Plots In Stands Research Articles

Seasonal carbon accumulation by groundcover in the Central Siberian subtaiga forest-steppe zone

The research is dedicated to comparing the above ground living vegetation carbon stock in various site conditions. The study was carried out in the Karaul'noe forestry located near Krasnoyarsk, Russia. We placed the research plots in stands of varying density (0.34-1.06) and landforms. Seven research plots are of the closed type (the groundcover develop under the canopy) and three research plots are of the open type (the bank of the Yenisei River, hayfield, area under power lines). Open (forestless) plots (the bank of the Yenisei River, hayfield, area under power lines) and pine forests with forest floor dominated by ferns/tall grasses were of the maximum above ground living vegetation carbon stocks values (from 2.01 to 2.46 tonnes of carbon per ha). A significant carbon sequestration was observed in the pine forest of lingonberry/moss type (1.58 tonnes of carbon per ha) since the moss layer makes a significant contribution to the groundcover carbon accumulation.

Distribution of Phytophthora species within recreational chestnut, beech and cork oak forests

Tree decline caused by exotic Phytophthora pathogens is a serious issue affecting forests around the world. The presence of Phytophthora has been reported in heavily visited natural forests; however, whether recreational forests are at higher risk of being attacked by Phytophthora than non-recreational forests has yet to be explored. In this study, we sampled soil from 44 forests in Catalonia (NE Spain) with high or low recreational use that were dominated by chestnut (Castanea sativa), beech (Fagus sylvatica) or cork oak (Quercus suber). A systematic soil sampling of 277 plots in stands of different tree species, predominantly Pinus and Quercus spp., was also conducted across Catalonia to compare soils of recreational forests with high and low recreational use with the baseline incidence of Phytophthora in the region. The putative impacts of the presence of Phytophthora in recreational areas were assessed by measuring tree defoliation and regeneration, and by performing pathogenicity trials using Phytophthora isolates from soil and root samples to inoculate seedlings of tree species growing in the region. The incidence of native and invasive Phytophthora species was higher in chestnut, beech and cork oak forests than in forests of other tree species. For chestnut and beech forests, we found that the likelihood of finding an invasive Phytophthora in forests with high recreational use was more than three times higher than in forests with low recreational use (76% vs 21%, respectively). No differences were observed in cork oak forests. In plots with invasive Phytophthora species, beech exhibited higher defoliation levels than in plots without Phytophthora. The presence of both native and invasive Phytophthora species was associated with lower chestnut and cork oak regeneration. Our data indicate that Phytophthora is widespread in some forests used for recreation and seems to be associated with defoliation and low regeneration. However, the primary mechanism explaining the high prevalence of Phytophthora in recreational areas remains unclear. Disturbance, soil movement due to construction, or visitors moving inoculum within and across sites could be studied as possible contributing factors to establish effective management actions.

Benefit or Liability? The Ectomycorrhizal Association May Undermine Tree Adaptations to Fire After Long-term Fire Exclusion

Long-term fire exclusion may weaken ecosystem resistance to the return of fire. We investigated how a surface wildfire that occurred after several decades of fire exclusion affected a southern Appalachian forest transitioning from a fire-adapted to a fire-intolerant state. Tree traits associated with fire adaptation often co-occur with traits for nutrient conservation, including the ectomycorrhizal (ECM) association. In the absence of fire, the ECM association may facilitate the accumulation of organic matter, which becomes colonized by fine roots that then become vulnerable to consumption or damage by fire. Therefore, a deeper organic horizon might make stands of fire-adapted, ECM trees less resistant to a surface wildfire than stands of arbuscular mycorrhizal (AM), fire-intolerant trees. To test this hypothesis, we established plots in stands that fall along a gradient of mycorrhizal tree relative abundance both inside and outside the perimeter of the 2016 Rock Mountain wildfire. With increasing relative abundance of ECM trees, we found increasing organic horizon depth and mass and slower rates of decay, even for litter of ECM tree species. We calculated a major (73–83%) reduction in fine root biomass and length in the organic horizon following the wildfire. Over three years post-fire, we observed a higher probability of crown decline, basal sprouting and aboveground biomass mortality with increasing abundance of ECM trees. We propose that the biogeochemistry of mycorrhizal associations can help explain why fire exclusion makes stands of fire-adapted trees less resistant to a surface wildfire than those with fire-intolerant trees.

