Variation In Tree Growth Research Articles

Effects of deficit irrigation treatments on yield and plant growth of young apricot trees

An experiment was conducted to investigate the effects of deficit irrigation on yield and tree growth of young apricot trees (Prunus armeniaca L. cv. Ninfa) during three growing seasons with three irrigation intervals (7, 14 and 21 days) and five irrigation levels based on reduction coefficients (Kcp) of class A pan evaporation (0.0, 0.25, 0.50, 0.75 and 1.00). Growth and yield variables such as trunk diameter, mean branch length, volume of tree, total number of fruit, mean fruit weight, total fruit yields of trees, evapotranspiration and water use efficiencies were determined. While the irrigation interval treatments had significant effects on trunk diameters and branch lengths of the trees, the irrigation level treatments significantly affected all the tree growth variables. Variation in irrigation level also affected yield, with yield and fruit size increasing as irrigation increased up to at least 0.75 of pan evaporation. The treatment with 25% water deficit and a 14-day irrigation interval is suggested as the most suitable irrigation strategy for young apricot trees under a Mediterranean climate.

Forestry under Climate Change. Is Time a Tool for Sustainable Forest Management?

Changing climate conditions are known to influence forest tree growth response and the CO2 cycle. Dendroclimatological research has shown that the climate signal, species composition, and growth trends have changed in different types of forest ecosystems during the last century. Under current and demonstrated changes in climate variability at the geographic, regional, and local levels tree growth shows also variability and trends that can be non-stationary during time even at relatively short distance between sites. In forest planning and management, yield tables, site quality indices, age class, rate of growth, and spatial distribution are some of the most used tools and parameters. However, these methods do not involve climate variability during time although climate is the main driver in trends of forest and tree growth. Previous research warns about the risk that forest management under changing climatic conditions could amplify their negative effects. For example, changing climate conditions may impact on temperature and/or precipitation thresholds critical to forest tree growth. Forest biomass, resilience, and CO2 storage may be damaged unless forest planning and management implement the relationships between climate variability and trends of tree growth. A positive aspect is that, periods of favorable climate conditions may allow harvesting higher amount of wood mass and storing more CO2 than traditional planning methods. And, the average length of both favorable and adverse periods appears to occur within the validity period of a forest management plan. Here, we show a conceptual development to implement climate variability in forest management in the view of continuing the research.

Canopy Layers Stratified Volume Equations for Pinus caribaea Stands in South West Nigeria using Linear Mixed Models

Background and Purpose: Efficient forest stand management requires reliable estimates of growing stock. The reliability of stem volume estimates depends on the range and extent of available sample data. The potentials of canopy layers stratification in pure plantations as a means of improving the accuracy of stem volume equations have not been fully explored. Linear Mixed Model (LMM) approach is a statistical technique capable of yielding a more efficient prediction under clustered data structure. This study investigates the existence and potentials of canopy stratifications for improving the reliability of stem volume prediction equations under pure plantations using linear mixed model approach. Materials and Methods: Pinus caribaea Morelet plantations in Oluwa Forest Reserve, Ondo State, Nigeria were investigated. Individual tree growth variables, including diameters, heights and crown measurements were obtained in 2010 on twenty-five 0.04 ha plots representing five different stands planted between 1979 and 1991. Visual assessment of the trees within each plot was also done to classify them into four canopy strata (i.e. dominant, co-dominant, intermediate and suppressed). Linear mixed model approach was used to analyze the tree growth data using SAS Proc Mixed. Two variants of volume equations; simple linear and exponential were investigated. Results: Results show that simple linear mixed model consistently give better fit criteria (e.g. AIC) of 135.8, 18.9, -214.7 and -174.6 under dominant, co-dominant, intermediate and suppressed canopy layers, respectively. The covariance parameter estimate for dominant canopy (0.2219) is about 370 as large as that of suppressed (0.0006). This implies that canopy layers not only influence stem volume prediction but also reduce within-stand variance as well.

