Detecting growth releases of mature retention trees in response to small-scale gap disturbances of known dates in natural-disturbance-based silvicultural systems in Maine

2021 ◽  
Vol 502 ◽  
pp. 119721
Author(s):  
David R. Carter ◽  
Margaret B. Bialecki ◽  
Marcella Windmuller-Campione ◽  
Robert S. Seymour ◽  
Aaron Weiskittel ◽  
...  
Keyword(s):  
Natural Disturbance ◽  
Small Scale ◽  
Retention Trees

Preadaptation and spatial effects on retention-tree survival in cut areas in Estonia

2008 ◽  
Vol 38 (10) ◽  
pp. 2616-2625 ◽  
Author(s):  
Raul Rosenvald ◽  
Asko Lõhmus ◽  
Andres Kiviste
Keyword(s):  
Natural Disturbance ◽  
Forest Edge ◽  
Forest Site ◽  
Spatial Effects ◽  
Forest Edges ◽  
Dead Trees ◽  
Tree Survival ◽  
Tree Retention ◽  
Standing Dead ◽  
Retention Trees

Survival of live retention trees is a key issue for stand-scale applications of natural-disturbance-based silviculture. We explored the survival of 3255 trees in 102 cut areas (mean size 2.3 ha) in Estonia for 6 years, focusing on spatial variation and preadaptation of the trees. Altogether, 35% of the trees died during the study period, contributing 4.4 m3 of downed dead trunks and 1 m3 of standing dead trees per hectare. The annual mortality rates declined over time. The main survival determinants were tree species (higher for hardwood deciduous trees), diameter (species dependent), position relative to forest edge (higher for trees near current or former forest edges), retention density (positive), and exposure (negative). The results suggest that (1) green-tree retention can effectively increase the abundance of large shade-tolerant trees, but it is equally important for producing deadwood; (2) larger individuals, former interior-forest trees near current forest edges, and preadapted trees in open conditions should be preferably retained; (3) there is no obvious necessity to modify tree-retention techniques for tree survival according to geographical region or forest site type.

scholarly journals Toward a definition of the range of variability of central European mixed Fagus–Abies–Picea forests: the nearly steady-state forest of Lom (Bosnia and Herzegovina)

2011 ◽  
Vol 41 (9) ◽  
pp. 1871-1884 ◽  
Author(s):  
Renzo Motta ◽  
Roberta Berretti ◽  
Daniele Castagneri ◽  
Vojislav Dukić ◽  
Matteo Garbarino ◽  
...  
Keyword(s):  
Bosnia And Herzegovina ◽  
Structural Characteristics ◽  
Abies Alba ◽  
Natural Disturbance ◽  
European Beech ◽  
High Volume ◽  
Permanent Plot ◽  
Small Scale ◽  
Silver Fir ◽  
Gap Size

Knowledge on the range of variability of montane European forests is hampered by limited data on the natural disturbance regime and by the small size of old-growth remnants. We studied the mixed Fagus – Abies – Picea Lom forest reserve (55.8 ha) in Bosnia and Herzegovina at three different scales: a grid of 40 sampling points to describe the structural characteristics and their range of variability, three transects to analyse gap size and gap fraction, and a 1.1 ha permanent plot to reconstruct age structure and disturbance history. The forest is characterized by a high volume of living trees (763 m3·ha–1 in the 55.8 ha core area and 1160 m3·ha–1 in the permanent plot) and of coarse woody debris (327 and 383 m3·ha–1, respectively). The percentages of forest area in canopy and expanded gaps are 19% and 41%, respectively. The median canopy gap size is 76.9 m2 and ranges from 11.1 to 708.0 m2. There are large (up to 120 cm diameter at breast height) and very old trees (441, 432, and 416 years for silver fir ( Abies alba Mill.), Norway spruce ( Picea abies (L.) Karst.), and European beech ( Fagus sylvatica L.), respectively). During the last three centuries, the disturbance patterns have been characterized by single-tree or small group mortality. In central Europe, this forest is at the end of a gradient from forests characterized by intermediate disturbances to those where very small-scale processes predominate.

