Thinned Pine Stands Research Articles

Динамика экосистем свежего бора центра Приволжской возвышенности

The results of a study of the dynamics of a rather rare type of forest ecosystem for the central part of the Volga Upland – fresh pinery (A2) – are presented. The research was carried out on the territory of the Upper Sura section of the Volga Forest-Steppe Nature Reserve. The progress of the process was studied in an age series, identified in homogeneous forest conditions based on the principles of dynamic classification of forest types. As a result of processing forest taxation data, average values of taxation indicators of forest stands were obtained for each age class. At the same time, an analysis of changes in all components of the plantings was carried out. On its basis, the age series was divided into separate periods and phases. Trends in the share of participation of each forest-forming species in the forest stand at different age stages are described by nonlinear equations. The study showed that the resulting age series represents a series of transformation of forest communities. Disruption of the forest formation process led to a large-scale replacement of indigenous plantings with derivatives. After the start of clear-cutting, the area occupied by deciduous trees (primarily birch) constantly grew. A consequence of the large-scale use of intermediate, sanitary and voluntary selective fellings was the formation of thinned pine stands. At the same time, a transformation of the lower tiers of communities also occurred. These factors caused a deterioration in the conditions for natural regeneration of pine (Pinus sylvestris L.). As a result, to date, the possibility of forming pine stands through natural regeneration is almost completely excluded.

Detecting Heterobasidion irregulare in Minnesota and Assessment of Indigenous Fungi on Pines

Heterobasidion irregulare is one of the most problematic forest pathogens in the northern hemisphere, but has only been found relatively recently in the north central United States. Discovered in Wisconsin in 1993, but probably established sometime before that, it quickly spread throughout the state. In November 2014, it was found in southeastern Minnesota. Field surveys were then conducted throughout Minnesota with the focus in the southeast near the initial discovery. To find additional infection sites, surveys were conducted with accompanying aerial imagery of red pine (Pinus resinosa Aiton) stands that were previously thinned. Samples were collected from selected sites with dead and dying trees as well as samples from stumps in recently thinned pine stands. These samples were processed first with a nested polymerase chain reaction (PCR) protocol, which was replaced by a real-time PCR assay after its development. No samples tested positive for H. irregulare using these methods and no cultures from isolations were obtained outside the original infection area. Other indigenous fungi were also identified. The majority were wood decay fungi in the Basidiomycota. A spore collection study was also conducted after field surveys. Automated rotary arm spore collectors were used and assayed with an ITS TaqMan real-time PCR assay. Collectors were placed strategically in different areas of Minnesota. A positive control was used in an infected red pine plantation in Wisconsin and this location had the highest number of spores trapped, with 63,776 over a week period. Spores of H. irregulare were detected at several sites in Minnesota, with the highest spore total observed in traps at 413 over a week period. All other locations sampled also had some spores collected except Itasca State Park located in northwestern Minnesota. The weekly deposition of spores ranged from 0 to 1.26 m−2 h−1. Low spore levels occurring in Minnesota indicate that some spores are present, but they are currently being detected in amounts that may not be sufficient for colonization to be successful.

Bird conservation potential of fire and herbicide treatments in thinned pine stands

Abstract Fire-maintained pine (Pinus spp.) forests, characterized by a diverse herbaceous layer, sparse midstory layer, and a dominant pine overstory, once covered approximately 30 million ha in the southeastern United States. Fire suppression, landscape changes, and land management changes have contributed to reduced suitability of many pine stands for fire-dependent species, including many avian species in regional decline. However, intensively managed loblolly pine (P. taeda) stands treated with prescribed fire and herbicide could help restore or maintain fire-dependent communities within working landscapes. Therefore, we investigated avian responses to combinations of prescribed fire and herbicide (imazapyr) treatments within a matrix of intensively managed pine stands in east-central Mississippi, USA. We used a randomized complete block design of 6 mid-rotation, thinned pine stands (blocks) each with 4 treatments (control, burn only, herbicide only, burn + herbicide) assigned to 10-ha experimental units. We applied imazapyr herbicide (Arsenal®) during fall 1999 and burned units during winter every 3 years, beginning in 2000. We conducted avian point counts from year pre-treatment (1999) through 9 years post-treatment (2000–2008) and summarized annual vegetation structure and composition. We used 34 of 64 observed avian species for analyses using mixed models, repeated measures ANCOVA. Across the 9-year post-treatment study period, fire and imazapyr differentially affected avian communities with our combination treatment (fire + imazapyr) favoring high-priority, open pine bird species most. However, remaining treatments (burn only, imazapyr only, controls) provided additional vegetation gradients for species preferring greater structure diversity or canopy coverage. Our results indicated that fire and herbicide treatments can maintain vegetation structure attractive to a bird community of high-conservation value, while concurrently meeting economic and sustainable forestry goals. Although primarily managed for economic gain, intensively managed forests can provide suitable habitat conditions for avian species of conservation concern helping land managers meet biodiversity objectives.