Climate variability, soil aridity, and growth rate of Pinus pinea L. in Castelporziano forest: an exploratory data analysis

Sensitivity to climate change and anthropogenic disturbance is a typical feature of Mediterranean forests growing under dynamic and manipulated environmental conditions. In the present study, a large sample of stone pines (Pinus pinea L.) was analyzed in five sites of Castelporziano and Castelfusano forests (Rome, central Italy) to assess tree-growth variability (1964–2009) with the aim to derive information on long-term climatic trends possibly reflected in the radial growth response. The multivariate exploratory analysis of tree ring widths, which were standardized to remove the age trend, showed a marked spatial variability among sites and a heterogeneous time pattern that allows for the classification of the investigated years into three homogeneous groups: 1964–1974, 1975–1997, and 1998–2009. The years 1975 and 1998 were identified as the candidate break points in the local climate regime. Coherence of the 1998 break point was verified by comparing two time intervals (1981–1997 and 1998–2011) of the meteorological time series of precipitation and temperatures available for Castelporziano station. Results indicate a significant shift toward aridity and warming in the area supporting the information obtained from the analysis of dendro-chronological time series. Implications of the spatio-temporal monitoring of climate variations through indirect sources are discussed in the light of conservation of the residual pristine forest of Castelporziano taken as a paradigmatic example for other Mediterranean coastal forests.

Long-term changes in tree basal area across the boreal zone, Canada

Permanent forest plots (PSP) were used to investigate long-term basal-area tree growth rates across the boreal forests in Canada. The objectives were to discern whether or not these rates i) are similar across the boreal zone and ii) correlate to change in climate from 1970 to 2010. The results show that rates vary by region, with decreasing growth rates for about 60% of individual trees in western Canada (Alberta, Saskatchewan, Manitoba) but increasing rates for about 70% of individual trees in eastern Canada (Ontario and Quebec). These changes are interpreted from an overall carbon sequestration perspective and within the context of available precipitation and air temperature data and an annual climate moisture index. This study provides long-term plot-based evidence for the ecological variability and regional differences in tree growth detected by satellite-based remote-sensing and tree-ring studies in Canada's boreal forests.

Evaluating the effects of liming and wood-ash treatment on forest ecosystems through systematic meta-analysis

Liming and wood-ash addition have long been used to attenuate the effects of acidic deposition on forest soils with the goal of promoting tree growth. We performed quantitative meta-analyses of treatment studies from managed forest ecosystems to assess general tendencies of effects of treatment on seven selected measures of performance thought to reasonably reflect the effects of Ca-addition treatment. We retrieved over 350 independent trials from 110 peer-reviewed liming and wood-ash addition studies that were integrated to determine soil pH, base saturation (BS), tree foliar Ca concentration, tree growth, ectomychorrhizae root colonization, soil C-to-N ratio, and microbial indices. The results were quantified through three separate meta-analysis effect size metrics: unweighted relative values and two weighted metrics, Hedges’ d and ln R. A surprising number of treatment trials (22%–85%) reported no significant effect, and soil pH and foliar Ca appeared more responsive to liming than to wood-ash addition, whereas BS and tree growth appeared more responsive to wood-ash addition. For six of the seven parameters, estimated mean effect sizes were similar in magnitude and positive in direction for all three meta-analysis metrics. Regression tree optimal models explained 38% of the variation in pH, 47% of the variation in BS, 51% of the variation in foliar Ca concentration, and 26% of the variation in tree growth. The largest predictors of effect size, within our selected group, were as follows: soil type for pH; soil type, trial duration in years, and species (hardwood or softwood) for BS; treatment dose and type for foliar Ca concentration; and trial duration, initial soil pH, and tree species for tree growth. This analysis shows that Ca additions are not universally beneficial and provides insight into when Ca additions to forest soils are likely to be most effective.

Parsimonious Crown Diameter Prediction Models for Tectona Grandis (Linn f Verbenaceae).

Tree crown is one complement of net primary production and its dimensions reflect general tree health. Crown diameter is often used as an important predictor variable for tree growth equation. The objective of the study was to develop parsimonious crown diameter prediction models for Tectona grandis (Linn F. Verbenaceae). Based on the data set from the temporary sample plots, several equations including linear, parable, cubic, power, growth and exponential functions were tested. These functions were evaluated in terms of coefficient of determination (R2) and standard error of the estimate (SEE). The significance of the estimated parameters was also verified. Plots of residuals against estimated crown diameter were observed. The power model had the highest R2 and the least SEE compared with the other models. It is therefore recommended as a parsimonious model for predicting crown diameter in the stand.Key Words: crown diameter, tree growth variables, modeling, Tectona grandis

