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Green barks of trees from drought deciduous forests (“bosque seco”) in northern Peru/southern Ecuador do not perform CAM
Abstract and Figures
Trees from drought deciduous forests (“bosque seco”) in northern Peru and southern Ecuador regularly shed their leaves at the onset of seven months-long periods without rain. This way they very effectively reduce the bulk water consumption by leaf transpiration, still loosing small amounts of water through their bark, but at the risk of too little or no carbon gain when leaf-less. Seven species studied here have good developed green cortex tissue on stems and axes, as especially evident for the “bottle tree” Ceiba trischistandra (A. Gray) Bakhuisen (Bombacaceae). In several leaf-less tree species at the end of summer drought, when xylem sap flows are very low, indications of higher xylem flows at night as compared to day-time were found, which led to the question of whether the trees are capable of perform- ing CAM in their axes. However, although quite low in some cases, the pH of the cortex tissues did not fluctuate diurnally. In addition, no night-time carbon uptake could be observed. Although no net carbon gain was measured in C. trischistandra and Erythrina smithiana Krukoff (Fabaceae) photosynthetic activity of the green cortex was sufficient to re-assimilate between 50% to 60% of the carbon released by mitochondrial respiration. In contrast, the obligate CAM plant Cereus diffusus (Britton & Rose) Werdermann (Cactaceae), which was studied as a reference in the same environment, showed both diurnal pH-fluctuations in its green tissue with lowest values before sun rise, and net carbon fixation at night.
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... Poorter & Markesteijn (2008) found that the presence of a taproot strongly increases the probability of seedlings under drought. Given a low weight (2) Trees/shrubs that can perform photosynthesis through their stems (e.g., Parkinsonia) can perform photosynthesis without leaves, rendering them less sensitive to extreme drought because of reduced evapotranspiration (Küppers et al., 2015). Given a low weight (2) because many species resistant to extreme drought do not have this capacity. ...
At the start of the UN Decade of Ecosystem Restoration (2021–2030),
the restoration of degraded ecosystems is more than ever a global priority. Tree planting will make up a large share of the ambitious restoration commitments made by countries around the world, but careful planning is needed to select species and seed sources that are suitably adapted to present and future restoration site conditions and that meet the restoration objectives. Here we present a scalable and freely available online tool, Diversity for Restoration (D4R), to identify suitable tree species and seed sources for climate-resilient tropical forest landscape restoration. The D4R tool integrates (a) species habitat suitability maps under current and future climatic conditions; (b) analysis of functional trait data, local ecologicalknowledge and other species characteristics to score how well species match
the restoration site conditions and restoration objectives; (c) optimization of species combinations and abundances considering functional trait diversity or phylogenetic diversity, to foster complementarity between species and to ensure ecosystem multifunctionality and stability; and (d) development of seed
zone maps to guide sourcing of planting material adapted to present and predicted future environmental conditions. We outline the various elements behind the tool and discuss how it fits within the broader restoration planning process, including a review of other existing tools.
The Diversity for Restoration tool enables non-expert users to combine species traits, environmental data and climate change models
to select tree species and seed sources that best match restoration site conditions and restoration objectives. Originally developed for the tropical dry forests of Colombia, the tool has now been expanded to the tropical dry forests of northwestern Peru–southern Ecuador and the countries of Burkina Faso and Cameroon, and further expansion is underway. Acknowledging that restoration has a wide range of meanings and goals, our tool is intended to support decision
making of anyone interested in tree planting and seed sourcing in tropical forest landscapes, regardless of the purpose or restoration approach.
Im Nordwesten Perus, nahe der ekuadorianischen Grenze, liegt das Biosphärenreservat „La Reserva de Biosféra del Noroeste“. Es umfasst vor allem Trockenwälder der arten- und endemitenreichen Florenregion Amotape-Huancabamba und gliedert sich in vier Schutzgebiete. Eines dieser Gebiete (Coto de Caza El Angolo) wird seit mehreren Jahren für ökophysiologische Untersuchungen von den Autoren aufgesucht. Die klimatischen Verhältnisse und die Vegetation dieser Region sowie charakteristische Pflanzenarten und deren Ökologie werden vorgestellt. Die tropische, regengrüne Vegetation dieses pazifischen Trockenwaldes dient als Vorbild für ein Trockenwaldhaus im Ökologisch-Botanischen Garten der Universität Bayreuth, mit dessen Gestaltung im Sommer 2007 begonnen wurde.
The new edition of Physicochemical and Environmental Plant Physiology uses elementary chemistry, physics, and mathematics to explain and develop key concepts in plant physiology. In fundamental ways, all physiological processes that occur in cells, tissues, organs, and organisms obey such relations. Topics include diffusion, membranes, water relations, ion transport, photochemistry, bioenergetics of energy conversion, photosynthesis, environmental influences on plant temperature, and gas exchange for leaves and whole plants. This new edition maintains the unparalleled commitment to clear presentation and improves upon the user friendliness of the previous versions. * All illustrations have been redrawn, many in two-color * New material includes: 14 new figures, 100 new references, 20 new equations and considerable new and revised text * Extensive cross-referencing with a simpler system for chapter sections and subsections * Easy-to-use format including major equations being presented at the beginning of each chapter, and calculations presented outside of the chapter text. Physicochemical and Environmental Plant Physiology, 3rd edition, establishes a new standard of excellence in the teaching and quantitative understanding of plant physiology.
Leaves are expected to be green (although they are sometimes reddish in the so-called blood forms or yellowish in the so-called aurea forms). The colour-determining pigments, the chlorophylls, are the cause of the leaves’ global importance in photosynthetic carbon fixation. The fact that stems can also contain chlorophyll is not directly evident. The outer bark layers are mostly brown (oak) or grey (beech, aspen) or sometimes even white (birch). However, bark tissues of younger twigs of trees are regularly greenish. The green colour is not caused by a surface layer of algae colonizing the outer wet parts of rhytidomes. By carefully peeling off layers of the dead outer bark of twigs and branches, a green colour indicates the presence of chlorophyll-containing tissues. The fact that the tree’s skeleton partly consists of green tissue has been known for centuries by bark-peeling basket makers, bast producers and even lovers who cut hearts into tree bark.
A lot about methods applied in the above studies can be found in a (hopefully) well-accepted textbook, I had the pleasure to contribute. In this book, we tried to clarify the methodological and theoretical background in a readable though physical and physico-chemical correct way. In addition, the use of these methods and relevant devices are explained. We think that it may be helpful for eco-physiological, and agricultural or horticultural science as well.
Among the people who do photosynthesis research at the leaf, plant or canopy level, the devices used to measure photosynthesis are usually referred to as gas-exchange systems or simply as ‘systems’. The concept that photosynthesis is measured with a system, rather than a single instrument, is an important place to start, for two reasons. First, the system concept emphasizes the fact that we have nothing like a discrete photosynthesis sensor. Photosynthesis is always a calculated parameter, determined from measurements of CO2 concentrations, gas flows and sometimes other parameters, depending on the measurement philosophy. Second, the system concept reminds us that gas-exchange systems typically measure more than just photosynthesis, for the reason that photosynthesis data are greatly enhanced by the simultaneous acquisition of other kinds of information.
