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Examines \"how an acorn grows up to be an oak tree, [including] the stages of growth of a tree throughout the seasons and year ... Also introduces the happenings around the tree, from children playing in its shade to squirrels climbing up its trunk and birds nesting in its branches\"--Amazon.com.

Background Amphibians are one of the most susceptible groups to climate change as their development occurs in aquatic environments or in microhabitats with high humidity. Accordingly, our primary objective was to investigate the chronic physiological responses seen in early larval to adult stages of Polypedates cruciger (Common hourglass tree frog) to future climate change based on continuous exposure to elevated temperature and elevated CO 2 -induced low water pH. Free-swimming and free-feeding tadpoles were observed until metamorphosis under four experimental treatments; two elevated temperatures, one elevated CO 2 (reduced pH) and a control maintained at ambient temperature (29 °C ± 1 °C) and CO 2 (pH = 7). Elevated temperature treatments were maintained at 32 °C ± 0.5 °C and 34 °C ± 0.5 °C to represent respectively, the future climate scenarios RCP2.6 (Representative Concentration Pathway 2.6, the ‘base-case’ scenario) and RCP8.5 (‘business-as-usual’ scenario) according to the 5 th Assessment Report of the IPCC. Elevated CO 2 treatment was maintained within the pH range of 5.5–5.6 representing the range expected between RCP8.5 and RCP2.6. Results Compared to the control, elevated CO 2 accelerated phenological progression of tadpoles through Gosner stages, thus resulting in lower body size at metamorphosis. Both elevated temperatures significantly delayed the development and reduced the growth of tadpoles. 100% mortality was observed in 34 °C treatment before metamorphosis (before Gosner stage 36) while all the tadpoles died after metamorphosis (at Gosner stage 46) in 32 °C treatment. Elevated CO 2 increased tadpole activity, in terms of their swimming speed, while both of the elevated temperatures reduced it compared to the control. Catalase activity increased at elevated CO 2 . Ammonia excretion by tadpoles was decreased by elevated CO 2 , but increased under temperature elevation. Both Elevated CO 2 and temperature treatments reduced the white blood cell count and its percentage of thrombocytes. Percentages of lymphocytes, monocytes and neutrophils were increased at 32 °C, while lymphocyte percentage and lysozyme activity were increased at elevated CO 2 . Several deformities were observed in tadpoles at elevated temperature and CO 2 . Conclusions Elevated temperatures and reduced pH due to elevated CO 2 , being major features of climate change, increase the vulnerability of amphibians, who are already one of the most threatened vertebrate groups. Based on our observations on the model amphibian species P. cruciger , increased vulnerability to climate change occurs by reducing their growth, body size and motility while also reducing their immunity and inducing physical deformities. These impacts are highly-likely to reduce the foraging, competitive and reproductive capabilities in their natural habitats. We conclude further that even the ‘best-case’ scenario of future climate change can impose significant physiological impacts that could threaten amphibian populations on broader spatial and temporal scales. Graphical abstract

\"The Case of the Wooden Timekeeper follows characters Scout and Daisy as they learn about trees. The book features Field Notes with more information about trees and a Nature Craft for kids to make at home.\"-- Provided by publisher.

