Tree Growth Research Articles

Benefits of Irrigation or Fertigation on Early Growth and Yield of a High-density Apple Planting in a Humid Climate

The success of a new high-density apple planting depends on how fast the grower can recoup the high investment that these systems require. The right balance between vegetative growth and cropping during the early life of the planting is where tree growth is sufficient to rapidly fill the allotted space while at the same time producing high early yields. In this study we evaluated irrigation or fertigation as strategies compared with the traditional nonirrigated control to improve growth and yield of five apple scion cultivars (Mutsu, Gala, Honeycrisp, Jonagold, and Macoun) on M.9 or B.9 rootstocks over the first 5 years at Geneva, NY. Calcium nitrate at the rate of 113 kg·ha−1 N was applied to all three irrigation treatments (dissolved in water for the fertigation treatment, broadcast dry with the irrigation treatment, or broadcast dry with the nonirrigated control). Our results showed that fertigation with dissolved N and irrigation with dry broadcast N increased yield and tree growth similarly and significantly over the first 5 years of orchard establishment compared with the nonirrigated treatment with dry broadcast N. There was a significant economic benefit of irrigation or fertigation in the humid climate of New York State.

Latitudinal gradients of biodiversity and ecosystem services in protected and non-protected oak forest areas can inform climate smart conservation

Adaptive governance of areas set aside for future protection of biodiversity, sustainable production, and recreation requires knowledge about whether and how effects of area protection are modulated by climate change and redistribution of species. To investigate this, we compare biodiversity of plants (assessed using vegetation plots) and arthropods (collected with Malaise traps, analyzed using metabarcoding) and productivity (tree growth, determined using dendrochronology) in protected and non-protected oak (Quercus spp.) forests along a latitudinal gradient (55.6 °N – 60.8 °N) in Sweden. We also compare historical, recent and projected future climate in the region. In contrast to established global latitudinal diversity gradients, species richness of plants and arthropods increased northwards, possibly reflecting recent climate-induced community redistributions, but neither was higher in protected than in non-protected areas, nor associated with contemporary ground temperature. Species composition of arthropods also did not differ between protected and non-protected areas. Arthropod biomass increased with latitude, suggesting that the magnitude of cascading effects mediated via their roles as pollinators, herbivores, and prey for other trophic levels, varies geographically and will change with a moving climate. Annual growth rate of oaks (an ecosystem service in the form of biomass increase and carbon sequestration) was independent of latitude and did not differ between protected and non-protected areas. Our findings question the efficacy of contemporary designation and management of protected oak forests, and emphasize that development and implementation of modified climate smart conservation strategies is needed to safeguard ecosystem functioning, biodiversity, and recreational values of protected forest areas against future challenges.

Podzolization in a 150-year chronosequence of soils under pine timber forest on inland dunes in the Toruń Basin (Northern Poland)

Studies on mechanisms and rates of podzolization have mostly been realized in natural landscapes and chronosequences. In this work, an artificial chronosequence of soils managed as a habitat for regularly planted and clear-cut, even-aged, monocultural pine stands (Pinus sylvestris) varying in age between 27 and 150 years has been investigated to determine changes in soil properties and development of genetic horizons with time and growth of pine trees. The soils in five profiles under 27-, 52-, 70-, 105- and 150-year-old pine stands are developed from poor aeolian quartz sands and situated in similar habitat conditions to one another on northern slopes of inland dunes in the Toruń Basin (northern Poland).The studied soils represent consecutive, early stages of podzolization corresponding to the age of the tree stands. In the organic horizon, the whole sequence of three subhorizons typical of the mor type of humus (Oi-Oe-Oa) develops after ∼100 years. Organic carbon, pedogenic Fe and Al content in the eluvial (AE-E) horizon achieve relative equilibrium after 70 years of forest growth. In the illuvial (Bhs-Bs) horizon, these elements continue to accumulate along the whole chronosequence and its development is certainly not finished after 150 years. Only the soils of more than 100-year-old fulfill the criteria of Podzols according to the WRB (2022) soil classification. Younger soils, although undoubtedly podzolized, have to be classified as Arenosols. The youngest profiles (under 27 and 52-year-old pines) have inherited traces of a former cycle of pedogenesis that ran under the previous generation of pine forest. The soil cover of dune areas in the Torun Basin, which have been managed as productive pine timber forests over the last two centuries, is entirely secondary and polycyclic and does not achieve maximal developmental stage and ecological efficiency, including carbon sequestration.

