Differential intensity of rehabilitation silviculture in mismanaged high-graded forest

There are an estimated two billion hectares of degraded forest worldwide. A high-graded forest is one from which the highest-quality individuals of commercial tree species have been selectively harvested. Successive high-grading results in degradation. Without proper management, these forests are unlikely to recover in the short term and will be unable to fulfil their potential capacity to provide goods and services to society. Human-led rehabilitation is required to restart essential processes such as regeneration. This concept note provides criteria for determining levels of degradation in high-graded old forests, citing implications for rehabilitation silviculture and proposing general strategies for their recovery

Stand density management diagram and its thinning applications in Drimys winteri second-growth forests in southern Chile

Stand density management (DMD) diagrams are graphical models of uniform stands at different ages that reflect the relationship among size, density, competition, site occupancy and self thinning. DMDs allow planning of thinnings through the definition of a target stand and the upper and lower limits of site occupancy. In this study we developed a DMD for Drimys winteri second-growth forests in southern Chile by using 300 sampling units with at least 70 % basal area of this species. The resulting DMD allowed the determination of the maximum density line, the volume and height isolines, and the evaluation of its use with information from permanent plots thinned 21 years ago. The results of the functions in the DMD present acceptable predictive power, and illustrate the usefulness and precision of this tool to plan silviculture activities. Results from applying the DMD suggest maintenance of site occupancy levels between the subutilization zone (30 % relative density index (RDI)) and the imminent mortality zone (45 % IDR), executing at least three thinnings to reach a target stand that will produce sawtimber and veneer at an age of at least 80 years for the study site. With this scheme the windfall risk is reduced and therefore so is the potential loss of production.Los diagramas de manejo de la densidad (DMD) son modelos gráficos de la dinámica de rodales uniformes a diferentes edades que reflejan la relación entre tamaño, densidad, competencia, ocupación del sitio y autorraleo; y permiten la planificación de raleos mediante la definición de un rodal meta y los límites superior e inferior de ocupación del sitio. Este estudio desarrolló un DMD para renovales de Drimys winteri en el sur de Chile, utilizando 300 unidades muestrales con una participación mayor a 70 % de área basal de D. winteri, que permitió determinar las líneas de tamaño máximo densidad, las isolíneas de volumen, isolíneas de altura, y evaluar su uso con datos de parcelas permanentes de raleo medidos durante 21 años. Los resultados de las funciones que conforman el DMD presentan aceptables capacidades predictivas, constatando la utilidad y precisión de esta herramienta para planificar intervenciones silviculturales. Los resultados de la aplicación del DMD sugieren mantener niveles de ocupación de sitio entre las zonas de subutilización (índice de densidad relativa (IDR) de 30 %) y la de inminente mortalidad por competencia (IDR de 45 %), realizando al menos tres raleos para alcanzar un rodal meta que genere productos aserrables y debobinables a una edad no menor a los 80 años para el sitio analizado. Con este esquema se reduce el riesgo de caída de árboles por viento y la pérdida de producción física del sitio

Financial evaluation of management in secondary forests of canelo (Drimys winteri) in the Coastal Range of Valdivia, Chile