Species coexistence in a mixed Mediterranean pine forest: Spatio-temporal variability in trade-offs between facilitation and competition

Studying species coexistence is key to understanding the way in which forests will respond to climate change. We studied the patterns of mixed stands including two main Mediterranean pine species: Pinus pinaster Ait. and Pinus pinea L. The spatial distribution of adult trees and saplings was studied via a point pattern approach. The effect of competition on growth of adult trees was investigated by comparing the performance of several competition indexes for each pine species through generalized linear models. Adult trees formed mixed clumps in which individuals of both species appeared together. Part of the tree growth variation was explained by tree size along with tree competition. However, the effect of conspecific vs heterospecific competition on tree growth differed and reflected species-specific neighbor-asymmetric competition. Facilitation was fundamental in the early stages for tree species development. The spatial distribution of saplings was strongly related to the spatial distribution of adult trees, also being asymmetrically clustered and neighbor-species-dependent. However, the required facilitation in early life-stage trees shifted to competition among trees in the adult stage. Species mixture may be desirable in terms of increasing and diversifying productivity, although the conditions currently present in the stand are likely to lead to future dominance of P. pinea over P. pinaster due not only to the greater competition tolerance of the former but also to a greater ability to successfully recruit in the plots, forming clusters that may be in turn be impenetrable to P. pinaster. Therefore, in order to maintain mixed stands, it would be necessary to enforce adequate silvicultural management strategies which avoid future stand dominance by P. pinea.

Pan-tropical analysis of climate effects on seasonal tree growth.

Climate models predict a range of changes in tropical forest regions, including increased average temperatures, decreased total precipitation, reduced soil moisture and alterations in seasonal climate variations. These changes are directly related to the increase in anthropogenic greenhouse gas concentrations, primarily CO2. Assessing seasonal forest growth responses to climate is of utmost importance because woody tissues, produced by photosynthesis from atmospheric CO2, water and light, constitute the main component of carbon sequestration in the forest ecosystem. In this paper, we combine intra-annual tree growth measurements from published tree growth data and the corresponding monthly climate data for 25 pan-tropical forest sites. This meta-analysis is designed to find the shared climate drivers of tree growth and their relative importance across pan-tropical forests in order to improve carbon uptake models in a global change context. Tree growth reveals significant intra-annual seasonality at seasonally dry sites or in wet tropical forests. Of the overall variation in tree growth, 28.7% was explained by the site effect, i.e. the tree growth average per site. The best predictive model included four climate variables: precipitation, solar radiation (estimated with extrasolar radiation reaching the atmosphere), temperature amplitude and relative soil water content. This model explained more than 50% of the tree growth variations across tropical forests. Precipitation and solar radiation are the main seasonal drivers of tree growth, causing 19.8% and 16.3% of the tree growth variations. Both have a significant positive association with tree growth. These findings suggest that forest productivity due to tropical tree growth will be reduced in the future if climate extremes, such as droughts, become more frequent.

Volume yield, tree species diversity and carbon hoard in protected areas of two developing countries

The contributions of Protected Areas (PAs) in two developing countries (India and Nigeria) to biodiversity conservation and carbon accumulation were assessed in this study. Data were collected through field inventory from 12 plots (25 × 25 m) randomly located in each of the PAs. In each plot, all woody plants were identified and tree growth variables were measured for trees with diameter at breast height ≥10 cm. We discovered that the two PAs are well stocked, mature and rich in tree species diversity with potentials for continuous growth as a result of the presence of young trees in the lower canopy. The biological diversity indices compared favorably with other similar PAs. The high above-ground biomass and carbon of the tree species revealed the roles of PAs in climate change mitigation through CO2 absorption from the atmosphere. The difference in their phytosociological characteristics and carbon sink capacities, with higher values obtained for Nigerian forest, was attributed to the variation in geographical location, climatic conditions and soil properties. The protection of these PAs should be enhanced for biodiversity conservation and climate change mitigation. The perceived challenges in developing countries with forest protection can be mitigated by introducing some institutional policies and rural community involvement in forest management.

