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Native Plant Production in Chile. Is It Possible to Achieve Restoration Goals by 2035?
Facing rapid loss of biodiversity as a consequence of climate change, Chile has formally pledged to restore 600,000 ha of native forest by 2035. This effort, however, has not considered the amount and quality of native plants required to meet this pledge. Thus, we examined data collected during the annual, government-conducted census of small- and medium-sized nurseries from central Chile, which account for 78% of the nation’s total plant production, to assess if current production is sufficient to meet Chile´s restoration needs. We coupled this with data collected during our series of ongoing research projects to determine if nurseries are currently meeting minimum seedling quality standards based on morpho-physiological attributes. Our four-year analysis (2016–2019) shows that the number of native seedlings has increased by only 4%, but because only 19% of nursery managers have training, just 29% of all seedlings meet quality criteria for restoration. Thus, under the current rate and quality of plant production, meeting restoration pledges desired by the year 2035 would not be achieved until 2181. This timeline can be accelerated through an urgent expansion of nursery space, implementation of a continuous program for technology and knowledge transference, and strong support through governmental policies.
Acevedo Tapia, Manuel-Álvarez, Carolina-Dumroese, R. Kasten-Bannister, Jan R.-Cartes Rodríguez, Eduardo-González Ortega, Marta
2021
Field Establishment Techniques for Guindo Santo, an Endemic Species from Central Chile
El rendimiento de plantación durante el primer año se midió en guindo santo (Eucryphia glutinosa (Poepp. & Endl.) Baill.), Una especie de árbol endémico de Chile en la zona climática mediterránea, que está catalogada como una especie casi amenazada. Los efectos sobre la supervivencia del tamaño inicial de la planta, la fertilización en el establecimiento y la sombra (con o sin arboles nodriza) se evaluaron durante la primera temporada de crecimiento. La plantación de guindo santo debajo de árboles nodriza fue el tratamiento más importante para aumentar la supervivencia, en comparación con los árboles plantados a pleno sol. Creemos que los efectos positivos de los árboles genealógicos en la supervivencia están relacionados con una disminución del estrés por sequía en las plantas durante el verano, en respuesta a niveles más altos de contenido de agua del suelo y una disminución en la irradiación incidente. Sugerimos encarecidamente el uso de sombra, como árboles nodriza o refugios de árboles, durante el establecimiento de guindo santo en un clima mediterráneo
Álvarez, Carolina-Acevedo Tapia, Manuel-González Ortega, Marta-Dumroese, R. Kasten-Cartes Rodríguez, Eduardo-Quiroz Marchant, Iván
2019
Intraspecific variation in drought response of three populations of Cryptocarya alba and Persea lingue, two native species from mediterranean Central Chile
An increase in the severity of drought events on Mediterranean climates highlights the need of using plant material adapted to drought during restoration efforts. Thus, we investigated between-population morpho-physiological differences in Cryptocarya alba and Persea lingue, two native species from Mediterranean central Chile, for traits that could effectively discriminate population performance in response to water restriction (WR) testing. Three populations from each species were subjected to WR treatment and physiological, morphological, and growth parameters were assessed at the beginning and at the end of the experiment. In C. alba, the most xeric population displayed smaller plants with mesophyllous leaves and lower photosynthetic rates indicating a resource saving strategy. Moreover, the xeric population performed better during WR than the most mesic populations, exhibiting higher water use efficiency (iWUE) and maintenance of growth rates. All C. alba populations responded equally to WR in terms of morphology and biomass partitioning. In contrast, differences among P. lingue populations were subtle at the morpho-physiological level with no apparent relation to provenance environmental conditions, and no morphological traits were affected by WR. However, in response to WR application, the most mesic population was, as observed through reduction in relative growth rates, more affected than xeric populations. We attribute such discrete differences between P. lingue provenances to the lower distributional range of selected populations. Our results show that relative growth rates in both species, and iWUE only in C. alba, exhibited population specific responses upon WR imposition; these results correspond with the environmental conditions found at the origin of each populations. Both traits could further assist in the selection of populations for restoration according to their response to water stress.