The problem of drying up spruce stands and ways to solve it

The last decades has been witnessed of the mass spruce stands drying up problem in different countries of the world. The investigation purpose consists in establishing influence of the growth conditions and the bark beetle, on the drying up of spruce forests. Forest stands of the coniferous-broadleaved (mixed) zone forests in Russian Federation served as an object of our researcb. Based on the results of the acts of pathologic inspection, it is established that the share of drying up spruce forests decreases with increasing soil fertility and moisture. The influence of the bark beetle was investigated on the basis of materials of three sample plots in stands of the green-moss spruce type of forest. We did not find traces of vital activities of the bark beetle by the drying spruce trees with a diameter at altitudes of 1.3 m to 14 cm fully, as well as with a diameter of 14 to 22 cm partly. The fact revealed is explained by the fact that these spruce trees have a thin bark which is not enough for the beetle laying inside of it the mother gallery, and the brood bark for subsequent feeding. The bark beetle is not the primary reason of the spruce forests drying in the Permsky Kray. It is necessary to conduct a much deeper study on this problem.

Biocontrol of Sirex noctilio by the parasitic nematode Deladenus siricidicola: A five season field study in southern Chile.

In 2001, the woodwasp Sirex noctilio was detected in Pinus radiata plantations in the Biobio region of southern Chile. Subsequently, an intense biological control program using the female sterilizing nematode Deladenus siricidicola was implemented in 2010. During five seasons between 2012 and 2017, we studied the parasitism of D. siricidicola nematode and its effect on woodwasp populations and infestation of P. radiata in different locations within the Biobio region. Parasitism was assessed by dissecting adult females of S. noctilio obtained from infested P. radiata logs. The total population of S. noctilio was determined by the emergence of individuals from the same logs. The level of damage caused by the S. noctilio pest was determined by establishing plots in stands of P. radiata at an intensity of 1 plot every 5 ha-1. During the study period, parasitism of S. noctilio by the nematode D. siricidicola increased from 29.6% in 2012 to 93.1% in 2016, while pest population decreased 3.4% in the same time period. Infestation increased from 0.3 to 11,6% of trees between 2012 and 2015, but subsequently decreased to 5.9% by 2017. We confirmed establishment of the nematode in the region under study and its natural dispersion to non-inoculated areas. Finally, we determined that the effect of inoculation age (antiquity) on parasitism levels reached 90% after three years of inoculation.

Long-term tree inventory data from mountain forest plots in France.

We present repeated tree measurement data from 63 permanent plots in mountain forests in France. Plot elevations range from 800 (lower limit of the montane belt) to 1942m above sea level (subalpine belt). Forests mainly consist of pure or mixed stands dominated by European beech (Fagus sylvatica), Silver fir (Abies alba), and Norway spruce (Picea abies), in association with various broadleaved species at low elevation and with Arolla pine (Pinus cembra) at high elevation. The plot network includes 23 plots in stands that have not been managed for the last 40years (at least) and 40 plots in plots managed according to an uneven-aged system with single-tree or small-group selection cutting. Plot sizes range from 0.2 to 1.9ha. Plots were installed from 1994 to 2004 and remeasured two to five times during the 1994-2015 period. During the first census (installation), living trees more than 7.5cm in dbh were identified, their diameter at breast height (dbh) was measured and their social status (strata) noted. Trees were spatially located, either with x, y, and z coordinates (40 plots) or within 0.25-ha square subplots (23 plots). In addition, in a subset of plots (58 plots), tree heights and tree crown dimensions were measured on a subset of trees and dead standing trees and stumps were included in the census. Remeasurements after installation include live tree diameters (including recruited trees), tree status (living, damaged, dead, stump), and for a subset of trees, height. At the time of establishment of the plots, plot densities range from 181 to 1328 stems/ha and plot basal areas range from 13.6 to 81.3m2 /ha.

