Annals of Forest Science最新文献

Key message

We used clustering to construct fuel classes from fuel inventory data based on three stand attributes relevant to crown fire behaviour: surface fuel load (SFL), canopy base height (CBH) and canopy bulk density (CBD). Resulting fuel classes explained more of the stand-to-stand variability in predicted crown fire behaviour than fuel types of the Canadian Forest Fire Behaviour Prediction (FBP) System.

Context

Wildfire behaviour is partly determined by stand structure and composition. Fuel characterization is essential for predicting fire behaviour and managing vegetation. Currently, categorical fuel types based on associations with major forested or open vegetated landcovers are used nationally in Canada for fire research and management applications.

Aim

To provide an alternative description of selected forest fuels in Alberta, Canada, using direct classification in which fuel categories are constructed from data using analytical methods.

Methods

Fuel inventory data for 476 stands were used to construct fuel classes with clustering. Potential crown fire behaviour was modelled for resulting fuel class clusters (FCCs) and FCCs were compared with assigned FBP System fuel types. Tree-based modelling was used to identify stand characteristics most influential on FCC membership. Fuel treatment effects on FCC and modelled crown fire behaviour were explored for the FCC most susceptible to crown fire.

Results

Four FCCs were identified: Red (low SFL, low CBH, low CBD); Green (high SFL, low-moderate CBH, low CBD); Blue (low SFL, high CBH, low-moderate CBD); and Black (low SFL, moderate CBH, high CBD). Stand density of live conifers and FBP System fuel type were the most important variables influencing FCC membership; however, FCCs did not align directly with assigned FBP System fuel types. Fuel reduction treatments in the Black FCC were effective at shifting the stand to a less flammable FCC.

Conclusion

FCCs explained more of the stand-to-stand variability in predicted crown fire behaviour than assigned FBP System fuel types, which suggests FCCs could be used to improve fire behaviour predictions and aid fire managers in prioritizing areas for fuel treatments. Future technological and remote sensing advances could enable mapping FCCs across large regions. 

Context

In temperate hardwood forests, increased intensity of soil and canopy disturbances tends to increase species richness due to the establishment of numerous early-successional plant species. However, while competitive pioneer species from early stages of succession can become recalcitrant and alter patterns of natural regeneration, very few studies have examined longer-term effects of these treatments on plant biodiversity.

Aims

In this study, we investigated mid-term (ca. 20 years) effects of different regeneration treatments with varying soil and canopy disturbance intensities. We compared understory plant communities in temperate hardwood forests from all the South of Quebec (Canada).

Methods

Using circular experimental plots of 1962.5 m² (radius = 25 m), we measured taxonomic and functional diversity indices and soil properties using four levels of disturbance intensity in six temperate hardwood forests of Quebec distributed along a longitudinal gradient. Reference forests, i.e. control forests with no silvicultural treatment known for ≥ 80 years, were compared to 20-year-old single-tree selection cuts, group-selection cuts and group-selection cuts with soil scarification.

Results

Species richness in both group-selection treatments was higher than that in reference forests. Plant equitability and beta diversity among sites in both group-selection treatments were lower than in single-tree selection cuts and control forests. More intense treatments contributed to the mid-term persistence of recalcitrant competitor species (e.g. Rubus idaeus L., Prunus pensylvanica L.f.) whereas soil scarification appears to have negative sustained effects on species known to be sensitive to regeneration treatments (e.g. Monotropa uniflora L., Dryopteris spinulosa Kuhn).

Conclusions

In temperate hardwood forests of Southern Quebec, silvicultural treatments of higher intensities resulted in detrimental effects on soil properties, especially in the surface horizon, 20 years after disturbance. This legacy, in turn, affected the composition and diversity of understory plant communities. The more intense silvicultural treatments contributed to the persistence of pioneer species better adapted to a wider range of environmental conditions and resulted in a decrease in understory plant community heterogeneity among sites. Conversely, single-tree selection cutting appeared to be the most appropriate silvicultural treatment for maintaining soil functions and heterogeneity of understory plant communities after 20 years; composition and structure being similar to long-undisturbed forests.

Key message

We provide a mathematical model to determine which trees should be ruled out from the grid to promote random mating in seed orchards under genetic thinning.

Context

Genetic thinning (roguing) is a common practice in forest tree breeding to remove inferior genotypes in seed orchards, thus boosting the genetic worth of the seed crop.

