Abstract
Regression models for spatially varying data use spatial random effects to reflect spatial correlation structure. Such random effects, however, may interfere with the covariate effect ...estimates and make them unreliable. This problem, known as spatial confounding, is complex and has only been studied for models with linear covariate effects. However, as illustrated by a forestry example in which we assess the effect of soil, climate, and topography variables on tree health, the covariate effects of interest are in practice often unknown and nonlinear. We consider, for the first time, spatial confounding in spatial models with nonlinear effects implemented in the generalised additive models (GAMs) framework. We show that spatial+, a recently developed method for alleviating confounding in the linear case, can be adapted to this setting. In practice, spatial+ can then be used both as a diagnostic tool for investigating whether covariate effect estimates are affected by spatial confounding and for correcting the estimates for the resulting bias when it is present. Supplementary materials accompanying this paper appear online.
Global forest area has declined over the past few years, forest quality has declined, and ecological and environmental events have increased with climate change and human activity. In the context of ...ecological civilization, forest health issues have received unprecedented attention. By improving forest health, forests can better perform their ecosystem service functions and promote green development. This study was carried out in the WuZhi Shan area of Hainan Tropical Rainforest National Park. We employed a decision tree algorithm, a machine learning technique, for our modeling due to its high accuracy and interpretability. The objective weighted method using criteria of importance through intercriteria correlation (CRITIC) was used to determine forest health classes based on survey and experimental data from 132 forest samples. The results showed that species diversity is the most important metric to measure forest health. An interpretable decision tree machine learning model was proposed to incorporate forest health indicators, providing up to 90% accuracy in the classification of forest health conditions. The model demonstrated a high degree of effectiveness, achieving an average precision of 90%, a recall of 67%, and an F1 score of 70.2% in predicting forest health. The interpretable decision tree classification results showed that breast height diameter is the most important variable in classifying the health status of both primary and secondary forests. This study highlights the importance of using interpretable machine learning methods for the decision‐making process. Our work contributes to the scientific underpinnings of sustainable forest development and effective conservation planning.
Machine learning can be used to classify whether forest health is healthy or not. This study highlights the importance of using interpretable machine learning methods for the decision‐making process. Our work contributes to the scientific underpinnings of sustainable forest development and effective conservation planning.
•Cohort-based live foliage retention of Douglas-fir (Pseudotsuga menziesii), repeatedly shown to be directly related to tree growth, was estimated for areas in western Oregon and Washington by ...correlating nearly 1000 plot-level estimates of foliage retention with variables of climate, soils, and topography. Sampling of Douglas-fir foliage retention, motivated by the Swiss needle cast-induced loss of foliage (causal agent Nothophaeocryptopus gueamanii) in western Oregon and Washington, covered the period from 1998 to 2021, with estimates collected from the Oregon Coast Range near the California border to the Olympic Peninsula and the foothills of the northern Oregon Cascades and the foothills near the border of Washington and Canada. Douglas-fir foliage retention was found to be correlated with average June/July relative humidity, December maximum temperature, and May precipitation averaged for the periods of budbreak for the 2–4 yr old needle cohorts, a transformation of slope and aspect, the number of meters above 400 m elevation, topographic position index, and soil cation exchange capacity. Using the constructed equation, foliage retention was estimated across a systematic grid of points in western Oregon and Washington and combined with a regional growth model to estimate potential volume growth loss across the region. The greatest implied average growth losses (∼23%) were in the zones closest to the Pacific Ocean between 46° and 48°N. Premature loss of Douglas-fir foliage in the Pacific Northwest has been primarily associated with Swiss needle cast, and this work may help explain conditions that favor Swiss needle cast or describe additional foliage retention drivers.
