C. Bettega, L. Marchesi, P. Pedrini, P. Partel, M. Brambilla
{"title":"No quiet after the storm: Emergency forestry operations put Alpine forest biodiversity at risk 5 years after major windstorm","authors":"C. Bettega, L. Marchesi, P. Pedrini, P. Partel, M. Brambilla","doi":"10.1111/acv.13008","DOIUrl":null,"url":null,"abstract":"<p>In forest ecosystems, birds influence forest structure and functioning through seed dispersal, pollination, predation and/or ecosystem engineering (Fraixedas <i>et al</i>., <span>2020</span>). Among forest birds, woodpeckers are key species of forest ecosystems: the cavities they build for nesting are used by many other species including birds, mammals and many insects (Martin, <span>2015</span>; Edworthy <i>et al</i>., <span>2018</span>). Woodpeckers are ecosystem engineers that modify the forest environment, supporting richer and complex biological communities, limiting demographic explosions of insects and enhancing sap availability for other organisms (Martin, <span>2015</span>). Thus, they foster biodiversity, especially in cold environments like the alpine forests where conifers, which normally lack natural cavities originating from decay, are dominant.</p><p>Among European woodpecker species, the black woodpecker, <i>Dryocopus martius</i>, is particularly relevant for forest biodiversity, since it provides large cavities (Gorman, <span>2011</span>). These holes are essential for large and mid-size secondary cavity nesters, for example, the boreal owl <i>Aegolius funereus</i>, a species that occurs as a relic of a colder past in the Alps, where its distribution range is shrinking towards higher elevation (Brambilla <i>et al</i>., <span>2020</span>). Recent trends have led to an improvement in the European forests' management techniques: some key forest elements, such as dead wood and tree-related microhabitats (Martin <i>et al</i>., <span>2022</span>), are now preserved in different areas (including in the Trento province where our study area is located), favouring forest biodiversity.</p><p>Large-scale natural disturbances, such as fires, windstorms and insect outbreaks, represent some of the main factors influencing the composition and structure of temperate forests (Fischer, Marshall, & Camp, <span>2013</span>; Senf & Seidl, <span>2021</span>). In October 2018, large portions of the forests covering North-Eastern Italy were severely damaged by the windstorm Vaia. Immediately after the storm, forest owners, in agreement with the local forestry authorities, removed an enormous amount of wood. In the subsequent years, there occurred the rapid diffusion of the European spruce bark beetle <i>Ips typographus</i>: the amount of windthrown stands on the ground triggered an epidemic cycle of the parasite, also favoured by mild winters and extremely warm and dry summers and autumns (Marini <i>et al</i>., <span>2012</span>). At the time of writing (September 2024), the bark beetle has damaged more than 2 million m<sup>3</sup> of wood in the Trento province (which is among the areas most severely hit by the Vaia storm), resulting in at least half the amount of damage caused by Vaia (Servizio Foreste Provincia Autonoma Trento, <span>2023</span>). To reduce the impact of the bark beetle outbreak, dried-out forest patches have been generally salvage-logged, sharply increasing clear-cut areas. Salvage-logging, in response to bark beetle outbreaks, had already jeopardized the ecological value of the main European temperate forest (Mikusiński <i>et al</i>., <span>2018</span>).</p><p>Here, we focus on the fate of trees with woodpecker holes (especially those of the black woodpecker) in the Paneveggio-Pale di San Martino Natural Park (Dolomites, Trento province, NE Italy), hit by Vaia and then by the bark beetle outbreak. In 2007, a still ongoing conservation project was started throughout the province, with the aim of identifying woodpecker nesting trees and marking them with a red ‘P’, thus preserving them from cutting. Two thousand five hundred trees were marked over the Trento province, 166 of which were in the Paneveggio Park territory, where c. 5000 ha of subalpine forests dominated by Norway spruce, <i>Picea abies</i>, had been regularly investigated for woodpecker cavities before and after the Vaia storm.</p><p>Within the surveyed area, 50% of the trees with black woodpecker cavities were destroyed by Vaia. However, the black woodpecker appeared to be resilient towards the impact of both the storm and the bark beetle outbreak. Data on the density and reproductive biology of the woodpecker 5 years after the storm (2023) indicated a stable population, which progressively moved from cavities built on living trees (pre-Vaia condition) to cavities built on dead stands. In May 2024, 60% of the breeding population nested on beetle-killed spruce trees which can provide optimal nesting sites for decades.