Environmental, biological and human drivers of the dieback of an evergreen Mediterranean forest

2020 ◽  
Author(s):  
Paolo De Angelis ◽  
Dario Liberati ◽  
Diego Giuliarelli ◽  
Loredana Oreti ◽  
Andrea Vannini
Keyword(s):  
Tree Mortality ◽  
Quercus Ilex ◽  
Central Italy ◽  
Mixed Forest ◽  
Forest Stand ◽  
Stress Factors ◽  
Ambrosia Beetle ◽  
Carbon Uptake ◽  
Typical Structure ◽  
General Decline

<p>Forests play a key role in the climate system thanks to their large carbon uptake and storage. On the other hand, forests are vulnerable to climate extremes and pest attacks, causing early tree mortality which in turn could reduce their carbon uptake capacity.</p><p>Early tree mortality is often associated to a complex interaction of predisposing stress factors (poor site quality, unfavourable stand conditions), inciting factors (frost, drought, mechanical damage) and contributing factors (fungi, insect borers).</p><p>In this context, the aim of the present work was to investigate the processes underlying the tree mortality observed in an evergreen mixed forest stand dominated by Quercus ilex, located in the Circeo National Park (central Italy).</p><p>The forest has the typical structure of an old-coppice not more managed (actual rotation time about 2 times that the normal), and was recently (2016) affected by an outbreak of Asian ambrosia beetle (Xylosandrus compactus) and Granulate ambrosia beetle (Xylosandrus crassiusculus) that caused an extensive trees crown browning. In 2019, plots were set in the area to monitor the beetle population dynamic and their impact on tree mortality. In each plot, species, dimension (DBH), stage of dieback, stem origin (resprouts after coppicing or from seed), presence of epicormic shoots and subcortical fungi stroma, were recorded for each woody plant.</p><p>The plot survey revealed a high frequency of stems classified in a declining stage or dead, on average 42% of the standing stems, with significant differences among the species: 97%, 85%, 74% and 47% for Arbutus unedo, Quercus ilex, Phyllirea latifolia and Fraxinus ornus respectively.</p><p>The higher stem mortality of Q. ilex was recorded in the smaller diameter classes, suggesting that the self-thinning process played an important role on the observed mortality as typical in the old not more managed coppices.</p><p>To disentangle the role of the interruption of the management from the climatic and biological drivers, time trends on NDVI index were constrained with the duration of the summer dry seasons and comparing our forest with similar Q. ilex forest coppices in the region and regularly managed.</p><p>Furthermore, the contribution of recent ambrosia beetles attack was assessed identifying the presence of twigs with signs of previous beetle attack on healthy, declining and dead plants.</p><p>Our findings point towards complex tree mortality dynamics, in which the competition generated by the stand abandonment predisposed the forest to the insect attack, leading to the general decline of the forest stand.</p>

scholarly journals Differences in the Response to Acute Drought and Phytophthora cinnamomi Rands Infection in Quercus ilex L. Seedlings

Forests ◽  
2018 ◽  
Vol 9 (10) ◽  
pp. 634 ◽  
Author(s):  
Francisco Ruiz Gómez ◽  
Alejandro Pérez-de-Luque ◽  
Rafael Sánchez-Cuesta ◽  
José Quero ◽  
Rafael Navarro Cerrillo
Keyword(s):  
Water Stress ◽  
Biomass Allocation ◽  
Root Rot ◽  
Tree Mortality ◽  
Quercus Ilex ◽  
Phytophthora Cinnamomi ◽  
Growth Patterns ◽  
Holm Oak ◽  
Stress Factors ◽  
Oak Decline

The sustainability of “dehesas” is threatened by the Holm oak decline. It is thought that the effects of root rot on plant physiology vary depending on external stress factors. Plant growth and biomass allocation are useful tools to characterize differences in the response to drought and infection. The study of physiological responses together with growth patterns will clarify how and to what extent root rot is able to damage the plant. A fully factorial experiment, including drought and Phytophtora cinnamomi Rands infection as factors, was carried out with Quercus ilex L. seedlings. Photosynthesis, biomass allocation and root traits were assessed. Photosynthetic variables responded differently to drought and infection over time. The root mass fraction showed a significant reduction due to infection. P. cinnamomi root rot altered the growth patterns. Plants could not recover from the physiological effects of infection only when the root rot coincided with water stress. Without additional stressors, the strategy of our seedlings in the face of root rot was to reduce the biomass increment and reallocate resources. Underlying mechanisms involved in plant-pathogen interactions should be considered in the study of holm oak decline, beyond the consideration of water stress as the primary cause of tree mortality.

