Restoration of Mediterranean ecosystems, particularly on seedling establishment success under dry conditions. Focused on ecophysiology of root growth and survival during first stages after planting and best management to encourage the process: nursery culture to optimize seedling quality and cultural treatments after planting to enhance environmental conditions of planted seedlings.
Nothofagus pumilio forests in the Southern Patagonia region of Chile are highly degraded because ... more Nothofagus pumilio forests in the Southern Patagonia region of Chile are highly degraded because of clearing for human settlements, extensive livestock grazing, and more recently, the impact of coal mining operations. Most of these legacy areas have remained as extensive meadows of non-native grasses and legumes with limited Nothofagus pumilio forest recovery due to dry soil moisture conditions and exposure to high wind and solar radiation. Therefore, active reforestation is needed to reclaim Nothofagus pumilio forests from abandoned grassland or disturbances caused by surface mine operation. In this study, a surface coal mine operation and an abandoned meadow established in the 1950 s needed to be restored back to N. pumilio forest on Riesco Island, in Southern Chilean Patagonia. We compared the establishment success of Nothofagus pumilio seedlings on replicated blocks under two conditions (experimental treatments): (i) four blocks of meadow previously disturbed by livestock grazing, (MS), and (ii) four blocks where a deep layer of the soil profile was removed, mixed, and then replaced simulating recommendations used for reclaiming surface coal mines (RS). To improve Nothofagus pumilio establishment and protection at each block under both soil conditions, seedlings were planted both unprotected and protected from wind and solar radiation using four different types of shelters: shade cloth, irregular log piles, white polypropylene shelters, and woody branches. Soil physical and chemical properties, seedling survival and growth, leaf water potential, and stomatal conductance were measured. Results at the end of the first and fourth growing seasons showed better conditions for seedling growth in the RS treatment. Mean survival rates began to be different following the second growing season with values of 84.7 ± 2.9% in RS and 60.2 ± 3.2% survival in MS treatments, respectively. At the end of the study, the difference between the treatments was even geater with values of 75.4 ± 5.5% and 32.2 ± 7.1%. Soil removal and replacement significantly changed soil physical properties, but values were still adequate for vegetation development. The use of shelters significantly influenced four-year survival rates of seedlings planted on the disturbed MS treatment with 60 ± 8.2% survival in plastic shelters and less than 25.5 ± 6.5% for all other shelters. The effects of the shelters were less clear in the RS treatment. Our study showed that Nothofagus pumilio restoration on abandoned grassland and reclaimed mine sites in Patagonia is a feasible option when soil conditions and planting techniques improve soil water availability, and when seedling are protected against excessive solar radiation and wind.
Statistical meta-analysis is a powerful and useful tool to quantitatively synthesize the informat... more Statistical meta-analysis is a powerful and useful tool to quantitatively synthesize the information conveyed in published studies on a particular topic. It allows identifying and quantifying overall patterns and exploring causes of variation. The inclusion of published works in meta-analyses requires, however, a minimum quality standard of the reported data and information on the methodology used. Our experience with conducting a meta-analysis on the relationship between seedling quality and field performance is that nearly one third of the apparently relevant publications had to be discarded because essential data, usually statistical dispersion parameters, were not properly reported. In addition, we encountered substantial difficulty to explore the effect of covariates due to the poor description of nursery cultivation methods, plantation location, and management in a significant proportion of the selected primary studies. Thus, we present guidelines for improving methodology detail and data presentation so that future forest restoration-oriented research can be more readily incorporated into meta-analyses. In general, research studies should report data on means, sample size, and any measure of variation even if they are not statistically significant. The online availability of raw data is the best practice to facilitate the inclusion of primary research on meta-analyses. Providing full information about the production of nursery seedlings, such as plant material and experimental conditions, is essential to test whether these procedures might have an effect on seedling quality. In addition, detailed information about field trials such as site climate, soil preparation techniques, previous land use, or post-plantation management, is needed to elucidate whether seedling quality is context-dependent. Thus, we provide a detailed checklist of important * Enrique Andivia
Plant hydraulics is key for plant survival and growth because it is linked to gas exchange and dr... more Plant hydraulics is key for plant survival and growth because it is linked to gas exchange and drought resistance. Although the environment influences plant hydraulics, there is no clear consensus on the effect of nitrogen (N) supply, which may be, in part, due to different hydraulic conductance normalization criteria and studied species. The objective of this study was to compare the variation of root hydraulic properties using several normalization criteria in four pine species in response to three contrasting N fertilization regimes. We studied four closely related, yet ecologically distinct species: Pinus nigra J.F. Arnold, Pinus pinaster Ait., Pinus pinea L. and Pinus halepensis Mill. Root hydraulic conductance (K h) was measured with a high-pressure flow meter, and values were normalized by total leaf area (leaf specific conductance, K l), xylem cross-section area (xylem specific conductance, K s), total root area (root specific conductance, K r) and the area of fine roots (fine root specific conductance, K fr). Controlling for organ size differences allowed comparison of the hydraulic efficiency of roots to supply or absorb water among fertilization treatments and species. The effect of N on the root hydraulic efficiency depended on the normalization criteria. Increasing N availability reduced K l and K s , but increased K h , K r and especially K fr. The positive effect of N on K r and K fr was positively related to seedling relative growth rate and was also consistent with published results at the interspecific level, whereby plant hydraulics is positively linked to photosynthesis and transpiration rate and fast growth. In contrast, normalization by leaf area and xylem cross-sectional area (K l and K s) reflected opposite responses to K r and K fr. This indicates that the normalization criteria determine the interpretation of the effect of N on plant hydraulics, which can limit species and treatment comparisons.