Álvarez, Carolina-Acevedo Tapia, Manuel-Dumroese, R. Kasten-González Ortega, Marta-Cartes Rodríguez, Eduardo
2020
Production and establishment techniques for the restoration of Nothofagus alessandrii, an endangered keystone species in a Mediterranean forest
Ruil (Nothofagus alessandrii) is an endangered keystone species from the Mediterranean climate zone of Chile. Ruil’s fragile state of conservation urges development of restoration programs, but specific protocols for nursery production and field establishment that ensure plant survival are largely unknown. Therefore, we examined the effect on nitrogen (N) fertilization and container size during nursery production in combination with the use of mesh shelters after outplanting on survival and growth during the first growing season in the field. First year outplanting survival of nursery-grown container seedlings was enhanced when seedlings were given nitrogen (N) during nursery production and deployed with mesh tree shelters in the field. The volume of the container had no effect on outplanting survival and growth. Increasing N from zero to 200 mg N L−1 provided sufficient N levels, resulting in increased seedling height, root-collar diameter, shoot biomass, and total seedling N and phosphorous concentrations. Additional N provided by the 400 and 600 mg N L−1 treatments underwent luxury consumption by the seedlings with no further benefits in field performance. Improved growth in the nursery, along with the use of mesh tree shelters after outplanting, especially during the typical summer drought, may be responsible for increased survival during the first growing season. Increasing the performance of nursery-grown ruil seedlings is essential to restoring this endangered, vulnerable, and foundation species within the highly biodiverse, yet seriously threatened endemic Maulino Costero Forest of the Mediterranean climate of central Chile.
Acevedo Tapia, Manuel-Álvarez, Carolina-Cartes Rodríguez, Eduardo-Dumroese, R. Kasten-González Ortega, Marta
2020
Nitrogen loading of Eucalyptus globulus seedlings: nutritional dynamics and influence on morphology and root growth potential
Achieving successful outplanting of trees on increasingly harsher sites is a global concern. In Chile, for example, new Eucalyptus globulus plantations are being targeted to poorer, low fertility sites where additional stresses often negatively affect seedling performance during the first field season. Nitrogen-loading during the later stages of nursery production can, however, significantly improve seedling physiological performance on harsher sites by increasing plant growth and nutrient storage reserves for subsequent root growth after outplanting. Maximizing these benefits, and applying the concept of loading throughout the entire crop cycle, requires a better understanding of nitrogen (N) dynamics. Thus, for container E. globulus, considered one of the most important plantation species worldwide, we evaluated the effects of increasing N supply (50 to 600 mg N L−1) on seedling morphological traits, biomass production, root growth potential, and foliar N. After 15 weeks of N application, seedlings showed an increase in all growth variables evaluated up to 300 mg N L−1, whereas higher rates allowed luxury consumption. Modeling growth responses revealed, however, an apparent ammonium antagonism with other macronutrient cations suggests that high rates of this N-form may negate the potential benefits of N-loading, or that other modifications to the fertilizer solution may promote additional growth at higher N rates. Foliar N concentration, which was easily and accurately measured with a leaf chlorophyll meter, showed a gradient from basal to apical leaves suggesting a strong translocation of N in E. globulus seedlings. Our results suggest nursery management that supplies 300 mg L−1 of N through the entire growing season could improve seedling nutritional status, morphological attributes, and growth of new roots, attributes that may improve establishment on low fertility sites.
Acevedo Tapia, Manuel-Rubilar, Rafael-Dumroese, R. Kasten-Ovalle, Juan F.-Sandoval, Simón-Chassin-Trubert Fuentealba, Rodrigo Andrés
2020
Root system architecture of Pinus ponderosa three decades after copper root pruning in a container nursery
We revisited a Pinus ponderosa planting 32 years after it was established with one-year-old seedlings grown in copper-treated containers that modified their root systems. This technique was intended to promote more root egress after outplanting from the entire length of the root plug with a goal of providing greater stem stability. After excavating and digitizing the root systems of five treated and five non-treated plants, we observed that regardless of treatment, all trees initiated more roots and accumulated more root volume in apparent response to mechanical stresses invoked by wind and slope, with more roots occurring windward and downslope. Few differences were noted between treatments for root length and volume for either the cage or the entire root system. Trees treated with copper were taller (8%) with stouter taproots (less taper) and less root volume in the lower soil profile than control trees. Although the copper treatment may have induced short-term changes to root system architecture, the long-term, plastic response of this species to mechanical stresses, and the time duration involved, was more critical to the observed expression of traits.
