Hülsmann and Hartig suggest that ecological mechanisms other than specialized natural enemies or intraspecific competition contribute to our estimates of conspecific negative density dependence ...(CNDD). To address their concern, we show that our results are not the result of a methodological artifact and present a null-model analysis that demonstrates that our original findings-(i) stronger CNDD at tropical relative to temperate latitudes and (ii) a latitudinal shift in the relationship between CNDD and species abundance-persist even after controlling for other processes that might influence spatial relationships between adults and recruits.
The goal of the study was to derive up-to-date and complex information on the current vegetation cover of the Praděd Reserve (Hrubý Jeseník Mountains, Czech Republic), with special regard to the ...unique alpine treeline ecotone formed by krummholz of Norway spruce. We argue that the data of remote sensing and automated techniques of image processing should be preferably used. Accordingly, a color-infrared orthophoto map was classified in a land cover map employing maximum likelihood spectral classifier, ancillary data, texture analysis, and a knowledge base classification technique. The overall classification accuracy was about 78%, distinguishing 7 land cover classes. Using a reclassified land cover map and the moving window mean filter, a spruce canopy closure map was calculated. The continuous map of the canopy closure was subsequently reclassified in predefined intervals that were used for an automated delimitation and mapping of complex transitional borders of the alpine treeline ecotone. The proposed method can serve for objectified mapping of gradual transitions between any land cover or vegetation classes.
The decline of Abies alba (fir) in natural fir–beech forests in Europe has fascinated scientists for over a century. During this period, Fagus sylvatica (beech) became the dominant species in this ...forest type. We hypothesised that (1) the success of beech over fir is significantly connected with the fact that beech suffers less than fir from the presence of conspecific neighbours; that (2) shade tolerance is not a factor which favours beech over fir; and that (3) this is due to a significantly reduced proportion of litter treethrow mounds with suitable conditions for the successful regeneration of fir. We investigated these hypotheses by means of tree spatial pattern analysis. Eight rectangular plots (2–8 ha) were analysed in mountain fir–beech forests of the Outer Western Carpathians, Czech Republic. Various types of the pair correlation function and L function were used to describe the tree density variability of trees with DBH ≥10 cm. The analyses were carried out on datasets from the 1970s, 1990s and 2000s. Our results suggest that negative density dependence is not responsible for the current decline of fir. It seems that a higher shade tolerance of the advanced regeneration could be one of the factors which favour beech over fir. It is evident that fir trees have a markedly stronger positive association to mounds than beech trees.
Present study has produced first detailed land-cover map of Socotra Island. A Landsat 7 ETM+ dataset was used as a main source of remotely sensed data. From numerous reference points (more than 250) ...coming from the ground data verification the set of training fields and the set of evaluation fields were digitised. As a classification method the supervised maximum likelihood classification without prior probabilities was used in combination with rule-based post-classification sorting, providing results of sufficient accuracy and subject resolution. Estimates of the area and degree of coverage of particular land-cover classes within Socotra Island have brought excellent overview on state of island biotopes. Overall accuracy of the map achieved is more than 80%, 19 terrestrial land-cover classes (including three types of Shrublands, three types of Woodlands, two types of Forests and Mangroves) have been distinguished. It consequently allows estimates of the current and potential occurrence of endemic plant populations, proposals of management and conservation plans and agro-forestry planning.
A sequentially shifting fine-scale mosaic of forest patches in different phases of development is widely accepted as being a basic description of the natural dynamics of temperate deciduous and mixed ...forests. The determination of these patches and phases has often been performed using subjective field observations and simplistic or loosely defined mapping criteria, with resulting maps being observer-dependent. The goal of this study is to develop a more objective, more complex and spatially explicit method for the determination and mapping of forest developmental stages and phases. We propose a new approach, based on local diameter distributions, presuming that their shape indicates the phase and trend of stand development. As input data, we used a stem position map of more than 18,500 trees in the Zofin natural forest (Czech Republic). Using focal filtering, we created local distributions of both live and dead tree counts and tree basal areas, across diameter classes, separately for every particular site in the stand and its circular surroundings (diameter of the moving filter was 21 m; mapping step 1 m). These distributions were then recognized by an artificial neural network and classified into pre-defined categories. Preliminary results indicate a classification accuracy of about 80% in distinguishing four developmental stages and above 68% in distinguishing eight developmental phases. The merits of this new method are in the fine scale and repeatability of mapping. It can be an objective unifying concept for the inter-comparison of stand dynamics from comparable site conditions.