Biological activity in the forest floor of artificial forests in the steppe zone

A special role in the biological cycle in forest biogeocoenoses plays forest floor, which connects the abiotic and biotic components in an integral system, affects the genesis of forest soils and productivity of forest plantations. The most informative indicators of biological activity of the soil and the forest floor are the activity of enzymes, the intensity of carbon dioxide emissions, the number and qualitative composition of the main groups of microorganisms. Particular specificity of these indicators acquire in artificial forest plantations in the steppe zone, due to the geographical, ecological and often a mismatch in habitat conditions for forest. The aim of this work was to study the biological activity of the forest floor in artificial forest plantations in the steppe zone of Ukraine (on the example of Staro-Berdyansk forest). Staro-Berdyansk forest (Zaporizhia region, Ukraine), founded in 1846 on the left bank of the Molochnaya river. Studies of the biological activity the forest floor carried out on stationary plots in stands of Quercus robur L., Robinia pseudoacacia L. and Pinus pallasiana D. Don during 2013 year seasonally. Analysis of the data series using correlation method showed that the increase in the forest floor the magnitude of algae, micromycete and oligotrophic microorganisms is accompanied by an increase in catalase activity (correlation coefficients: 0,80; 0,91; 0,95), at the same time micromycete and oligotrophs positively associated with thermolabile component of catalase activity (correlation coefficients: 0,75; 0,95). In periods of reduction of catalase activity increases the number of actinomycetes (r = -0,67). Polyphenol oxidase activity is positively correlated with the magnitude of micromycete in the forest floor (r = +0,68) and negatively with the population of actinomycetes (r = -0,86) and bacteria, that use mineral nitrogen compounds (r = -0,69). In periods of activation of phosphatase the magnitude of algae and micromycete decreases (r = -0,92 and r = -0,80; respectively) and cellulolytic microorganisms increases (r = +0,75). Integral indicator of biological activity of the forest floor is the amount of carbon dioxide emitted, indicating the intensity of the processes of transformation of organic matter. The greatest intensity of carbon dioxide emissions recorded in autumn samples of locust bean and pine plantations. The oak stands a high level of carbon dioxide emissions occur in summer and autumn. The magnitude of microorganisms and algae, enzyme activity and the intensity of carbon dioxide emissions in the forest floor changed by seasonal, which corresponds to the dynamics of the overall progress of biological processes occurring in the forest floor. On the biological activity of the forest floor is significantly affected by the composition of plant residues, which generally corresponds to the views of various researchers who have noted a correlation of enzyme activity in the soil with the magnitude of microorganisms, as well as biochemical and chemical composition of forest floor and the stages of its destruction.

Analysis of Norway spruce dieback phenomenon in Latvia – a belowground perspective

ABSTRACTIn 2010, dieback of Norway spruce (Picea abies) was observed in Latvia. As mostly stands on seasonally or permanently water-saturated soils were damaged, we hypothesized that the recorded foliar damage might be associated with belowground factors. We established 48 sample plots in stands with damage symptoms for soil parameter evaluation and fine root sampling to determine the number of fine roots in different growth stages and to describe the associated fungal community. Among sample plots on organic soils, there were fewer viable older fine roots and greater number of dead fine roots in more damaged sites than in less damaged. These root parameters were significantly correlated with higher groundwater level and soil pH. The fungal community was dominated by ectomycorrhizal (ECM) species (the most common was Tylospora asterophora), the endophyte Oidiodendron maius and saprotrophic species Cryptococcus magnus. Saprotrophic species had higher abundance in more damaged sites, suggesting a shift in fungal communities from ECM fungi. In conclusion, the results of this work suggest Norway spruce root system response to short-term climatic stress, which should be considered when planning spruce forest management, especially on organic soils with a high groundwater level.

Effects of thinning on stand structure and tree stability in an afforested oriental beech (Fagus orientalis Lipsky) stand in northeast Turkey

We studied relationships between stand structure and stand stability according to thinning intensity in an afforested oriental beech stand. Various thinning intensities were applied in sample stands. We sampled eight plots in stands that were lightly thinned, eight plots in heavily thinned stands and eight plots in unthinned stands as a control. Height and diameter distributions of the stands were measured to assess stand structure. We quantified individual tree stability and collective stability. Heavy thinning during the first thinning operation damaged the storied structure of the stand in thicket stage and affected collective structuring ability. While most control plots had multi-storied stands, after light and heavy thinning two-storied structure became more common. Large gaps occurred in the canopy after heavy thinning. On average, nine tree collectives were formed per sampling plot in the untreated stand, seven collectives after thinning in 2008 and four collectives after thinning in 2009. Stable trees accounted for 17 % of trees in control plots, 24 % in lightly thinned plots, and 15 % in heavily thinned plots. Collective stability values were 83 % in control plots, 82 % in lightly thinned plots and 36 % in heavily thinned plots. We conclude that it is necessary to retain collective structuring capacity during thinning operations for sustaining stand stability.