Cohort-based live foliage retention of Douglas-fir (Pseudotsuga menziesii), repeatedly shown to be directly related to tree growth, was estimated for areas in western Oregon and Washington by correlating nearly 1000 plot-level estimates of foliage retention with variables of climate, soils, and topography. Sampling of Douglas-fir foliage retention, motivated by the Swiss needle cast-induced loss of foliage (causal agent Nothophaeocryptopus gaeumanii) in western Oregon and Washington, covered the period from 1998 to 2021, with estimates collected from the Oregon Coast Range near the California border to the Olympic Peninsula and the foothills of the northern Oregon Cascades and the foothills near the border of Washington and Canada. Douglas-fir foliage retention was found to be correlated with average June/July relative humidity, December maximum temperature, and May precipitation averaged for the periods of budbreak for the 2–4 yr old needle cohorts, a transformation of slope and aspect, the number of meters above 400 m elevation, topographic position index, and soil cation exchange capacity. Using the constructed equation, foliage retention was estimated across a systematic grid of points in western Oregon and Washington and combined with a regional growth model to estimate potential volume growth loss across the region. The greatest implied average growth losses (∼23%) were in the zones closest to the Pacific Ocean between 46° and 48°N. Premature loss of Douglas-fir foliage in the Pacific Northwest has been primarily associated with Swiss needle cast, and this work may help explain conditions that favor Swiss needle cast or describe additional foliage retention drivers.
Oleoresin defenses in conifers Celedon, Jose M.; Bohlmann, Jörg
The New phytologist,
December 2019, Letnik:
224, Številka:
4
Journal Article
Recenzirano
Odprti dostop
Conifers have evolved complex oleoresin terpene defenses against herbivores and pathogens. In co-evolved bark beetles, conifer terpenes also serve chemo-ecological functions as pheromone precursors, ...chemical barcodes for host identification, or nutrients for insect-associated microbiomes. We highlight the genomic, molecular and biochemical underpinnings of the large chemical space of conifer oleoresin terpenes and volatiles. Conifer terpenes are predominantly the products of the conifer terpene synthase (TPS) gene family. Terpene diversity is increased by cytochromes P450 of the CYP720B class. Many conifer TPS are multiproduct enzymes. Multisubstrate CYP720B enzymes catalyse multistep oxidations. We summarise known terpenoid gene functions in various different conifer species with reference to the annotated terpenoid gene space in a spruce genome. Overall, biosynthesis of terpene diversity in conifers is achieved through a system of biochemical radiation and metabolic grids. Expression of TPS and CYP720B genes can be specific to individual cell types of constitutive or traumatic resin duct systems. Induced terpenoid transcriptomes in resin duct cells lead to dynamic changes of terpene composition and quantity to fend off herbivores and pathogens. While terpenoid defenses have contributed much to the evolutionary success of conifers, under new conditions of climate change, these defences may become inconsequential against range-expanding forest pests.
The 2012–2015 drought has left California with severely reduced snowpack, soil moisture, ground water, and reservoir stocks, but the impact of this estimated millennial-scale event on forest health ...is unknown. We used airborne laser-guided spectroscopy and satellite-based models to assess losses in canopy water content of California’s forests between 2011 and 2015. Approximately 10.6 million ha of forest containing up to 888 million large trees experienced measurable loss in canopy water content during this drought period. Severe canopy water losses of greater than 30% occurred over 1 million ha, affecting up to 58 million large trees. Our measurements exclude forests affected by fire between 2011 and 2015. If drought conditions continue or reoccur, even with temporary reprieves such as El Niño, we predict substantial future forest change.
•Treatments help multiple species resist drought and bark beetle outbreak.•Thinning and prescribed fire promote tree resistance to multiple disturbances.•Despite unprecedented drought, thinning and ...prescribed fire mitigate tree mortality.