Incorporating tiny forests in the neighbourhood of Singapore - Opportunities and Challenges

‘Tiny forests’ have gained traction across the globe as a promising solution for restoring natural ecosystems and enriching biodiversity in highly urbanized areas. In land scarce cities, planting forests could mitigate the impacts of climate change and other urban socio-ecological challenges. This article investigates the potential for tiny forests to be part of the greening strategy in Singapore – a compact city that is already championing greening initiatives. Using a case study of the Jurong West neighbourhood, we conducted a survey aiming to understand people's perceptions and use of urban nature. We complement these results with a rapid assessment of land availability confirming the feasibility of implementing tiny forests in Singapore. From the survey, we found that residents were receptive to the idea of having nature closer to their residential areas despite highlighting disadvantages such as undesirable insects and animals. Factors such as minimal spatial requirements and planting methods that enhance trees growth make tiny forest a useful part of the landscaping portfolio to achieve national greening principles. Overall, we find that tiny forests have the potential to become part of the city-state's greening strategies.

Habitat association and demographic rates for large tree species: implications for native tree species used in forestry

AbstractExotic tree species, though widely used in forestry and restoration projects, pose great threats to local ecosystems. They need to be replaced with native species from natural forests. We hypothesized that natural forests contain large, fast-growing, dominant native tree species that are suitable for specific topographic conditions in forestry. We tested this hypothesis using data from a 50-ha forest dynamics plot in subtropical China. We classified the plot into the ridge, slope, and valley habitats and found that 34/87 species had significant associations with at least one topographic habitat. There were 90 tree species with a maximum diameter ≥ 30 cm, and their abundances varied widely in all habitat types. In all habitat types, for most species, rate of biomass gain due to recruitment was < 1% of its original biomass, and rate of biomass gain due to tree growth was between 1 and 5% of its original biomass. For most species, biomass loss due to tree mortality was not significantly different than biomass gain due to recruitment, but the resulting net biomass increment rates did not significantly differ from zero. The time required to reach a diameter of 30 cm from 1 cm diameter for Altingia chinensis in the slope habitat, for Quercus chungii and Morella rubra in the ridge habitat and for Castanopsis carlesii in all habitats could be as short as 30 years in our simulations based on actual distributions of tree growth observed in the forest. Principal component analyses of maximum diameter, abundance and net biomass increment rates suggested several species were worthy of further tests for use in forestry. Our study provides an example for screening native tree species from natural forests for forestry. Because native tree species are better for local ecosystems, our study will also contribute to biodiversity conservation in plantations.

Comparative Study on the Effect of GiSelA 5 Rootstock Propagation Methods on Sweet Cherry Growth and Physiology

The basis of orchard production is rootstocks that reduce the vigor of sweet cherry trees. However, not all rootstocks for this species can be easily propagated using traditional methods of stooling or cutting. Some of these must be propagated using the in vitro method. This is expensive and, consequently, increases the price of maiden sweet cherry trees. Our experiment assessed the growth of maiden trees of selected sweet cherry varieties (‘Bellise’, ‘Earlise’, ‘Lapins’, ‘Vanda’) depending on the method of propagation of a semi-dwarf GiSelA 5 rootstock. Additionally, the intensity of physiological processes taking place in the obtained maiden trees was also examined. The experiment compared one type of GiSelA 5 rootstock, obtained using a cheaper softwood cuttings method, with another rootstock propagated using an in vitro method. During the two years of study, there were no significant differences in the percentage of maiden trees obtained in the case of the propagation methods for both types of rootstocks, ranging from 77.43% to 87.74%. The vigor of maiden tree growth in the first year of this study was stronger than in the second year. In particular, the stem diameter of maiden trees varied from 7% to 39%, depending on the variety considered. With the exception of one variety, maiden trees produced from a rootstock propagated by stem cuttings were characterized by a larger stem diameter for the three varieties, ranging from 23% to 29%, and by a greater number of side shoots, ranging from 73% to 172%, compared to those from in vitro. Additionally, when using the stem cutting method of propagation, the rootstocks had a better developed root system, except for the ‘Earlise’ variety. However, most often, no significant differences were found between the methods of propagation regarding the fresh weight of the maiden trees and leaves and their leaf blade area. The activity of physiological processes of maiden sweet cherry trees varied, and no constant regularities were found. In the second year of the experiment, maiden trees were more often characterized by lower levels of net photosynthetic intensity and internal CO2 concentration, which was associated with worse growth results. Based on the collected results, it is recommended to propagate the considered rootstock using stem cuttings, which yields maiden trees with similar and sometimes even better growth parameters than those propagated using the in vitro method.