Regeneration Potential of Floodplain Forests Under the Influence of Nonnative Tree Species: Soil Seed Bank Analysis in Northern Italy

AbstractSoil seed banks are the ecological memory of plant communities and might represent their regeneration potential. This study examines the soil seed bank in hardwood floodplain forests of the biosphere reserve “Valle del Ticino” (Northern Italy) to find out whether the natural forest vegetation can potentially be restored by the soil seed bank. We compared near natural forests of the phytosociological association Polygonato multiflori–Quercetum roboris with stands dominated by the nonnative tree species Robinia pseudoacacia and Prunus serotina in order to investigate whether the composition of the soil seed bank is significantly influenced by the composition of the main canopy tree species and soil properties. Soil seed bank samples were taken from 20 randomly selected plots in stands that were differentiated into four groups related to the dominant forest canopy species. The germinated plants were counted and their species determined. A total of 2,427 plants belonging to 84 species were recorded. The composition of the dominant tree species and soil parameters significantly influence the composition of the seed bank. The similarity with the standing vegetation was very low. Only 13% of the species in the soil seed bank represent the target vegetation. The low percentage of target species and the high percentage of nonnative species imply that the regeneration of near‐natural forest vegetation from the soil seed bank is not feasible. Consequently, disturbances that may activate the soil seed bank should be minimized. Thus, we recommend stopping the mechanical removal of the nonnative tree species in the Ticino Park.

Aplicação da função hiperbólica na construção de curvas de índice de local

Neste estudo foi avaliada a eficiência da função hiperbólica, para geração de curvas anamórficas e polimórficas de índices de local. As curvas de índice de local foram construídas utilizando os métodos: da curva-guia, da equação das diferenças, da predição de parâmetros, de Hammer e dos índices de local definidos preliminarmente. Para aplicação desses métodos foram utilizados dados de parcelas permanentes de povoamentos de eucalipto. A eficiência foi confirmada, sendo a função indicada para descrever tendências polimórficas e anamórficas, podendo ser utilizada na classificação da capacidade produtiva de povoamentos de eucalipto.

Age-related and stand-wise estimates of carbon stocks and sequestration in the aboveground coarse wood biomass of wetland forests in the northern Pantanal, Brazil

Abstract. In this study we use allometric models combined with tree ring analysis to estimate carbon stocks and sequestration in the aboveground coarse wood biomass (AGWB) of wetland forests in the Pantanal, located in central South America. In four 1-ha plots in stands characterized by the pioneer tree species Vochysia divergens Pohl (Vochysiaceae) forest inventories (trees ≥10 cm diameter at breast height, D) have been performed and converted to estimates of AGWB by two allometric models using three independent parameters (D, tree height H and wood density ρ). We perform a propagation of measurement errors to estimate uncertainties in the estimates of AGWB. Carbon stocks of AGWB vary from 7.8 ± 1.5 to 97.2 ± 14.4 Mg C ha−1 between the four stands. From models relating tree ages determined by dendrochronological techniques to C-stocks in AGWB we derived estimates for C-sequestration which differs from 0.50 ± 0.03 to 3.34 ± 0.31 Mg C ha−1 yr−1. Maps based on geostatistic techniques indicate the heterogeneous spatial distribution of tree ages and C-stocks of the four studied stands. This distribution is the result of forest dynamics due to the colonizing and retreating of V. divergens and other species associated with pluriannual wet and dry episodes in the Pantanal, respectively. Such information is essential for the management of the cultural landscape of the Pantanal wetlands.