Aims

To develop a general methodology for spatial optimization of genetic thinning. It should promote random mating and consider any existing seed orchard layout.

Methods

The model is based on the Optimum-Neighborhood Allocation algorithm (Chaloupková et al., Forests 10:1-6, 2019). The algorithm’s efficiency was evaluated using computer simulation. A fully randomized scheme was used as a reference. In addition, the study provides a demonstration on an actual seed orchard.

Results

Simulations confirm the method’s efficiency in promoting random mating compared to the fully randomized allocation across a wide range of selection intensities. We suggest Linear Deployment as a preferred method for calculating optimum deployment contributions at higher thinning intensities. The algorithm was programmed in R and is publicly available.

Conclusion

Breeders can use the software and follow the example to implement genetic thinning in different practical scenarios assuming any seed orchard layout. The approach enhances random mating while maximizing genetic response to selection.

Key message

MADS-box genes family may play important roles in the flower sex determination in Excoecaria agallocha. A total of 73 MADS-box genes were identified in E. agallocha. De novo transcriptome assembly analysis suggested that AP1/FUL, AP3/PI, AGL104, and SOC1 plays potential roles in E. agallocha flower sex determination.

Context

Excoecaria agallocha is a dioecious species containing both male and female individuals producing unisexual flowers. The underlying mechanisms regulating inflorescence differentiation in these species remains poorly understood.

Aims

Flower development influences reproduction and breeding in E.agallocha, which contributes to ecological restoration in the intertidal zone.

Methods

We performed de novo transcriptome assembly analysis on male and female flowers and leaves from E. agallocha.

Results

We identified a total of 73 MADS-box genes in the E. agallocha genome, which we grouped into five distinct classes (MIKC^c, Mα, Mβ, Mγ, MIKC*) after phylogenetic comparisons with J. curcas homologs. We analyzed expression profiles and suggested AP1/FUL, AP3/PI, AGL104, and SOC1 as candidate regulators of sex determination. In addition, several EaMADS genes were significantly upregulated in flowers compared to leaves.

Conclusion

Our study represents the first detailed, comprehensive evaluation of the regulation of MADS-box genes associated with sex determination in E. agallocha. The assembled transcriptomic profiles increase the genetic information available for this species and constitute an important contribution to functional studies of inflorescence genes. In turn, this will help exploring the molecular mechanisms underlying the evolution of E. agallocha.

Key message

Climate envelope analysis of nine tree species shows that Fagus sylvatica L. and Picea abies H. Karst could lose 58% and 40% of their current distribution range. Quercus pubescens Willd and Quercus cerris L. may win areas equal with 47% and 43% of their current ranges. The ratio of poorly predictable areas increases by 105% in southern and south-eastern Europe.

Context

Climate change requires adaptive forest management implementations. To achieve climate neutrality, we have to maintain and expand forest areas. Impact assessments have great importance.

Aims

The study estimates the potential climate envelopes of nine European tree species for a past period (1961–1990) and for three future periods (2011–2040, 2041–2070, 2071–2100) under two emission scenarios (RCP4.5 and RCP8.5) based on the current species distribution.

Methods

Climate envelopes were estimated simultaneously using the random forest method. Multi-resolution segmentation was used to determine the climatic characteristics of each species and their combinations. Models were limited to the geographical area within which the climatic conditions correspond to the climatic range of the training areas.

Results

Results showed remarkable changes in the extent of geographic areas of all the investigated species’ climate envelopes. Many of the tree species of Central Europe could lose significant portions of their distribution range. Adhering to the shift in climate, these tree species shift further north as well as towards higher altitudes.

Conclusion

European forests face remarkable changes, and the results support climate envelope modelling as an important tool that provides guidelines for climate adaptation to identify threatened areas or to select source and destination areas for reproductive material.

Context

Forest harvest removal may cause nutrient depletion of soils, when removal of essential nutrients, including nitrogen (N), phosphorus (P), sulphur (S), calcium (Ca), potassium (K) and magnesium (Mg) exceeds their net input by deposition and weImpacts of acid atmospheric deposition on woodland athering minus leaching. Nutrient removal by harvest depends on tree species and the harvesting method, i.e. whole-tree harvesting (removal of stems and branches) versus stem wood removal only.