Long-term trends show increased tree mortality over the last several decades, coinciding with above-average temperatures, high climatic water deficits, and bark beetle outbreaks. California’s recent unprecedented drought (2012–2016) highlights the need to evaluate whether thinning and prescribed fire can improve individual tree drought resistance and reduce bark beetle-associated mortality. Using a thinning and prescribed fire study on the Stanislaus-Tuolumne Experimental Forest in the central Sierra Nevada implemented prior to the drought (2011–2013), we used dendrochronological methods to estimate metrics of tree vigor (i.e., growth and resin ducts) of sugar pine (Pinus lambertiana Douglas) and white fir (Abies lowiana Gordon & Glend. A. Murray bis) among treatments, as well as between trees that died from bark beetle-associated mortality and their paired counterparts that survived. We used tree vigor to estimate drought resistance as the ratio between growth during drought (2012–2016) and pre-drought (2007–2011) for both species. For sugar pine, we also created analogous ratios for multiple resin duct characteristics to evaluate defense during drought. Our findings indicate that lower competition increased growth resistance of white fir, while prescribed fire had negligible impacts on growth. This translated to lower mortality, with live white fir showing higher growth resistance than those that died. While competition did not strongly affect sugar pine growth, greater growth resistance was noted for trees that lived than trees that died. However, reduced competition and prescribed fire increased defense resistance and resin duct density and relative resin duct area were negatively associated with sugar pine mortality. Live sugar pine showed greater defense resistance than dead counterparts particularly under higher levels of competition. These findings suggest thinning can promote or maintain growth during severe drought conditions and prescribed fire can be applied with negligible costs to tree growth while also producing the additional benefit of stimulating defense systems in sugar pine, which may enable them to better survive bark beetle outbreaks. Therefore, susceptibility to bark beetle-associated mortality may be ameliorated through increasing tree vigor with a combination of forest thinning and prescribed fire.
This study put forward an evaluation index system for measuring forest ecological security index (FESI). Taking the 1086 counties located in the Yangtze River Economic Belt as a case study, we ...investigated the change and its spatial pattern of FESI, as well as the determining indicators (both natural and socio-economic), with the support of Arcmap and GeoDA software. The average FESI value of the study counties in 2010 and 2015 was found to be 0.4226 and 0.4990, increased by 18.08%. Spatially, an evident spatial gradient change was identified, with FESI values in the upstream areas of the Yangtze River being higher than those in midstream areas, and the values of midstream areas in turn being higher than those in downstream areas. The eight tributary basins within the economic belt witnessed significantly different FESI values. Based on the results of this evaluation of FESI and its sub-evaluation indexes, we identified 46.04% of the total counties as constituting “problem areas”. These problem areas were mainly concentrated in Shanghai, Jiangsu and Anhui provinces, followed by counties around Dongting Lake, Poyang Lake and in Sichuan province. A regression analysis was conducted in order to identify the determining indicators behind forest ecological security, with results indicating that the ratio of secondary industry, the urbanization rate, the per capita financial institution loan balance, accumulated temperature and wind speed all negatively impacted on FESI values, while population structure, soil organic matter and rainfall were revealed to play a positive role; all of these indicators were highly significant. Given these findings, we also set out a series of policy measures intended to promote the sustainable forest development of the study region. These include the vigorous development of tertiary industry and moves to reduce the proportion of the secondary industry in the national economy, the development of a circular economy, slowing the pace of urbanization, and continued increases in forestry investment in central cities – particularly in problem areas.
•>This study attempted to investigate the forest ecological security index (FESI).•>The spatial pattern of FESI in China and its impact factors were investigated.•>The average FESI value in 2010 and 2015 was 0.4226 and 0.4990, increased by 18.08%.•>An evident spatial gradient change in relation to the FESI value was identified.•>A regression analysis was conducted to identify the impact factors behind FESI.
