Tree dieback, woody plant diversity, and topography-related ecosystem in semi-arid montane forests: Implications for ecosystem management (2023)

Science of The Total Environment, Band 864, 2023, Artikel 161151

Patterns of phylogenetic structure have been used extensively to predict community formation processes. However, the distribution patterns of evolutionary diversity and its drivers in the context of conservation in boreal forests are not yet well understood. Here we surveyed 1,738 sample plots and subplots from Zones of Different Conservation Intensities (PI) in five representative National Nature Reserves (NNRs). Multiple comparisons, redundancy analysis, and a linear mixed model were performed to identify changes in community phylogeny across different PIs and NNRs and the drivers of these variations. Our results revealed significant differences in plant community phylogeny at different NNRs. As indicated by SesMPD (standardized mean pairwise distance) and SesMNTD (standardized distance from nearest taxon), trees, shrubs, and grasses in different PIs showed scattered, clumped, and random distribution patterns, respectively. The protection caused the phylogenetic structure to show a more sparse pattern between the closest tree species (Page<0.05). Protection reduced the level of phylogenetic clustering between closely related shrub species (Page>0.05), while the herbs still showed a random pattern. Community traits explained more about the phylogenetic variation of different communities (24%–71%,Page<0.01), followed by geoclimatic factors (2%–24%) and conservation processes (1%–21%). Higher mean annual precipitation and higher altitudes under branches at the lower latitudes were associated with higher SesMPD and SesMNTD values. Higher PIs were associated with higher tree SesMPD, and longer protection period resulted in higher PSR (phylogenetic species richness) and PSV (phylogenetic species variability) of shrubs. Including the location of the NNRs, community traits, and years of protection, rather than just highlighting the PI itself, could optimize the phylogenetic structure of the community and preserve the evolutionary potential of biodiversity.

Forest Ecology and Management, Volume 537, 2023, Article 120950

Conserving the biodiversity of softwood and deciduous trees in riparian and mountainous areas is of increasing interest to foresters. For example, the input of softwood and hardwood into streams increases structural diversity and affects the accumulation of aquatic and terrestrial organisms, and the presence of both components in stands can have a positive effect on post-disruption resilience. Investigating the effects of density and weed control on the establishment of red alder (with rotorBong.) and western hemlock (Tsuga heterophylla(Raf.) Sarg.) Combined Nelder plots and replacement series were established at three sites in western Oregon. The species ratio of hemlock to alder was 100:0, 75:25, 50:50, 25:75 and 0:100, with densities ranging from 988 to 85,400 tons per hour. Measurements were available after 24 years for two locations and after 14 years for one location. Weed height and diameter increased at lower densities, especially in the early years. As the canopy closed, the effects of weed control diminished over time, but were still visible on some plots after 24 years. Increased red alder density resulted in decreased survival and growth of both species. The density of the hemlock had no effect on the growth of the red alder for 24 years. Although the mixed stocks resulted in higher volume in the early years, this did not hold up in later years. The higher juvenile growth rates of red alder compared to western hemlock led to a dominance of alder over hemlock in early years, particularly at higher alder densities and ratios. Cultivation of hemlock with a lower alder density has maintained a co-dominance with alder and will become dominant as alder growth rates decline. The density of the alder must be low enough for the hemlock to survive and grow. Density, location, species ratio, animal damage, and the presence of other competing vegetation resulted in different dominance scenarios of hemlock and alder, making it difficult to accurately predict long-term outcomes.