To assess the diversity of tropical tree life histories, a conceptual framework is needed to guide quantitative comparative study of many species. We propose one such framework, which focuses on long-term performance through ontogeny and over the natural range of microsites. For 6 yr we annually evaluated survival, growth, and microsite conditions of six non-pioneer tree species in primary tropical wet forest at the La Selva Biological Station, Costa Rica. The species were: Lecythis ampla, Hymenolobium mesoamericanum, Dipteryx panamensis, Pithecellobium elegans, Hyeronima alchorneoides (all emergents), and Minquartia guianensis (a canopy species). The study was based on long-term measurement of individuals from all post-seedling size classes. Trees were sampled from 150 ha of primary forest spanning several watersheds and soil types. To evaluate individuals' microsites we recorded the number of overtopping crowns, forest phase (gap, building, mature), and crown illumination index (an estimate of the tree's light environment). For comparison, we also evaluated the microsites of three species that have been categorized as pioneers (Cecropia insignis, C. obtusifolia) or high-light demanders (Simarouba amara). For the six species of non-pioneers, mortality rates declined with increasing juvenile size class. As a group, these emergent and canopy trees showed a much lower exponential annual mortality rate (0.44%/yr at >10 cm diameter) than has been found for the La Selva forest as a whole. Growth rates increased with juvenile size class for all six species. As adults (trees >30 cm in diameter), all five emergent species showed substantial annual diameter increments (medians of 5-14 mm/yr). Small saplings and adults of all species had significant year-to-year variation in diameter growth, with much greater growth occurring in the year of lowest rainfall. Passage time analysis suggests that all six species require >150 yr for growth from small saplings to the canopy. Evaluation of all nine species revealed four patterns of microsite occupancy by juveniles. Among the non-pioneers, one species pair (Lecythis and Minquartia: Group A) was associated with low crown illumination and mature-phase forest in all juvenile stages. For two species (Dipteryx and Hymenolobium: Group B) the smallest saplings were in predominantly low-light, mature-forest sites, but crown illumination and association with gap- or building-phase sites increased with juvenile size (Simarouba also showed this pattern). Two species (Pithecellobium and Hyeronima: Group C) were strongly associated with gap or building phase as small juveniles (@<4 cm diameter) and again as subcanopy trees (>10-20 cm diameter), but were predominantly in mature-phase sites at intermediate sizes. Juveniles of the two pioneer species (Cecropia: Group D) showed the highest crown illumination and association with gap or building sites. Among the six non-pioneer species, only one aspect of juvenile performance clearly varied according to microsite group. The smallest saplings (@<1 cm diameter) of Groups B and C showed significant mortality differences across a small gradient in crown illumination; neither of the Group A species showed this pattern. Otherwise, juvenile performance was strikingly similar among the six species. All showed a capacity for growth responses to small increases in light, substantial height and diameter increments at higher light levels, equal ability to survive 4-yr periods of no growth, and very low mortality rates at intermediate-to-large juvenile sizes. Species differed significantly in growth rates, but relative differences shifted with tree size and were unrelated to microsite group. These findings do not support prevailing paradigms concerning trade-offs and correlated suites of traits. For non-pioneer tropical trees, life history classification based on generalized concepts such as gap dependence and shade tolerance is inadequate to describe the complex size-dependent patterns of life history differences and similarities that exist among species.

An analytical model of disturbance and plant population dynamics is developed to explore the optimal life history for a plant within a @'shifting mosaic@' meta-population. The population dynamics consist of short-lived recruitment events followed by longer intervals of thinning. Plants balance costs and benefits of delayed maturation time that result from cohort thinning, a correlation between maturation time and longevity, and the distribution of recruitment events in space and time. Two fundamentally different responses to disturbance are explored: (1) the plant is killed by the disturbance that allows for new recruitment (type A response), and (2) the plant may survive many such disturbances (type B response). Species maximize either the probability of being reproductively mature at the time of the next recruitment opportunity (type A) or the total number of recruitment opportunities to occur during the period of reproductive maturity (type B). Predictions of the theory are compared with the actual life histories of trees that occur in different disturbance regimes. The costs and benefits associated with delayed maturation from an energy standpoint must be weighed against the probability that a recruitment opportunity (disturbance) will occur at a particular age. Trees subject to low thinning rates should reach reproductive maturity t\"1 at t\"1 @? 0.4 x (expected disturbance interval in years). At high thinning rates, this optimum is t\"1 @? 0.4/(mortality rate per year). Disturbance probabilities that increase with time since the last disturbance select for maturation times that are greater than these values. Species that are not killed by disturbances have optimal maturation times that are independent of disturbance frequency. However, when such species are susceptible as juveniles, optimal maturation time does depend on disturbance frequency. This optimum maturation time is still greater than it is for the case of a mortality response (type A) to disturbance, but less than the case of no susceptibility period (type B). Application of the theory to real-world disturbance regimes results in predictions that closely match the life histories of species that actually occur there. The optimal maturation time for a gap species in temperate North American forests is 30-60 yr, a value that agrees with observed maturation time. A second test involved fire regimes where two species having very different responses to fire and life histories co-occur, Pinus resinosa and P. banksiana. The maturation times of these species both match the predicted optima for a species that survives fire (P. resinosa) vs. one that is killed by fire (P. banksiana) subjected to identical fire regimes. Different modes of dispersal are predicted to have important effects on reproductive potential, but little effect on the optimal maturation time. Application of the models to these actual cases is consistent with that prediction. The @'intermediate@' disturbance is predicted to be that which implies the optimum life history that coincides with the life histories of the greatest number of species.