Nursery nitrogen (N) fertilization influences seedling N reserves, morphology, photosynthesis rat... more Nursery nitrogen (N) fertilization influences seedling N reserves, morphology, photosynthesis rate and stress tolerance and frequently enhances outplanting performance. Although mineral nutrition is a critical aspect of seedling quality, fertility targets of Mediterranean sclerophylous species have not been thoroughly quantified. We sought to define those fertility targets for seedlings of Quercus ilex, a key species in Mediterranean areas. Nine fertility treatments, ranging from 0 to 200 mg N seedling-1 applied under an exponential regime were tested in a greenhouse dose response trial in which phosphorus (P) and potassium (K) were increased in the same proportion as N (15N:5P:15K). Height and diameter growth were measured weekly, and biomass and nutritional status were analyzed at the end of culture (24 week). Plant growth and nutritional response to increased fertilization followed a curvilinear pattern depicting phases that ranged from deficiency to luxury consumption. Seedling dry mass production was maximized at 125 mg N seedling-1 (sufficiency level). N content and concentration increased with fertilization, reaching a maximum at 200 mg N seedling-1 (luxury consumption). P and K concentrations peaked at 75 and 25 mg N, respectively, suggesting a dilution effect of these nutrients. Root volume increased linearly up to 100 mg N and declined thereafter. The sufficiency level for Q. ilex (125 mg of applied N seedling-1) is notably higher than for other Quercus species from other biomes but intermediate to other Mediterranean Quercus species. No toxicity was observed at the highest treatment rate (200 mg N) suggesting that increased exponential N rates along with greater P and K proportions than those used in our experiment may further maximize nutrient storage.
Iforest - Biogeosciences and Forestry, Oct 13, 2016
Drought-avoidance traits of South American Mediterranean tree species are crucial attributes to b... more Drought-avoidance traits of South American Mediterranean tree species are crucial attributes to be considered in nursery practices aimed at improving the performance of seedlings exposed to intense summer drought in dryland reforestation projects. In this study, we determined the relation between nursery fertilization doses and the development of drought-avoidance traits of the soapbark tree Quillaja saponaria (Mol.) under contrasting watering regimes following post-planting. Seedlings were grown for 6 months using four increasing doses of controlled-release fertilizer (0, 3, 6, and 12 g L-1 of Basacote ® Plus 15:8:12). After outplanting, half of the seedlings were watered weekly and the other half were left unwatered for one growing season from September 2011 to May 2012. Seedlings were periodically measured for morphological and ecophysiological parameters, and carefully harvested for root measurements at the end of the study. Our results showed that high fertilization doses produced significantly larger seedlings in the nursery with high nitrogen and phosphorous foliar concentrations, which resulted in a significantly higher shoot dry mass after outplanting. Unfertilized seedlings grown with water application had a significantly higher stem diameter, root dry mass and lower shoot/root compared with seedlings with high fertilizer dose. These results highlight the ability of this species to maintain drought-avoidance traits, such as high xylem water potential and chlorophyll fluorescence, during the first 3 months of the 7-month drought period. High nutrient loading, although resulting in improved shoot productivity after outplanting, did not make a significant contribution to the early development of drought-avoidance traits in Q. saponaria.
Grafted, Tippecanoe 1 cultivar black walnut (Juglans nigra L.) trees were planted and grown in an... more Grafted, Tippecanoe 1 cultivar black walnut (Juglans nigra L.) trees were planted and grown in an intensively managed plantation in west-central Spain and subjected to six fertilizer treatments (defined as 0, 25, 50, 75, 150, and 300 g tree Ϫ1 nitrogen [N]) delivered via daily fertigation during the 1st year after outplanting. Stem diameter, volume, and mass increased from the unfertilized control to the second fertilizer treatment (50 g N) but showed no gains thereafter. N utilization efficiency (stem volume growth per unit fertilizer) was greatest for the 25 and 50 g tree Ϫ1 N treatments, and fertilizer N use efficiency (gain in stem volume growth over the unfertilized control per unit fertilizer) was greatest at 50 g tree Ϫ1 N. Foliar N concentrations in mid-July provided the best predictors of seasonal stem volume growth. Optimal foliar N was 3.2%, which is higher than values recommended for other black walnut production systems: less than 2.8% was deficient, 3.0% was sufficient, and more than 3.4% suggested toxicity. Branch biomass and branch mass/trunk mass ratio were greater in all fertilizer treatments than in the unfertilized control, indicating that high fertilization rates may shift biomass allocation away from the desired product (stem wood). FOR. SCI. 59(4):453-463.
Autores. Editado por la AEET. [Ecosistemas no se hace responsable del uso indebido de material su... more Autores. Editado por la AEET. [Ecosistemas no se hace responsable del uso indebido de material sujeto a derecho de autor] Efectos de la forestación de tierras agrícolas mediterráneas y de su manejo en el establecimiento de árboles y arbustos Introducción La deforestación causada por los humanos desde el comienzo del Neolítico ha sido contrarrestada en algunas partes del mundo durante las últimas décadas (García-Barreda y Reyna 2013; FAO 2021) con consecuencias ambientales dispares (Martińez-Valderrama et al. 2021). La restauración forestal se puede llevar a cabo de tres formas: la restauración espontánea o pasiva, basada en los procesos de sucesión secundaria tras la eliminación del factor de degradación, por ejemplo, la regeneración natural como consecuencia del abandono de tierras cultivadas y pastizales; la restau-ración activa asistida, que combina la estrategia anterior con actuaciones puntuales para acelerar la sucesión; y la restauración activa reconstructiva, una combinación de las anteriores más la introducción de una proporción elevada de la biota deseada, es decir, las plantaciones forestales (Gann et al. 2019; Atkinson y Bonser 2020). La reforma de la PAC de 1992 introdujo en Europa la forestación de tierras agrícolas, un tipo de restauración activa. La superficie de forestación de tierras agrícolas de la PAC en España hoy en día, teniendo en cuenta las plantaciones forestales ejecu
Drought is a limiting factor to forest regeneration and restoration, which is likely to increase ... more Drought is a limiting factor to forest regeneration and restoration, which is likely to increase in intensity and duration under future climates. Nitrogen (N) nutrition is related to drought-resistance mechanisms in trees. However, the influence of chemical N form (inorganic and organic N) on physiological traits related to drought resistance has been sparsely studied in conifer seedlings. We investigated the effect of N forms on morpho-physiological traits of Pinus ponderosa Dougl. ex Laws. seedlings and subsequent influences in drought tolerance and acclimation. One-year-old seedlings were fertilized during 10 weeks at 9 mM N with different N forms [either NH 4 + , NO 3 − or organic N (amino acids mixture)] in their second year of growth. After fertilization, we measured traits associated with intrinsic drought tolerance (shoot water relations, osmotic regulation, photosynthesis and cell membrane stability). Seedlings were then subjected to an 8-week drought period at varying drought intensities to evaluate plant acclimation mechanisms. We demonstrated that P. ponderosa seedlings could efficiently use amino acids as a primary N source, showing similar performance to those grown with inorganic N forms. Nitrogen form influenced mainly drought-acclimation mechanisms rather than intrinsic drought tolerance. Osmotic potential at saturation (πsat) was marginally affected by N form, and a significant relationship between proline concentration in needles and πsat was found. During acclimation, seedlings fertilized with organic N minimized needle senescence, retained more nutrients in the oldest needles, had maximum increments in proline concentration and hastened the development of water-use efficiency mechanisms compared with those fertilized with inorganic N sources. Our results suggest an improved physiological drought acclimation of organic N-fertilized seedlings.