Effects of gap size on nutrient release from plant litter decomposition in a natural forest ecosystem

1995 ◽  
Vol 25 (10) ◽  
pp. 1627-1638 ◽  
Author(s):  
Qishui Zhang ◽  
Yuwu Liang
Keyword(s):  
Litter Decomposition ◽  
Nutrient Dynamics ◽  
Nutrient Release ◽  
Natural Disturbance ◽  
Plant Litter ◽  
Small Scale ◽  
Gap Size ◽  
Size Classes ◽  
Plant Litter Decomposition ◽  
Decomposition Processes

The rates of nutrient release were investigated during the Castanopsiskawakamii (Hayata) leaf, branch, and bark litter decomposition processes over a 360-day period within five different size classes of forest gaps that comprise a gap size gradient. Five different size classes of gaps were gap 1, under the closed canopy of pure C. kawakamii vegetation; gap 2, small gaps with a diameter of less than 5 m; gap 3, small to intermediate gaps with a diameter of 5–15 m; gap 4, intermediate to large gaps with a diameter of 15–30 m; gap 5, large gaps with a diameter of bigger than 30 m. After 360 days, decomposing plant litter under canopy condition or small gaps lost weight more rapidly than those in large gaps. Loss of K was highest among all nutrients measured for all three types of litter in all five size classes of gaps. Net immobilization of N and P occurred for all three types of litter in the first 2 or 4 months. Litter residue concentrations of N and P then declined until the end of this study, decreasing to 47% and 70%, respectively, of initial amounts. Loss of Ca and Mg averaged 60 and 40%, respectively, during the period of this study; loss of S averaged 50% and was continuous. Loss of nutrients measured were highest in leaves, intermediate in bark, and lowest in branches under the same size class of gaps, and were highest in gaps 1 and 2, intermediate in gap 3, and lowest in gaps 4 and 5 for the same type of litter. Cellulose and lignin components showed the similar patterns of mass loss as nutrients with highest in gaps 1 and 2, intermediate in gap 3, lowest in gaps 4 and 5 (P ≤ 0.001). Annual decomposition rate was correlated to the microclimatic factors for all types of litter within five different gap size conditions. Soil moisture content was the best predictor of annual decay rate (R2 = 0.922, P ≤ 0.001) among the microclimatic factors. The results indicated that small scale of natural disturbance do not influence the nutrient dynamics during plant litter decomposition; however, rates of nutrient release are strongly inhibited with the increase of scales of disturbance. In this study, gap size of 15 m in diameter is critical in determining the rates of nutrient release from plant litter decomposition processes.

Recolonization dynamics of benthic macroinvertebrates after artificial and natural disturbances in an Australian temporary stream

1991 ◽  
Vol 42 (3) ◽  
pp. 295 ◽  
Author(s):  
SS Brooks ◽  
AJ Boulton
Keyword(s):  
Particle Size ◽  
Species Richness ◽  
Benthic Macroinvertebrates ◽  
Large Scale ◽  
South Australia ◽  
Natural Disturbance ◽  
Small Scale ◽  
Temporary Stream ◽  
Large Scale Disturbance ◽  
Coarse Gravel

The effects of substratum particle size (cobbles, coarse gravel and medium-fine gravel) on recolonization by benthic macroinvertebrates after disturbance was investigated in small plots (0.05 m2) in the Finniss River, an intermittent stream in South Australia. Six weeks after flow resumed, the intermediate particle size (coarse gravel) supported the greatest densities of taxa and individuals. Experimental disturbance reduced species richness by 83% and numbers of individuals by 97%. Rapid recolonizers (e.g. mayfly and stonefly nymphs) showed little substratum specificity and attained predisturbance densities within one day. Slow recolonizers (e.g. chironomid hatchlings) favoured gravel substrata and had not reached predisturbance densities within 4 days. Recolonization of small plots appeared to be by surface movement from neighbouring intact areas. A spate on Day 7 prevented further sampling, destroying all experimental plots, but this permitted a study of macroinvertebrate recolonization following a natural disturbance at a larger spatial scale. The spate reduced species richness by 45% and numbers of individuals by 70%. Vertical migration rather than drift appeared to be the major source of recolonizing fauna. Our data show that results from small-scale experiments can not be extrapolated to large-scale disturbance because the scale of disturbance strongly influences the rate and pathways of recolonization as well as the sources and faunal composition of the recolonists.

