Seed dispersal, microsites or competition-what drives gap regeneration in an old-growth forest? An application of spatial point process modelling

The spatial structure of trees is a template for forest dynamics and the outcome of a variety of processes in ecosystems. Identifying the contribution and magnitude of the different drivers is an age-old task in plant ecology. Recently, the modelling of a spatial point process was used to identify factors driving the spatial distribution of trees at stand scales. Processes driving the coexistence of trees, however, frequently unfold within gaps and questions on the role of resource heterogeneity within-gaps have become central issues in community ecology. We tested the applicability of a spatial point process modelling approach for quantifying the effects of seed dispersal, within gap light environment, microsite heterogeneity, and competition on the generation of within gap spatial structure of small tree seedlings in a temperate, old growth, mixed-species forest. By fitting a non-homogeneous Neyman–Scott point process model, we could disentangle the role of seed dispersal from niche partitioning for within gap tree establishment and did not detect seed densities as a factor explaining the clustering of small trees. We found only a very weak indication for partitioning of within gap light among the three species and detected a clear niche segregation of Picea abies (L.) Karst. on nurse logs. The other two dominating species, Abies alba Mill. and Fagus sylvatica L., did not show signs of within gap segregation

Mountain Forests and Sustainable Development: The Potential for Achieving the United Nations\u27 2030 Agenda

The world is facing numerous and severe environmental, social, and economic challenges. To address these, in September 2015 the General Assembly of the United Nations adopted the resolution Transforming our World: The 2030 Agenda for Sustainable Development. The United Nations\u27 17 sustainable development goals (SDGs) and their 169 targets are ambitious, broadly encompassing, and indivisible. They are intended to guide nations and communities toward attaining healthy and peaceful livelihoods free of poverty and hunger. Collectively the goals envision sound and safe environments, where global threats like climate change are successfully combated through both mitigation and adaptation. Agenda 2030 envisages sustainable production patterns with inclusive, effective economies and institutions. It is of specific relevance to mountain communities, where the population is predominantly rural and half of the rural inhabitants experience food insecurity and are often highly dependent on forest resources. Mountain forests also contribute to human welfare well beyond the local community: Through functions such as climate and hydrological services provided at regional and global scales, and harvested commodities traded at multiple economic scales. In this introductory essay we argue that sustainable forest management in mountain areas disproportionately contributes to achieving the SDGs. We discuss (1) the potential of mountain forests to help achieve SDGs in mountainous regions and beyond, (2) the potential of the SDGs to help solve severe socioeconomic and ecological problems in forested mountain areas, and (3) challenges and opportunities associated with implementing the SDGs. We base our argumentation also on the 8 papers presented in this Focus Issue of Mountain Research and Development. Together, they establish a clear connection between sustainable use and protection of mountain forests and vital ecosystem services upon which many regions depend. We discuss challenges of understanding interactions between goals and targets, and highlight the role of science in achieving the SDGs. Finally, we stress the urgent need for establishing a new narrative of socioeconomic transformation to ensure that Agenda 2030 is successful

Forest Grazing and Natural Regeneration in a Late Successional Broadleaved Community Forest in Bhutan

This study investigated the sustainability of combining forest grazing and timber harvesting with selection felling in a cool broadleaved community forest (CF) in Bhutan. Forest grazing and timber production are critical livelihood activities for many farmers throughout the world, so it is important to understand under what conditions the 2 activities can be combined. The study was based on a household survey to quantify livestock holdings and grazing patterns, a comparison of 2 forest inventories to assess forest structure and regeneration, and a study of stumps to quantify harvesting intensities. During a 5-year period the number of cattle grazing inside the CF significantly decreased and the number of naturally regenerated tree seedlings and saplings significantly increased. There were no other changes in forest management practices during the period that would affect natural regeneration, and there were no significant changes in the volume of wood harvested or the volume/number of standing trees (with a diameter at breast height ≥10 cm). We concluded that moderate intensities of forest grazing (0.4 cattle*ha−1) and timber harvesting (4.64 m3*ha−1*y−1) can be combined in this type of forest without negative impacts on forest regeneration. Our findings support Bhutan\u27s policy of allowing forest grazing in CFs

Spatial patterns and determinants of smallholder tree planting in Northwest Highlands of Ethiopia

