Demographic variation and habitat specialization of tree species in a diverse tropical forest of Cameroon

Background： Many tree species in tropical forests have distributions tracking local ridge-slope-valley topography. Previous work in a 50-ha plot in Korup National Park, Cameroon, demonstrated that 272 species, or 63% of those tested, were significantly associated with topography. Methods： We used two censuses of 329,000 trees ≥1 cm dbh to examine demographic variation at this site that would account for those observed habitat preferences. We tested two predictions. First, within a given topographic habitat, species specializing on that habitat （＇residents＇） should outperform species that are specialists of other habitats （＇foreigners＇）. Second, across different topographic habitats, species should perform best in the habitat on which they specialize （＇home＇） compared to other habitats （＇away＇）. Species＇ performance was estimated using growth and mortality rates. Results： In hierarchical models with species identity as a random effect, we found no evidence of a demographic advantage to resident species. Indeed, growth rates were most often higher for foreign species. Similarly, comparisons of species on their home vs. away habitats revealed no sign of a performance advantage on the home habitat. Conclusions＂ We reject the hypothesis that species distributions along a ridge-valley catena at Korup are caused by species differences in trees _〉1 cm dbh. Since there must be a demographic cause for habitat specialization, we offer three alternatives. First, the demographic advantage specialists have at home occurs at the reproductive or seedling stage, in sizes smaller than we census in the forest plot. Second, species may have higher performance on their preferred habitat when density is low, but when population builds up, there are negative density-dependent feedbacks that reduce performance. Third, demographic filtering may be produced by extreme environmental conditions that we did not observe during the census interval.

Comparison of stem taper models for the four tropical tree species in Mount Makiling, Philippines

This study was conducted to evaluate the performance of six stem taper models on four tropical tree species, namely Celtis luzonica(Magabuyo),Diplodiscus paniculatus(Balobo), Parashorea malaanonan(Bagtikan), and Swietenia macrophylla(Mahogany) in Mount Makiling Forest Reserve(MMFR), Philippines using fit statistics and lack-of-fit statistics. Four statistical criteria were used in this study, including the standard error of estimate(SEE),coefficient of determination(R^2), mean bias( E),and absolute mean difference(AMD). For the lack-offit statistics, SEE, E and AMD were determined in different relative height classes. The results indicated that the Kozak02 stem taper model offered the best fit for the four tropical species in most statistics. The Kozak02 model also consistently provided the best performance in the lack-of-fit statistics with the best SEE, E and AMD in most of the relative height classes. These stem taper equations could help forest managers and researchers better estimate the diameter of the outside bark with any given height,merchantable stem volumes and total stem volumes of standing trees belonging to the four species of thetropical forest in MMFR.

Concept of the integrative aspects of the forest ecosystem services with case study on recreation services assessment in Slovakia

Introduction:This paper presents basic information on the research,classification,and application of the functions of tree species and their communities(mainly forest)in Slovakia.The main aim is a scientific assessment of acquired knowledge regarding the functional effects of forests under real ecological,forest management and socio-economic conditions from various regions in Slovakia;the most up-to-date findings concerning the ecology and economics of natural resources will be applied here.The second part of the paper presents methodological possibilities for valuation of outdoor recreation in forests.Different methods and methodological approaches suitable to a valuation of recreation based on various principles and criteria(preference and non-preference methods,cost-based methods,revenue-based methods,and direct and indirect methods)are analyzed.A practical application of one indirect preference method(travel cost method)is made to evaluate outdoor recreation in forests in Slovakia.Results and conclusions:A new classification system and a methodology of integrative utilization of forest functions for the forest ecosystem services are constructed.Outdoor recreation in forests,besides recreational forests and areas,assumes the character of a public good:its use by individuals has some influence on utilization by other individuals,and single users cannot be excluded from its utilization.Therefore,some stimulation for its production is missing.In principle,there are no markets for these kinds of public goods and services.The total value of outdoor recreation in forests in Slovakia amounted to€163.4 million;if opportunity time costs were included,this amounted to as much as€825.7 million.