Natural disturbance, vegetation patterns and ecological dynamics in tropical montane forests

2016 ◽  
Vol 32 (5) ◽  
pp. 384-403 ◽  
Author(s):  
Shelley D. Crausbay ◽  
Patrick H. Martin
Keyword(s):  
Environmental Gradients ◽  
Natural Disturbance ◽  
High Energy ◽  
Small Scale ◽  
Vegetation Patterns ◽  
Environmental Complexity ◽  
Montane Forests ◽  
Central Process ◽  
Rich Mixture ◽  
Tropical Montane Forests

Abstract:Disturbance is a central process in forest dynamics, yet the role of natural disturbance in tropical montane forests (TMFs) has not been systematically addressed. We posit that disturbance in TMFs has a wider role than commonly acknowledged and its effects are distinctive because: (1) TMFs often have very low rates of productivity due to low resources, and so recovery from disturbance may be slow, (2) montane forests have marked environmental heterogeneity which interacts with disturbance, (3) a large percentage of TMFs are regularly exposed to high energy windstorms and landslides, and (4) TMFs contain a biogeographically rich mixture of tree species with divergent evolutionary histories that interact differently with different disturbance types. We reviewed the literature on natural disturbance in TMFs and found 119 peer-reviewed papers which met our search criteria. Our review shows that disturbance is widespread in TMFs with pronounced effects on structure, function, composition and dynamics. Disturbance is also evident in the ecology of TMF biota with clear examples of plant life-history traits adapted to disturbance, including disturbance-triggered germination, treefall gap strategies and resprouting ability. Important aspects of TMF disturbances are stochastic and site-specific, but there are broad patterns in disturbance type, frequency and severity along latitudinal, altitudinal and environmental gradients. Compared with the lowland tropics, TMF disturbances are more spatially structured, TMFs experience more disturbance types in a given area due to environmental complexity, and TMFs are much more prone to small-scale yet severe landslides as well the large and potentially catastrophic disturbances of cyclones, forest die-back and fire. On the whole, natural disturbance should assume a larger role in models of ecosystem processes and vegetation patterns in TMFs. An improved understanding of what creates variation in disturbance severity and post-disturbance recovery rates, how composition and diversity feedback on disturbance type and likelihood, and how global change will alter these dynamics are important priorities in future TMF ecology research.

Mechanism of nitrate loss from a forested catchment following a small-scale, natural disturbance

2001 ◽  
Vol 31 (8) ◽  
pp. 1326-1335 ◽  
Author(s):  
Satoru Hobara ◽  
Naoko Tokuchi ◽  
Nobuhito Ohte ◽  
Keisuke Koba ◽  
Masanori Katsuyama ◽  
...  
Keyword(s):  
Nutrient Dynamics ◽  
Root Zone ◽  
Stream Water ◽  
Natural Disturbance ◽  
Pine Wilt Disease ◽  
Small Scale ◽  
Nitrification Rate ◽  
Forested Catchment ◽  
Disturbed Area ◽  
Nitrate Concentrations

In Matsu-zawa catchment, central Japan, nitrate concentrations in stream water increased following a small-scale, natural disturbance involving an outbreak of pine wilt disease that affected ~25% of the forested catchment. To clarify nutrient dynamics in soils and their relationship with stream water nitrate, we investigated soil nitrogen dynamics and soil water chemistry in disturbed and undisturbed, water-unsaturated and -saturated plots. The highest values for nitrification rate, nitrate concentration in soil solution, and nitrate exported from the root zone were observed for the disturbed plot. The ratio of nitrification to mineralization in surface soil of the disturbed plot dramatically increased from 1989 (pre-disturbance) to 1997. Root zone leachate from the disturbed area showed gradually increasing groundwater nitrate concentrations in the temporarily saturated zone during lateral, matrix flow. The catchment's deep soils and associated hydrologic processes limited the degree of plant uptake of the nitrate generated in the disturbed area. It was inferred that the persistent high levels of nitrate observed in the stream water resulted largely from the stable high nitrate concentrations observed in the saturated groundwater of this catchment. Stream water nitrate loads discharged following the disturbance were about 16 times greater than prior to it.