Rootstock effect on growth, branch morphology and flowering precocity of young monoaxis and biaxis trees of ‘Scilate’ and ‘Fuji supreme’ apple cultivars

ABSTRACT The New Zealand Institute for Plant and Food Research has developed three semi-dwarfing apple rootstocks: PFR2, 4 and 5 with pest and disease resistance/tolerance. Nursery performance and flowering of ‘Scilate' and ‘Fuji Supreme' grafted onto PFR rootstocks and grown as monoaxis or biaxis trees were evaluated in comparison with ‘Malling 9' (dwarf) and ‘G.202' (semi-dwarf) at Hawkes' Bay research centre. For monoaxis ‘Scilate' trees, PFR rootstocks promoted primary, axillary and total shoot length/scion by (11–15%), (54–76%) and (22–37%), respectively compared with ‘M.9', but the same were lower by (4–11%), (25–62%) and (17–42%) compared with ‘G.202'. On PFR2 and PFR5, ‘Scilate' produced 6 axillary shoots/tree, compared with ‘M.9' (4) and ‘G.202' (7). ‘Scilate' on PFR2, 4 and 5 produced 74%, 62% and 93% of axillary shoots with moderate (30°–45°) crotch angle compared with ‘M.9' (30%) and ‘G.202' (79%). On biaxis trees, the total shoot length was higher on PFR2, 4 and 5 compared with ‘M.9', but not different from ‘G.202'. Flowering precocity was not affected by rootstocks. Overall, PFR2, 4, 5 and ‘G.202’ produced high-grade young trees expressing greater potential for early canopy development.

Optimizing PIλDμ controller parameters using tree seed optimization for enhanced control performance and stability

This research article exploits the tree seed optimization algorithm to optimize the parameters of the fractional-order proportional–integral–derivative (FOPID) controller. The study focuses on designing an FOPID controller by imposing constraints on both the performance metrics and closed-loop amplitude ratio to achieve enhanced control system performance. The tree seed algorithm is inspired by the growth and reproductive behavior of trees and demonstrates its efficacy in finding optimal solutions within constrained search spaces. The optimization process involves formulating an objective function subject to the constraints on performance metrics and closed-loop amplitude ratio, reflecting both tracking performance and stability. Besides, inverted decoupling is used to reduce the interaction between the control loops and enable individual tuning of each loop for improved performance. Besides, the smallest disc perturbation is employed to determine the system’s stability. The proposed approach is implemented in various industrial processes to demonstrate its effectiveness in achieving desirable performance. The tree seed algorithm efficiently navigates the parameter space, thereby converging to ideal FOPID controller configurations that meet the specified constraints. Comparative studies with other methods highlight the improved performance and robustness obtained by the tree seed–based FOPID controller.

Electrical Tree and Partial Discharge Characteristics of Silicone Rubber Under Mechanical Pressure

Silicone rubber (SIR) is a crucial insulating material in cable accessories, but it is also susceptible to faults. In practical applications, mechanical pressure from bending or shrinking can impact the degradation of SIR, necessitating the study of its electrical tree and partial discharge (PD) characteristics under such pressure. This work presents the construction of a test platform for electrical trees under varying pressures to observe their growth process. A high-frequency current transformer is used to measure PD patterns during tree growth, enabling analysis of the effect of PD on tree initiation and propagation under pressure. The experimental results demonstrate a significant decrease in tree inception probability and increase in PD inception voltage under pressure. The pressure also influences the tree structure and PD during the treeing process, where the longest tree with a branch-like structure appears under 800 kPa. The effect of pressure on electrical tree and PD characteristics can be attributed to changes in free volume, alterations in air pressure within the tree channels, and the affected charge accumulation.

Infinite chains in the tree of numerical semigroups

AbstractOne major problem in the study of numerical semigroups is determining the growth of the semigroup tree. We study infinite chains of numerical semigroups in the semigroup tree, firstly introduced by Bras-Amorós (Semigroup Forum, 71:561–574, 2009). Computational results show that these chains are rare, but without them the tree would not be infinite. It is proved that for each genus $$g\ge 5$$ g ≥ 5 there are more semigroups of that genus not belonging to infinite chains than semigroups belonging. Bras-Amorós (Semigroup Forum, 71:561–574, 2009) presented a characterization of the semigroups that belong to infinite chains in terms of the coprimality of the left elements of the semigroup as well as a result on the cardinality of the set of infinite chains to which a numerical semigroup belongs in terms of the primality of the greatest common divisor of these left elements. We revisit these results and fix an imprecision on the cardinality of the set of infinite chains to which a semigroup belongs in the case when the greatest common divisor of the left elements is a prime number. We then look at infinite chains in subtrees with fixed multiplicity. When the multiplicity is a prime number there is only one infinite chain in the tree of semigroups with such multiplicity. When the multiplicity is 4 or 6 we prove a self-replication behavior in the subtree and provide a formula for the number of semigroups in infinite chains of a given genus and multiplicity 4 and 6, respectively.