Dumroese, R. Kasten-Terzaghi, Mattia-Acevedo Tapia, Manuel-Lasserre, Bruno-Scippa, Gabriella S.-Scott Baggett, L.-Chiatante, Donato-Montagnoli, Antonio
2022
Fall fertilization during nursery production increases nitrogen status of Purshia tridentata seedlings: implications for outplanting
During container nursery production of Purshia tridentata (antelope bitterbrush), we found that three fall fertilization applications successfully loaded plants with nitrogen (N) with little effect on plant biomass. Using 15N-labeled fertilizer to track N movements, we observed that N-loaded seedlings attained luxury consumption and ultimately translocated more N toward roots. In trees, such N-loading efforts have been reported to increase seedling survival and growth after outplanting by improving initial root growth. This leads to enhanced access to water and nutrients that increases overall plant competitiveness and performance. Our results add, in general, to the paucity of information concerning fall fertilization of shrubs, and specifically that this technique offers promise to enhance the quality of antelope bitterbrush seedlings. This could improve overall planting success of this important shrub native to western United States rangelands. Increasing the effectiveness of planting antelope bitterbrush, which can often improve restoration trajectories more than direct seeding or reliance on natural regeneration of this species, could accelerate the pace and scope of critical habitat restoration. Restoration is needed as antelope bitterbrush abundance has been reduced across the landscape because of conversion to agriculture, invasion by nonnative annual grasses, and an increase in fire frequency and intensity, among other reasons. In addition, this species provides browse for ungulates and critical habitat for at-risk species, such as Centrocercus urophasianus (greater sage-grouse). Although N loading antelope bitterbrush has potential to improve outplanting performance, the resulting higher nutrient status of this preferred browse species may lead to elevated browsing during seedling establishment.
Dumroese, R. Kasten-Zhu, Yan-Acevedo Tapia, Manuel-Pinto, Jeremiah R.-Álvarez, Carolina-Liu, Yong
2023
Examining physiological, water relations, and hydraulic vulnerability traits to determine anisohydric and isohydric behavior in almond (Prunus dulcis) cultivars: Implications for selecting agronomic cultivars under changing climate
The search for drought tolerant species or cultivars is important to address water scarcity caused by climate change in Mediterranean regions. The anisohydric–isohydric behavior concept has been widely used to describe stomatal regulation during drought, simply in terms of variation of minimal water potential (Ψmin) in relation to pre-dawn water potential (Ψpd). However, its simplicity has sometimes failed to deliver consistent results in describing a complex behavior that results from the coordination of several plant functional traits. While Prunus dulcis (almond) is known as a drought tolerant species, little information is available regarding consistent metrics to discriminate among cultivars or the mechanisms underlying drought tolerance in almond. Here we show a sequence of plant stomatal, hydraulic, and wilting responses to drought in almonds, and the main differences between anisohydric and isohydric cultivars. In a pot desiccation experiment we observed that stomatal closure in P. dulcis is not driven by loss in turgor or onset of xylem cavitation, but instead, occurs early in response to decreasing Ψmin that could be related to the protection of the integrity of the hydraulic system, independently of cultivar. Also, we report that anisohydric cultivars of P. dulcis are characterized by maximum stomatal conductance, lower water potentials for stomatal closure and turgor loss, and lower vulnerability to xylem cavitation, which are traits that correlated with metrics to discriminate anisohydric and isohydric behavior. Our results demonstrate that P. dulcis presents a strategy to avoid cavitation by closing stomata during the early stages of drought. Future research should also focus on below-ground hydraulic traits, which could trigger stomatal closure in almond.
Álvarez, Carolina-Acevedo Tapia, Manuel-Estay, Daniela-Aros, Fabián-Dumroese, R. Kasten-Sandoval, Simón-Pinto, Manuel
2022

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