Introducción: La relación parásito-hospedero entre Dendroctonus y Pinus es reconocida como una amenaza importante para los bosques de coníferas, debido a que puede causar una alta mortalidad de ...árboles y consecuentemente una pérdida de cobertura forestal. Objetivo: Identificar potenciales interacciones parásito-huésped entre descortezadores y pinos, así como la contribución de las condiciones ambientales para el establecimiento de estas interacciones ecológicas. Métodos: Se realizaron modelos de nicho ecológico y análisis de redes ecológicas con la plataforma web de minería de datos espaciales SPECIES (http://species.conabio.gob.mx/). Se incluyeron siete especies de descortezadores, 52 de pinos y 19 variables bioclimáticas del portal WorldClim. Resultados: Se identificaron 140 interacciones potenciales, de las cuales el 42 % no han sido registradas previamente. El análisis de redes ecológicas nos permitió caracterizar las relaciones parásito-hospedero en generalistas y especialistas. En cuanto al análisis de nicho ecológico, se determinó la distribución potencial de los descortezadores combinando las distribuciones de Pinus y variables climáticas como predictores. Se observó que las variables climáticas contribuyen de forma negativa para la mayoría de las especies de Dendroctonus, es decir, estas variables son restrictivas en casi toda su distribución, por el contrario, las variables bióticas (Pinus) fueron positivas e informativas sobre la mayoría de las distribuciones. Conclusiones: Los patrones de coexistencia de descortezadores y pinos nos proporcionan información sobre las interacciones que se pueden establecer entre estas especies y que hasta hoy pueden ser desconocidas. Además, la integración de factores bióticos (hospederos) y abióticos (clima), permite obtener modelos de distribución geográfica que caracteriza las regiones con condiciones favorables para la presencia de las especies, así como las especies de hospederos con los que podrían estar interactuando en dichas regiones. Considerando el riesgo fitosanitario por descortezadores, nuestros resultados brindan escenarios geográficos y ecológicos de riesgo donde infestaciones por descortezadores podrían darse, así como la posible emergencia de nuevas interacciones parásito-hospedero desconocidas hasta hoy. Estos modelos son una herramienta que en el futuro pueden dirigir esfuerzos de trabajo de campo para validar y complementar nuestros resultados.
Shade trees have enormous benefits for the urban environment, both ecologically and economically. The level of tree health is important as an ingredient in determining management decisions that will ...be carried out so that the sustainability of road shade trees remains consistent and maintained. This study aims to inventory shade tree species and analyze the health level of shade trees in the protocol roads of Pangkalpinang City. The research method used the Forest Health Monitoring method. Based on the results of the study, 12 types of shade trees were found in six main streets of Pangkalpinang City with a total of 849 individuals. The most common types of shade trees found were mahogany (Swietenia mahagoni) with 372 individuals (43.82%) and angsana (Pterocarpus indicus) with 296 individuals (34.86%). The health level of shade trees on the Pangkalpinang City protocol road was still dominated by shade trees with a healthy category of 516 individuals (61.36%). Shade trees with light damage category were 175 individuals (20.81%), moderate damage were 66 individuals (7.85%) individuals and severe damage were 84 individuals (9.98%). It can be concluded that the condition of the shade trees in Pangkalpinang City was quite well maintained since the shade trees were still in the healthy category.
Forest vulnerability to climate change is expected to differ between species and across species ranges. Therefore, it is important to develop tools that can standardize the variability in regional ...climate patterns and extreme events for populations and species. Extreme climate events, such as droughts and heat waves, have the potential to severely impact populations that are already close to the limits of their physiological tolerance. These factors can be further exacerbated in tree populations when coupled with detrimental biotic interactions, such as pathogen and insect infestations. We analysed a monitoring network dataset of tree defoliation from 2005 to 2013 including 560 plots situated in the Iberian Peninsula. We utilized a climatic suitability index obtained from Ecological Niche Models (ENMs), to investigate whether changes in the climatic suitability for seven forest species and the presence of biotic agents correlated with tree defoliation. Our results emphasized that higher levels of tree defoliation were significantly associated with lower climatic suitability. Likewise, these levels increased significantly with high pest intensity. Interestingly, climatic suitability interacted with pests to explain defoliation patterns. Pinus sylvestris and Quercus pyrenaica were particularly susceptible to defoliation in areas with lower climatic suitability and with increasing pest intensity. This suggest that pests play an important role in understanding species performance under less climatic suitable conditions, at least in the forests of the Spanish Iberian Peninsula. Our fundings can serve as a valuable tool for identifying forest populations and species especially susceptible to the impacts of changing climatic conditions on a regional scale. This contribution aids in the incorporation of innovative conceptual tools and processes into the decision-making and management of forest ecosystems in the current context of climate change.
•We quantified the combined effect of abiotic and biotic stress factors in Mediterranean forests.•Tree defoliation correlated positively with lower climatic suitability and higher intensity of pest severity.•Trees were more vulnerable to defoliation in areas with unsuitable climatic conditions and higher pest severity.•Climatic suitability index can be useful for standardizing tree responses to climate variability.
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