Predictive Health Monitoring of Palm Trees: Techniques and Applications for Enhanced Processing

This paper presents new framework for predictive health monitoring in palm trees using advanced deep learning methods. The system then selects the YOLOv8 method for the detection of the health of palm trees and further divides them into their real-time classification. Here, the model will, after training on its dataset, classify the palm tree as healthy, diseased, and stressed trees, keeping all the influential factors of the growth of the palm tree in consideration. It makes provision for the profiling of health status by way of early intervention, reducing risks and preventing diseases with a view to optimizing crop yields within palm plantations. The proposed model leverages state-of-the-art methodologies in object detection to process images of the palm tree with identification of key indicators of health issues. This approach has great implications for agricultural productivity in view of the maintenance of plant health through early detection. Further, the paper discusses challenges presented during the training and validation of the model, their strategies for overcoming such obstacles, and goes further into relating details to the technical architecture of the model. Further details on the works related to plant disease detection, image-based classification, and further applications of deep learning in agriculture have inspired the research work. Based on the obtained results, it can be observed that the proposed system provides a scalable and efficient solution for continuous monitoring and assessment of the health conditions of palm trees, hence enabling sustainable agricultural practices.

An Ecoinformatic Model Using Rényi's Entropy Predicts Soil Chemistry Effect on Tree Species Abundance Distributions

ABSTRACTAimAn ecological community consists of species of various abundances that reflect their responses to the environmental conditions. A classic macroecological pattern, the species abundance distribution (SAD), has been studied for diverse taxa and communities and integrated into numerous modelling tools. Despite its widespread use, a mathematical model that can capture variations in the empirical SAD and describe its response to environmental changes is still lacking. By integrating the Maximum Entropy Theory of Ecology (METE) with a generalised entropy called Rényi's entropy, we aim to develop a new ecoinformatic model that can predict the variation of empirical SAD along multiple environmental gradients.LocationPanama.TaxonAngiosperms.MethodsWe extend the METE using the Rényi's entropy as an uncertainty measure. We apply this extended METE, called Rényi model, to the tree abundance data from 49 plots in Panama and predict the SAD within each plot. We estimate Rényi's parameter q by fitting the predicted SAD to the empirical SAD in each plot. We further compile climate and soil data from the Panama plots and analyse their relationships with the estimated q using multiple regressions.ResultsRényi model provides adequate description of the empirical SADs and outperforms lognormal or log‐series models in 40 of the 49 tree plots, according to the Akaike information criterion. Variations in Renyi's q estimates (from 1/2 to 1) reflect shifts in the empirical SADs. Multiple regressions reveal that P, Al and NH4, three soil chemicals that are important for tree growth and species distribution, significantly affect Renyi's q across plots.Main ConclusionsThese findings suggest that the Rényi model and Rényi's q can characterise the SAD of communities under environmental changes. They also indicate the potential of using generalised entropies to predict macroecological patterns in stressed ecosystems.

Regional variation in growth and survival responses to atmospheric nitrogen and sulfur deposition for 140 tree species across the United States

Atmospheric deposition of nitrogen (N) and sulfur (S) alter tree demographic processes via changes in nutrient pools, soil acidification, and biotic interactions. Previous work established tree growth and survival response to atmospheric N and S deposition in the conterminous United States (CONUS) data by species; however, it was not possible to evaluate regional variation in response using that approach. In this study, we develop species- and region-specific relationships for growth and survival responses to N and S deposition for roughly 140 species within spatially demarcated regions of the U.S. We calculated responses to N and S deposition separately for 11 United States Forest Service (USFS) Divisions resulting in a total of 241 and 268 species × Division combinations for growth and survival, respectively. We then assigned these relationships into broad categories of vulnerability and used ordinal logistic regressions to explore the covariates associated with vulnerability in growth and survival to N and S deposition. As with earlier studies, we found growth and survival responses to air pollution differed by species; but new to this study, we found 45%−70% of species responses also varied spatially across regions. The regional variation in species responses was not simply related to atmospheric N and S deposition, but was also associated with regional effects from precipitation, soil pH, mycorrhizal association, and deciduousness. A large amount of the variance remained unexplained (total variation explained ranged from 6.8%−13.8%), suggesting that these or additional factors may operate at finer spatial scales. Taken together, our results demonstrate that regional variation in tree species' response has significant implications for setting critical load targets, as critical loads can now be tailored for specific species at management-relevant scales.