Aim

The aim of this study was to assess the impacts of these two harvesting methods on nutrient removal in Dutch forests exposed to high-nitrogen deposition.

Methods

To assess those impacts, we measured nutrient concentrations in stem wood and branch wood of seven major tree species in the Netherlands, i.e. Japanese larch (Larix kaempferi Lamb.), Norway spruce (Picea abies L. Karst.), Douglas fir (Pseudotsuga menziesii Mirb.), Scots pine (Pinus sylvestris L.), silver birch (Betula pendula Roth), beech (Fagus sylvatica L.) and common oak (Quercus robur L.). Average nutrient concentrations in stems were based on measured concentrations in heartwood, sapwood and bark and estimated volumes and densities of these compartments. Similarly, average nutrient concentrations in branches were based on measured concentrations in coarse branches, fine branches and the bark of coarse branches and estimated volumes and densities of these compartments. Removal was assessed by using the average growth rates of these tree species on nutrient poor sandy soils in the Netherlands.

Results

Compared to other countries, N concentrations in the Netherlands were higher in stems, while phosphorus, Ca, K and Mg concentrations in both stems and branches were nearly always lower. The elevated long-term N deposition levels in the Netherlands most likely contribute to this finding, since N deposition causes soil acidification reducing the availability of Ca, K, Mg and P, that could become limiting to growth. Limits for sustainable harvest, above which outputs exceed inputs of nutrients, depend on nutrient, soil type and tree species and are mostly determined by K and P and sometimes Ca, which may already be depleted at relatively low harvest levels on poor sandy soils, in particular for broadleaved species, while depletion of Mg is not likely. Nevertheless, the average growth of forests in the Netherlands appears to be slightly higher than in most other countries in Europe.

Conclusion

Overall, we thus conclude that limited P, Ca, Mg and K availability in response to elevated N deposition is reflected in reduced contents of these nutrients in stem wood and branch wood but not in growth.

当必需营养物质，包括氮(N)、磷(P)、硫(S)、钙(Ca)、钾(K)和镁(Mg)的去除超过它们通过沉积的净输入时，森林采伐的去除可能导致土壤养分枯竭。通过采伐去除养分取决于树种和采伐方法，即整棵采伐(去除茎和枝)与仅去除茎材。目的评价两种采伐方式对高氮沉降荷兰森林养分去除的影响。方法采用荷兰7种主要树种，即日本落叶松(Larix kaempferi Lamb.)、挪威云杉(Picea abies L. Karst.)、花旗松(Pseudotsuga menziesii Mirb.)、苏地松(Pinus sylvestris L.)、白桦(Betula pendula Roth)、山毛榉(Fagus sylvatica L.)和栎树(Quercus robur L.)，测定其茎材和枝材中的营养物质浓度。茎中的平均营养物质浓度基于心材、边材和树皮的测量浓度以及这些隔室的估计体积和密度。同样，树枝中的平均营养物质浓度是基于粗枝、细枝和粗枝树皮的测量浓度以及这些隔室的估计体积和密度。利用这些树种在荷兰营养贫乏的沙质土壤上的平均生长率来评估清除效果。结果与其他国家相比，荷兰茎秆中氮含量较高，而茎秆和枝条中磷、钙、钾和镁含量几乎总是较低。荷兰长期氮沉降水平的升高最有可能促成这一发现，因为氮沉降导致土壤酸化，减少了钙、钾、镁和磷的可用性，这可能会限制生长。可持续收获的限度取决于养分、土壤类型和树种，并主要由钾和磷决定，有时由钙决定，在贫瘠的沙质土壤上，特别是阔叶物种，在相对较低的收获水平上，钾和磷可能已经耗尽，而镁不太可能耗尽。然而，荷兰森林的平均生长似乎比欧洲大多数其他国家略高。综上所述，随着N沉降量的增加，茎材和枝材中磷、钙、镁和钾的有效度受到限制，但在生长过程中并未发生变化。关键信息对荷兰7种主要树种的树室养分浓度进行了评估。茎和枝中的磷、钙、钾和镁(碱阳离子)浓度大多低于其他国家，而氮浓度较高。长期的氮沉积可能导致了这些差异。尽管磷和碱阳离子的可用性较低，但平均生长并未下降。建议在养分贫乏的土壤上限制枝材的采伐，以避免磷和碱阳离子的耗竭。