Iforest - Biogeosciences and Forestry, Jun 1, 2016
Biogeosciences and Forestry Biogeosciences and Forestry Combined pre-hardening and fall fertiliza... more Biogeosciences and Forestry Biogeosciences and Forestry Combined pre-hardening and fall fertilization facilitates N storage and field performance of Pinus tabulaeformis seedlings Guolei Li (1) , Jiaxi Wang (1) , Juan A Oliet (2) , Douglass F Jacobs (3) Exponential fertilization during the pre-hardening stage and fall fertilization during the hardening stage have each been used independently to nutrient load seedlings. However, nursery and field responses of seedlings to the combination of exponential fertilization and fall fertilization have received little attention. Chinese pine (Pinus tabulaeformis Car.) container seedlings were exponentially fertilized with accumulated totals of 40, 80 or 120 mg N per seedling during pre-hardening, and fall-fertilized with 0, 12, 24 or 48 mg N per seedling, and were subsequently outplanted and followed for two growing seasons. Interactions of exponential and fall fertilization had significant effects on plant N content in the nursery and first-year height after outplanting. Fall fertilization promoted additional nutrient loading during hardening for the 40-80 mg N per seedling pre-hardening regimes. The highest exponential fertilization rate enhanced N concentration in foliage and roots compared to the other two rates. Maximum diameter was observed in the lowest exponential fertilization rate at the second year after outplanting. Fall fertilization enhanced foliar N concentration. Supplemental 12 and 24 mg N per seedling during fall were more effective in increasing height increment at the second year after outplanting. Our results indicate that pre-hardening fertilization is a useful tool to nutrient load Chinese pine in the nursery and facilitate outplanting performance in the field. In combination, fall fertilization has potential to further augment this response, although further research is needed to precisely match rates of pre-hardening and fall fertilization to optimize seedling performance.
Restoration of abandoned, high-elevation pastures is needed across many ecosystems. Diverse abiot... more Restoration of abandoned, high-elevation pastures is needed across many ecosystems. Diverse abiotic and biotic stressors often limit establishment of native trees species, however, justifying the need for novel approaches to alleviate such stressors. Freezing damage often negatively impacts survival of planted trees across temperate landscapes and on some high-elevation tropical restoration sites, such as for Acacia koa (koa) in Hawaii, USA. Koa performs poorly under forest canopies, a potential limitation to the use of nurse trees for establishment on frost-prone sites. Using a heterogeneous canopy of a non-native conifer, Cryptomeria japonica, we underplanted koa seedlings along a simulated range of canopy shelter levels in combination with field fertilization. We tested the effect of a canopy cover gradient and nutrient availability on frost avoidance and tolerance responses, as well as the potential to harness koa's developmental plasticity to optimize growth and survival. C. japonica canopy cover provided protection from frost damage, with increased sheltering under greater canopy closure. When combined with fertilization, increasing canopy closure reduced frost damage and increased koa growth. Although we observed limited frost damage in our study, leaf-level soluble sugars increased during the winter and in more open microsites, reflecting a potential mechanism for frost tolerance in this tropical species. We conclude that frost-tolerant conifers used as nurse trees represent a potential tool to help establish native tree species on high-elevation, frost-prone sites.
Frontiers in forests and global change, Jan 5, 2023
effect on pine growth. Lack of response to main effects of competition suppression treatments can... more effect on pine growth. Lack of response to main effects of competition suppression treatments can be attributed to the minimum changes of soil water content to mulching or weeding under arid conditions. Thus, 20 years after planting, tube-shelters and competition suppression treatments were relatively ineffective at improving survival or growth of P. halepensis. Meshshelters are recommended as the most effective protection method for restoration under arid site conditions.
The effect of shelter tubes on plant performance has been widely studied. Although, the role of s... more The effect of shelter tubes on plant performance has been widely studied. Although, the role of shelter tubes in alleviating the effects of drought and high-irradiance stresses during seedling establishment has been less studied than its effect on survival. The present study compares the effects of shelter tubes with different light transmissivities (Lt) on survival and morpho-physiological responses of two coexisting tree species (drought-tolerant Quillaja saponaria and relatively more drought-sensitive Maytenus boaria ) of the Chilean matorral during an exceptionally dry and warm growing season (2014–2015). Two-year-old seedlings were randomly assigned to shelter tubes differing in Lt (20, 40, 60, 80%) or to a control (no shelter, Lt 100%) at field conditions. Survival was measured monthly, while shoot and root biomass, root length, pre-dawn xylem water potential, and non-structural carbohydrate concentration (NSC) were measured 8 months after transplanting. Shelter tubes increased the seedling survival of Q. saponaria by 80–100% relative to the control conditions, where full mortality was observed by the end of the experiment. By contrast, M. boaria exhibited high mortality regardless of the presence of shelters, suggesting that tubes were ineffective to alleviate the summer-related stresses in this species. Xylem water potential of Q. saponaria seedlings was significantly lower at 80% Lt than at 40% Lt, where maximum values were observed. Also, at 40% Lt, plant height and root length were highest and shoot/root ratio the lowest. By contrast, no differences in NSC, stomatal conductance, and photochemical efficiency were observed among Lt treatments. We conclude that shelter tubes may alleviate summer stresses in drought-tolerant species such as Q. saponaria ; hence, they appear to be effective reforestation ecotechnology under severe water limitations and high-irradiance stress imposed by the current drought and heatwaves conditions in central Chile.
