Reduced simple ratio better than NDVI for estimating LAI in Finnish pine and spruce stands

Abstract

Canopy openness and lai estimates in two seasonally deciduous forests on limestone outcrops in central Brazil using hemispherical photographs

Patches of seasonally dry tropical forests occur on limestone outcrops in Central Brazil surrounded by the dominant savanna vegetation. They contain valuable timber species but are threatened by farming and mining activities. The objective of this study was to describe canopy opening and light relations in two seasonally deciduous dry forests on slopes and limestone outcrops, in the Paranã valley at the northeastern region of the Goiás state, Brazil. The studied forests were in the Fazenda Sabonete in Iaciara-Go and Fazenda Forquilha in Guarani-GO. Woody plants were sampled in 25 (20 x 20 m) plots in each forest. In the Sabonete forest 40 species, 705 ind./ha-1 with a basal area of 15.78 m²/ha-1 were found, while in Forquilha there were 55 species, 956 ind./ha-1 with a basal area of 24.76 m²/ha-1. Using hemispherical photographic techniques, 25 black and white photographs were taken at each site, during the dry season, totaling 50 photographs. These were taken at the beginning of each vegetation-sampling plot. The photographs were scanned in grey tones and saved as 'Bitmap'. The canopy opening and leaf area index (LAI) were calculated using the software Winphot. The mean canopy opening was 54.0% (±9.36) for Fazenda Sabonete and 64.6% (±11.8) in Fazenda Forquilha, with both sites presenting significant differences in the opening estimates (P < 0.05). Their floristic richness and structure also differed with the more open canopy forest, Forquilha, being richer and denser, suggesting the need for further studies on species-environment relationships in these forests.

杜奧定先生東來渡海苦跡Du ao ding xian sheng dong lai du hai ku ji.Vie du P. Augustin Tudeschini (1598-?).

Par le P. Étienne le Fèvre (1598-1659).

細思將來審判Xi si jiang lai shen pan.

Réflexions sur le jugement à venir.82 feuillets.

未來辯論Wei lai bian lun.

Contre la divination.Par le P. Brancati, avec autorisation du P. da Cunha. Préface incomplète.6 feuillets.

Introduction to LAI

Why LAI? How does LAI work? What use is LAI to others? How far has LAI come and where will we go next?

Effective LAI and CHP of a single tree from small-footprint full-waveform LiDAR

This letter has tested the canopy height profile (CHP) methodology as a way of effective leaf area index (LAIe) and vertical vegetation profile retrieval at a single-tree level. Waveform and discrete airborne LiDAR data from six swaths, as well as from the combined data of six swaths, were used to extract the LAIe of a single live Callitris glaucophylla tree. LAIe was extracted from raw waveform as an intermediate step in the CHP methodology, with two different vegetation-ground reflectance ratios. Discrete point LAIe estimates were derived from the gap probability using the following: 1) single ground returns and 2) all ground returns. LiDAR LAIe retrievals were subsequently compared to hemispherical photography estimates, yielding mean values within ±7% of the latter, depending on the method used. The CHP of a single dead Callitris glaucophylla tree, representing the distribution of vegetation material, was verified with a field profile manually reconstructed from convergent photographs taken with a fixed-focal-length camera. A binwise comparison of the two profiles showed very high correlation between the data reaching R2 of 0.86 for the CHP from combined swaths. Using a study-area-adjusted reflectance ratio improved the correlation between the profiles, but only marginally in comparison to using an arbitrary ratio of 0.5 for the laser wavelength of 1550 nm.

Commentary: not just genes - reclaiming a role for environmental influences on aetiology and outcome in autism. A commentary on Mandy and Lai (2016)

Mandy and Lai (2015) do the field a service in 'reclaiming' the role of pre- and postnatal environmental influences on the aetiology and course of autism spectrum conditions (ASC). This follows several decades where now discredited theories about putative psychogenic and biological disease models held sway, not least in the public mind. We discuss issues that arise from their review; including the need to identify how large the environmental influences on ASC are likely to be; the specificity of these environmental influences to ASC as opposed to a broader range of neurodevelopmental conditions and outcomes; how best to study complex interactions between genetic and environmental influences; and the promise of novel insights into their mechanisms of action. The review highlights current research that aims to better our understanding of the role of environmental factors in the aetiology and course of ASC and, in the near future, may offer the potential for personalised medicine approaches to intervention based on these discoveries.

Transparência nos bancos públicos brasileiros: um estudo sobre a implementação da Lei de Acesso à Informação (LAI) no Banco do Brasil (BB), Caixa Econômica Federal (CEF) e Banco Nacional de Desenvolvimento Econômico e Social (BNDES)

Os bancos públicos representam, historicamente, importante instrumento do governo federal no âmbito da formulação e implementação de políticas públicas. A relevância das ações materializadas por eles, principalmente, em relação ao desenvolvimento econômico e social, por meio da utilização de vultosos recursos oriundos do tesouro nacional, desperta a atenção da sociedade interessada em conhecer mais sobre as operações de empréstimos. A política de transparência torna-se central à luz de relevantes conceitos de democracia e de desdobramentos importantes de publicidade, prestação de contas e Accountability, principalmente após a Constituição de 1988 pela necessidade de efetivação de mecanismos democráticos. Desta forma, esta pesquisa busca contribuir tanto para a discussão teórica quanto para a base empírica do tema de transparência nos bancos públicos. Com a realização de pesquisa documental estruturada para levantamento de dados e informações, foi possível analisar os fatores apresentados a partir dos casos do Banco do Brasil (BB), da Caixa Econômica Federal (CEF) e do Banco Nacional de Desenvolvimento Econômico e Social (BNDES), avançando no debate da transparência dos bancos públicos. Esta pesquisa exploratória explica, além de outros fatores, como o conceito de transparência aplicado ao objeto de banco público no Brasil assume a característica de “conceito essencialmente contestado” (GALLIE, 1956).

Calibration of a Species-Specific Spectral Vegetation Index for Leaf Area Index (LAI) Monitoring: Example with MODIS Reflectance Time-Series on Eucalyptus Plantations

The leaf area index (LAI) is a key characteristic of forest ecosystems. Estimations of LAI from satellite images generally rely on spectral vegetation indices (SVIs) or radiative transfer model (RTM) inversions. We have developed a new and precise method suitable for practical application, consisting of building a species-specific SVI that is best-suited to both sensor and vegetation characteristics. Such an SVI requires calibration on a large number of representative vegetation conditions. We developed a two-step approach: (1) estimation of LAI on a subset of satellite data through RTM inversion; and (2) the calibration of a vegetation index on these estimated LAI. We applied this methodology to Eucalyptus plantations which have highly variable LAI in time and space. Previous results showed that an RTM inversion of Moderate Resolution Imaging Spectroradiometer (MODIS) near-infrared and red reflectance allowed good retrieval performance (R-2 = 0.80, RMSE = 0.41), but was computationally difficult. Here, the RTM results were used to calibrate a dedicated vegetation index (called "EucVI") which gave similar LAI retrieval results but in a simpler way. The R-2 of the regression between measured and EucVI-simulated LAI values on a validation dataset was 0.68, and the RMSE was 0.49. The additional use of stand age and day of year in the SVI equation slightly increased the performance of the index (R-2 = 0.77 and RMSE = 0.41). This simple index opens the way to an easily applicable retrieval of Eucalyptus LAI from MODIS data, which could be used in an operational way.