Leaf Optical Responses to Light and Soil Nutrient Availability in Temperature Deciduous Trees

Leaf optical parameters influence light availability at the cellular, leaf, and canopy scale of integration. While recent studies have focused on leaf optical responses to acute plant stress, the effects of changes in plant resources on leaf optics remain poorly characterized. We examined leaf optical and anatomical responses of five temperate deciduous tree species to moderate changes in nutrient and light availability. Spectral reflectance in the visible waveband generally increased at high light, but decreased with increased nutrient availability. Patterns of both spectral reflectance and absorptance were primarily determined by chlorophyll concentration although carotenoid concentration was also influential. While most anatomical features did not explain residual variation in reflectance, cuticle thickness was significantly related to reflectance at complementary angles compared to the angle of incidence. Absorptance did not change with light environment; however, absorption efficiency per unit biomass increased by approximately 40% under low light, due to reduced leaf mass per area. We conclude that changes in resource availability differentially influence leaf optical properties and that such changes are driven primarily by changes in pigment concentrations. The magnitude of leaf optical responses to moderate changes in resource availability was comparable to those of acute stress responses and varied among species

A report on the wetland avifauna of South Sulawesi

The bird communities of the wetlands in South Sulawesi are discussed from results and observations made from an ecological survey undertaken over seven months in the province. The present status of the surveyed wetland habitats is listed. The bird communities observed in these wetlands are then reported and discussed. Annotations are made on selected species. Results from frequent surveys In the Tempe lake system indicate it to be a wetland habitat of international importance according to the Ramsar Convention, mainly because of large concentrations of birds including 10,000+ Garganey . 5,000 Glossy Ibis and 26,000 Great/Clamorous Reed-Warbler. New distribution recordings are made for the Maleo, the Woolly-necked Stork and the Grey-headed Fish-Eagle. Threats to the bird populations are discussed which include threats from pesticide use, live bird trading, hunting and loss of habitat

Edaphic Specialization in Tropical Trees: Physiological Correlates and Responses to Reciprocal Transplantation

Recent research has documented the importance of edaphic factors in determining the habitat associations of tree species in many tropical rain forests, but the underlying mechanisms for edaphic associations are unclear. At Sepilok Forest Reserve, Sabah, Malaysian Borneo, two main soil types derived from sandstone (ridges) and alluvium (valleys) differ in nutrient and water availability and are characterized by forests differing markedly in species composition, structure, and understory light availability. We use both survey and reciprocal transplants to examine physiological adaptations to differences in light, nutrient, and water availability between these soil types, and test for the importance of resource-use efficiency in determining edaphic specialization. Photosynthetic surveys for congeneric and confamilial pairs (one species per soil type) of edaphic specialists and for generalists common to both soil types show that species specializing on sandstone derived soil had lower stomatal conductance at a given assimilation rate than those occurring on alluvial soil and also had greater instantaneous and integrated water-use efficiencies. Foliar dark respiration rates per unit photosynthesis were higher for sandstone ridge than alluvial lowland specialists. We suggest that these higher respiration rates are likely due to increases in photosynthetic enzyme concentrations to compensate for lower internal CO2 concentrations resulting from increased stomatal closure. This is supported by lower photosynthetic nitrogen-use efficiencies in the sandstone ridge specialists. Generalist species had lower water-use efficiencies than sandstone ridge specialists when growing on the drier, sandy ridgetops, but their nitrogen-use efficiencies did not differ from the species specialized to the more resource-rich alluvial valleys. We varied light environment and soil nutrient availability in a reciprocal transplant experiment involving two specialist species from each soil type. Edaphic specialist species, when grown on the soil type for which they were not specialized, were not capable of acclimatory shifts to achieve similar resource-use efficiencies as species specialized to that soil type. We conclude that divergent water-use strategies are an important mechanism underlying differences in edaphic associations and thus contributing to maintenance of high local tree species diversity in Bornean rain forests

Apoptotic cell death in the lactating mammary gland is enhanced by a folding variant of α-lactalbumin

Apoptosis is essential to eliminate secretory epithelial cells during the involution of the mammary gland. The environmental regulation of this process is however, poorly understood. This study tested the effect of HAMLET (human α-lactalbumin made lethal to tumor cells) on mammary cells. Plastic pellets containing HAMLET were implanted into the fourth inguinal mammary gland of lactating mice for 3 days. Exposure of mammary tissue to HAMLET resulted in morphological changes typical for apoptosis and in a stimulation of caspase-3 activity in alveolar epithelial cells near the HAMLET pellets but not more distant to the pellet or in contralateral glands. The effect was specific for HAMLET and no effects were observed when mammary glands were exposed to native a-lactalbumin or fatty acid alone. HAMLET also induced cell death in vitro in a mouse mammary epithelial cell line. The results suggest that HAMLET can mediate apoptotic cell death in mammary gland tissu