</p><p>We are now witnessing that both the black woodpecker trees with nesting cavities not affected by the windstorm and those that, after the storm, had been excavated in beetle-killed trees, are being logged during forestry operations. Moreover, these activities are undertaken in the breeding season of woodpeckers and many other species, in exception to pre-Vaia protection measures.</p><p>The salvage-logging of beetle-killed trees is progressively removing all the breeding sites of the ecologically most important forest species of Alpine valleys, potentially creating an ecological trap for the species (Fig. 1). In fact, the black woodpecker nests in spruce trees only when they are at least 80 years old (LM personal observation). Therefore, until 2100, the species will be able to nest only on the already existing trees, and thus, there is an urgent need to preserve nesting trees for this and all the species dependent on its cavities.</p><p>To mitigate the possible dramatic impacts of post-disturbance salvage-logging, based on our direct experience, we propose to exclude some spruce woods from the logging, preserving groups of 20–30 trees (both dead and/or alive) around the trees with cavities (Fig. 1). Those groups of trees could guarantee the availability of some tens of cavities, which are essential for the reproduction of black woodpeckers and of all the species reliant on their nest cavities, until the end of the current century.</p><p>In conclusion, the local population of black woodpecker and the species utilizing its cavities, after overcoming the effects of the windstorm Vaia, have a new challenge to face: due to the salvage-logging performed to contain the bark beetle outbreak, the speed of the removal of woodpecker holes has exceeded the capacity of the species to build new nests. Adjusting the current management is key to the survival of forest biocenoses in the unique landscapes of the Dolomites; new management maintaining plots with woodpecker holes is currently starting in the State Forest inside the Paneveggio Park. This simple and relatively low-cost conservation measure represents an easy-to-implement strategy that can be applied in similar circumstances elsewhere. Considering the current knowledge on black woodpecker ecology in the Alps, and the habits of the species typically associated with its cavities, such a measure would promote biodiversity by making available tens of cavities for decades, also favouring the natural antagonists of the bark beetle. Further research is required into the detailed responses of the black woodpecker, and the associated species, to this conservation measure, exploring in particular the effects of the number and cover of dead and live trees, the size and shape of the uncut tree patches and their spatial relationships with other forest and non-forest habitats. Such knowledge would help identify the most effective configuration of the patches to be preserved from salvage logging to maintain forest animal biodiversity and key ecosystem processes in forested landscapes hit by bark beetle outbreaks.</p>","PeriodicalId":50786,"journal":{"name":"Animal Conservation","volume":"28 3","pages":"329-331"},"PeriodicalIF":2.6000,"publicationDate":"2024-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/acv.13008","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Animal Conservation","FirstCategoryId":"93","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1111/acv.13008","RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"BIODIVERSITY CONSERVATION","Score":null,"Total":0}
引用次数: 0
Abstract
In forest ecosystems, birds influence forest structure and functioning through seed dispersal, pollination, predation and/or ecosystem engineering (Fraixedas et al., 2020). Among forest birds, woodpeckers are key species of forest ecosystems: the cavities they build for nesting are used by many other species including birds, mammals and many insects (Martin, 2015; Edworthy et al., 2018). Woodpeckers are ecosystem engineers that modify the forest environment, supporting richer and complex biological communities, limiting demographic explosions of insects and enhancing sap availability for other organisms (Martin, 2015). Thus, they foster biodiversity, especially in cold environments like the alpine forests where conifers, which normally lack natural cavities originating from decay, are dominant.
Among European woodpecker species, the black woodpecker, Dryocopus martius, is particularly relevant for forest biodiversity, since it provides large cavities (Gorman, 2011). These holes are essential for large and mid-size secondary cavity nesters, for example, the boreal owl Aegolius funereus, a species that occurs as a relic of a colder past in the Alps, where its distribution range is shrinking towards higher elevation (Brambilla et al., 2020). Recent trends have led to an improvement in the European forests' management techniques: some key forest elements, such as dead wood and tree-related microhabitats (Martin et al., 2022), are now preserved in different areas (including in the Trento province where our study area is located), favouring forest biodiversity.