Trees outside forest have immense benefits for people's welfare in rural Ethiopia. Understanding and characterizing the incentives and constraints of smallholder tree growers is essential to hasten efforts in rural transformation. This study has investigated the most important tree species grown by smallholder farmers in the highlands of northwest Ethiopia. Data was collected from 150 households that grow the trees. Survey with semi­ structured questionnaire interviews was used to collect information on tree species grown, tree growing niches and uses, as well as, selected socio­ economic characteristics. The number of trees and types of tree species grown by each household was calculated with and without adjusting to farm size. Linear regression model and other tests were employed to identify the most important determinants of tree growing behaviour of households and spatial variables affecting the abundance and frequency of tree species. About 25 tree species were found grown by farmers. The total number of trees, tree species and their spatial patterns differed markedly among farms. Multiple linear regression of tree abundance and frequency of tree species on household characteristics showed significant relationship. The number of livestock owned by the household, land holding size and age of the head of the household affect positively the number of trees and number of tree species grown by the households. Gender affected the species and spatial pattern of trees. Our result support the proposition that farmers assign their parcels of lands to land uses that increase the rent value of the land, and this rent value was affected by spatial variables. Our results suggest that future policy and extension program should target increasing the number of tree species on resource endowed households, and increasing the number of trees on younger and less resource endowed ones. Our finding that farm land and boundary planting to be important tree growing niche may indicate future intervention points

Climatic variability and other site factor influences on natural regeneration of Pinus pinaster Ait. in Mediterranean forests

Background: How environmental factors affect forest regeneration is relevant for systems that depend partially or fully on natural regeneration. Objective: P. pinaster post-disturbance regeneration and its relationship to environmental factors was studied in five P. pinaster forest populations of central Spain. We expected that 1) different harvesting methods or wildfire would promote natural regeneration in all populations, but with local and regional variations; 2) alternatively, different site-dependent stand factors would affect natural regeneration, although generalized climate effects would be seen. Analysis of variance and multivariate analysis were used to test differences, to classify ecological variations and to search for the most important factors affecting regeneration. Results: The results suggest that the recovery of P. pinaster forest in burnt stands, and stand replacement in harvested stands can be achieved soon after disturbance if climatic conditions and other local-site factors (e.g. soil and overstorey structure in harvested stands, cone bank in burnt stands) make the stand suitable for natural regeneration. Heterogeneous regeneration can be expected in all cases. The time of precipitation strongly influenced seedling density and successive regeneration development stages. Edaphic properties combined with water availability from precipitation can seriously limit the natural establishment of P. pinaster in xeric systems or during years of intense drought. Although many factors contribute to high variability natural regeneration was very effective (successful) in P. pinaster forests, which contributes to the generalization that natural regeneration is a viable forestry option in many forest types.Instituto Universitario de Gestión Forestal Sostenibl

Epiphytic Recruitment of Schefflera abyssinica (A. Rich) Harms. and the Rle of Microsites in Affecting Tree Community Structure in Remnant Forests in Northwest Ethiopia

Epiphytic recruitment of trees on trees is a form of facilitation allowing trees to escape herbivory and abiotic stress. In terms of survival and reaching the upper canopy sooner, this form of recruitment may be more successful than recruitment from the ground. Hence epiphytic recruitment may play a major role in affecting plant community structure and vegetation dynamics. To this effect, we studied epiphytic Schefflera abyssinica (A. Rich) Harms. density and characteristics in a church forest and the surrounding degraded matrix in northwest Ethiopia using different sampling techniques. The role of suitable microsites was evaluated as a secondary objective. The result showed that no seedling of Schefflera abyssinica was found on the ground. The average density of epiphytic Schefflera abyssinica was much higher than already standing mature trees. Schefflera abyssinica rejuvenates majorly by forming canopy seedling bank on six different kinds of tree species. Rot holes, branch forks and moss layer on the host tree were important microsites for successful establishment. Our result substantiates earlier reports that Schefflera abyssinica does not form persistent soil seed bank. The result also suggests that the spatial configuration of trees in the forest and in the landscape will remain largely the same; however, the dominant species will change as the epiphyte will gradually outcompete the host. Dominance of only one tree species might have a negative effect on the tree community structure of the forest and the surrounding agro ecosystem

Natural disturbance regimes as a guide for sustainable forest management in Europe