Vegetation responses to fire and herbicide in intensively managed, mid-rotation pine

Intensively managed pine forests in the southeastern U.S. now cover approximately 15.8millionha. Forest managers are increasingly expected to consider biodiversity in land management decisions. Habitat management, particularly dormant-season prescribed fire with or without prior herbicide application may provide an opportunity for achieving sustainability goals relative to biodiversity in intensively managed pine stands. Therefore, we investigated vegetation structure, coverage, and diversity responses to combinations of prescribed fire and herbicide (imazapyr) treatments within mid-rotation, thinned, intensively managed pine stands within a managed forest matrix in east-central Mississippi, USA during 1999–2008. We used a randomized complete block design of 6 mid-rotation, thinned pine stands (blocks) each with 4 treatments [control, burn only (dormant-season 3year fire return interval), herbicide only (Arsenal AC® at 12oz./acre), burn+herbicide) assigned to 10-ha experimental units. We measured vegetation structure (understory, midstory, and overstory components) and understory plant coverage using standard techniques from one year pre-treatment (1999; our baseline) through 9years post-treatment (2008). To evaluate treatment effects, we used repeated measures mixed models analysis of covariance with baseline data as our covariate. We detected 338 plant species including 140 forbs, 5 ferns, 35 grasses, 11 herbaceous vines, 21 legumes, 26 sedges and rushes, 9 semi-woody vines, 76 woody plants, and 15 woody vine species. Treatment effects included concomitant reductions in upper level visual obstruction (m), increased herbaceous understory coverage, and hardwood midstory competition reduction. Herbicide was more effective at reducing hardwood midstory basal area, but repeated disturbances by prescribed fire maintained favorable vegetation structure conditions and improved understory plant species diversity throughout the latter years of study. Overstory pine basal area demonstrated positive responses to treatments. Prescribed fire and herbicide, within thinned, intensively managed pine stands at levels investigated here, appears to promote a stand structure consisting of a pine overstory and a diverse understory, reflective of historic conditions in the southeastern U.S. Implementation of these treatments can help forest managers achieve sustainable forestry goals in intensively managed pine stands of the southeastern U.S.

Natural mortality in thinning and fertilisation experiments with pine and spruce in Sweden

Natural mortality in a 30-year period was examined in thinning and fertilisation experiments with 48 blocks in Scots pine ( Pinus sylvstris L.) and 23 blocks in Norway spruce ( Picea abies (L.) Karst.) with up to 12 different treatments. Of about 90,000 living trees at start of the experiments 18.7% were registered as dead by natural mortality in the 30-year observation period. In non-thinned stands about 20% of the volume growth disappeared by natural mortality, in thinned stands about 10%. In normally thinned pine stands (repeated thinning from below with moderate intensity) the annual mortality of the basal area at start of an average 7-year period was 0.34%. In spruce stands, on more fertile sites, the corresponding figure was about 0.6%. In an effort to model the mortality, severe damage not leading to final felling was identified in 1.7% of the observation periods. It was assumed that this part of the mortality, representing 24% of the total volume mortality, could be recovered by active thinning. The probability for severe damage increased sharply with stand top height, as shown in a logistic regression. The more sparse mortality was expressed as a function of site fertility, stand density, disturbance by thinning and form of treatment (thinned from above or below or non-thinned). The naturally dead trees were approximately of mean size in normally thinned stands while the self-thinning in non-thinned stands tended to occur amongst smaller than average trees. Diagrams were presented for basal area development and stem number reduction in the non-thinned stands.

Response of antelope bitterbrush to repeated prescribed burning in Central Oregon ponderosa pine forests

Antelope bitterbrush is a dominant shrub in many interior ponderosa pine forests in the western United States. How it responds to prescribed fire is not well understood, yet is of considerable concern to wildlife and fire managers alike given its importance as a browse species and as a ladder fuel in these fire-prone forests. We quantified bitterbrush cover, density, and biomass in response to repeated burning in thinned ponderosa pine forests. Low- to moderate-intensity spring burning killed the majority of bitterbrush plants on replicate plots. Moderately rapid recovery of bitterbrush density and cover resulted from seedling recruitment plus limited basal sprouting. Repeated burning after 11 years impeded the recovery of the bitterbrush community. Post-fire seed germination following the repeated burns was 3–14-fold lower compared to the germination rate after the initial burns, while basal sprouting remained fairly minor. After 15 years, bitterbrush cover was 75–92% lower on repeated-burned compared to unburned plots. Only where localized tree mortality resulted in an open stand was bitterbrush recovery robust. By controlling bitterbrush abundance, repeated burning eliminated the potential for wildfire spread when simulated using a customized fire behavior model. The results suggest that repeated burning is a successful method to reduce the long-term fire risk imposed by bitterbrush as an understory ladder fuel in thinned pine stands. Balancing the need to limit fire risk yet provide adequate bitterbrush habitat for wildlife browse will likely require a mosaic pattern of burning at the landscape scale or a burning frequency well beyond 11 years to allow a bitterbrush seed crop to develop.