Elevated mortality of residual trees following structural retention harvesting in boreal mixedwoods

In recent years boreal forests have been harvested to retain a portion of the original canopy, thereby providing forest structure, mostly for biodiversity reasons. Boreal mixedwood cutovers were surveyed at one and five years after harvesting with approximately 10% structural retention, to quantify the mean annual mortality rates of the residual trembling aspen, balsam poplar, paper birch and white spruce trees. For comparison, "natural" mortality rates by species were estimated from permanent sample plots in stands of similar composition. Species ranking of the annual mortality rates of residuals in areas harvested with structural retention were: poplar (10.2%) > birch (8.7%) > aspen (6.1%) > spruce (2.9%). Annual mortality rates were 2.5 to 4 times greater than in the reference stands. The majority of broadleaved species died as snags (~70%–90%), while most spruce died due to windthrow (80%). Mortality rates increased with slenderness coefficient for codominant and understory poplar and for understory birch. For aspen, codominants were most likely to die, while in spruce, dominant trees and trees with the greatest damage to the bole from harvesting operations had the highest mortality. Key words: Alberta, Betula papyrifera, dieback, harvesting damage, mixedwood forests, variable retention, Picea glauca, Populus balsamifera, Populus tremuloides, structural retention, sustainable forest management

Resilience of bryophyte communities to clear-cutting of boreal stream-side forests

We asked if short-term changes in bryophyte communities in response to clear-cutting of boreal stream-side forests are persistent and whether species with low resilience may survive in narrow riparian buffer strips. To assess short-term changes and the function of buffer strips we compared the bryophyte community in permanent 0.1 ha plots of mature forest before and after clear-cutting. Persistent changes were inferred by pair-wise comparisons of 0.1 ha plots of mature forests with carefully matched 0.1 ha plots in stands established after clear-cutting 30–50 years earlier. Total bryophyte species richness did not respond significantly to clear-cutting. However, richness changed in many subgroups defined by phylogenetic, habitat or substrate affinity. Numbers of both liverwort and forest species were significantly reduced on clear-cuts and these differences remained significant, although smaller, 30–50 years after clear-cutting. In contrast, there were short-term increases in richness of mosses and of species growing on disturbed mineral soil, but these species numbers returned to mature-forest levels in the young stands. Number of species associated with convex substrates, especially woody debris species, was strongly reduced by clear-cutting and showed no significant recovery after 30–50 years. Hence, most of the negative effects of clear-cutting on bryophyte species persist almost halfway into the next forestry rotation period. However, narrow buffer strips (10 m on each side) prevented most of the short-term extirpations of species with low resilience on clear-cuts. Buffer strips may thus be effective in conserving the bryophyte flora of stream-side forests, but their long-term function as refugia and their contribution to population recovery in other parts of the landscape need further evaluation.

Abundance and Size Distribution of Cavity Trees in Second-Growth and Old-Growth Central Hardwood Forests

Abstract In central hardwood forests, mean cavity-tree abundance increases with increasing stand-size class (seedling/sapling, pole, sawtimber, old-growth). However, within a size class, the number of cavity trees is highly variable among 0.1-ha inventory plots. Plots in young stands are most likely to have no cavity trees, but some plots may have more than 50 cavity trees/ha. Plots in old-growth stands often had 25 to 55 cavity trees/ha, but individual plots ranged from 0 to 155/ha. The Weibull probability density function was used to mathematically describe the variation in cavity-tree abundance for plots in stands of differing size (or age) class. A graph of the cumulative probability of cavity-tree abundance is a particularly easy way for managers to estimate the probability that a stand of a given size class will have any specified number of cavity trees per hectare. Results for individual plots or stands can be combined to estimate cavity abundance probabilities for landscapes. Because the results are presented in terms of plot-size classes (or age classes), this approach to cavity tree estimation is compatible with relatively simple forest inventorysystems.North. J. Appl. For. 22(3):162–169.