Dette er den aksepterte versjonen av en artikkel publisert i Ecological Applications. Den blir tilgjengelig fra og med 28.03.2023 etter en embargoperiode på 12 måneder. Du finner den publiserte artikkelen her: https://doi.org/10.1002/eap.2596. / This is the postprint version of the article published in Ecological Applications. It will be available 28.03.2023 after an embargo period of 12 months.You can find the published article here: https://doi.org/10.1002/eap.2596.In Europe, forest management has controlled forest dynamics to sustain commodity production over multiple centuries. Yet over-regulation for growth and yield diminishes resilience to environmental stress as well as threatens biodiversity, leading to increasing forest susceptibility to an array of disturbances. These trends have stimulated interest in alternative management systems, including natural dynamics silviculture (NDS). NDS aims to emulate natural disturbance dynamics at stand and landscape scales through silvicultural manipulations of forest structure and landscape patterns. We adapted a “Comparability Index” (CI) to assess convergence/divergence between natural disturbances and forest management effects. We extended the original CI concept based on disturbance size and frequency by adding the residual structure of canopy trees after a disturbance as a third dimension. We populated the model by compiling data on natural disturbance dynamics and management from 13 countries in Europe, covering four major forest types (i.e., spruce, beech, oak, and pine-dominated forests). We found that natural disturbances are highly variable in size, frequency, and residual structure, but European forest management fails to encompass this complexity. Silviculture in Europe is skewed toward even-aged systems, used predominately (72.9% of management) across the countries assessed. The residual structure proved crucial in the comparison of natural disturbances and silvicultural systems. CI indicated the highest congruence between uneven-aged silvicultural systems and key natural disturbance attributes. Even so, uneven-aged practices emulated only a portion of the complexity associated with natural disturbance effects. The remaining silvicultural systems perform poorly in terms of retention compared to tree survivorship after natural disturbances. We suggest that NDS can enrich Europe’s portfolio of management systems, for example where wood production is not the primary objective. NDS is especially relevant to forests managed for habitat quality, risk reduction, and a variety of ecosystem services. We suggest a holistic approach integrating NDS with more conventional practices.acceptedVersio

MASTREE+: Time-series of plant reproductive effort from six continents.

Significant gaps remain in understanding the response of plant reproduction to environmental change. This is partly because measuring reproduction in long-lived plants requires direct observation over many years and such datasets have rarely been made publicly available. Here we introduce MASTREE+, a data set that collates reproductive time-series data from across the globe and makes these data freely available to the community. MASTREE+ includes 73,828 georeferenced observations of annual reproduction (e.g. seed and fruit counts) in perennial plant populations worldwide. These observations consist of 5971 population-level time-series from 974 species in 66 countries. The mean and median time-series length is 12.4 and 10 years respectively, and the data set includes 1122 series that extend over at least two decades (≥20 years of observations). For a subset of well-studied species, MASTREE+ includes extensive replication of time-series across geographical and climatic gradients. Here we describe the open-access data set, available as a.csv file, and we introduce an associated web-based app for data exploration. MASTREE+ will provide the basis for improved understanding of the response of long-lived plant reproduction to environmental change. Additionally, MASTREE+ will enable investigation of the ecology and evolution of reproductive strategies in perennial plants, and the role of plant reproduction as a driver of ecosystem dynamics

Limits to reproduction and seed size-number trade-offs that shape forest dominance and future recovery

International audienceThe relationships that control seed production in trees are fundamental to understanding the evolution of forest species and their capacity to recover from increasing losses to drought, fire, and harvest. A synthesis of fecundity data from 714 species worldwide allowed us to examine hypotheses that are central to quantifying reproduction, a foundation for assessing fitness in forest trees. Four major findings emerged. First, seed production is not constrained by a strict trade-off between seed size and numbers. Instead, seed numbers vary over ten orders of magnitude, with species that invest in large seeds producing more seeds than expected from the 1:1 trade-off. Second, gymnosperms have lower seed production than angiosperms, potentially due to their extra investments in protective woody cones. Third, nutrient-demanding species, indicated by high foliar phosphorus concentrations, have low seed production. Finally, sensitivity of individual species to soil fertility varies widely, limiting the response of community seed production to fertility gradients. In combination, these findings can inform models of forest response that need to incorporate reproductive potential