Adriano Mazziotta

Spatially dynamic forest management to sustain biodiversity and economic returns

Production of marketed commodities and protection of biodiversity in natural systems often conflict and thus the continuously expanding human needs for more goods and benefits from global ecosystems urgently calls for strategies to resolve this conflict. In this paper, we addressed what is the potential of a forest landscape to simultaneously produce habitats for species and economic returns, and how the conflict between habitat availability and timber production varies among taxa. Secondly, we aimed at revealing an optimal combination of management regimes that maximizes habitat availability for given levels of economic returns. We used multi-objective optimization tools to analyze data from a boreal forest landscape consisting of about 30,000 forest stands simulated 50 years into future. We included seven alternative management regimes, spanning from the recommended intensive forest management regime to complete set-aside of stands (protection), and ten different taxa representing a wide variety of habitat associations and social values. Our results demonstrate it is possible to achieve large improvements in habitat availability with little loss in economic returns. In general, providing dead-wood associated species with more habitats tended to be more expensive than providing requirements for other species. No management regime alone maximized habitat availability for the species, and systematic use of any single management regime resulted in considerable reductions in economic returns. Compared with an optimal combination of management regimes, a consistent application of the recommended management regime would result in 5% reduction in economic returns and up to 270% reduction in habitat availability. Thus, for all taxa a combination of management regimes was required to achieve the optimum. Refraining from silvicultural thinnings on a proportion of stands should be considered as a cost-effective management in commercial forests to reconcile the conflict between economic returns and habitat required by species associated with dead-wood. In general, a viable strategy to maintain biodiversity in production landscapes would be to diversify management regimes. Our results emphasize the importance of careful landscape level forest management planning because optimal combinations of management regimes were taxon-specific. For cost-efficiency, the results call for balanced and correctly targeted strategies among habitat types.

Conflict between insect conservation and public safety: the case study of a saproxylic beetle (Osmoderma eremita) in urban parks

Urban parks can harbour small populations of saproxylic insects of high conservation concern, such as Osmoderma eremita and other rare beetles. These areas often host old trees which have become very uncommon in rural areas where they are threatened by commercial forestry management procedures based on frequent tree cutting. Nevertheless, old trees of urban parks may represent a hazard for public safety and are sometimes cut by management authorities. The aim of this work was to assess the loss of reproductive sites for saproxylic beetles of the Scarabaeidae, Lucanidae and Cerambycidae, when felling plans are adopted according to a Visual Tree Assessment Procedure (VTA), in a Mediterranean urban park. On July–August 2004, 1,247 holm oaks were surveyed within the border of an urban park of Rome (Villa Borghese). The occurrence of saproxylic beetles (i.e. the presence of frass, living insects or their remains) was verified in 66 old holm oaks, 41% of which were doomed to cutting by VTA. Eleven of these trees (41% of the trees doomed to be cut) held fragments of adults and sometimes living larvae of Osmoderma eremita, and four of them (36%) were included in the felling plan. The presence of Osmodermaeremita in tree holes was more frequent in deep cavities. The presence of frass in the cavities was positively associated with tree height and a high degree of damage at the root collar and negatively with the presence of hole-nesting birds.

Surveying an endangered saproxylic beetle, Osmoderma eremita, in Mediterranean woodlands: a comparison between different capture methods

Measuring population size is riddled with difficulties for wildlife biologists and managers, and in the case of rare species, it is sometimes practically impossible to estimate abundance, whereas estimation of occupancy is possible. Furthermore, obtaining reliable population size estimates is not straightforward, as different sampling techniques can give misleading results. A mark-recapture study of the endangered saproxylic beetle Osmoderma eremita was performed in central Italy by applying four independent capture methods within a study area where 116 hollow trees were randomly selected to set traps. Detection probability and population size estimates were drawn from each of these four capture methods. There were strong differences in detection probability among methods. Despite using pheromone and beetle manipulation, capture histories were not affected by trap-happiness or trap-shyness. Population size estimates varied considerably in both abundance and precision by capture method. A number of 0.5 and 0.2 adult beetles per tree was estimated using the whole data set by closed and open population models, respectively. Pitfall trap appeared the optimal method to detect the occurrence of this species. Since in the southern part of its distribution range, a single population of O. eremita is widespread in the landscape, and includes beetles from more than one hollow tree, conservation efforts should focus not only on preserving few and isolated monumental hollow trees, but should be extended to large stands.