Response of a Reptile Guild to Forest Harvesting

Despite the growing concern over reptile population declines, the effects of modern industrial silviculture on reptiles have been understudied, particularly for diminutive and often overlooked species such as small-bodied snakes. We created 4 replicated forest-management landscapes to determine the response of small snakes to forest harvesting in the Coastal Plain of the southeastern United States. We divided the replicated landscapes into 4 treatments that represented a range of disturbed habitats: clearcut with coarse woody debris removed; clearcut with coarse woody debris retained; thinned pine stand; and control (unharvested second-growth planted pines). Canopy cover and ground litter were significantly reduced in clearcuts, intermediate in thinned forests, and highest in unharvested controls. Bare soil, maximum air temperatures, and understory vegetation all increased with increasing habitat disturbance. Concomitantly, we observed significantly reduced relative abundance of all 6 study species (scarletsnake[Cemophora coccinea], ring-neck snake[Diadophis punctatus], scarlet kingsnake[Lampropeltis triangulum], red-bellied snake[Storeria occipitomaculata], southeastern crowned snake[Tantilla coronata], and smooth earthsnake[Virginia valeriae]) in clearcuts compared with unharvested or thinned pine stands. In contrast, the greatest relative snake abundance occurred in thinned forest stands. Our results demonstrate that at least one form of forest harvesting is compatible with maintaining snake populations. Our results also highlight the importance of open-canopy structure and ground litter to small snakes in southeastern forests and the negative consequences of forest clearcutting for small snakes.

Stand and landscape-level factors related to bird assemblages in exotic pine plantations: Implications for forest management

Plantations cover a substantial amount of Earth's terrestrial surface and this area is expected to increase dramatically in the coming decades. Pinus plantations make up approximately 32% of the global plantation estate. They are primarily managed for wood production, but have some capacity to support native fauna. This capacity likely varies with plantation management. We examined changes in the richness and frequency of occurrence of bird species at 32 plots within a Pinus radiata plantation (a management unit comprising multiple Pinus stands) in south-eastern Australia. Plots were stratified by distance to native forest, stand age class and thinning regime. We also assessed the landscape context of each plot to determine relationships between bird assemblages and stand and landscape-level factors. Bird species richness was significantly higher at plots ≥300 m from native forest and in mature (∼20 years since planting) and old (∼27 years since planting) thinned pine stands. We were able to separate the often confounding effects of stand age and thinning regime by including old stands that had never been thinned. These stands had significantly fewer species than thinned stands suggesting thinning regime, not age is a key factor to improving the capacity of pine plantations to support native species (although an age × thinning interaction may influence this result). At the landscape level, species richness increased in pine stands when they were closer to native riparian vegetation. There were no significant differences in species composition across plots. Our study indicates the importance of stand thinning and retention of native riparian vegetation in improving the value of pine plantations for the conservation of native fauna.

Selection of diurnal roosts by red bats ( Lasiurus borealis) in an intensively managed pine forest in Mississippi

Forest managers are increasingly expected to incorporate biodiversity objectives within forest landscapes devoted to timber production. However, data on which to base management recommendations for bats within these systems are limited. Although the red bat ( Lasiurus borealis) is a widespread and common species in temperate forests of North America, little is known of its ecology within intensively managed pine ( Pinus spp.) forests of the southeastern United States. Diurnal roost sites of red bats may be limiting on industrial pine forests due to a lack of large hardwoods within managed stands. Therefore, we investigated selection of day roosts by red bats at multiple spatial scales during June–September 2000 and May–August 2001 in an intensively managed pine landscape in east-central Mississippi, USA. We captured bats using 4-tier mist nets placed over water and attached 0.47–0.54 g radiotransmitters to captured red bats ( n = 46). We located day roosts of red bats ( n = 141 roosts of 27 bats) for the life of the transmitters. Red bats roosted in 16 species of hardwood trees (70% of day roosts) and loblolly pine ( Pinus taeda; 30% of day roosts). In contrast to other studies in the southeastern United States, red bats roosted in pine trees and in midstory hardwood trees. Within thinned pine stands, red bats tended to prefer roost trees with a denser subcanopy and higher basal area as compared to random sites. Stand-level characteristics appeared more important than individual tree characteristics in choice of diurnal roosts. Except for adult males, logistic regression models of roost sites of red bats had high (≥79%) correct classification rates. Day roost site requirements of red bats may exhibit greater plasticity than previously thought. On our study area, intensive forest management appears compatible with diurnal roost needs of this species.