Large-scale natural disturbances, such as fires, windstorms and insect outbreaks, represent some of the main factors influencing the composition and structure of temperate forests (Fischer, Marshall, & Camp, 2013; Senf & Seidl, 2021). In October 2018, large portions of the forests covering North-Eastern Italy were severely damaged by the windstorm Vaia. Immediately after the storm, forest owners, in agreement with the local forestry authorities, removed an enormous amount of wood. In the subsequent years, there occurred the rapid diffusion of the European spruce bark beetle Ips typographus: the amount of windthrown stands on the ground triggered an epidemic cycle of the parasite, also favoured by mild winters and extremely warm and dry summers and autumns (Marini et al., 2012). At the time of writing (September 2024), the bark beetle has damaged more than 2 million m3 of wood in the Trento province (which is among the areas most severely hit by the Vaia storm), resulting in at least half the amount of damage caused by Vaia (Servizio Foreste Provincia Autonoma Trento, 2023). To reduce the impact of the bark beetle outbreak, dried-out forest patches have been generally salvage-logged, sharply increasing clear-cut areas. Salvage-logging, in response to bark beetle outbreaks, had already jeopardized the ecological value of the main European temperate forest (Mikusiński et al., 2018).
Here, we focus on the fate of trees with woodpecker holes (especially those of the black woodpecker) in the Paneveggio-Pale di San Martino Natural Park (Dolomites, Trento province, NE Italy), hit by Vaia and then by the bark beetle outbreak. In 2007, a still ongoing conservation project was started throughout the province, with the aim of identifying woodpecker nesting trees and marking them with a red ‘P’, thus preserving them from cutting. Two thousand five hundred trees were marked over the Trento province, 166 of which were in the Paneveggio Park territory, where c. 5000 ha of subalpine forests dominated by Norway spruce, Picea abies, had been regularly investigated for woodpecker cavities before and after the Vaia storm.
Within the surveyed area, 50% of the trees with black woodpecker cavities were destroyed by Vaia. However, the black woodpecker appeared to be resilient towards the impact of both the storm and the bark beetle outbreak. Data on the density and reproductive biology of the woodpecker 5 years after the storm (2023) indicated a stable population, which progressively moved from cavities built on living trees (pre-Vaia condition) to cavities built on dead stands. In May 2024, 60% of the breeding population nested on beetle-killed spruce trees which can provide optimal nesting sites for decades.
We are now witnessing that both the black woodpecker trees with nesting cavities not affected by the windstorm and those that, after the storm, had been excavated in beetle-killed trees, are being logged during forestry operations. Moreover, these activities are undertaken in the breeding season of woodpeckers and many other species, in exception to pre-Vaia protection measures.
The salvage-logging of beetle-killed trees is progressively removing all the breeding sites of the ecologically most important forest species of Alpine valleys, potentially creating an ecological trap for the species (Fig. 1). In fact, the black woodpecker nests in spruce trees only when they are at least 80 years old (LM personal observation). Therefore, until 2100, the species will be able to nest only on the already existing trees, and thus, there is an urgent need to preserve nesting trees for this and all the species dependent on its cavities.
To mitigate the possible dramatic impacts of post-disturbance salvage-logging, based on our direct experience, we propose to exclude some spruce woods from the logging, preserving groups of 20–30 trees (both dead and/or alive) around the trees with cavities (Fig. 1). Those groups of trees could guarantee the availability of some tens of cavities, which are essential for the reproduction of black woodpeckers and of all the species reliant on their nest cavities, until the end of the current century.
In conclusion, the local population of black woodpecker and the species utilizing its cavities, after overcoming the effects of the windstorm Vaia, have a new challenge to face: due to the salvage-logging performed to contain the bark beetle outbreak, the speed of the removal of woodpecker holes has exceeded the capacity of the species to build new nests. Adjusting the current management is key to the survival of forest biocenoses in the unique landscapes of the Dolomites; new management maintaining plots with woodpecker holes is currently starting in the State Forest inside the Paneveggio Park. This simple and relatively low-cost conservation measure represents an easy-to-implement strategy that can be applied in similar circumstances elsewhere. Considering the current knowledge on black woodpecker ecology in the Alps, and the habits of the species typically associated with its cavities, such a measure would promote biodiversity by making available tens of cavities for decades, also favouring the natural antagonists of the bark beetle. Further research is required into the detailed responses of the black woodpecker, and the associated species, to this conservation measure, exploring in particular the effects of the number and cover of dead and live trees, the size and shape of the uncut tree patches and their spatial relationships with other forest and non-forest habitats. Such knowledge would help identify the most effective configuration of the patches to be preserved from salvage logging to maintain forest animal biodiversity and key ecosystem processes in forested landscapes hit by bark beetle outbreaks.