Species Mixing Improves Tree Growth and Timber Quality of Chinese Fir in Mixtures with Broad-Leaved Species in Central China

Mixed stands of tree species with complementary traits can modulate stand growth and timber quality. At the Fengshushan Forest Farm, mixtures of Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) with Liquidambar formosana Hance, Schima superba Gardner & Champ., Elaeocarpus sylvestris (Lour.) Poir., Cinnamomum camphora (L.) Presl, and Chinese fir monoculture were established. Differences in stand growth and timber quality among these mixtures were assessed and a test was conducted to evaluate the factors influencing the mixture effects. The average diameter at breast height, tree height, stand volume, and individual tree annual increment of mixtures generally exceeded those of Chinese fir monocultures but not necessarily those of broad-leaved monocultures. When the net interaction between species was complementary, overyielding in mixtures occurred (RPfir,bl > 0), which was influenced significantly by stand density, soil properties, and timber quality. The timber quality and wood production of Chinese fir were enhanced by mixture with some broad-leaved species, with reduced slenderness and knottiness in mixtures, and notable increases in medium- (average outturn rates of 56.13%) and large-diameter (11.71%) timber in C. lanceolata/C. camphora mixture. The growth and timber quality of Chinese fir are largely promoted when grown mixed with broad-leaved species. Overyielding at the stand level occurs where Chinese fir compensates for the underperformance of broad-leaved trees.

Climate Sensitivity and Tree Growth Patterns in Subalpine Spruce-Dominated Forests of the North-Western Dinaric Alps

The mountain forests in Europe, especially the ecosystems dominated by Norway spruce [Picea abies (L.) Karst], are facing major challenges due to climate change. Climatic stress factors such as increased temperatures and drought contribute to reduced growth and increased mortality, especially at lower altitudes. In this study, which was conducted in the northern Velebit region, the growth dynamics and climate sensitivity of Norway spruce were analyzed using standard dendrochronological methods. The focus was on samples collected at altitudes between 1135 and 1545 m. The results show two different growth trends: a positive trend from 1950 to 1977, followed by a negative trend from 1977 to 2013. Precipitation proved to be a key factor for the stability of spruce growth, while the high summer temperatures of the previous year correlated negatively with growth increment. In addition, trees at higher altitudes showed greater resistance to climatic stress. These results underline the crucial role of precipitation and site-specific conditions in maintaining the vitality of spruce forests in mountainous regions, and suggest that climate change could further destabilize spruce ecosystems in the Dinaric Alps.

Changing role of water table and weather conditions in diameter growth of Scots pine on drained peatlands

We investigated the impact of water table (WT), monthly temperature, and precipitation of current and previous growing seasons on annual diameter growth of Scots pine in boreal drained peatlands. The data were collected from six sites across Finland. WT was monitored during 5-8 growing seasons depending on site during 2007-2014. The sites contained altogether 19 sample plots, where diameter growth from 339 trees was measured, resulting in 1,599 growth observations. Tree-level diameter growth was analysed using mixed linear models, including variables describing tree size, competition, and environment. The higher precipitation in June of the previous year and May of the current year increased diameter growth, whereas the higher temperature in July of the current year and the deeper WT in August of the previous year decreased growth. The results suggest that Scots pine grows better at shallow than deep WT in drained peatlands. This contradicts earlier findings that a deep WT is needed to support tree growth in drained peatlands. We suggest that the development of a mor layer on the peat is changing nutrient cycling and hydrology. The results encourage the avoidance of intensive drainage in forested peatlands, which may also diminish the adverse environmental impacts of peatland forestry.

Seedling Recruitment at the Upper Limit of Tree Growth in the Alborz Mountains, Northern Iran: Safe Site Characteristics and Edaphic Conditions

Seedling Recruitment at the Upper Limit of Tree Growth in the Alborz Mountains, Northern Iran: Safe Site Characteristics and Edaphic Conditions

Epigenetic memory of temperature sensed during somatic embryo maturation in 2-year-old maritime pine trees.

