title: Light interception efficiency explained by two simple variables: a test using a diversity of small- to medium-sized woody plants

authors: Duursma, R.A.

subjects: leaf area index

abstract: •Plant light interception efficiency is a crucial determinant of carbon uptake by individual plants and by vegetation. Our aim was to identify whole-plant variables that summarize complex crown architecture, which can be used to predict light interception efficiency.
•We gathered the largest database of digitized plants to date (1831 plants of 124 species), and estimated a measure of light interception efficiency with a detailed three-dimensional model. Light interception efficiency was defined as the ratio of the hemispherically averaged displayed to total leaf area. A simple model was developed that uses only two variables, crown density (the ratio of leaf area to total crown surface area) and leaf dispersion (a measure of the degree of aggregation of leaves).
•The model explained 85% of variation in the observed light interception efficiency across the digitized plants. Both whole-plant variables varied across species, with differences in leaf dispersion related to leaf size. Within species, light interception efficiency decreased with total leaf number. This was a result of changes in leaf dispersion, while crown density remained constant.
•These results provide the basis for a more general understanding of the role of plant architecture in determining the efficiency of light harvesting.

text: Light interception efficiency explained by two simple variables: a test using a diversity of small- to medium-sized woody plants •Plant light interception efficiency is a crucial determinant of carbon uptake by individual plants and by vegetation. Our aim was to identify whole-plant variables that summarize complex crown architecture, which can be used to predict light interception efficiency.
•We gathered the largest database of digitized plants to date (1831 plants of 124 species), and estimated a measure of light interception efficiency with a detailed three-dimensional model. Light interception efficiency was defined as the ratio of the hemispherically averaged displayed to total leaf area. A simple model was developed that uses only two variables, crown density (the ratio of leaf area to total crown surface area) and leaf dispersion (a measure of the degree of aggregation of leaves).
•The model explained 85% of variation in the observed light interception efficiency across the digitized plants. Both whole-plant variables varied across species, with differences in leaf dispersion related to leaf size. Within species, light interception efficiency decreased with total leaf number. This was a result of changes in leaf dispersion, while crown density remained constant.
•These results provide the basis for a more general understanding of the role of plant architecture in determining the efficiency of light harvesting.

year: 2012-01

title: “Use-It-or-Lose-It”? Interrogating an educational message from teen brain research

authors: Payne, Monica A.

subjects: education

abstract: Recent neuroimaging research has encouraged a fundamental shift in psychological thinking about cognitive development in adolescence. Challenging the existing view that early childhood was the most critical period for intellectually hard-wiring the brain, findings led researchers to speculate that early adolescence might be the more important use-it-or-lose-it period. Despite cautions from critics and some neuroscientists themselves, the new story seems to be following its predecessor in acquiring the status of hard fact. An eclectic sampling of texts examines possible implications of the penetration of this hypothesis into educational discourse. Elements of classism and adultism are identified, and considered with reference to contemporary understandings of adolescence as a period when lifelong habits and lifestyles are established.

text: “Use-It-or-Lose-It”? Interrogating an educational message from teen brain research Recent neuroimaging research has encouraged a fundamental shift in psychological thinking about cognitive development in adolescence. Challenging the existing view that early childhood was the most critical period for intellectually hard-wiring the brain, findings led researchers to speculate that early adolescence might be the more important use-it-or-lose-it period. Despite cautions from critics and some neuroscientists themselves, the new story seems to be following its predecessor in acquiring the status of hard fact. An eclectic sampling of texts examines possible implications of the penetration of this hypothesis into educational discourse. Elements of classism and adultism are identified, and considered with reference to contemporary understandings of adolescence as a period when lifelong habits and lifestyles are established.

year: 2010

title: The Price of Mauri: Exploring the validity of Welfare Economics when seeking to measure Mātauranga Māori

authors: Awatere, Shaun

subjects: welfare economics

abstract: Since the 1980s New Zealand has pursued neo-classical or market-based policies with a particular fervour. Market-based options are seen by resource management decision makers as essential frameworks for efficiently allocating resources, an approach that continues to support the view of the inherent dominance of Western knowledge. This is particularly concerning, given that Māori (the indigenous people of New Zealand), have an important role to play in New Zealand resource management and perceive their own knowledge systems have been marginalised. The primary goal of this thesis is to explore the validity of welfare economics when seeking to measure quantitatively Mātauranga Māori or Māori views of the environment through the contingent valuation method. A contingent valuation study is carried out using three separate samples drawn from the general Māori population in Auckland city, a hāpu/sub-tribe indigenous to the Auckland isthmus, and drivers of motor vehicles in Auckland city. Data collection modes include a postal survey and face-to-face interviews. This thesis challenges the validity of political-legal ethnicity constructs to measure Mātauranga Māori. The search for a central tendency will lead to biased, misleading and inaccurate results. The thesis also challenges the validity of contingent valuation to produce true economic measures and to measure and identify Mātauranga Māori. Despite advances in analytical techniques, economic efficiency measures are always deficient, given the difficulty of capturing and anticipating all impacts and valuing them appropriately. Mātauranga Māori is derived from a Māori epistemology and should be considered or analysed with primary reference to this body of knowledge. Economic analysis is only one important cog in the machinery of resource management policy. Given that an economist's contribution to local and regional resource management is most valuable when focusing on the  economic efficiency  of the proposed resource allocation, it is appropriate that other perspectives such as Mātauranga Māori be considered.

text: The Price of Mauri: Exploring the validity of Welfare Economics when seeking to measure Mātauranga Māori Since the 1980s New Zealand has pursued neo-classical or market-based policies with a particular fervour. Market-based options are seen by resource management decision makers as essential frameworks for efficiently allocating resources, an approach that continues to support the view of the inherent dominance of Western knowledge. This is particularly concerning, given that Māori (the indigenous people of New Zealand), have an important role to play in New Zealand resource management and perceive their own knowledge systems have been marginalised. The primary goal of this thesis is to explore the validity of welfare economics when seeking to measure quantitatively Mātauranga Māori or Māori views of the environment through the contingent valuation method. A contingent valuation study is carried out using three separate samples drawn from the general Māori population in Auckland city, a hāpu/sub-tribe indigenous to the Auckland isthmus, and drivers of motor vehicles in Auckland city. Data collection modes include a postal survey and face-to-face interviews. This thesis challenges the validity of political-legal ethnicity constructs to measure Mātauranga Māori. The search for a central tendency will lead to biased, misleading and inaccurate results. The thesis also challenges the validity of contingent valuation to produce true economic measures and to measure and identify Mātauranga Māori. Despite advances in analytical techniques, economic efficiency measures are always deficient, given the difficulty of capturing and anticipating all impacts and valuing them appropriately. Mātauranga Māori is derived from a Māori epistemology and should be considered or analysed with primary reference to this body of knowledge. Economic analysis is only one important cog in the machinery of resource management policy. Given that an economist's contribution to local and regional resource management is most valuable when focusing on the  economic efficiency  of the proposed resource allocation, it is appropriate that other perspectives such as Mātauranga Māori be considered.

year: 2008