Freezing stress is a critical environmental factor affecting survival, distribution, and evolutio... more Freezing stress is a critical environmental factor affecting survival, distribution, and evolution of plants. Although there is evidence that nitrogen (N) affects frost tolerance of juvenile conifers, the magnitude and direction of such effect can diverge among species. The influence of the N source on frost tolerance has been barely studied. Particularly, how organic N sources could affect the cold acclimation dynamics of seedlings is poorly understood. We studied morpho‐physiological responses to organic N supply (amino acids) in comparison to inorganic N in seedlings of two Mediterranean pine species: Pinus halepensis and P. sylvestris. Fertilization was applied at low and high N doses (30 and 130 mg N seedling−1) in the first growing season. Then, tolerance of seedlings to freezing stress was evaluated through the cold season. This study confirmed that organic N supply promotes growth of both species as effectively as inorganic N sources. At low N availability, seedlings had acute phosphorus deficiencies when grown with inorganic N, but not with organic N. Likewise, high organic‐N availability improved chlorophylls concentration. Both species increased their frost tolerance through time, especially during late autumn. Although organic N supply did not show clear benefits on frost tolerance, it seemed to enhance cold acclimation via increases of compatible solutes, such as soluble sugars and proline, particularly in P. halepensis. Thus, the effects of organic N supply could depend on the extent that such osmolytes contribute to the dormancy strategy of the species. Other species‐specific mechanisms to cope with freezing stress are further discussed.
Effect of controlled release fertilizer type and rate on mineral nutrients, non-structural carboh... more Effect of controlled release fertilizer type and rate on mineral nutrients, non-structural carbohydrates, and field performance of Chinese pine container-grown seedlings Fu Y., Oliet J.A., Li G., Wang J. (2017). Effect of controlled release fertilizer type and rate on mineral nutrients, non-structural carbohydrates, and field performance of Chinese pine containergrown seedlings.
Nursery cultivation practices can be modified to increase resistance to water stress in forest se... more Nursery cultivation practices can be modified to increase resistance to water stress in forest seedlings following field establishment, which may be increasingly important under climate change. We evaluated the morphological (survival, growth) and physiological (chlorophyll fluorescence, leaf water potential) responses to water stress for three ecologically diverse Quercus species (Q. robur, Q. pubescens, and Q. ilex) with varying traits resulting from the combination of growing media (peat, coir) and fertilization (standard, P-enriched, K-enriched). For all species under water stress, seedlings grown in coir had generally higher growth than those grown in peat. Seedlings fertilized with P performed better, particularly for survival; conversely, K fertilization resulted in inconsistent findings. Such results could be explained by a combination of factors. P fertilization resulted in higher P accumulation in seedlings, while no K accumulation was observed in K fertilized seedlings. A...
Forest restoration is challenging in arid and semiarid lands. Research has identified ecotechnolo... more Forest restoration is challenging in arid and semiarid lands. Research has identified ecotechnologies that may alleviate stressful conditions of planted seedlings, but studies are often limited to the first few years of regeneration establishment. Over 20 years, we tested the effects of tree shelters (mesh- and tube-shelters) and competition suppression (two types of synthetic mulch and manual weeding) on soil water content and development of Pinus halepensis on an arid site in southeastern Spain. Competition suppression increased soil water content at shallow depths only using a polyethylene sheet, with no effect on survival. Tree shelters had a much greater effect than competition suppression on tree responses. Survival was mostly affected by shelter type, with lower survival in tube-shelters compared to mesh-shelters and non-protected seedlings; differences began after the first year, but became more pronounced following an intense drought at 3 years. Survival for pines protected...
Forestry: An International Journal of Forest Research
Mycological resources have attracted considerable interest from the public recently. In this cont... more Mycological resources have attracted considerable interest from the public recently. In this context, forest mycological management of wild mushrooms has emerged a research field and is developing rapidly with the objective to sustainably use and conserve mushrooms in multifunctional forests. Although the term ‘mycosilviculture’ was coined relatively recently, forest management of mycological resources and fungal silviculture began already in the 1980s. This study reviews the literature on the forest management of wild mycological resources with emphasis on studies in Spanish Mediterranean forests. The review covers some of the most important aspects of management, such as the diagnosis of mycological resources through inventory and sampling protocols, predictive models of mushroom yield, stand variables and mycosilvicultural practices that affect mushroom yield and fungal diversity. Finally, the potential of mycorrhizal applications for mycosilviculture is briefly discussed. Most o...
Nothofagus pumilio forests in the Southern Patagonia region of Chile are highly degraded because ... more Nothofagus pumilio forests in the Southern Patagonia region of Chile are highly degraded because of clearing for human settlements, extensive livestock grazing, and more recently, the impact of coal mining operations. Most of these legacy areas have remained as extensive meadows of non-native grasses and legumes with limited Nothofagus pumilio forest recovery due to dry soil moisture conditions and exposure to high wind and solar radiation. Therefore, active reforestation is needed to reclaim Nothofagus pumilio forests from abandoned grassland or disturbances caused by surface mine operation. In this study, a surface coal mine operation and an abandoned meadow established in the 1950 s needed to be restored back to N. pumilio forest on Riesco Island, in Southern Chilean Patagonia. We compared the establishment success of Nothofagus pumilio seedlings on replicated blocks under two conditions (experimental treatments): (i) four blocks of meadow previously disturbed by livestock grazing, (MS), and (ii) four blocks where a deep layer of the soil profile was removed, mixed, and then replaced simulating recommendations used for reclaiming surface coal mines (RS). To improve Nothofagus pumilio establishment and protection at each block under both soil conditions, seedlings were planted both unprotected and protected from wind and solar radiation using four different types of shelters: shade cloth, irregular log piles, white polypropylene shelters, and woody branches. Soil physical and chemical properties, seedling survival and growth, leaf water potential, and stomatal conductance were measured. Results at the end of the first and fourth growing seasons showed better conditions for seedling growth in the RS treatment. Mean survival rates began to be different following the second growing season with values of 84.7 ± 2.9% in RS and 60.2 ± 3.2% survival in MS treatments, respectively. At the end of the study, the difference between the treatments was even geater with values of 75.4 ± 5.5% and 32.2 ± 7.1%. Soil removal and replacement significantly changed soil physical properties, but values were still adequate for vegetation development. The use of shelters significantly influenced four-year survival rates of seedlings planted on the disturbed MS treatment with 60 ± 8.2% survival in plastic shelters and less than 25.5 ± 6.5% for all other shelters. The effects of the shelters were less clear in the RS treatment. Our study showed that Nothofagus pumilio restoration on abandoned grassland and reclaimed mine sites in Patagonia is a feasible option when soil conditions and planting techniques improve soil water availability, and when seedling are protected against excessive solar radiation and wind.