scholarly journals Quantifying Canopy Tree Loss and Gap Recovery in Tropical Forests under Low-Intensity Logging Using VHR Satellite Imagery and Airborne LiDAR

2019 ◽  
Vol 11 (7) ◽  
pp. 817 ◽  
Author(s):  
Ricardo Dalagnol ◽  
Oliver L. Phillips ◽  
Emanuel Gloor ◽  
Lênio S. Galvão ◽  
Fabien H. Wagner ◽  
...  
Keyword(s):  
Tropical Forests ◽  
Satellite Imagery ◽  
Regional Scale ◽  
Natural Disturbance ◽  
Selective Logging ◽  
Airborne Lidar ◽  
Small Scale ◽  
Difference Threshold ◽  
Validation Data ◽  
Canopy Tree

Logging, including selective and illegal activities, is widespread, affecting the carbon cycle and the biodiversity of tropical forests. However, automated approaches using very high resolution (VHR) satellite data (≤ 1 m spatial resolution) to accurately track these small-scale human disturbances over large and remote areas are not readily available. The main constraint for performing this type of analysis is the lack of spatially accurate tree-scale validation data. In this study, we assessed the potential of VHR satellite imagery to detect canopy tree loss related to selective logging in closed-canopy tropical forests. To do this, we compared the tree loss detection capability of WorldView-2 and GeoEye-1 satellites with airborne LiDAR, which acquired pre- and post-logging data at the Jamari National Forest in the Brazilian Amazon. We found that logging drove changes in canopy height ranging from −5.6 to −42.2 m, with a mean reduction of −23.5 m. A simple LiDAR height difference threshold of −10 m was enough to map 97% of the logged trees. Compared to LiDAR, tree losses can be detected using VHR satellite imagery and a random forest (RF) model with an average precision of 64%, while mapping 60% of the total tree loss. Tree losses associated with large gap openings or tall trees were more successfully detected. In general, the most important remote sensing metrics for the RF model were standard deviation statistics, especially those extracted from the reflectance of the visible bands (R, G, B), and the shadow fraction. While most small canopy gaps closed within ~2 years, larger gaps could still be observed over a longer time. Nevertheless, the use of annual imagery is advised to reach acceptable detectability. Our study shows that VHR satellite imagery has the potential for monitoring the logging in tropical forests and detecting hotspots of natural disturbance with a low cost at the regional scale.

Reasons to strike first

2019 ◽  
Vol 42 ◽  
Author(s):  
William Buckner ◽  
Luke Glowacki
Keyword(s):  
Intergroup Conflict ◽  
Small Scale

Abstract De Dreu and Gross predict that attackers will have more difficulty winning conflicts than defenders. As their analysis is presumed to capture the dynamics of decentralized conflict, we consider how their framework compares with ethnographic evidence from small-scale societies, as well as chimpanzee patterns of intergroup conflict. In these contexts, attackers have significantly more success in conflict than predicted by De Dreu and Gross's model. We discuss the possible reasons for this disparity.

Exploring Coronal Structures with SOHO

2000 ◽  
Vol 179 ◽  
pp. 403-406
Author(s):  
M. Karovska ◽  
B. Wood ◽  
J. Chen ◽  
J. Cook ◽  
R. Howard
Keyword(s):  
Solar Corona ◽  
Image Enhancement ◽  
Coronal Mass Ejections ◽  
Dynamical Evolution ◽  
Small Scale ◽  
Low Contrast ◽  
Contrast Structures ◽  
Scale Structures ◽  
Small Scale Structures ◽  
Coronal Structures

AbstractWe applied advanced image enhancement techniques to explore in detail the characteristics of the small-scale structures and/or the low contrast structures in several Coronal Mass Ejections (CMEs) observed by SOHO. We highlight here the results from our studies of the morphology and dynamical evolution of CME structures in the solar corona using two instruments on board SOHO: LASCO and EIT.

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