在森林生态系统中,鸟类通过种子传播、授粉、捕食和/或生态系统工程影响森林结构和功能(Fraixedas et al., 2020)。在森林鸟类中,啄木鸟是森林生态系统的关键物种:它们为筑巢建造的洞穴被许多其他物种使用,包括鸟类、哺乳动物和许多昆虫(Martin, 2015;Edworthy et al., 2018)。啄木鸟是改变森林环境的生态系统工程师,支持更丰富和复杂的生物群落,限制昆虫的人口爆炸,提高其他生物的汁液可用性(Martin, 2015)。因此,它们促进了生物多样性,特别是在寒冷的环境中,如高山森林,针叶树通常缺乏因腐烂而产生的自然空洞,在那里占主导地位。在欧洲的啄木鸟物种中,黑啄木鸟Dryocopus martius与森林生物多样性特别相关,因为它提供了大洞(Gorman, 2011)。这些洞对于大中型次级洞穴筑巢者至关重要,例如,北方猫头鹰Aegolius funereus,这是阿尔卑斯山寒冷过去的遗迹,其分布范围正在向更高海拔缩小(Brambilla et al., 2020)。最近的趋势导致了欧洲森林管理技术的改进:一些关键的森林元素,如枯木和与树木相关的微栖息地(Martin et al., 2022),现在在不同的地区(包括我们研究区域所在的特伦托省)得到了保护,有利于森林生物多样性。大规模的自然干扰,如火灾、风暴和虫害暴发,是影响温带森林组成和结构的一些主要因素(Fischer, Marshall, &;营地,2013;Senf,Seidl, 2021)。2018年10月,覆盖意大利东北部的大部分森林受到“瓦亚”风暴的严重破坏。风暴过后,森林所有者与当地林业当局达成协议,立即移走了大量的木材。在随后的几年中,欧洲云杉树皮甲虫(Ips typographus)迅速扩散:地面上被风吹倒的树木数量引发了寄生虫的流行周期,也受到暖冬和极其温暖干燥的夏秋的青睐(Marini et al., 2012)。在撰写本文时(2024年9月),树皮甲虫已经在特伦托省(受Vaia风暴影响最严重的地区之一)破坏了200多万立方米的木材,造成的损失至少是Vaia造成的损失的一半(Servizio Foreste Provincia Autonoma Trento, 2023)。为了减少树皮甲虫爆发的影响,干枯的森林斑块一般都被回收,大大增加了砍伐面积。为了应对树皮甲虫的爆发,回收砍伐已经破坏了欧洲主要温带森林的生态价值(Mikusiński等人,2018)。在这里,我们关注的是Paneveggio-Pale di San Martino自然公园(意大利东北部特伦托省白云石)中有啄木鸟洞的树木(尤其是黑啄木鸟)的命运,这些树木先是受到了Vaia的袭击,然后又受到了树皮甲虫爆发的袭击。2007年,全省启动了一项仍在进行的保护项目,旨在识别啄木鸟筑巢树,并在其上标记红色的“P”,从而保护它们免受砍伐。在特伦托省有2500棵树被标记,其中166棵在Paneveggio公园,那里有大约5000公顷的亚高山森林,主要是挪威云杉和云杉,在Vaia风暴前后,这些森林被定期调查啄木鸟的蛀洞。在调查区域内,50%有黑色啄木鸟蛀洞的树木被Vaia摧毁。然而,黑啄木鸟似乎对风暴和树皮甲虫爆发的影响都很有弹性。风暴后5年(2023年)的密度和繁殖生物学数据表明,啄木鸟的种群稳定,它们逐渐从建在活树上的洞(vaia前的条件)转移到建在死树上的洞。2024年5月,60%的繁殖种群在被甲虫杀死的云杉树上筑巢,这可以提供几十年的最佳筑巢地点。我们现在看到,在林业作业期间,没有受到风暴影响的筑巢腔的黑啄木鸟树和那些在风暴后被甲虫杀死的树木中挖掘出来的树都被砍伐了。此外,这些活动是在啄木鸟和许多其他物种的繁殖季节进行的,除了在维亚保护措施之前。对被甲虫杀死的树木的回收采伐正在逐步消除阿尔卑斯山谷中生态上最重要的森林物种的所有繁殖地,潜在地为该物种创造了一个生态陷阱(图1)。
期刊介绍:
Animal Conservation provides a forum for rapid publication of novel, peer-reviewed research into the conservation of animal species and their habitats. The focus is on rigorous quantitative studies of an empirical or theoretical nature, which may relate to populations, species or communities and their conservation. We encourage the submission of single-species papers that have clear broader implications for conservation of other species or systems. A central theme is to publish important new ideas of broad interest and with findings that advance the scientific basis of conservation. Subjects covered include population biology, epidemiology, evolutionary ecology, population genetics, biodiversity, biogeography, palaeobiology and conservation economics.