Guides for Estimating Forest Stand Losses to Gypsy Moth

1984 ◽  
Vol 1 (2) ◽  
pp. 21-23 ◽  
Author(s):  
David A. Gansner ◽  
Owen W. Herrick
Keyword(s):  
Species Composition ◽  
Gypsy Moth ◽  
Tree Mortality ◽  
Cost Effective ◽  
Forest Stand ◽  
Measure Data ◽  
Effective Management ◽  
Field Plot ◽  
Crown Condition ◽  
As Species

Abstract People who have to make decisions about cost-effective management for gypsy moth need help in predicting and evaluating its effects. Field plot data collected during recent outbreaks in Pennsylvania are being used to develop guides for predicting forest stand losses to the pest Presented here are some of the more useful products of that effort to date. Easy-to-measure data for forest characteristics such as species composition and crown condition can be collected and applied in models that estimate potential stand and tree mortality and changes in timber value. North. J. Appl. For. 2:21-23, June 1984.

scholarly journals Combining GF-2 and Sentinel-2 Images to Detect Tree Mortality Caused by Red Turpentine Beetle during the Early Outbreak Stage in North China

Forests ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 172 ◽  
Author(s):  
Zhan ◽  
Yu ◽  
Li ◽  
Ren ◽  
Gao ◽  
...  
Keyword(s):  
Tree Mortality ◽  
Spatial Scales ◽  
Binary Classification ◽  
Insect Pest ◽  
Forest Stand ◽  
Machine Learning Algorithms ◽  
Classification And Regression Tree ◽  
Support Vector ◽  
Single Tree ◽  
Sentinel 2

In recent years, the red turpentine beetle (RTB) (Dendroctonus valens LeConte) has invaded the northern regions of China. Due to the short invasion time, the outbreak of tree mortality corresponded to a low level of damage. Important information about tree mortality, provided by remote sensing at both single-tree and forest stand scale, is needed in forest management at the early stages of outbreak. In order to detect RTB-induced tree mortality at a single-tree scale, we evaluated the classification accuracies of Gaofen-2 (GF2) imagery at different spatial resolutions (1 and 4 m) using a pixel-based method. We also simultaneously applied an object-based method to 1 m pan-sharpened images. We used Sentinel-2 (S2) imagery with different resolutions (10 and 20 m) to detect RTB-induced tree mortality and compared their classification accuracies at a larger scale—the stand scale. Three kinds of machine learning algorithms—the classification and regression tree (CART), the random forest (RF), and the support vector machine (SVM)—were applied and compared in this study. The results showed that 1 m resolution GF2 images had the highest classification accuracy using the pixel-based method and SVM algorithm (overall accuracy = 77.7%). We found that the classification of three degrees of damage percentage within the S2 pixel (0%, <15%, and 15% < x < 50%) was not successful at a forest stand scale. However, 10 m resolution S2 images could acquire effective binary classification (<15%: overall accuracy = 74.9%; 15% < x < 50%: overall accuracy = 81.0%). Our results indicated that identifying tree mortality caused by RTB at a single-tree and forest stand scale was accomplished with the combination of GF2 and S2 images. Our results are very useful for the future exploration of the patterns of spatial and temporal changes in insect pest transmission at different spatial scales.

Flow modeling within a Central European forest using large-eddy simulation

2020 ◽  
Author(s):  
Max Plorin ◽  
Sandra Grunicke ◽  
Christian Bernhofer ◽  
Ronald Queck
Keyword(s):  
Laser Scanning ◽  
Mixed Forest ◽  
Forest Stand ◽  
Windward Side ◽  
Monitoring Site ◽  
Neutral Atmosphere ◽  
Vegetation Model ◽  
Lateral Direction ◽  
Central European ◽  
European Forest

&lt;p&gt;With the aim to simulate the exchange of energy and matter between air and vegetation, we applied the LES PALM to a typical Central European forest. The presentation shows how the level of detail within vegetation model and the orography alters the simulated flow.&lt;/p&gt;&lt;p&gt;The site of investigation is a managed mixed forest stand (mainly Picea abies, height 30 m; a long-term CarboEurope monitoring site) within the Tharandter Wald near Dresden, Germany. Terrestrial laser scans (TLS) provided the data basis for the high-resolution vegetation model of this forest stand and a nearby clearing (50x90 m) building the inner range of the model domain. To investigate orographic effects on the flow, we extended the domain for about 1.5 km to the west. This includes the S-Berg, which is about 40 m height and therefore the highest elevation on the windward side. We used information from airborne laser scanning (ALS) along with forest inventory data to build a vegetation model as well as a digital elevation model for the extended area (2 km in streamwise and 1.5 km in lateral direction) with a resolution of (2m)&lt;sup&gt;3&lt;/sup&gt;.&amp;#160;&lt;/p&gt;&lt;p&gt;In a first step, we restricted all simulations to a neutral atmosphere to exclude effect of buoyancy.&lt;/p&gt;&lt;p&gt;Wind data from four measurement towers (from DFG SPP 1276 MetStr&amp;#246;m) provided data for a validation of the simulations. They were located within the inner domain along a west-east transect over the clearing.&lt;/p&gt;

scholarly journals On the Occurrence of Natural Norway Spruce Woodland in the Pieniny Mts (Western Carpathians)