Forest Ecology and Management, Volume 537, 2023, Article 120911

Environmental Management Magazine, Band 339, 2023, Artikel 117933

Sewage sludge (SS) is often used in plantation forests as an alternative fertilizer, which has a positive effect on the wood supply and climate protection. However, if the additional nitrogen (N) introduced by SS would improve the nitrous oxide (N) content in the soil₂O) Emissions, an important greenhouse gas, in plantation forests are not well understood. The aim of this study is to evaluate the ecological impact of the application of SS in the soils, examining the N-value of the soil₂O emission and toxicity of potentially toxic elements (PTEs) in soil. A field fertilization experiment was conductedEucalyptusPlantations with four fertilizer doses (0 kgm⁻², 1,5 kg⁻², 3,0 kg⁻²and 4.5kg⁻²). the floor N₂O emissions were monitored at a soil depth of 0 to 10 cm using the static chamber method, soil chemistry and PTEs were determined at soil depths of 0 to 10 cm, 10 to 20 cm and 20 to 40 cm. The middle N of the ground₂The emission rate of O was 8.1 μg N₂O-N h⁻¹Metro⁻²in plots without application of SS (control). The SS application significantly increased the N-value of the soil₂O emissions between 7 and 10 times the control. The rise of N₂O emissions were positively related to total soil phosphorus and nitrogen levels and negatively related to copper and zinc, which increased with SS application. The potential ecological risk index (E_I) and the potential ecological risk (RI) integral index of the ETPs were below 40 and 150, respectively, indicating low toxicity of the ETPs to soil health. After seven months of SS application, the preparatory effects of SS on soil N were evident₂O emissions gradually decreased. These results suggest that SS application may increase N₂O emissions in the initial phase of application (<7 months) and potentially low risk of PTE contamination even at high SS addition rate (4.5 kgm).⁻²).

Science of The Total Environment, Band 876, 2023, Artikel 162697

Refugia can facilitate species persistence under long-term environmental change, but it is unclear whether Pleistocene refugia will continue to function as anthropogenic climate change progresses. Die-offs in populations where refuge is restricted therefore raise concerns about their long-term persistence. Using repeated field studies, we investigated die-off in an isolated populationEukalyptus Macrorhynchaduring two periods of drought and discuss the prospects for their continued existence in a Pleistocene refuge. We first confirm that Clare Valley in South Australia has provided a long-term sanctuary for the species, although the population is genetically very different from other conspecific populations. However, the population lost more than 40% of individuals and biomass due to drought, with mortality being just under 20% after the Millennium Drought (2000–2009) and almost 25% after the Great Drought (2017–2019). The best predictors of mortality differed after each drought. While north orientation of a sampling site was a significant positive predictor after both droughts, biomass density and slope were significant negative predictors only after the Millennium Drought, and distance to the northwest corner of the population, which intercepts hot, dry winds, was a significant one positive predictor only after the Great Drought. This suggests that while more marginal low-biomass sites and sites on flat plateaus were initially more vulnerable, heat stress was an important factor in die-offs during the Great Drought. Therefore, the causative causes of die-offs may change as the population declines. The regeneration took place mainly on the south and east side, where the solar radiation was lowest. Although this protected area population is experiencing sharp declines, some ravines with less sun exposure appear to be harboring relatively healthy and regenerating stands of red fibrous bark, offering hope for continued existence in small pockets. Monitoring and managing this herd during future droughts will be critical to ensure the continued existence of this isolated and genetically unique population.

Environmental Management Magazine, Band 337, 2023, Artikel 117713

Around the world, approximately 2 billion hectares of land are degraded and in need of ecological restoration. Active recovery often involves revegetation, leading to the question of direct sowing or planting seedlings from nurseries. Choice of reclamation method can regulate plant survival and performance, with economic implications that ultimately affect our ability to carry out reclamation. We follow a peer-reviewed protocol to develop a systematic map that collects, describes, and catalogs available studies on how seeding versus planting compares to achieve recovery goals. We create a database with the characteristics of all surveys retrieved, which can be searched to identify surveys on specific sites and habitats, restoration targets, plant material, technical aspects and measured results. The search was conducted in eight languages ​​and returned 3,355 publications, of which 178 were retained. The systematic map identifies research gaps, such as missing studies in the Global South, in rainforests and over a long period of time offers opportunities for expanding fieldwork. In addition, many studies have overlooked reports of important technical aspects such as seed origin and nursery culture methods, and others, such as irrigation or seedling protection, have been applied more often to planting than to sowing, limiting our ability to learn from previous research. Most studies measured outcomes in the context of target crops, but avoided measuring overall recovery outcomes or economics. This represents a major research gap, as the choice of revegetation method is largely based on economics, and achieving recovery goals goes beyond plant establishment. Finally, we identified a significant body of studies conducted in temperate regions and over short time periods (0-5 years). This research group needs further in-depth synthesis, possibly through meta-analysis, to show the overall balance between sowing and planting and to assess whether the answer to this question is mediated by species traits, environmental traits or technical aspects. The systematic mapping database allows managers not only to identify clusters and research gaps, but also to find the most relevant scientific literature on plant suitability.against. Planting for specific conditions, such as specific species or habitats.