An individual-based growth and competition model for coastal redwood forest restoration

Thinning treatments to accelerate coastal redwood forest stand development are in wide application, but managers have yet to identify prescriptions that might best promote Sequoia sempervirens (Lamb. ex D. Don) Endl. (redwood) growth. The creation of successful thinning prescriptions would be aided by identifying the underlying mechanisms governing how individual tree growth responds to competitive environments in coastal redwood forests. We created a spatially explicit individual-based model of tree competition and growth parameterized using surveys of upland redwood forests at Redwood National Park, California. We modeled competition for overstory trees (stems ≥ 20 cm stem diameter at breast height, 1.37 m (dbh)) as growth reductions arising from sizes, distances, and species identity of competitor trees. Our model explained up to half of the variation in individual tree growth, suggesting that neighborhood crowding is an important determinant of growth in this forest type. We used our model to simulate the effects of novel thinning prescriptions (e.g., 40% stand basal area removal) for redwood forest restoration, concluding that these treatments could lead to substantial growth releases, particularly for S. sempervirens. The results of this study, along with continued improvements to our model, will help to determine spacing and species composition that best encourage growth.

Temperature and rainfall strongly drive temporal growth variation in Asian tropical forest trees

Climate change effects on growth rates of tropical trees may lead to alterations in carbon cycling of carbon-rich tropical forests. However, climate sensitivity of broad-leaved lowland tropical trees is poorly understood. Dendrochronology (tree-ring analysis) provides a powerful tool to study the relationship between tropical tree growth and annual climate variability. We aimed to establish climate-growth relationships for five annual-ring forming tree species, using ring-width data from 459 canopy and understory trees from a seasonal tropical forest in western Thailand. Based on 183/459 trees, chronologies with total lengths between 29 and 62 years were produced for four out of five species. Bootstrapped correlation analysis revealed that climate-growth responses were similar among these four species. Growth was significantly negatively correlated with current-year maximum and minimum temperatures, and positively correlated with dry-season precipitation levels. Negative correlations between growth and temperature may be attributed to a positive relationship between temperature and autotrophic respiration rates. The positive relationship between growth and dry-season precipitation levels likely reflects the strong water demand during leaf flush. Mixed-effect models yielded results that were consistent across species: a negative effect of current wet-season maximum temperatures on growth, but also additive positive effects of, for example, prior dry-season maximum temperatures. Our analyses showed that annual growth variability in tropical trees is determined by a combination of both temperature and precipitation variability. With rising temperature, the predominantly negative relationship between temperature and growth may imply decreasing growth rates of tropical trees as a result of global warming.

Understanding causes of tree growth response to gap formation: ∆13C-values in tree rings reveal a predominant effect of light

Carbon isotope ratios in growth rings of a tropical tree species show that treefall gaps stimulate diameter growth mainly through changes in the availability of light and not water. The formation of treefall gaps in closed canopy forests usually entails considerable increases in light and nutrient availability for remaining trees, as well as altered plant water availability, and is considered to play a key role in tree demography. The effects of gaps on tree growth are highly variable and while usually stimulatory they may also include growth reductions. In most studies, the causes of changes in tree growth rates after gap formation remain unknown. We used changes in carbon isotope 13C discrimination (Δ13C) in annual growth rings to understand growth responses after gap formation of Peltogyne cf. heterophylla, in a moist forest of Northern Bolivia. We compared growth and Δ13C of the 7 years before and after gap formation. Forty-two trees of different sizes were studied, half of which grew close (<10 m) to single treefall gaps (gap trees), the other half more than 40 m away from gaps (controls). We found variable responses among gap trees in growth and Δ13C. Increased growth was mainly associated with decreased Δ13C, suggesting that the growth response was driven by increased light availability, possibly in combination with improved nutrient availability. Most trees showing zero or negative growth change after gap formation had increased Δ13C, suggesting that increased water stress did not play a role, but rather that light conditions had not changed much or nutrient availability was insufficient to support increased growth. Combining growth rates with Δ13C proved to be a valuable tool to identify the causes of temporal variation in tree growth.