Gradient analysis of exotic Pinus radiata plantations and potential restoration of natural vegetation in Tenerife, Canary Islands (Spain)

Afforestation on the island of Tenerife has been carried out mainly with the native species of pine Pinus canariensis Chr. Sm. Ex DC. However, the exotic pine Pinus radiata D. Don has been introduced in some areas. Several studies have shown that plantations of exotic species facilitate forest succession in their understories on sites where disturbances prevent the recolonization by native forest species. We randomly located 250 plots in stands of P. radiata, on the island of Tenerife and recorded species. Abiotic characteristics of the plots were also noted. We evaluated the regeneration of potential vegetation of the laurel forest and pine forest under a canopy of an exotic pine species. Analysis of the species composition, resulted in four well defined groups: advanced laurel forest group (ALF), undeveloped laurel forest group (ULF), ruderal group (RU) and Canarian pine stand group (CPS). These groups can also be discriminated base on altitude, slope or canopy cover. For ALF and ULF we propose thinning restoration management and the planting of new individuals of laurel forest species. For RU and CPS, because they are potentially P. canariensis stands, we propose continuous elimination of P. radiata and enrichment with new individuals of P. canariensis.

Vegetation structure, floristic composition and growth characteristics of Aucoumea klaineana Pierre stands as influenced by stand age and thinning

The coastal forest of Gabon abounds in monospecific secondary Aucoumea klaineana stands derived from natural regeneration after shifting cultivation. This paper aims to describe the changes in the structure and dynamics of these stands with age. It then assesses the impact of selective thinning in the upper storey on both structural and dynamic parameters. The experiment consisted of 34 Permanent Plots in stands from establishment to more mature stages (ca. 50 years old). Thirteen plots (17–45 years old) were thinned. More than 80% of the removal came from supernumerary dominant A. klaineana. A. klaineana represented 60% of the total density in stands ca. 15 years old but >90% of the dominant trees in older stands. The changes with age in the floristic composition of the unthinned stands showed three successional stages during which pioneer species associated with A. klaineana (from establishment to ca. 15 years) were progressively replaced by mature forest species. Basal area increased and density decreased with age before reaching stable values at ca. 40–45 years. Mortality was very high in young stands but decreased in the older ones. Mortality generally affected small diameter individuals in the dominated storey. Diameter and basal area increments showed that the stand growth resulted from the growth of dominant A. klaineana. Diameter increments of A. klaineana were elevated during the first years of colonisation (1.9 cm/year) and were still ca. 0.7 cm/year for 50-year-old dominant trees. Thinning did not increase the mortality of the dominant population. It favoured the individual growth of A. klaineana. The gain was substantial for dominated trees and small dominant trees (from 60 to 100%) but was lower for large dominant trees (ca. 25–30%). Therefore, stimulation of individual growth did not compensate for the loss of basal area at the stand level.

Incidence and Impact of Swiss Needle Cast in Forest Plantations of Douglas-fir in Coastal Oregon.

An epidemic of Swiss needle cast, caused by the ascomycete Phaeocryptopus gaeumannii, is causing defoliation and growth reductions in Douglas-fir forest plantations along the Oregon Coast. The area of symptomatic plantations has been monitored annually since 1996 by aerial survey; in spring 1999, 119,500 ha were affected. Pathogen and symptom development have also been monitored on nine permanent plots in stands of differing disease severity. Infection levels and symptom severity are greatest in low elevation plantations close to the coast. In areas of severe disease, trees retain only current year needles. Defoliation is proportional to the number of stomata occluded by pseudothecia of the fungus, with needles being shed when about 50% of stomata are occupied, regardless of needle age. Fungus sporulation and premature needle abscission are greatest on the upper branches of trees. Annual application of fungicides increases needle retention significantly. Tree height and diameter growth and total tree volume are reduced by disease, and tree volume is significantly correlated with needle retention on our plot trees. The epidemic continues to be most severe in Douglas-fir plantations established on sites where Sitka spruce and western hemlock or red alder predominated in earlier times.

