Effects of Nutrient Availability and Other Elevational Changes on Bromeliad Populations and Their Invertebrate Communities in a Humid Tropical Forest in Puerto Rico

Nutrient inputs into tank bromeliads were studied in relation to growth and productivity, and the abundance, diversity and biomass of their animal inhabitants, in three forest types along an elevational gradient. Concentrations of phosphorus, potassium and calcium in canopy-derived debris, and nitrogen and phosphorus in phytotelm water, declined with increasing elevation. Dwarf forest bromeliads contained the smallest amounts of debris/plant and lowest concentrations of nutrients in plant tissue. Their leaf turnover rate and productivity were highest and, because of high plant density, they comprised 12.8and contained 3.3 t ha -1 of water. Annual nutrient budgets indicated that these microcosms were nutrient-abundant and accumulated \u3c 5dwarf forest, where accumulation was c. 25biomass/plant peaked in the intermediate elevation forest, and were positively correlated with the debris content/bromeliad across all forest types. Animal species richness showed a significant mid-elevational peak, whereas abundance was independent of species richness and debris quantities, and declined with elevation as forest net primary productivity declined. The unimodal pattern of species richness was not correlated with nutrient concentrations, and relationships among faunal abundance, species richness, nutrient inputs and environment are too complex to warrant simple generalizations about nutrient resources and diversity, even in apparently simple microhabitats

Living on borrowed time – Amazonian trees use decade‐old storage carbon to survive for months after complete stem girdling

Nonstructural carbon (NSC) reserves act as buffers to sustain tree activity during periods when carbon (C) assimilation does not meet C demand, but little is known about their age and accessibility; we designed a controlled girdling experiment in the Amazon to study tree survival on NSC reserves. We used bomb-radiocarbon (14C) to monitor the time elapsed between C fixation and release (‘age’ of substrates). We simultaneously monitored how the mobilization of reserve C affected δ13CO2. Six ungirdled control trees relied almost exclusively on recent assimilates throughout the 17 months of measurement. The Δ14C of CO2 emitted from the six girdled stems increased significantly over time after girdling, indicating substantial remobilization of storage NSC fixed up to 13–14 yr previously. This remobilization was not accompanied by a consistent change in observed δ13CO2. These trees have access to storage pools integrating C accumulated over more than a decade. Remobilization follows a very clear reverse chronological mobilization with younger reserve pools being mobilized first. The lack of a shift in the δ13CO2 might indicate a constant contribution of starch hydrolysis to the soluble sugar pool even outside pronounced stress periods (regular mixing). © 2018 The Authors. New Phytologist © 2018 New Phytologist Trus

Going outside the box: skills development, cultural change and the use of on-line resources

Using an academic library has always been a crucial part of studying in higher education, but this has presented problems for independent learners taking distance education courses. In the past, Open University (UKOU) students received almost everything needed to successfully complete any course. Nowadays, growth in Internet use enables learners to go 'outside the box' to locate resources that might be relevant for their studies. Although such resources are increasingly being included as components of UKOU courses, the extent to which students use them varies enormously between courses. Data from a large-scale survey is examined and a number of explanatory factors are considered in an attempt to account for this variability. It is argued that students' use of on-line 'external' resources is closely related to the pedagogic design of courses and to assessment requirements, not merely to the increased availability of information sources on the World Wide Web

Using organic phosphorus to sustain pasture productivity: A perspective

Organic phosphorus (P) in grazed pastures/grasslands could sustain production systems that historically relied on inorganic P fertiliser. Interactions between inorganic P, plants and soils have been studied extensively. However, less is known about the transformation of organic P to inorganic orthophosphate. This paper investigates what is known about organic P in pasture/grassland soils used for agriculture, as well as the research needed to utilise organic P for sustainable plant production. Organic P comprises > 50% of total soil P in agricultural systems depending on location, soil type and land use. Organic P hydrolysis and release of orthophosphate by phosphatase enzymatic activity is affected by a range of factors including: (a) the chemical nature of the organic P and its ability to interact with the soil matrix; (b) microorganisms that facilitate mineralisation; (c) soil mineralogy; (d) soil water electrolytes; and (e) soil physicochemical properties. Current biogeochemical knowledge of organic P processing in soil limits our ability to develop management strategies that promote the use of organic P in plant production. Information is particularly needed on the types and sources of organic P in grassland systems and the factors affecting the activity of enzymes that mineralise organic P. Integrated approaches analysing the soil matrix, soil water and soil biology are suggested to address this knowledge gap