Nothofagus pumilio forests in the Southern Patagonia region of Chile are highly degraded because ... more Nothofagus pumilio forests in the Southern Patagonia region of Chile are highly degraded because of clearing for human settlements, extensive livestock grazing, and more recently, the impact of coal mining operations. Most of these legacy areas have remained as extensive meadows of non-native grasses and legumes with limited Nothofagus pumilio forest recovery due to dry soil moisture conditions and exposure to high wind and solar radiation. Therefore, active reforestation is needed to reclaim Nothofagus pumilio forests from abandoned grassland or disturbances caused by surface mine operation. In this study, a surface coal mine operation and an abandoned meadow established in the 1950 s needed to be restored back to N. pumilio forest on Riesco Island, in Southern Chilean Patagonia. We compared the establishment success of Nothofagus pumilio seedlings on replicated blocks under two conditions (experimental treatments): (i) four blocks of meadow previously disturbed by livestock grazing, (MS), and (ii) four blocks where a deep layer of the soil profile was removed, mixed, and then replaced simulating recommendations used for reclaiming surface coal mines (RS). To improve Nothofagus pumilio establishment and protection at each block under both soil conditions, seedlings were planted both unprotected and protected from wind and solar radiation using four different types of shelters: shade cloth, irregular log piles, white polypropylene shelters, and woody branches. Soil physical and chemical properties, seedling survival and growth, leaf water potential, and stomatal conductance were measured. Results at the end of the first and fourth growing seasons showed better conditions for seedling growth in the RS treatment. Mean survival rates began to be different following the second growing season with values of 84.7 ± 2.9% in RS and 60.2 ± 3.2% survival in MS treatments, respectively. At the end of the study, the difference between the treatments was even geater with values of 75.4 ± 5.5% and 32.2 ± 7.1%. Soil removal and replacement significantly changed soil physical properties, but values were still adequate for vegetation development. The use of shelters significantly influenced four-year survival rates of seedlings planted on the disturbed MS treatment with 60 ± 8.2% survival in plastic shelters and less than 25.5 ± 6.5% for all other shelters. The effects of the shelters were less clear in the RS treatment. Our study showed that Nothofagus pumilio restoration on abandoned grassland and reclaimed mine sites in Patagonia is a feasible option when soil conditions and planting techniques improve soil water availability, and when seedling are protected against excessive solar radiation and wind.
Statistical meta-analysis is a powerful and useful tool to quantitatively synthesize the informat... more Statistical meta-analysis is a powerful and useful tool to quantitatively synthesize the information conveyed in published studies on a particular topic. It allows identifying and quantifying overall patterns and exploring causes of variation. The inclusion of published works in meta-analyses requires, however, a minimum quality standard of the reported data and information on the methodology used. Our experience with conducting a meta-analysis on the relationship between seedling quality and field performance is that nearly one third of the apparently relevant publications had to be discarded because essential data, usually statistical dispersion parameters, were not properly reported. In addition, we encountered substantial difficulty to explore the effect of covariates due to the poor description of nursery cultivation methods, plantation location, and management in a significant proportion of the selected primary studies. Thus, we present guidelines for improving methodology detail and data presentation so that future forest restoration-oriented research can be more readily incorporated into meta-analyses. In general, research studies should report data on means, sample size, and any measure of variation even if they are not statistically significant. The online availability of raw data is the best practice to facilitate the inclusion of primary research on meta-analyses. Providing full information about the production of nursery seedlings, such as plant material and experimental conditions, is essential to test whether these procedures might have an effect on seedling quality. In addition, detailed information about field trials such as site climate, soil preparation techniques, previous land use, or post-plantation management, is needed to elucidate whether seedling quality is context-dependent. Thus, we provide a detailed checklist of important * Enrique Andivia
Plant hydraulics is key for plant survival and growth because it is linked to gas exchange and dr... more Plant hydraulics is key for plant survival and growth because it is linked to gas exchange and drought resistance. Although the environment influences plant hydraulics, there is no clear consensus on the effect of nitrogen (N) supply, which may be, in part, due to different hydraulic conductance normalization criteria and studied species. The objective of this study was to compare the variation of root hydraulic properties using several normalization criteria in four pine species in response to three contrasting N fertilization regimes. We studied four closely related, yet ecologically distinct species: Pinus nigra J.F. Arnold, Pinus pinaster Ait., Pinus pinea L. and Pinus halepensis Mill. Root hydraulic conductance (K h) was measured with a high-pressure flow meter, and values were normalized by total leaf area (leaf specific conductance, K l), xylem cross-section area (xylem specific conductance, K s), total root area (root specific conductance, K r) and the area of fine roots (fine root specific conductance, K fr). Controlling for organ size differences allowed comparison of the hydraulic efficiency of roots to supply or absorb water among fertilization treatments and species. The effect of N on the root hydraulic efficiency depended on the normalization criteria. Increasing N availability reduced K l and K s , but increased K h , K r and especially K fr. The positive effect of N on K r and K fr was positively related to seedling relative growth rate and was also consistent with published results at the interspecific level, whereby plant hydraulics is positively linked to photosynthesis and transpiration rate and fast growth. In contrast, normalization by leaf area and xylem cross-sectional area (K l and K s) reflected opposite responses to K r and K fr. This indicates that the normalization criteria determine the interpretation of the effect of N on plant hydraulics, which can limit species and treatment comparisons.
Nursery nitrogen (N) fertilization influences seedling N reserves, morphology, photosynthesis rat... more Nursery nitrogen (N) fertilization influences seedling N reserves, morphology, photosynthesis rate and stress tolerance and frequently enhances outplanting performance. Although mineral nutrition is a critical aspect of seedling quality, fertility targets of Mediterranean sclerophylous species have not been thoroughly quantified. We sought to define those fertility targets for seedlings of Quercus ilex, a key species in Mediterranean areas. Nine fertility treatments, ranging from 0 to 200 mg N seedling-1 applied under an exponential regime were tested in a greenhouse dose response trial in which phosphorus (P) and potassium (K) were increased in the same proportion as N (15N:5P:15K). Height and diameter growth were measured weekly, and biomass and nutritional status were analyzed at the end of culture (24 week). Plant growth and nutritional response to increased fertilization followed a curvilinear pattern depicting phases that ranged from deficiency to luxury consumption. Seedling dry mass production was maximized at 125 mg N seedling-1 (sufficiency level). N content and concentration increased with fertilization, reaching a maximum at 200 mg N seedling-1 (luxury consumption). P and K concentrations peaked at 75 and 25 mg N, respectively, suggesting a dilution effect of these nutrients. Root volume increased linearly up to 100 mg N and declined thereafter. The sufficiency level for Q. ilex (125 mg of applied N seedling-1) is notably higher than for other Quercus species from other biomes but intermediate to other Mediterranean Quercus species. No toxicity was observed at the highest treatment rate (200 mg N) suggesting that increased exponential N rates along with greater P and K proportions than those used in our experiment may further maximize nutrient storage.
