trees to prolonged (3-year) extreme water deficit and the ability of this species to recover following water stress. Our study focused on the changes in basal area, stem radius, and total height measured by high-temporal resolution dendrometers and periodical surveys of trees affected by 80% throughfall reduction (treatment group) and in a control group. The differences in basal area, stem radius, and total height growth rate were compared between groups over (i) 37 months of 80% throughfall reduction and (ii) 31 months following the end of 80% throughfall reduction. The correlations among growth rates, stem radius fluctuations, and meteorological variables in each group were determined to gain insights into the trees’ responses to environmental conditions and stem water status.The 80% reduction in throughfall over 3 years significantly reduced tree growth rates by 73% in basal area and 95% in total height. However, under normal water availability following throughfall reduction, the basal area growth rate of water-stressed trees was 97% higher than that of the control trees while total height growth rate was only 8% higher. Despite the severe water stress, no tree mortality was observed. Trees recovered 51% of their basal area over the 31-month recovery period. In contrast, only 5% of total height was recovered.In the treatment group, rapid responses to variation in rainfall events were observed during the 80% throughfall reduction period. Also, correlations between stem radius fluctuations and vapor pressure deficit indicate increased transpiration following the end of throughfall reduction. These relationships indicate high conservation of the integrity of the xylem vascular system over the 3 years of 80% throughfall reduction, a key factor in the increased resilience of the trees. In the absence of tree mortality, our results suggest the 80% throughfall reduction had a severe impact on tree growth but demonstrate great recovery ability of Eucalyptus grandis trees in basal area growth following such a severe water deficit.

Are leaf, stem and hydraulic traits good predictors of individual tree growth?

Abstract A major foundation of trait‐based ecology is that traits have an impact on individual performance. However, trait–growth relationships have not been extensively assessed in trees, especially outside tropical ecosystems. In addition, measuring traits directly related to physiological processes remains difficult and the differences between inter‐ and intraspecific relationships are seldom explored. Here, we use individual‐level data on a set of hydraulic, leaf and stem traits to assess their ability to predict basal area increment (BAI) and growth efficiency (BAI per unit of tree leaf area, GE) among and within species for six dominant tree species along a water availability gradient under Mediterranean climate (Catalonia, NE Spain). Measured traits include: leaf mass per area (LMA), leaf nitrogen concentration (N), leaf C isotopic composition (δ13C), the leaf water potential at turgor loss (Ptlp), stem wood density (WD) and branch‐level estimates of the Huber value (Hv), sapwood‐ and leaf‐specific hydraulic conductivity (KS and KL) and resistance to xylem embolism (P50). Trait–growth associations were generally weak, particularly for BAI and within species. High values of both growth metrics were associated with ‘conservative’ leaf and hydraulic traits. In particular, BAI was negatively associated with KL (and wood density), while GE increased with LMA, allocation to sapwood relative to leaves (Hv) and resistance to xylem embolism (P50). Climate effects on BAI and GE were indirectly mediated by changes in traits, stand structure and tree basal area. Overall, these results suggest that maintaining functionality over extended periods of time may be more important than maximum gas exchange or hydraulic capacity to achieve high radial growth under Mediterranean climates. Our study reveals that widely used ‘functional traits’ may be poor predictors of tree growth variability along environmental gradients. Moreover, trait effects (when present) do not necessarily conform to simple hypotheses based on our understanding of organ‐level processes. An improved understanding of trait coordination along common axes of variation together with a revaluation of the variables that better reflect whole‐tree performance can greatly improve our understanding of trait–growth relationships. A free Plain Language Summary can be found within the Supporting Information of this article.

Changes in host basal area explain associational resistance of mixed forests to primary pests

Tree species diversity generally has positive effects on forest primary productivity and resistance to natural perturbations, but diversity-function relationships can vary with site conditions. Recently, studies in forest diversity experiments have shown that tree diversity and local climate, in particular drought intensity, interactively affect insect herbivory. On the other hand, many studies focused on the response of forests to drought in terms of tree growth but without analysing the concomitant effects on susceptibility to pests. It is of particular interest to understand the combined effects of drought and tree diversity on the growth of the host tree, since host resource concentration is a determining factor of a pest’s host choice.We used a tree diversity experiment where tree species diversity and drought conditions were both manipulated to evaluate their interactive effects on the susceptibility of maritime pine (Pinus pinaster Aït.) forests to two primary pests (i.e. infesting healthy trees): the pine stem borer (PSB) Dioryctria sylvestrella, and the pine processionary moth (PPM; a leaf chewer), Thaumetopoea pityocampa. Using structural equation models, we investigated the direct and indirect effects (i.e. mediated by host resources) of the presence of birch and drought on the total number of attacks of PPM and PSB, in the same plots and in the same year.We showed that pine-birch plots were more resistant to both PPM and PSB attacks than pine monocultures. Furthermore, we found that this associational resistance pattern was due to direct effects of birch trees on attacks, possibly related to disrupting non-host volatiles (NHVs), but also to indirect, resource-mediated effects whereby the presence of birch trees reduced the amount of host pine resources available to the pests. Drought conditions modulated birch mediated effects on resistance of maritime pine forests only for PSB attacks. Overall, our work improves our understanding of tree diversity-herbivory relationships and helps explain how climate might modulate such relationships.

Stand-scale climate change impacts on forests over large areas: transient responses and projection uncertainties.

The increasing impacts of climate change on forest ecosystems have triggered multiple model‐based impact assessments for the future, which typically focused either on a small number of stand‐scale case studies or on large scale analyses (i.e., continental to global). Therefore, substantial uncertainty remains regarding the local impacts over large areas (i.e., regions to countries), which is particularly problematic for forest management. We provide a comprehensive, high‐resolution assessment of the climate change sensitivity of managed Swiss forests (~10,000 km2), which cover a wide range of environmental conditions. We used a dynamic vegetation model to project the development of typical forest stands derived from a stratification of the Third National Forest Inventory until the end of the 22nd century. Two types of simulations were conducted: one limited to using the extant local species, the other enabling immigration of potentially more climate‐adapted species. Moreover, to assess the robustness of our projections, we quantified and decomposed the uncertainty in model projections resulting from the following sources: (1) climate change scenarios, (2) local site conditions, and (3) the dynamic vegetation model itself (i.e., represented by a set of model versions), an aspect hitherto rarely taken into account. The simulations showed substantial changes in basal area and species composition, with dissimilar sensitivity to climate change across and within elevation zones. Higher‐elevation stands generally profited from increased temperature, but soil conditions strongly modulated this response. Low‐elevation stands were increasingly subject to drought, with strong negative impacts on forest growth. Furthermore, current stand structure had a strong effect on the simulated response. The admixture of drought‐tolerant species was found advisable across all elevations to mitigate future adverse climate‐induced effects. The largest uncertainty in model projections was associated with climate change scenarios. Uncertainty induced by the model version was generally largest where overall simulated climate change impacts were small, thus corroborating the utility of the model for making projections into the future. Yet, the large influence of both site conditions and the model version on some of the projections indicates that uncertainty sources other than climate change scenarios need to be considered in climate change impact assessments.