Tree Growth and Resilience to Extreme Drought Across an Urban Land-use Gradient

Understanding the response of urban forests to extreme climatic events, such as drought, will be essential to predicting impacts of climate change on the urban tree canopy and related ecosystem services. This study evaluated variation in tree growth and drought resistance (growth during drought) and resilience (growth in period following drought) across four land-use categories (built, transportation, park, and semi-natural forest) and four species (Acer saccharum, Gymnocladus dioicus, Liriodendron tulipifera, and Pinus strobus) at The Morton Arboretum in suburban Lisle, Illinois, U.S. Tree growth and resistance to drought both varied as an interaction between landuse and species (F15, 100 = 5.25, p &lt; 0.001; F15, 100 = 2.42, p = 0.005). Resilience of tree growth to extreme drought was generally high and did not vary across species and land-uses. In this study, individual tree species responses to drought varied across land-uses, illustrating the difficulty of predicting the reaction of urban forests to projected increases in the frequency of extreme climatic events. Tree growth response to drought varied even across the relatively narrow range of growing conditions studied here. Investigation of a broader range of sites, encompassing the full urban forest continuum, would likely demonstrate even greater variation in tree response to extreme climatic events.

Foliar and litter needle carbon and oxygen isotope compositions relate to tree growth of an exotic pine plantation under different residue management regimes in subtropical Australia

Background and aim Significant differences in tree growth were observed in an exotic pine plantation under different harvest residue management regimes at ages 2–10 years. However, the variations in tree growth between residue management treatments could not be explained by soil and foliar nutrient analyses, except by potassium (K) concentration. Therefore, this study determined the carbon isotope composition (δ13C) and oxygen isotope composition (δ18O) of current and archived foliar samples from the exotic pine plantation to establish relationships with foliar K concentration and tree growth indices as a means to determine changes in stomatal conductance (gs) and photosynthetic rate (Amax) or water use efficiency (WUE), and therefore understand the variations in tree growth across treatments.

Growth rate and climate responses of Pinus pinea L. in Italian coastal stands over the last century

Sensitivity to climate change and anthropogenic disturbance is a typical feature of Mediterranean forests, which grow under dynamic and manipulated environmental conditions. In this study, we examine stone pine (Pinus pinea L.) along the Tyrrhenian coast of Italy to analyse the tree-growth variability on a temporal scale and to evaluate the radial growth response to climate trends over the last century. The analysis of tree ring widths at the decadal and multidecadal scale, which were standardised to remove the age trend, showed primarily significant downward trends and time periods with lower growth rates. Characterised by a clear decline in tree ring widths, the two periods of 20 years from the mid-1920s and the early 1970s appeared to be the least favourables for tree growth. Precipitation was the main factor driving growth, and the effect was cumulative over consecutive years because of the increase in soil water content. Including the current year of ring formation, correlations between decline in precipitation and tree growth were greatest with 3-year precipitation sums. The shifting influence of winter rainfall on tree ring growth toward not significant values during the last decades, together with the lack of significant correlation between the current year’s precipitation and growth decline from the 1970s, might suggest an increasingly dependence on long periods of water supply to utilise the water content stored due to the previous rainy years. The negative effect on tree-growth decline of summer and early-fall temperatures appeared as a forcing influence related to long-term changes in climate rather than high-frequency climate fluctuations.

Modelo linear misto para o incremento em área basal de árvores individuais de cedro (&lt;i&gt;Cedrela odorata&lt;/i&gt; L.) na Amazônia ocidental, Brasil

http://dx.doi.org/10.5902/1980509810557Dados confiáveis de crescimento de árvores são importantes para o manejo florestal. Características da árvore como o tamanho, arquitetura da copa e índices de competição, associados aos dados de crescimento da árvore são utilizados com freqüência como variáveis preditoras. Entretanto, a efetividade desse tipo de variáveis na modelagem do crescimento de árvores tropicais é pouco conhecida. Nesta pesquisa, reconstruímos o incremento periódico em área basal (IPG) de árvores individuais deCedrela odorata,amostradas na floresta Amazônica, para desenvolver um modelo de crescimento utilizando preditores potenciais como: (1) tamanho da árvore; (2) dados morfométricos; (3) competição; (4) posição sociológica e infestação de lianas na copa. Apesar da alta variação no tamanho da árvore e no crescimento, observamos que estas variáveis descrevem muito bem o IPG em nível de árvore individual. O modelo misto ajustado apresentou alta eficiência (R2=92.7 %) e estimou para três anos o IPG com casca em árvores com diâmetro a altura do peito variando desde 10 a 110 cm. A altura total, grau de esbelteza e formal de copa demonstraram elevada influência no crescimento em área basal e explicaram a maior parte da variação no crescimento (R2 parcial=87.2%). Variáveis de competição apresentaram influência negativa no IPG, entretanto, explicaram cerca de 7% da variação total. A introdução do parâmetro aleatório no modelo de regressão (modelo misto) conduziu a uma melhor aproximação aos dados observados (acurácia) com predição mais realística quando comparado ao modelo fixo.

