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ArticleResponses to water scarcity in six sclerophyllous species established in a dry and burned site in central Chile
XV World Forestry Congress, 2-6 May 2022
2022Also available in:
No results found.In this study, we investigated the responses to water scarcity after the post-transplant shock in six sclerophyllous species established in a Mediterranean-type climate site severely burned by fire. Seedlings of the species Acacia caven, Lithraea caustica, Quillaja saponaria, Escallonia pulverulenta, Peumus boldus and Colliguaya odorifera were cultured in the nursery on 140 mL pots and then planted in the field under tree shelters and submitted to two irrigation treatments during summer (2 L-1 week-1 seedling-1 cf. no watering). Species differed by irrigation treatment in survival, stomatal conductance, and transpiration, with P. boldus and E. pulverulenta exhibiting the lowest values in the treatment with no watering. This suggests that young seedlings of both species have not the capacity to survive during dry summers in Mediterranean-type climates unless irrigations are increased in frequency and quantity. Keywords: Outplanting survival; Mediterranean-type climate; gas exchange; forest restoration; burn severity ID: 3624041 -
ArticleOverstory-regeneration relationships in mixed-conifer forests of the southwestern United States
XV World Forestry Congress, 2-6 May 2022
2022Also available in:
No results found.The ponderosa pine, dry- and wet-mixed conifers, and spruce-fir forests are major forest types in the southwestern United States. The ponderosa pine and dry mixed-conifer systems have historically relied on fire to maintain structure and composition. With the changes in fire regimes, there has been a long-term progression toward more shade-tolerant species such as Abies concolor. Using data from the USDA Forest Service Forest Inventory and Analysis program, this study focused on the relative proportions of each species in the seedling, sapling, and overstory tree cohorts. The hypothesis is that regeneration and subsequent development by species were proportional to the species in the overstory, accounting for shade tolerance. Transitions to a different future forest combination, if that transition was occurring, was related to the time since the previous disturbance, usually fire, and the relative proportion of Abies in the overstory mix. This paper examines a subset of the relationship between overstory basal area, latitude, elevation, and seedling numbers in the understory by species. We found three species – Picea engelmannii, Pseudotsuga menziesii, and Pinus ponderosa – displayed an interaction between overstory basal area and latitude upon seedling numbers in the understory. There was little separation at the more southerly locations, suggesting an external limiting factor, soil moisture availability, overcame species-specific silvical characteristics and competitive abilities. Future work will examine the presence of particular species in the overstory and their influence upon their own and other species' regeneration. Keywords: multiple species forests, regeneration trends, succession, microenvironment ID: 3486970 -
ArticleGrowth and physiological acclimation to shade in young plants of Adesmia bijuga Phil., critically endangered species in central Chile
XV World Forestry Congress, 2-6 May 2022
2022Also available in:
No results found.Adesmia bijuga Phil. is an endemic and endangered shrub species of central Chile. Its potential shade intolerance is one of the leading hypotheses for its vigor loss when the species grows beneath closed canopies. In this study we aimed to assess growth and physiological acclimation to shade in young of A. bijuga plants. A nursery experiment was established with three light levels based on the interception of photosynthetic active radiation (PAR) (TRT0: control at full sun, TRT60: 60% shaded, and TRT90: 90% shaded), and maintained for 71 days during the summer season. Growth and leaf morpho-physiological responses were evaluated at the beginning, at the middle, and at the end of the experiment. The shading treatment increased plant height (H) and live crown percentage (Lcrown) compared to the control treatment at full sun. However, light-saturated photosynthetic rate (Amax), dark respiration rate (Rd), and light compensation point (Gi) were higher in TRT60 than in the other treatments.No differences were found among treatments for the apparent quantum yield (α). At this stage of plant development, our results suggest high acclimation plasticity of A. bijuga to light levels; however, a semi-shade environment (i.e., TRT60) favored a better performance of the species. Keywords: Shade tolerance, photosynthesis, light acclimation, forest restoration. ID: 3624055
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