Optimizing management to enhance multifunctionality in a boreal forest landscape

Summary nThe boreal biome, representing approximately one-third of remaining global forests, provides a number of crucial ecosystem services. A particular challenge in forest ecosystems is to reconcile demand for an increased timber production with provisioning of other ecosystem services and biodiversity. However, there is still little knowledge about how forest management could help solve this challenge. Hence, studies that investigate how to manage forests to reduce trade-offs between ecosystem services and biodiversity are urgently needed to help forest owners and policy makers take informed decisions. nWe applied seven alternative forest management regimes using a forest growth simulator in a large boreal forest production landscape. First, we estimated the potential of the landscape to provide harvest revenues, store carbon and maintain biodiversity across a 50-year time period. Then, we applied multiobjective optimization to identify the trade-offs between these three objectives and to identify the optimal combination of forest management regimes to achieve these objectives. nIt was not possible to achieve high levels of either carbon storage or biodiversity if the objective of forest management was to maximize timber harvest revenues. Moreover, conflicts between biodiversity and carbon storage became stronger when simultaneously targeting high levels of timber revenues. However, with small reductions in timber revenues, it was possible to greatly increase the multifunctionality of the landscape, especially the biodiversity indicators. nForest management actions, alternative to business-as-usual management, such as reducing thinnings, extending the rotation period and increasing the amount of area set aside from forestry may be necessary to safeguard biodiversity and non-timber ecosystem services in Fennoscandia. nSynthesis and applications. Our results show that no forest management regime alone is able to maximize timber revenues, carbon storage and biodiversity individually or simultaneously and that a combination of different regimes is needed to resolve the conflicts among these objectives. We conclude that it is possible to reduce the trade-offs between different objectives by applying diversified forest management planning at the boreal landscape level and that we need to give up the all-encompassing objective of very intensive timber production, which is prevailing particularly in Fennoscandian countries.

Impacts of forestry on boreal forests: An ecosystem services perspective

Forests are widely recognized as major providers of ecosystem services, including timber, other forest products, recreation, regulation of water, soil and air quality, and climate change mitigation. Extensive tracts of boreal forests are actively managed for timber production, but actions aimed at increasing timber yields also affect other forest functions and services. Here, we present an overview of the environmental impacts of forest management from the perspective of ecosystem services. We show how prevailing forestry practices may have substantial but diverse effects on the various ecosystem services provided by boreal forests. Several aspects of these processes remain poorly known and warrant a greater role in future studies, including the role of community structure. Conflicts among different interests related to boreal forests are most likely to occur, but the concept of ecosystem services may provide a useful framework for identifying and resolving these conflicts.

Applying a framework for landscape planning under climate change for the conservation of biodiversity in the Finnish boreal forest

Conservation strategies are often established without consideration of the impact of climate change. However, this impact is expected to threaten species and ecosystem persistence and to have dramatic effects towards the end of the 21st century. Landscape suitability for species under climate change is determined by several interacting factors including dispersal and human land use. Designing effective conservation strategies at regional scales to improve landscape suitability requires measuring the vulnerabilities of specific regions to climate change and determining their conservation capacities. Although methods for defining vulnerability categories are available, methods for doing this in a systematic, cost-effective way have not been identified. Here, we use an ecosystem model to define the potential resilience of the Finnish forest landscape by relating its current conservation capacity to its vulnerability to climate change. In applying this framework, we take into account the responses to climate change of a broad range of red-listed species with different niche requirements. This framework allowed us to identify four categories in which representation in the landscape varies among three IPCC emission scenarios (B1, low; A1B, intermediate; A2, high emissions): (i) susceptible (B1 = 24.7%, A1B = 26.4%, A2 = 26.2%), the most intact forest landscapes vulnerable to climate change, requiring management for heterogeneity and resilience; (ii) resilient (B1 = 2.2%, A1B = 0.5%, A2 = 0.6%), intact areas with low vulnerability that represent potential climate refugia and require conservation capacity maintenance; (iii) resistant (B1 = 6.7%, A1B = 0.8%, A2 = 1.1%), landscapes with low current conservation capacity and low vulnerability that are suitable for restoration projects; (iv) sensitive (B1 = 66.4%, A1B = 72.3%, A2 = 72.0%), low conservation capacity landscapes that are vulnerable and for which alternative conservation measures are required depending on the intensity of climate change. Our results indicate that the Finnish landscape is likely to be dominated by a very high proportion of sensitive and susceptible forest patches, thereby increasing uncertainty for landscape managers in the choice of conservation strategies.

