First year survival of Pinus hartwegii following prescribed burns at different intensities and different seasons in central Mexico
Bibliographic record
Abstract
In forests of young Pinus hartwegii Lindl. on the Ajusco volcano in southern Mexico City, central Mexico, a study was made of tree mortality resulting from low and high intensity prescribed burns. Low intensity burns (backing fire in early morning with high relative humidity) and high intensity burns (head fire at midday with low relative humidity) were conducted in two different seasons: 21 March and 29 May 2002. Five contiguous sites were selected, each consisting of open stands (300–700 trees ha–1) and closed stands (900–2500 trees ha–1). Two sites were used for morning burns, two for afternoon burns, and the fifth remained an unburned control plot. Logistic regression was used to estimate probability of mortality 1 year after the burns as a function of fire season, fire intensity, stand density, and tree diameter at breast height (dbh). Logistic regression was also used to estimate probability of infestation by bark beetles as a function of crown kill. A multiple linear regression model was used to show the effect of crown kill and tree height on live crown area. The probability of mortality was greatest in May high intensity burns, on closed stands and for low dbh trees. May burns had the driest conditions, and closed stands had needle layers that produced fire smouldering. The root system heating is a key mechanism influencing mortality of Pinus hartwegii in closed stands. The treatments creating greatest mortality also resulted in lower live crown areas. According to the multiple regression model, the lower the tree height and the higher the crown kill, the lower the live crown area. The probability of infestation by bark beetles also increased with crown kill. Resume. Se estudió la mortalidad de Pinus hartwegii Lindl. juveniles ante quemas prescritas de baja y alta intensidad, en el volcán Ajusco, México central. Las primeras fueron en contra de viento y pendiente, por la mañana, con alta humedad relativa; las segundas a favor de viento y pendiente, a mediodía, con baja humedad. Se condujeron en dos épocas: marzo 21 y mayo 29 de 2002. Fueron establecidas cinco parcelas contiguas, cada una con masas abiertas (300–700 árboles ha–1) y masas densas (900–2500 árboles ha–1). Dos parcelas fueron usadas para quemas por la mañana, dos para quemas por la tarde, y una como testigo. Se empleó regresión logística para estimar la probabilidad de mortalidad a un año de las quemas como función de época de quema, intensidad, densidad arbórea, y diámetro normal. También se usó regresión logística para estimar la probabilidad de infestación por insectos descortezadores como función del chamuscado de copa. Mediante regresión lineal múltiple se relacionó el chamuscado de copa y la altura del árbol con el área de copa viva. La mayor probabilidad de mortalidad correspondió a la combinación: quemas en mayo, alta intensidad, masas densas y árboles de diámetro pequeño. Las quemas en mayo mostraron las condiciones más secas, y las masas densas tuvieron hojarasca como combustible principal, que produce combustión sin llamas. El sistema de calentamiento de la raíz es un mecanismo clave que influencia la mortalidad de Pinus hartwegii en masas densas. Los tratamientos con mayor mortalidad exhibieron menores áreas de copa viva. Se tuvo menor área de copa viva a menor altura del árbol y a mayor chamuscado de copa. La probabilidad de infestación por descortezadores aumentó con el chamuscado de copa.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".