QUESTIONS: What are the differences between the tree spatial patterns (TSP) of various recruit and mortality waves in alluvial hardwood forests and mountain fir–beech forests? Are there any ...statistically significant differences between the mean TSP of these forest types? Are these differences stable over time? LOCATION: Alluvial floodplain forests at the confluence of the Morava and Dyje rivers, and mountain fir–beech forests in the Outer Western Carpathians, Czech Republic. METHODS: In both forest types, seven 2‐ha rectangular plots were analysed. The pair correlation function g(r) was used to describe tree density variability of trees with DBH ≥ 10 cm. The analyses were carried out for data sets from the 1970s, 1990s and 2000s. A bootstrap method was used to test for significant differences between the mean values of g(r) from alluvial forests and from fir–beech forests. RESULTS: Recruits in mountain fir–beech forests revealed consistent clustering to at least 5 m. In alluvial hardwood forests, recruits also showed random distribution as well as occasional regular distribution at distances over 20 m. Bootstrap significance tests revealed significant differences between the mean values of g(r) for alluvial forests and fir–beech forests. Alluvial floodplain forests showed statistically significant stronger clustering up to a distance of 4 m in all study periods. At distances over 20 m, mountain fir–beech forests demonstrated stronger clustering. In the 1970s, this was statistically significant only at a distance of 32 m, but in the 2000s, it was at intervals of 22–30 and 34–38 m. CONCLUSIONS: The methods of data analysis in this study enabled us to find significant features of TSP at finer resolution than the common resulting trichotomy of univariate analysis: clustering, randomness and regularity. We believe that, on the basis of detailed spatial analyses, it is possible to create a TSP model that reflects the typical features of particular forest types.
Conceptual models that describe temperate forest dynamics differ substantially between Europe and America. In Europe, the concept of the forest cycle describes a sequentially shifting fine-scale ...mosaic of patches in different phases of forest development. In North America, the descriptive concept is largely based on severe coarse-scale disturbances that repeat in a cyclic fashion and restart the succession of the whole forest stand from initiation through to ‘old-growth,’ neglecting the within-stand dynamics on the patch level. Here, we investigate fine-scale stand structures across European and North American forests by applying the European concept of forest developmental phases to all stands. The patches of four major forest developmental stages were recognized and delineated by the spatially explicit rule-based classification system implemented in GIS, which employs stem position maps of live and dead trees for analysis. The basic quantitative characteristics of identified patch structures in the N. American stands, as the Mean Patch Size of the mosaic (between 760 and 890 m
2
), were comparable with European old-growth stands, although mosaic complexity was higher in the latter. We demonstrated that in addition to the large-scale forest cycle assumed by N. American conceptual models there simultaneously exist finer-scale patch dynamics described by the European conceptual model. We also demonstrated that the occurrence of the Steady State stage was promoted by higher local tree species richness, which may explain the abundant occurrence of this stage in N. American secondary stands. The Steady State stage of the European model might represent an important commonality across both paradigms.
The paper presents a list of local geographical names and their alternatives quoted in entomological literature related to the Socotra Archipelago. It includes their exact localization with ...coordinates and visualization on the map.
We provide a study on long-term canopy gap dynamics in the Žofin Virgin Forest (total area 98 ha), which has been strictly protected since 1838. Our aims were i) to describe the size distribution of ...gaps at a given time; ii) to determine the area where dynamic processes occurred within a given period; and iii) to determine the role of deciduous versus coniferous trees in gap formation. The fate of individual gaps was followed in a 47-ha beech-dominated part of the reserve by analyzing aerial photographs taken in 1971, 1983, 1991, and 2004. The role of individual trees in canopy gap dynamics was studied by combining gap distribution maps with stem position maps of 1975 and 1997 for a 10-ha sample plot. We showed that i) total gap area (9–11%) and average gap size (88–99 m2) was stable during the 33-y study period; ii) canopy dynamics occurred in 0.1% of the area annually; iii) most gaps were created by the simultaneous death of 1–3 canopy trees; iv) death of deciduous trees played a more important role in the creation of gaps than their proportion among dead trees would suggest; and v) tree size and neighbourhood also determined if a dead tree became a gap maker. Nomenclature: Jalas & Suominen, 1988.
Within the area of Central Europe, and especially in the Czech Republic (and former Czechoslovakia), geobiocoenological landscape differentiation has been applied for more than 40 years to create a ...spatial model of the natural (potential) condition of geobiocoenoses in the landscape. Because long-term objective of geobiocoenology is to contribute to the creation of harmonic cultural landscape by gradual development of a comprehensive system of groundworks for sustainable landscape use, and as Mendel University experts work in various countries, adaptions of geobiocoenology were used also outside Europe, in tropical areas. Examples of such a work could be shown on islands such as Socotra (belonging politically to Yemen), Tasmania, and Cuba.
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