Modeling the effects of climate change and management on the dead wood dynamics in boreal forest plantations

AbstractnThe present research examines the joint effects of climate change and management on the dead wood dynamics of the main tree species of the Finnish boreal forests via a forest ecosystem simulator. Tree processes are analyzed in stands subject to multiple biotic and abiotic environmental factors. A special focus is on the implications for biodiversity conservation thereof. Our results predict that in boreal forests, climate change will speed up tree growth and accumulation ending up in a higher stock of dead wood available as habitat for forest-dwelling species, but the accumulation processes will be much smaller in the working landscape than in set-asides. Increased decomposition rates driven by climate change for silver birch and Norway spruce will likely reduce the time the dead wood stock is available for dead wood-associated species. While for silver birch, the decomposition rate will be further increased in set-aside in relation to stands under ordinary management, for Norway spruce, set-asides can counterbalance the enhanced decomposition rate due to climate change thereby permitting a longer persistence of different decay stages of dead wood.

Exploring co-extinction correlates: the effects of habitat, biogeography and anthropogenic factors on ground squirrels–dung beetles associations

Co-extinction is a recurring topic in conservation biology. Quantification of co-extinction has been generally restricted to parasite–host, predator–prey and herbivore–host plant interactions. The loss of detritivorous insects upon the depletion of herbivore mammals has been poorly explored. Here, we used rarefaction curves to predict co-decline involving the decrease in scarab dung beetles diversity due to a reduction in the number of dens of the Asia minor ground squirrel in the Turkish steppe biome. We also evaluated the potential benefits provided by livestock in mitigating the decline of scarab beetle communities. Rarefaction curves estimated that a 50% reduction in the number of sample units where squirrel faecal pellets are the only available food resource accounts for a reduction of 28% of all the scarab species, and of 24% of the squirrel-linked species. The current decline of ground squirrels, mainly due to intensification of agriculture, may represent a threat for biodiversity in steppic environments because it may affect the specialized insects, and may produce a cascade effect also on their predators, i.e., saker falcon, buzzards, eagles and mustelids. We also showed that the conservation of ground squirrels and their affiliate scarab species may be ensured by a moderate livestock grazing, owing to the higher ecological success of these rodents in the presence of large herbivores keeping low the grass cover.

Optimal conservation resource allocation under variable economic and ecological time discounting rates in boreal forest

Resource allocation to multiple alternative conservation actions is a complex task. A common trade-off occurs between protection of smaller, expensive, high-quality areas versus larger, cheaper, partially degraded areas. We investigate optimal allocation into three actions in boreal forest: current standard forest management rules, setting aside of mature stands, or setting aside of clear-cuts. We first estimated how habitat availability for focal indicator species and economic returns from timber harvesting develop through time as a function of forest type and action chosen. We then developed an optimal resource allocation by accounting for budget size and habitat availability of indicator species in different forest types. We also accounted for the perspective adopted towards sustainability, modeled via temporal preference and economic and ecological time discounting. Controversially, we found that in boreal forest set-aside followed by protection of clear-cuts can become a winning cost-effective strategy when accounting for habitat requirements of multiple species, long planning horizon, and limited budget. It is particularly effective when adopting a long-term sustainability perspective, and accounting for present revenues from timber harvesting. The present analysis assesses the cost-effective conditions to allocate resources into an inexpensive conservation strategy that nevertheless has potential to produce high ecological values in the future.

Habitat associations drive species vulnerability to climate change in boreal forests

Species climate change vulnerability, their predisposition to be adversely affected, has been assessed for a limited portion of biodiversity. Our knowledge of climate change impacts is often based only on exposure, the magnitude of climatic variation in the area occupied by the species, even if species sensitivity, the species ability to tolerate climatic variations determined by traits, plays a key role in determining vulnerability. We analyse the role of species’ habitat associations, a proxy for sensitivity, in explaining vulnerability for two poorly-known but species-rich taxa in boreal forest, saproxylic beetles and fungi, using three IPCC emissions scenarios. Towards the end of the 21st century we projected an improvement in habitat quality associated with an increase of deadwood, an important resource for species, as a consequence of increased tree growth under high emissions scenarios. However, climate change will potentially reduce habitat suitability for ~9–43xa0% of the threatened deadwood-associated species. This loss is likely caused by future increase in timber extraction and decomposition rates causing higher deadwood turnover, which have a strong negative effect on boreal forest biodiversity. Our results are species- and scenario-specific. Diversified forest management and restoration ensuring deadwood resources in the landscape would allow the persistence of species whose capacity of delivering important supporting ecosystem services can be undermined by climate change.