Iforest - Biogeosciences and Forestry, Oct 13, 2016
Drought-avoidance traits of South American Mediterranean tree species are crucial attributes to b... more Drought-avoidance traits of South American Mediterranean tree species are crucial attributes to be considered in nursery practices aimed at improving the performance of seedlings exposed to intense summer drought in dryland reforestation projects. In this study, we determined the relation between nursery fertilization doses and the development of drought-avoidance traits of the soapbark tree Quillaja saponaria (Mol.) under contrasting watering regimes following post-planting. Seedlings were grown for 6 months using four increasing doses of controlled-release fertilizer (0, 3, 6, and 12 g L-1 of Basacote ® Plus 15:8:12). After outplanting, half of the seedlings were watered weekly and the other half were left unwatered for one growing season from September 2011 to May 2012. Seedlings were periodically measured for morphological and ecophysiological parameters, and carefully harvested for root measurements at the end of the study. Our results showed that high fertilization doses produced significantly larger seedlings in the nursery with high nitrogen and phosphorous foliar concentrations, which resulted in a significantly higher shoot dry mass after outplanting. Unfertilized seedlings grown with water application had a significantly higher stem diameter, root dry mass and lower shoot/root compared with seedlings with high fertilizer dose. These results highlight the ability of this species to maintain drought-avoidance traits, such as high xylem water potential and chlorophyll fluorescence, during the first 3 months of the 7-month drought period. High nutrient loading, although resulting in improved shoot productivity after outplanting, did not make a significant contribution to the early development of drought-avoidance traits in Q. saponaria.
Grafted, Tippecanoe 1 cultivar black walnut (Juglans nigra L.) trees were planted and grown in an... more Grafted, Tippecanoe 1 cultivar black walnut (Juglans nigra L.) trees were planted and grown in an intensively managed plantation in west-central Spain and subjected to six fertilizer treatments (defined as 0, 25, 50, 75, 150, and 300 g tree Ϫ1 nitrogen [N]) delivered via daily fertigation during the 1st year after outplanting. Stem diameter, volume, and mass increased from the unfertilized control to the second fertilizer treatment (50 g N) but showed no gains thereafter. N utilization efficiency (stem volume growth per unit fertilizer) was greatest for the 25 and 50 g tree Ϫ1 N treatments, and fertilizer N use efficiency (gain in stem volume growth over the unfertilized control per unit fertilizer) was greatest at 50 g tree Ϫ1 N. Foliar N concentrations in mid-July provided the best predictors of seasonal stem volume growth. Optimal foliar N was 3.2%, which is higher than values recommended for other black walnut production systems: less than 2.8% was deficient, 3.0% was sufficient, and more than 3.4% suggested toxicity. Branch biomass and branch mass/trunk mass ratio were greater in all fertilizer treatments than in the unfertilized control, indicating that high fertilization rates may shift biomass allocation away from the desired product (stem wood). FOR. SCI. 59(4):453-463.
Autores. Editado por la AEET. [Ecosistemas no se hace responsable del uso indebido de material su... more Autores. Editado por la AEET. [Ecosistemas no se hace responsable del uso indebido de material sujeto a derecho de autor] Efectos de la forestación de tierras agrícolas mediterráneas y de su manejo en el establecimiento de árboles y arbustos Introducción La deforestación causada por los humanos desde el comienzo del Neolítico ha sido contrarrestada en algunas partes del mundo durante las últimas décadas (García-Barreda y Reyna 2013; FAO 2021) con consecuencias ambientales dispares (Martińez-Valderrama et al. 2021). La restauración forestal se puede llevar a cabo de tres formas: la restauración espontánea o pasiva, basada en los procesos de sucesión secundaria tras la eliminación del factor de degradación, por ejemplo, la regeneración natural como consecuencia del abandono de tierras cultivadas y pastizales; la restau-ración activa asistida, que combina la estrategia anterior con actuaciones puntuales para acelerar la sucesión; y la restauración activa reconstructiva, una combinación de las anteriores más la introducción de una proporción elevada de la biota deseada, es decir, las plantaciones forestales (Gann et al. 2019; Atkinson y Bonser 2020). La reforma de la PAC de 1992 introdujo en Europa la forestación de tierras agrícolas, un tipo de restauración activa. La superficie de forestación de tierras agrícolas de la PAC en España hoy en día, teniendo en cuenta las plantaciones forestales ejecu
Drought is a limiting factor to forest regeneration and restoration, which is likely to increase ... more Drought is a limiting factor to forest regeneration and restoration, which is likely to increase in intensity and duration under future climates. Nitrogen (N) nutrition is related to drought-resistance mechanisms in trees. However, the influence of chemical N form (inorganic and organic N) on physiological traits related to drought resistance has been sparsely studied in conifer seedlings. We investigated the effect of N forms on morpho-physiological traits of Pinus ponderosa Dougl. ex Laws. seedlings and subsequent influences in drought tolerance and acclimation. One-year-old seedlings were fertilized during 10 weeks at 9 mM N with different N forms [either NH 4 + , NO 3 − or organic N (amino acids mixture)] in their second year of growth. After fertilization, we measured traits associated with intrinsic drought tolerance (shoot water relations, osmotic regulation, photosynthesis and cell membrane stability). Seedlings were then subjected to an 8-week drought period at varying drought intensities to evaluate plant acclimation mechanisms. We demonstrated that P. ponderosa seedlings could efficiently use amino acids as a primary N source, showing similar performance to those grown with inorganic N forms. Nitrogen form influenced mainly drought-acclimation mechanisms rather than intrinsic drought tolerance. Osmotic potential at saturation (πsat) was marginally affected by N form, and a significant relationship between proline concentration in needles and πsat was found. During acclimation, seedlings fertilized with organic N minimized needle senescence, retained more nutrients in the oldest needles, had maximum increments in proline concentration and hastened the development of water-use efficiency mechanisms compared with those fertilized with inorganic N sources. Our results suggest an improved physiological drought acclimation of organic N-fertilized seedlings.