Young secondary forests of Drimys winteri have excellent growth and regeneration, and cover an area of 230,000 hectares in Chile. However, there is no supply of high-value timber to feed the growing market opportunities. The objective of this study was to evaluate the profitability of thinning trials in secondary forests of Drymis winteri in a medium-productivity site. The thinning treatments were considered late thinning, and were named as moderate thinning (E1), heavy (E2) and heavy (E3), in addition to a control treatment (E4). The yield was determined using the net present value (NPV), land expected value (LEV), and modified internal rate of return (MIRR), incorporating discount rates of 6 %, 8 % and 10 % and low administration costs in two scenarios, no costs before thinning (S1) and costs since the establishment of the stand (S2). The results for the NPV and VPS in S2 were negative, in contrast with S1, which doubled its profitability compared with the control treatment. The E2 treatment had the highest profitability in the S1 case, with a NPV of USD 2,724 ha–1, a VPS of USD 3,771 for a 6 % rate, and a MIRR of 19 %. For an operational level the moderate thinning treatment (E1) is desirable since it reduces the risk of windfall, generates the highest yield in volume, and profitability values slightly lower than E2.Los bosques secundarios de canelo presentan excelentes crecimientos y regeneran fácilmente en forma natural, alcanzando una superficie de 230.000 hectáreas en Chile. A pesar de ello, no existe una oferta de madera que permita aprovechar las oportunidades de los mercados nacionales e internacionales. El objetivo de este estudio fue evaluar la rentabilidad de ensayos de raleo en bosques secundarios de Drimys winteri en un sitio de productividad media. Los tratamientos corresponden a raleos aplicados tardíamente, denominados como raleo moderado (E1), fuerte (E2 y E3) y un tratamiento control (E4). La rentabilidad se determinó a través del valor actual neto (VAN), valor económico del suelo (VES) y la tasa interna de retorno modificada (TIRm) incorporando tasas de descuento de 6 %, 8 % y 10 %; se consideraron costos de administración bajo dos escenarios: sin costo antes de las intervenciones (S1) y con costo desde el establecimiento del rodal (S2). Los resultados para el VAN y VPS en S2 fueron negativos, a diferencia del S1 que duplicó al menos su rentabilidad respecto de no intervenir los bosques secundarios. El tratamiento E2 presentó la mayor rentabilidad para el supuesto S1 con un VAN de US$2.724 ha–1, un VPS de US$ 3.771 para una tasa de 6 % y una TIRm de 19 %. Es recomendable para un nivel operacional el tratamiento de raleo moderado (E1), ya que reduce el riesgo de caída por viento, genera el mayor rendimiento en volumen y presenta cifras de rentabilidad levemente inferiores a E2

The differential influences of human-induced disturbances on tree regeneration community: a landscape approach

Understanding the processes shaping biological communities under interacting disturbances is\ud a core challenge in ecology. Although the impacts of human-induced disturbances on forest ecosystems have\ud been extensively studied, less attention has been paid to understanding how tree regeneration at the\ud community level responds to such disturbances. Moreover, these previous studies have not considered how\ud these effects change according to major social and environmental factors that can influence forest use at a\ud landscape scale. In this study, we investigate the effects of cattle grazing and selective logging on the\ud composition of tree regeneration communities in relation to forest successional stage and land tenure regime\ud in Chilean temperate forests, a global biodiversity hotspot. We recorded seedlings, saplings and basal area of\ud stumps of tree species (as a surrogate for selective logging), and number of cattle dung pats (as a surrogate\ud for cattle pressure) in 129 25 3 20 m plots in small (,200 ha) and large properties in different successional\ud stages (old-growth, intermediate, secondary forests). The regeneration of the ten more abundant species as\ud predicted by human disturbance, land tenure, forest successional stage, and number of parent trees was\ud modelled using generalised linear models. Predictions for each individual model were made under different\ud scenarios of human disturbance. The predicted regeneration results were assembled and subjected to\ud ordination analyses and permutation multivariate analyses of variance to determine differences in\ud regeneration composition under each scenario. In most cases, best-fit models contained at least one of the\ud explanatory variables accounting for human disturbance. The effects of selective logging on tree regeneration\ud varied depending on land tenure regime, but cattle grazing always exhibited a negative effect. Our results\ud revealed that cattle have a more negative effect on forest regeneration than selective logging, especially in\ud old-growth forests and small properties. Our analytical approach contributes to the understanding of the\ud differential influence of human-induced disturbances on the tree regeneration community at a landscape\ud scale. It can inform conservation policies and actions, which should focus on addressing themain disturbance\ud factors and on developing strategies to conserve the most sensitive species to such disturbances.C. Zamorano-Elgueta was supported by a CON-\ud ICYT pre-doctoral fellowship (Government of Chile),\ud the European Comission (Project contract DCI-ENV/\ud 2010/222-412), the Chilean NGO Forest Engineers for\ud Native Forest (Forestales por el Bosque Nativo, www.\ud bosquenativo.cl) and project REMEDINAL-2 (Comu-\ud nidad de Madrid, S2009/AMB-1783). L. Cayuela was\ud supported by project REMEDINAL-2. This work is\ud part of the objectives of projects CGL2010-18312\ud (CICYT, Ministerio de Economı́a y Competividad de\ud Espana). The authors acknowledge the valuable\ud support of Vero ́nica Pı́riz, Cony Becerra, Rodrigo\ud Gangas, Oscar Concha, Eduardo Neira and staff from\ud the Valdivian Coastal Reserve, as well as the National\ud Forest Service of Chile (Corporación Nacional Forestal