Effects of Hurricane Andrew on stands of slash pine (Pinus elliottii var. densa) in the everglades region of south Florida (USA)

Few hurricanes affect intact stands of subtropical pines. We examined effects of winds in the eyewalls of Hurricane Andrew, where wind speeds were>200 km h 1 , on all remaining large mainland stands of Pinus elliottii var. densa (south Florida slash pine) on limestone outcroppings (rocklands) in the everglades region of southern Florida. We measured densities and sizes of trees and assessed damage and mortality in plots in old-growth stands in the Lostman’s Pines (LOP) region of Big Cypress National Preserve and in second-growth stands in the Pines West (PIW) and Long Pine Key (LPK) regions of Everglades National Park. We also examined age-size relationships using sections from trees killed by the hurricane in LOP and LPK. We used the data to predict effects of recurrent hurricanes on the structure and dynamics of the old-growth stand and to compare effects of hurricanes on old- and second-growth stands. Slash pine was resistant to hurricane winds. Most trees in stands (68‐76%) were not severely damaged; mortality in the three regions averaged 17‐25% shortly after the hurricane and 3‐7% during the following year. Mortality was positively associated with tree size; mean tree sizes decreased and size-selective thinning occurred in all stands. Nonetheless, local mortality ranged from 3‐4% to 50‐60% among plots in all stands. Such local variation in mortality resulted from clustering of large trees, especially in old-growth stands, and from microbursts during the hurricane, which affected all stands. Recurrent, intense hurricanes are predicted to kill larger trees, slowly opening new patches and increasing sizes of extant patches, thus resulting in almost continual presence of openings suitable for recruitment in old-growth stands. Age-size relationships also indicated that large trees in old-growth stands may survive 2‐3 centuries. The combination of frequent openings and wind resistance of large trees is predicted to result in old-growth stands that are highly uneven aged, with trees locally distributed in similar-aged patches. The extent to which such stands deviate from demographic equilibrium, as well as turnover rates within stands, are likely to increase as the frequency of recurrent, intense hurricanes increases. Damage and mortality differed in old- and second-growth stands. Large trees were more, but small trees less likely to be damaged in old- than second-growth stands. In contrast, mortality was significantly lower in old- (LOP: 16.9% 3.1 [mean s.e.]) than second-growth stands (PIW: 22.5% 2.0; LPK: 25.2% 2.7). Total hurricanerelated mortality was 30‐60% higher in second- than old-growth stands. Size class structure, more uneven in oldthan second growth stands prior to the hurricane, diverged even more afterwards. Hurricane Andrew removed

Surface Lidar Remote Sensing of Basal Area and Biomass in Deciduous Forests of Eastern Maryland, USA

A method of predicting two forest stand structure attributes, basal area and aboveground biomass, from measurements of forest vertical structure was developed and tested using field and remotely sensed canopy structure measurements. Coincident estimates of the vertical distribution of canopy surface area (the canopy height profile), and field-measured stand structure attributes were acquired for two data sets. The chronosequence data set consists of 48 plots in stands distributed within 25 miles of Annapolis, MD, with canopy height profiles measured in the field using the optical-quadrat method. The stem-map data set consists of 75 plots subsetted from a single 32 ha stem-mapped stand, with measurements of their canopy height profiles made using the SLICER (Scanning Lidar Imager of Canopies by Echo Recovery) instrument, an airborne surface lidar system. Four height indices, maximum, median, mean, and quadratic mean canopy height (QMCH) were calculated from the canopy height profiles. Regressions between the indices and stand basal area and biomass were developed using the chronosequence data set. The regression equations developed from the chronosequence data set were then applied to height indices calculated from the remotely sensed canopy height profiles from the stem map data set, and the ability of the regression equations to predict the stem map plot’s stand structure attributes was then evaluated. The QMCH was found to explain the most variance in the chronosequence data set’s stand structure attributes, and to most accurately predict the values of the same attributes in the stem map data set. For the chronosequence data set, the QMCH predicted 70% of variance in stand basal area, and 80% of variance in aboveground biomass, and remained nonasymptotic with basal areas up to 50 m 2 ha −1, and aboveground biomass values up to 450 Mg ha −1. When applied to the stem-map data set, the regression equations resulted in basal areas that were, on average, underestimated by 2.1 m 2 ha −1, and biomass values were underestimated by 16 Mg ha −1, and explained 37% and 33% of variance, respectively. Differences in the magnitude of the coefficients of determination were due to the wider range of stand conditions found in the chronosequence data set; the standard deviation of residual values were lower in the stem map data set than on the chronosequence data sets. Stepwise multiple regression was performed to predict the two stand structure attributes using the canopy height profile data directly as independent variables, but they did not improve the accuracy of the estimates over the height index approach.