Iforest - Biogeosciences and Forestry, Jun 1, 2016
Biogeosciences and Forestry Biogeosciences and Forestry Combined pre-hardening and fall fertiliza... more Biogeosciences and Forestry Biogeosciences and Forestry Combined pre-hardening and fall fertilization facilitates N storage and field performance of Pinus tabulaeformis seedlings Guolei Li (1) , Jiaxi Wang (1) , Juan A Oliet (2) , Douglass F Jacobs (3) Exponential fertilization during the pre-hardening stage and fall fertilization during the hardening stage have each been used independently to nutrient load seedlings. However, nursery and field responses of seedlings to the combination of exponential fertilization and fall fertilization have received little attention. Chinese pine (Pinus tabulaeformis Car.) container seedlings were exponentially fertilized with accumulated totals of 40, 80 or 120 mg N per seedling during pre-hardening, and fall-fertilized with 0, 12, 24 or 48 mg N per seedling, and were subsequently outplanted and followed for two growing seasons. Interactions of exponential and fall fertilization had significant effects on plant N content in the nursery and first-year height after outplanting. Fall fertilization promoted additional nutrient loading during hardening for the 40-80 mg N per seedling pre-hardening regimes. The highest exponential fertilization rate enhanced N concentration in foliage and roots compared to the other two rates. Maximum diameter was observed in the lowest exponential fertilization rate at the second year after outplanting. Fall fertilization enhanced foliar N concentration. Supplemental 12 and 24 mg N per seedling during fall were more effective in increasing height increment at the second year after outplanting. Our results indicate that pre-hardening fertilization is a useful tool to nutrient load Chinese pine in the nursery and facilitate outplanting performance in the field. In combination, fall fertilization has potential to further augment this response, although further research is needed to precisely match rates of pre-hardening and fall fertilization to optimize seedling performance.
Restoration of abandoned, high-elevation pastures is needed across many ecosystems. Diverse abiot... more Restoration of abandoned, high-elevation pastures is needed across many ecosystems. Diverse abiotic and biotic stressors often limit establishment of native trees species, however, justifying the need for novel approaches to alleviate such stressors. Freezing damage often negatively impacts survival of planted trees across temperate landscapes and on some high-elevation tropical restoration sites, such as for Acacia koa (koa) in Hawaii, USA. Koa performs poorly under forest canopies, a potential limitation to the use of nurse trees for establishment on frost-prone sites. Using a heterogeneous canopy of a non-native conifer, Cryptomeria japonica, we underplanted koa seedlings along a simulated range of canopy shelter levels in combination with field fertilization. We tested the effect of a canopy cover gradient and nutrient availability on frost avoidance and tolerance responses, as well as the potential to harness koa's developmental plasticity to optimize growth and survival. C. japonica canopy cover provided protection from frost damage, with increased sheltering under greater canopy closure. When combined with fertilization, increasing canopy closure reduced frost damage and increased koa growth. Although we observed limited frost damage in our study, leaf-level soluble sugars increased during the winter and in more open microsites, reflecting a potential mechanism for frost tolerance in this tropical species. We conclude that frost-tolerant conifers used as nurse trees represent a potential tool to help establish native tree species on high-elevation, frost-prone sites.
Frontiers in forests and global change, Jan 5, 2023
effect on pine growth. Lack of response to main effects of competition suppression treatments can... more effect on pine growth. Lack of response to main effects of competition suppression treatments can be attributed to the minimum changes of soil water content to mulching or weeding under arid conditions. Thus, 20 years after planting, tube-shelters and competition suppression treatments were relatively ineffective at improving survival or growth of P. halepensis. Meshshelters are recommended as the most effective protection method for restoration under arid site conditions.
The effect of shelter tubes on plant performance has been widely studied. Although, the role of s... more The effect of shelter tubes on plant performance has been widely studied. Although, the role of shelter tubes in alleviating the effects of drought and high-irradiance stresses during seedling establishment has been less studied than its effect on survival. The present study compares the effects of shelter tubes with different light transmissivities (Lt) on survival and morpho-physiological responses of two coexisting tree species (drought-tolerant Quillaja saponaria and relatively more drought-sensitive Maytenus boaria ) of the Chilean matorral during an exceptionally dry and warm growing season (2014–2015). Two-year-old seedlings were randomly assigned to shelter tubes differing in Lt (20, 40, 60, 80%) or to a control (no shelter, Lt 100%) at field conditions. Survival was measured monthly, while shoot and root biomass, root length, pre-dawn xylem water potential, and non-structural carbohydrate concentration (NSC) were measured 8 months after transplanting. Shelter tubes increased the seedling survival of Q. saponaria by 80–100% relative to the control conditions, where full mortality was observed by the end of the experiment. By contrast, M. boaria exhibited high mortality regardless of the presence of shelters, suggesting that tubes were ineffective to alleviate the summer-related stresses in this species. Xylem water potential of Q. saponaria seedlings was significantly lower at 80% Lt than at 40% Lt, where maximum values were observed. Also, at 40% Lt, plant height and root length were highest and shoot/root ratio the lowest. By contrast, no differences in NSC, stomatal conductance, and photochemical efficiency were observed among Lt treatments. We conclude that shelter tubes may alleviate summer stresses in drought-tolerant species such as Q. saponaria ; hence, they appear to be effective reforestation ecotechnology under severe water limitations and high-irradiance stress imposed by the current drought and heatwaves conditions in central Chile.