Nanomolar clodronate induces adenosine accumulation in the perfused rat mesenteric bed and mesentery-derived endothelial cells

The vesicular nucleotide transporter (VNUT) is critical for sympathetic co-transmission and purinergic transmission maintenance. To examine this proposal, we assessed whether the bisphosphonate clodronate, claimed as a potent in vitro VNUT blocker, modified spontaneous and/or the electrically evoked overflow of ATP/metabolites and NA from mesentery sympathetic perivascular nerve terminals. Additionally, in primary endothelial cell cultures derived from this tissue, we also evaluated whether clodronate interfered with ATP/metabolite cell outflow and metabolism of N6-etheno adenosine 5′-triphosphate (eATP), N6-etheno adenosine (eADO), and adenosine deaminase enzyme activity. Rat mesenteries were perfused in the absence or presence of .01–1,000 nM clodronate, 1–1,000 nM Evans blue (EB), and 1–10 µM DIDS; tissue perfusates were collected to determine ATP/metabolites and NA before, during, and after perivascular electrical nerve terminal depolarization. An amount of 1–1,000 nM clodronate did not modify the time course of ATP or NA overflow elicited by nerve terminal depolarization, and only 10 nM clodronate significantly augmented perfusate adenosine. Electrical nerve terminal stimulation increased tissue perfusion pressure that was significantly reduced only by 10 nM clodronate [90.0 ± 18.6 (n = 8) to 35.0 ± 10.4 (n = 7), p = .0277]. As controls, EB, DIDS, or reserpine treatment reduced the overflow of ATP/metabolites and NA in a concentration-dependent manner elicited by nerve terminal depolarization. Moreover, mechanical stimulation of primary endothelial cell cultures from the rat mesentery added with 10 or 100 nM clodronate increased adenosine in the cell media. eATP was metabolized by endothelial cells to the same extent with and without 1–1,000 nM clodronate, suggesting the bisphosphonate did not interfere with nucleotide ectoenzyme metabolism. In contrast, extracellular eADO remained intact, indicating that this nucleoside is neither metabolized nor transported intracellularly. Furthermore, only 10 nM clodronate inhibited (15.5%) adenosine metabolism to inosine in endothelial cells as well as in a commercial crude adenosine deaminase enzyme preparation (12.7%), and both effects proved the significance (p < .05). Altogether, present data allow inferring that clodronate inhibits adenosine deaminase activity in isolated endothelial cells as in a crude extract preparation, a finding that may account for adenosine accumulation following clodronate mesentery perfusion

Cambios en cobertura y regeneración arbórea en bosques siempreverdes en diferentes estados sucesionales en el sitio experimental de Llancahue, Cordillera de la Costa de Valdivia, Chile

In the Llancahue experimental site (39°50’; 300-400 m) we evaluated richness of tree and understory species in an old-growth forest and in two secondary forests. Having similar species’ richness in these forests, the study supports our hypothesis that this is a result of successional development and natural and anthropogenic disturbances.In the Llancahue experimental site (39°50’; 300-400 m) we evaluated richness of tree and understory species in an old-growth forest and in two secondary forests. Having similar species’ richness in these forests, the study supports our hypothesis that this is a result of successional development and natural and anthropogenic disturbances