Embryogenesis is a brief but potentially critical phase in the tree life cycle for adaptive phenotypic plasticity. Using somatic embryogenesis in maritime pine (Pinus pinaster Ait.), we found that temperature during the maturation phase affects embryo development and post-embryonic tree growth for up to three years. We examined whether this somatic stress memory could stem from temperature- and/or development-induced changes in DNA methylation. For this, we developed a 200 Mb custom sequence capture bisulfite analysis of genes and promoters to identify differentially methylated cytosines (DMCs) between temperature treatments (18, 23, and 28°C) and developmental stages (immature and cotyledonary embryos, shoot apical meristem of 2-year-old plants) and investigate if these differences can be mitotically transmitted from embryonic to post-embryonic development (epigenetic memory). We revealed a high prevalence of temperature-induced DMCs in genes (8-14%) compared to promoters (less than 1%) in all 3 cytosine contexts. Developmental DMCs showed a comparable pattern but only in the CG context and with a strong trend towards hypomethylation, particularly in the promoters. A high percentage of DMCs induced by developmental transitions were found memorized in genes (up to 45-50%) and promoters (up to 90%). In contrast, temperature-induced memory was lower and confined to genes after both embryonic (up to 14%) and post-embryonic development (up to 8%). Using stringent criteria, we identified ten genes involved in defense responses and adaptation, embryo development, and chromatin regulation that are candidates for the establishment of a persistent epigenetic memory of temperature sensed during embryo maturation in maritime pine. Here, we provide evidence that DNA methylation marks established during the embryonic phase are transmitted to the post-embryonic plant development phase.

Groundcover improves nutrition and growth of citrus trees and reduces water runoff, soil erosion and nutrient loss on sloping farmland

IntroductionGroundcover management plays a crucial role in improving water retention and soil nutrition in orchard systems, thereby preventing environmental constrains by non-point source pollution. However, effectiveness of groundcover management in citrus orchards developed on sloping farmland with eroded purple soil has not been studied in detail. In particular, information on the soil nutrient losses, e.g., nitrogen (N) and phosphorus (P), through interflow and its effects on growth and nutrition of citrus plants has not been reported.MethodsThe present study evaluated the effects of different cover crops, i.e., Lolium perenne L. (Lolium), Vicia villosa Roth (Vicia) and Orychophragmus violaceus (Ory), on nutrition and growth of citrus trees as well as water, soil and nutrient retention in an orchard developed in sloping farmland during two consecutive years.Results and discussionThe results show that the groundcover species Lolium and Vicia mediated nursing effects on nutrition and growth of citrus trees. These nursing effects included enhanced foliar levels of carbon(C), N and P as well as increased tree height, stem diameter, and crown width. Groundcover management generally reduced the annual surface runoff, interflow, soil loss, total N loss and total P loss. Among the cover crop species studied, Lolium and Vicia were overall more efficient than Ory in this context. Lolium reduced the average annual total loss of N and P by 42.53% and 49.23%, respectively, compared with clean tillage. The estimated annual reduction potentials of soil, N and P losses in Southwestern China were 16.3, 3.4 and 8.5 million tons yr-1, respectively. Obviously, Lolium and Vicia provide highly beneficial ground coverage on sloping farmland and, thus, can be used for future sustainable development of citrus orchards.

Adjusting the significance of daily climate responses in tree-ring proxies

Correlating tree-ring parameters with daily resolved climate data is becoming increasingly common for understanding the complex relationships between tree growth and the surrounding environment. However, with an increased number of calculated correlations, there is an inherent risk of spurious significance. In this study, we present an analysis using synthetic weather and tree-ring data mimicking the statistical properties of ten real-world sites across Europe to quantify the extent to which numerous comparisons may inflate maximum correlations. Comparisons of different tree-ring proxies, considering varying overlapping period lengths and seasons, revealed 95th percentile correlation differences reaching 0.25 by chance. Using synthetic tree-ring chronologies with an assigned non-signal (r = 0.00), spurious correlations can reach statistical significance in over 60% of tests. Correlation inflation is greater when: (1) the climate-proxy relationship is weaker; (2) comparison periods are shorter; and (3) the length of seasonal windows is longer. Autocorrelation in the proxy records does not appear to have a major effect. These findings indicate that caution should be exercised when computing high numbers of correlations with limited observations. We provide tables listing correlation inflations for precipitation- and temperature-sensitive tree-ring chronologies that can inform interpretations of significance.