Freezing stress is a critical environmental factor affecting survival, distribution, and evolutio... more Freezing stress is a critical environmental factor affecting survival, distribution, and evolution of plants. Although there is evidence that nitrogen (N) affects frost tolerance of juvenile conifers, the magnitude and direction of such effect can diverge among species. The influence of the N source on frost tolerance has been barely studied. Particularly, how organic N sources could affect the cold acclimation dynamics of seedlings is poorly understood. We studied morpho‐physiological responses to organic N supply (amino acids) in comparison to inorganic N in seedlings of two Mediterranean pine species: Pinus halepensis and P. sylvestris. Fertilization was applied at low and high N doses (30 and 130 mg N seedling−1) in the first growing season. Then, tolerance of seedlings to freezing stress was evaluated through the cold season. This study confirmed that organic N supply promotes growth of both species as effectively as inorganic N sources. At low N availability, seedlings had acute phosphorus deficiencies when grown with inorganic N, but not with organic N. Likewise, high organic‐N availability improved chlorophylls concentration. Both species increased their frost tolerance through time, especially during late autumn. Although organic N supply did not show clear benefits on frost tolerance, it seemed to enhance cold acclimation via increases of compatible solutes, such as soluble sugars and proline, particularly in P. halepensis. Thus, the effects of organic N supply could depend on the extent that such osmolytes contribute to the dormancy strategy of the species. Other species‐specific mechanisms to cope with freezing stress are further discussed.
Effect of controlled release fertilizer type and rate on mineral nutrients, non-structural carboh... more Effect of controlled release fertilizer type and rate on mineral nutrients, non-structural carbohydrates, and field performance of Chinese pine container-grown seedlings Fu Y., Oliet J.A., Li G., Wang J. (2017). Effect of controlled release fertilizer type and rate on mineral nutrients, non-structural carbohydrates, and field performance of Chinese pine containergrown seedlings.
Nursery cultivation practices can be modified to increase resistance to water stress in forest se... more Nursery cultivation practices can be modified to increase resistance to water stress in forest seedlings following field establishment, which may be increasingly important under climate change. We evaluated the morphological (survival, growth) and physiological (chlorophyll fluorescence, leaf water potential) responses to water stress for three ecologically diverse Quercus species (Q. robur, Q. pubescens, and Q. ilex) with varying traits resulting from the combination of growing media (peat, coir) and fertilization (standard, P-enriched, K-enriched). For all species under water stress, seedlings grown in coir had generally higher growth than those grown in peat. Seedlings fertilized with P performed better, particularly for survival; conversely, K fertilization resulted in inconsistent findings. Such results could be explained by a combination of factors. P fertilization resulted in higher P accumulation in seedlings, while no K accumulation was observed in K fertilized seedlings. A...
Forest restoration is challenging in arid and semiarid lands. Research has identified ecotechnolo... more Forest restoration is challenging in arid and semiarid lands. Research has identified ecotechnologies that may alleviate stressful conditions of planted seedlings, but studies are often limited to the first few years of regeneration establishment. Over 20 years, we tested the effects of tree shelters (mesh- and tube-shelters) and competition suppression (two types of synthetic mulch and manual weeding) on soil water content and development of Pinus halepensis on an arid site in southeastern Spain. Competition suppression increased soil water content at shallow depths only using a polyethylene sheet, with no effect on survival. Tree shelters had a much greater effect than competition suppression on tree responses. Survival was mostly affected by shelter type, with lower survival in tube-shelters compared to mesh-shelters and non-protected seedlings; differences began after the first year, but became more pronounced following an intense drought at 3 years. Survival for pines protected...
Forestry: An International Journal of Forest Research
Mycological resources have attracted considerable interest from the public recently. In this cont... more Mycological resources have attracted considerable interest from the public recently. In this context, forest mycological management of wild mushrooms has emerged a research field and is developing rapidly with the objective to sustainably use and conserve mushrooms in multifunctional forests. Although the term ‘mycosilviculture’ was coined relatively recently, forest management of mycological resources and fungal silviculture began already in the 1980s. This study reviews the literature on the forest management of wild mycological resources with emphasis on studies in Spanish Mediterranean forests. The review covers some of the most important aspects of management, such as the diagnosis of mycological resources through inventory and sampling protocols, predictive models of mushroom yield, stand variables and mycosilvicultural practices that affect mushroom yield and fungal diversity. Finally, the potential of mycorrhizal applications for mycosilviculture is briefly discussed. Most o...
Nothofagus pumilio forests in the Southern Patagonia region of Chile are highly degraded because ... more Nothofagus pumilio forests in the Southern Patagonia region of Chile are highly degraded because of clearing for human settlements, extensive livestock grazing, and more recently, the impact of coal mining operations. Most of these legacy areas have remained as extensive meadows of non-native grasses and legumes with limited Nothofagus pumilio forest recovery due to dry soil moisture conditions and exposure to high wind and solar radiation. Therefore, active reforestation is needed to reclaim Nothofagus pumilio forests from abandoned grassland or disturbances caused by surface mine operation. In this study, a surface coal mine operation and an abandoned meadow established in the 1950 s needed to be restored back to N. pumilio forest on Riesco Island, in Southern Chilean Patagonia. We compared the establishment success of Nothofagus pumilio seedlings on replicated blocks under two conditions (experimental treatments): (i) four blocks of meadow previously disturbed by livestock grazing, (MS), and (ii) four blocks where a deep layer of the soil profile was removed, mixed, and then replaced simulating recommendations used for reclaiming surface coal mines (RS). To improve Nothofagus pumilio establishment and protection at each block under both soil conditions, seedlings were planted both unprotected and protected from wind and solar radiation using four different types of shelters: shade cloth, irregular log piles, white polypropylene shelters, and woody branches. Soil physical and chemical properties, seedling survival and growth, leaf water potential, and stomatal conductance were measured. Results at the end of the first and fourth growing seasons showed better conditions for seedling growth in the RS treatment. Mean survival rates began to be different following the second growing season with values of 84.7 ± 2.9% in RS and 60.2 ± 3.2% survival in MS treatments, respectively. At the end of the study, the difference between the treatments was even geater with values of 75.4 ± 5.5% and 32.2 ± 7.1%. Soil removal and replacement significantly changed soil physical properties, but values were still adequate for vegetation development. The use of shelters significantly influenced four-year survival rates of seedlings planted on the disturbed MS treatment with 60 ± 8.2% survival in plastic shelters and less than 25.5 ± 6.5% for all other shelters. The effects of the shelters were less clear in the RS treatment. Our study showed that Nothofagus pumilio restoration on abandoned grassland and reclaimed mine sites in Patagonia is a feasible option when soil conditions and planting techniques improve soil water availability, and when seedling are protected against excessive solar radiation and wind.
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