MP753: The Role of Interfering Plants in Regenerating Hardwood Stands of Northeastern North America

An annotated bibliography for American beech (Fagus grandifolia Ehrh.), striped maple (Acer pensylvanicum L.), hobblebush (Viburnum alnifolium Marsh.), hayscented fern (Dennstaedtia punctilobula L.), New York fern (Thelypteris noveborecensis L.), bracken fern (Pteridium aquilinum (L.) Kuhn), raspberries (Rubus spp.), and pin cherry (Prunus pensylvanica L.f.). While accessible literature includes many references to these species, the information remains scattered. No one has previously consolidated the separate reports for easy reference, nor summarized the findings relative to interference with tree regeneration. This annotated bibliography serves that purpose.https://digitalcommons.library.umaine.edu/aes_miscpubs/1023/thumbnail.jp

Silvicultural alternatives to conventional even-aged forest management - what limits global adoption?

Background The development of forestry as a scientific and management discipline over the last two centuries has mainly emphasized intensive management operations focused on increased commodity production, mostly wood. This “conventional” forest management approach has typically favored production of even-aged, single-species stands. While alternative management regimes have generally received less attention, this has been changing over the last three decades, especially in countries with developed economies. Reasons for this change include a combination of new information and concerns about the ecological consequences of intensive forestry practices and a willingness on the part of many forest owners and society to embrace a wider set of management objectives. Alternative silvicultural approaches are characterized by a set of fundamental principles, including avoidance of clearcutting, an emphasis on structural diversity and small-scale variability, deployment of mixed species with natural regeneration, and avoidance of intensive site-preparation methods. Methods Our compilation of the authors’ experiences and perspectives from various parts of the world aims to initiate a larger discussion concerning the constraints to and the potential of adopting alternative silvicultural practices. Results The results suggest that a wider adoption of alternative silvicultural practices is currently hindered by a suite of ecological, economic, logistical, informational, cultural, and historical constraints. Individual contexts display their own unique combinations and relative significance of these constraints, and accordingly, targeted efforts, such as regulations and incentives, may help to overcome specific challenges. Conclusions In a broader context, we propose that less emphases on strict applications of principles and on stand structures might provide additional flexibility and facilitate the adoption of alternative silvicultural regimes in a broader set of circumstances. At the same time, the acceptance of alternative silvicultural systems as the “preferred or default mode of management” will necessitate and benefit from the continued development of the scientific basis and valuation of a variety of ecosystem goods and services. This publication is aimed to further the discussion in this context

Are Farm-Reared Quails for Game Restocking Really Common Quails (Coturnix coturnix)?: A Genetic Approach

The common quail (Coturnix coturnix) is a popular game species for which restocking with farm-reared individuals is a common practice. In some areas, the number of released quails greatly surpasses the number of wild breeding common quail. However, common quail are difficult to raise in captivity and this casts suspicion about a possible hybrid origin of the farmed individuals from crosses with domestic Japanese quail (C. japonica). In this study we used a panel of autosomal microsatellite markers to characterize the genetic origin of quails reared for hunting purposes in game farms in Spain and of quails from an experimental game farm which was founded with hybrids that have been systematically backcrossed with wild common quails. The genotypes of these quail were compared to those of wild common quail and domestic strains of Japanese quail. Our results show that more than 85% of the game farm birds were not common quail but had domestic Japanese quail ancestry. In the experimental farm a larger proportion of individuals could not be clearly separated from pure common quails. We conclude that the majority of quail sold for restocking purposes were not common quail. Genetic monitoring of individuals raised for restocking is indispensable as the massive release of farm-reared hybrids could represent a severe threat for the long term survival of the native species