2015 ◽  
Vol 11 (2) ◽  
pp. 123-138
Author(s):  
Peter Kučera
Keyword(s):  
Picea Abies ◽  
Norway Spruce ◽  
Mixed Forest ◽  
Abies Alba ◽  
Field Research ◽  
Forest Stand ◽  
Published Data ◽  
Mountain Range ◽  
Acer Pseudoplatanus ◽  
Altitudinal Limit

Abstract According to Kulczyński (1928), a natural Picea abies forest occurs in the mountain range of the Pieniny Mts on the slopes of the mountain Vysoke skalky. Later, various data on the altitudinal range of this stand (and thus on the locality itself) were published: (1) 890 (900) - 950 m, (2) 1000 - 1050 m or (3) around 1000 m. The aim of the field research was to verify published data on the occurrence of a woodland of Upper Mountain Norway spruce (association Polysticho-Piceetum) in the territory of Vysoke skalky. A field study in the area has revealed that most of published data on the occurrence of the Kulczyński’s Picea woodland are incorrect, as its real upper altitudinal limit reaches ± 940 m. The main result is the confirmation of the real existence of a Vaccinium myrtillus-Homogyne alpina-Picea abies phytocoenosis in the territory of Vysoke skalky. However, tree species other than Picea abies (e.g. Fagus sylvatica, Abies alba, Acer pseudoplatanus) could persist in the special habitat of Kulczyński’s ‘Picea woodland’. The natural vegetation of this place was formed by mixed forest stand.

The Relationship between Soil Moisture and Root Density under Different Types Phyllostachys edulis Forests in Northern Fujian

2014 ◽  
Vol 1073-1076 ◽  
pp. 1090-1094
Author(s):  
Wei Yi Liu ◽  
Shao Hui Fan ◽  
Guang Lu Liu ◽  
Feng Ying Guan
Keyword(s):  
Soil Moisture ◽  
Soil Water ◽  
Soil Depth ◽  
Mixed Forest ◽  
Forest Stand ◽  
The North ◽  
Broad Leaved Forest ◽  
Relationship Model ◽  
Routine Observation ◽  
The Relationship

The soil moisture of three typical P. edulis forests (P. edulis and Cunninghamia lanceolata mixed forest, P. edulis pure forest , P. edulis and broad-leaved tree mixed forest ) in the North of Fujian province were studied in comparison with C. lanceolata pure forest and evergreen broad-leaved forest. Based on the routine observation, characteristics of spatial and temporal change of soil water content were studied. According to the roots distribution which were analyzed on different forest stand, the Linear and relationship model were established about the soil water and roots distribution. Results showed that the forest stand roots density decreasing with increasing soil depth, roots density and spatial distribution of soil moisture are related closely.

scholarly journals Thick bark can protect trees from a severe ambrosia beetle attack

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e10755
Author(s):  
John M. Boland ◽  
Deborah L. Woodward
Keyword(s):  
Structural Damage ◽  
Tree Mortality ◽  
River Valley ◽  
Host Tree ◽  
Ambrosia Beetle ◽  
Bark Thickness ◽  
Black Willow ◽  
Entry Points ◽  
Salix Gooddingii ◽  
Preferred Hosts

Thick bark has been shown to protect trees from wildfires, but can it protect trees from an ambrosia beetle attack? We addressed this question by examining the distribution of holes of the invasive Kuroshio Shot Hole Borer (KSHB, Euwallacea kuroshio; Coleoptera: Scolytinae) in the bark of Goodding’s black willow (Salix gooddingii), one of the KSHB’s most-preferred hosts. The study was conducted in the Tijuana River Valley, California, in 2016–17, during the peak of the KSHB infestation there. Using detailed measurements of bark samples cut from 27 infested trees, we tested and found support for two related hypotheses: (1) bark thickness influences KSHB attack densities and attack locations, i.e., the KSHB bores abundantly through thin bark and avoids boring through thick bark; and (2) bark thickness influences KSHB impacts, i.e., the KSHB causes more damage to thinner-barked trees than to thicker-barked trees. Our results indicate that thick bark protects trees because it limits the density of KSHB entry points and thereby limits internal structural damage to low, survivable levels. This is the first study to identify bark thickness as a factor that influences the density of KSHB—or any ambrosia beetle—in its host tree, and the first to link bark thickness to rates of host tree mortality.

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