Philosophical Foundations of Wisdom

Practical wisdom (hereafter simply ‘wisdom’), which is the understanding required to make reliably good decisions about how we ought to live, is something we all have reason to care about. The importance of wisdom gives rise to questions about its nature: what kind of state is wisdom, how can we develop it, and what is a wise person like? These questions about the nature of wisdom give rise to further questions about proper methods for studying wisdom. Is the study of wisdom the proper subject of philosophy or psychology? How, exactly, can we determine what wisdom is and how we can get it? In this chapter, we give an overview of some prominent philosophical answers to these questions. We begin by distinguishing practical wisdom from theoretical wisdom and wisdom as epistemic humility. Once we have a clearer sense of the target, we address questions of method and argue that producing a plausible and complete account of wisdom will require the tools of both philosophy and empirical psychology. We also discuss the implications this has for prominent wisdom research methods in empirical psychology. We then survey prominent philosophical accounts of the nature of wisdom and end with reflections on the prospects for further interdisciplinary research

The “isohydric trap”: A proposed feedback between water shortage, stomatal regulation, and nutrient acquisition drives differential growth and survival of European pines under climatic dryness

Climatic dryness imposes limitations on vascular plant growth by reducing stomatalconductance, thereby decreasing CO2 uptake and transpiration. Given that transpiration-driven water flow is required for nutrient uptake, climatic stress-induced nutrientdeficit could be a key mechanism for decreased plant performance underprolonged drought. We propose the existence of an "isohydric trap," a drynessinduceddetrimental feedback leading to nutrient deficit and stoichiometry imbalancein strict isohydric species. We tested this framework in a common garden experimentwith 840 individuals of four ecologically contrasting European pines (Pinushalepensis, P. nigra, P. sylvestris, and P. uncinata) at a site with high temperature andlow soil water availability. We measured growth, survival, photochemical efficiency,stem water potentials, leaf isotopic composition (d13C, d18O), and nutrient concentrations(C, N, P, K, Zn, Cu). After 2 years, the Mediterranean species Pinus halepensis showed lower d18O and higher d13C values than the other species, indicatinghigher time-integrated transpiration and water-use efficiency (WUE), along withlower predawn and midday water potentials, higher photochemical efficiency, higher leaf P, and K concentrations, more balanced N:P and N:K ratios, and much greaterdry-biomass (up to 63-fold) and survival (100%).Comunidad de MadridMinisterio de Educación, Cultura y Deport

Macrosystems ecology: Understanding ecological patterns and processes at continental scales

Macrosystems ecology is the study of diverse ecological phenomena at the scale of regions to continents and their interactions with phenomena at other scales. This emerging subdiscipline addresses ecological questions and environmental problems at these broad scales. Here, we describe this new field, show how it relates to modern ecological study, and highlight opportunities that stem from taking a macrosystems perspective. We present a hierarchical framework for investigating macrosystems at any level of ecological organization and in relation to broader and finer scales. Building on well-established theory and concepts from other subdisciplines of ecology, we identify feedbacks, linkages among distant regions, and interactions that cross scales of space and time as the most likely sources of unexpected and novel behaviors in macrosystems. We present three examples that highlight the importance of this multiscaled systems perspective for understanding the ecology of regions to continents

Age, allocation and availability of nonstructural carbon in mature red maple trees

The allocation of nonstructural carbon (NSC) to growth, metabolism and storage remains poorly understood, but is critical for the prediction of stress tolerance and mortality. We used the radiocarbon (14C) ‘bomb spike’ as a tracer of substrate and age of carbon in stemwood NSC, CO2 emitted by stems, tree ring cellulose and stump sprouts regenerated following harvesting in mature red maple trees. We addressed the following questions: which factors influence the age of stemwood NSC?; to what extent is stored vs new NSC used for metabolism and growth?; and, is older, stored NSC available for use? The mean age of extracted stemwood NSC was 10 yr. More vigorous trees had both larger and younger stemwood NSC pools. NSC used to support metabolism (stem CO2) was 1–2 yr old in spring before leaves emerged, but reflected current-year photosynthetic products in late summer. The tree ring cellulose 14C age was 0.9 yr older than direct ring counts. Stump sprouts were formed from NSC up to 17 yr old. Thus, younger NSC is preferentially used for growth and day-to-day metabolic demands. More recently stored NSC contributes to annual ring growth and metabolism in the dormant season, yet decade-old and older NSC is accessible for regrowth