Stand-total tree-ring measurements and forest inventory documented climate-induced forest dynamics in the semi-arid Altai Mountains

Unbiased assessment of forest dynamics, including both tree radial growth and forest regeneration, for marginal forests is an urgent task in the context of widely reported forest decline and die-off caused by recent climate change. Based on a network of stand-total tree ring samplings and forest inventory data from eight stands, we reconstructed tree growth and forest recruitment dynamics during the past decades and investigated the linkages of forest dynamics to climate variations in the western and central Altai Mountains in the Inner Asian drylands. Our results revealed a strong coupling between tree growth, forest recruitment and climate variations. A favorable climate generally increases tree growth and triggers growth release and forest recruitments in these semi-arid forests. Differences in local environmental conditions, disturbance regimes and forest histories could possibly modify the forest recruitment dynamics among these forests. Tree radial growth and forest recruitments in both low and high altitudinal Altai Mountain show divergent responses to climate, especially to the spring temperature. A warmer spring will benefit forest recruitment but tends to limit larch radial growth at lower altitudinal mountains. Our study could provide insights into accurate predictions of forest dynamics in this huge mountainous region with complicated climate patterns.

Varying climate sensitivity at the dry distribution edge of Pinus sylvestris and P. nigra

Rear edge populations, those residing at the low-latitude margins of species ranges, represent a critical genetic diversity for species conservation, management, and evolutionary potential. The present study analyses climate-radial growth relations for Pinus sylvestris and Pinus nigra at their dry distribution limit in the Mediterranean basin. The study was conducted in native relict forests of the two species in SE Spain, analyzing radial growth variability and climate-growth relations over time and between different ecological conditions. The lack of strong precipitation signals found could be due to high tree density, appropriate microclimatic conditions and/or high local adaptation. However, previous September temperatures exerted a negative impact on radial growth at all sites, presumably as a result of a prolonged summer drought. By contrast, high temperatures during winter and spring boosted radial growth at most locations. Both the negative and positive effects of temperature have gained relevancy in the last decades and can determine future performance of these Mediterranean pinewoods. Besides common patterns, recorded site-specific signals in climate-growth relationships reveal the influence of different ecological conditions. In this respect, tree-growth variability increased at low elevation coupled with increasing aridity, indicating higher vulnerability to rapid climate changes at low elevations. In contrast, the lack of strong precipitation signals and positive effects of temperatures at high elevation, could buffer the impact of drought and favor the persistence of P. sylvestris and P. nigra rear edge populations.

Climate Control on Tree Growth at the Upper and Lower Treelines: A Case Study in the Qilian Mountains, Tibetan Plateau

It is generally hypothesized that tree growth at the upper treeline is normally controlled by temperature while that at the lower treeline is precipitation limited. However, uniform patterns of inter-annual ring-width variations along altitudinal gradients are also observed in some situations. How changing elevation influences tree growth in the cold and arid Qilian Mountains, on the northeastern Tibetan Plateau, is of considerable interest because of the sensitivity of the region’s local climate to different atmospheric circulation patterns. Here, a network of four Qilian juniper (Sabina przewalskii Kom.) ring-width chronologies was developed from trees distributed on a typical mountain slope at elevations ranging from 3000 to 3520 m above sea level (a.s.l.). The statistical characteristics of the four tree-ring chronologies show no significant correlation with increasing elevation. All the sampled tree growth was controlled by a common climatic signal (local precipitation) across the investigated altitudinal gradient (520 m). During the common reliable period, covering the past 450 years, the four chronologies have exhibited coherent growth patterns in both the high- and low-frequency domains. These results contradict the notion of contrasting climate growth controls at higher and lower elevations, and specifically the assumption that inter-annual tree-growth variability is controlled by temperature at the upper treeline. It should be stressed that these results relate to the relatively arid conditions at the sampling sites in the Qilian Mountains.