Review of Doctoral Programs in Technical Education

This article describes the third phase of a study which examined the readiness of technology education and career and technical education fields for online and hybrid doctoral degree programs in technical education. In this phase, interviews were conducted with chairs and coordinators of 19 doctoral programs in the US and Canada, creating a snapshot of existing doctoral programs in technical education, to inform those undertaking doctoral program design or revision of the variety of approaches to doctoral education. Findings may also be useful to those pursuing employment as faculty members in institutions such as these, and to those considering doctoral study in the field

A Second Dimension to the Leaf Economics Spectrum Predicts Edaphic Habitat Association in a Tropical Forest

Strong patterns of habitat association are frequent among tropical forest trees and contribute to the maintenance of biodiversity. The relation of edaphic differentiation to tradeoffs among leaf functional traits is less clear, but may provide insights into mechanisms of habitat partitioning in these species rich assemblages.We quantify the leaf economics spectrum (LES) for 16 tree species within a Bornean forest characterized by highly pronounced habitat specialization. Our findings suggest that the primary axis of trait variation in light-limited, lowland tropical forests was identical to the LES and corresponds with the shade tolerance continuum. There was no separation with respect to edaphic variation along this primary axis of trait variation. However, a second orthogonal axis determined largely by foliar P concentrations resulted in a near-perfect separation of species occupying distinct soil types within the forest.We suggest that this second axis of leaf trait variation represents a "leaf edaphic habitat spectrum" related to foliar P and potentially other nutrients closely linked to geological substrate, and may generally occur in plant communities characterized by strong edaphic resource gradients

A Re-Examination of the Taxonomic Boundaries of \u3cem\u3eSymphysia\u3c/em\u3e (Ericaceae)

DNA sequence data were generated for the nuclear ITS region for Symphysia racemosa and for 26 additional Vaccinieae representing 12 sections in the genus Vaccinium plus one species from each of five additional segregate genera. Our focus is on the placement of S. racemosa relative to Vaccinium sensu scricto and Vaccinium sect. Oreades (represented by V. poasanum). Maximum parsimony analysis of 608 bp of nrITS region suggests that S. racemosa and V. poasanum form a well-supported clade in spite of substantial morphological divergence. Futhermore, this clade is a sister group to a clade consisting of all segregate genera examined. These molecular results led us to undertake a morphological cladistic analysis of all of the other Central American green-flowered taxa. We suggest that the genus Symphysia should be expanded to encompass these 15 taxa, despite the lack of phylogenetic resolution within this group. This will necessitate eight new combinations, via. Symphysia almedae (= V. almedae), Symphysia costaricensis (= V. costaricense), Symphysia jefensis (= V. jefense), Symphysia orosiensis (= V. orosiense), Symphysia ovata (= Lateropora ovata), Symphysia perardua (= V. santafeënsis), Symphysia poasana (= Vaccinium poasanum), Symphysia santafeënsis (= L. santafeënsis), and Symphysia tubulifera (= L. tubulifera)

Towards generalized measures grasping CA dynamics

In this paper we conceive Lyapunov exponents, measuring the rate of separation between two initially close configurations, and Jacobians, expressing the sensitivity of a CA's transition function to its inputs, for cellular automata (CA) based upon irregular tessellations of the n-dimensional Euclidean space. Further, we establish a relationship between both that enables us to derive a mean-field approximation of the upper bound of an irregular CA's maximum Lyapunov exponent. The soundness and usability of these measures is illustrated for a family of 2-state irregular totalistic CA

Patterns of Ecosystem Structure and Wildfire Carbon Combustion Across Six Ecoregions of the North American Boreal Forest

Increases in fire frequency, extent, and severity are expected to strongly impact the structure and function of boreal forest ecosystems. An important function of the boreal forest is its ability to sequester and store carbon (C). Increasing disturbance from wildfires, emitting large amounts of C to the atmosphere, may create a positive feedback to climate warming. Variation in ecosystem structure and function throughout the boreal forest is important for predicting the effects of climate warming and changing fire regimes on C dynamics. In this study, we compiled data on soil characteristics, stand structure, pre-fire C pools, C loss from fire, and the potential drivers of these C metrics from 527 sites distributed across six ecoregions of North America’s western boreal forests. We assessed structural and functional differences between these fire-prone ecoregions using data from 417 recently burned sites (2004–2015) and estimated ecoregion-specific relationships between soil characteristics and depth from 167 of these sites plus an additional 110 sites (27 burned, 83 unburned). We found that northern boreal ecoregions were generally older, stored and emitted proportionally more belowground than aboveground C, and exhibited lower rates of C accumulation over time than southern ecoregions. We present ecoregion-specific estimates of depth-wise soil characteristics that are important for predicting C combustion from fire. As climate continues to warm and disturbance from wildfires increases, the C dynamics of these fire-prone ecoregions are likely to change with significant implications for the global C cycle and its feedbacks to climate change