Tree Species Diversity and Abundance of Akure Forest Reserve, Ondo State, Nigeria

This study was carried out to examine the tree species diversity and abundance in a natural forest ecosystem in the Southwestern region of Nigeria. Data were collected from a four equal size sampling plot of 50×50m in a permanent sample plot section of Akure Forest Reserve. All living trees with DBH ≥ 10cm were measured and identified. A total of 956 trees were encountered. These trees were from 42 genera and 20 families. Celtis zenkeri belonging to the family of Ulmaceae was the species with the highest population distribution while Sterculiaceae was the dominant family in the study area. The Shannon-Wiener Diversity Index (Hˈ) of 3.196 and species evenness of 0.84 were obtained from the study area. The high values of diversity indices obtained indicated that the forest is rich in biodiversity and hence should be protected from any forms of disturbance to enhance sustainability as well as protect the rare species in it from going into extinction.

Assessing the influence of climate on the growth rate of boreal tree species in northeastern Canada through long term permanent sample plot datasets

Climate has a considerable influence on tree growth. Forest managers benefit from the empirical study of the historic relationship between climatic variables and tree growth to support forest management frameworks which are to be applied under scenarios of climate change. Through this research, we have utilized long-term permanent sample plot records, historic climate datasets, and linear mixed modelling techniques to evaluate the historic influence of climatic variables on the growth rates of major boreal tree species in Newfoundland and Labrador, Canada. For the commercially significant spruce and fir forests of the province, we found growing degree days (GDD) to negatively correlate with tree productivity in warmer regions, such as much of Newfoundland (±1,350 GDD), but positively correlate with growth in cooler regions, such as those in Labrador (±750 GDD). With respect to precipitation, environmental moisture was not on average a limiting factor to species productivity in the province. These dynamics have implications for the productivity of the spruce-fir forests of the study area when considered alongside contemporary climate projections for the region, which generally entail both a warmer and wetter growing environment.

Repeated thinning treatments reduce long-term soil carbon and nitrogen storage: An 87-year study at the Petawawa Research Forest, Canada

Forest management activities are increasingly analyzed through a lens that quantifies their effects on soil carbon (C) and nitrogen (N) storage, because forest soils are an important C sink. Data on the longer-term impacts of repeated interventions are often lacking. At the Petawawa Research Forest, Ontario, treatments to evaluate the effect of repeated thinnings on wood quality of red and white pine were initiated in 1918 with the first experimental plots in Canada, permanent sample plot 1 (thinned) and 2 (control). In 2005, 16 years after the last thinning in 1989, we observed that repeated thinnings reduced soil C and N stocks in the surface L and F and Ah horizons. Contrary to our hypotheses, concentrations and stocks of C and N increased in the Bm1 horizon, indicating that these elements could be accumulated in deeper horizons after surface disturbance and potentially increased decomposition associated with thinning. However, total C and N accumulation in the profile to 30 cm contributed to reduced storage (-35 % for C, and -30 % for N). Many forest sites in the Great Lakes Forest Region that are selectively cut repeatedly over decades could experience this level of soil C and N decline.

Partitioning risks of tree mortality by modes of death in managed and unmanaged northern hardwoods and mixedwoods

We used a permanent sample plot network established to monitor the effects of forest management practiced in mature northern hardwood and mixedwood stands in Québec, Canada to address two important questions related to tree mortality: (1) How does partial cutting affect tree mortality? (2) Which variables best explain tree mortality by different modes of death (standing death, uprooting or stem breakage)? Decennial tree deaths were lower after partial cutting than in unharvested plots, but the annual proportion of tree death was similar (1.25%·year-1). At the tree level, a risk-product classification demonstrated the strongest evidence on influencing total mortality, followed by species, the presence of a logging injury, and tree size. Annual temperature was the only climatic variable explaining variations in total risk of tree mortality, and always among the first three variables explaining differences among the three modes of death. The risk of standing death also increased with increasing annual precipitation, while the risk of stem breakage and, to a lesser extent, of being uprooted, decreased with increasing precipitation. Additionally, we found strong evidence to support the effect of the potassium/magnesium ratio of the humus layer on the risk of being uprooted. This information is critical to better understand tree mortality processes.

Evaluation of stand-level hybrid PipeQual model with permanent sample plot data of Norway spruce

The evaluation of process-based models (PBM) includes ascertaining their ability to produce results consistent with forest growth in the past. In this study, we parameterized and evaluated the hybrid model PipeQual with datasets containing traditional mensuration variables collected from permanent sample plots (PSP) of even-aged Norway spruce (Picea abies (L.) Karst.) stands in Finland. To initialize the model in the middle of stand development and reproduce observed changes in Norway spruce crown structure, the built-in empirical relationships of crown characteristics were made explicitly dependent on the light environment. After these modifications, the model accuracy at the whole dataset level was high, with slope values of linear regressions between the observations and simulations ranging from 0.77 to 0.99 depending on the variable. The average bias ranged between −0.72 and 0.07 m in stand dominant height, –0.68 and 0.57 cm in stand mean diameter, –2.62 and 1.92 m2 in stand basal area, and 20 and 29 m3 in stand total stem volume. Stand dynamics after thinning also followed reasonable closely the observed patterns. Accurate predictions illustrate the potential of the model for predicting forest stand growth and forest management effects in changing environmental conditions.

Population Dynamics of Pometia for The Period of Post-Selective Logging in Tropical Rainforest, Southern Papua, Indonesia

<p>Tropical rainforest changed in term of structure, composition and population, resulting from logging. One of target trees during logging is <em>Pometia</em>. Our goals of this research were to answer that (1) How were survival, growth, fecundity and population growth rate (λ) of <em>Pometia</em> within remnant stands?; (2) what were driving factors to explain population dynamics of <em>Pometia</em> within logged forest?. Data were derived from three hectares-permanent sample plot (PSP) in logged forest of PT Tunas Timber Lestari. Integral Projection Models (IPMs) were applied to analyze population dynamics. The study showed dynamically that probability of the individuals of <em>Pometia</em> survived in this area did not significantly differ among their size, while stands showed the significant difference between small and large individuals. The growth of both individuals of <em>Pometia</em> and stands varied significantly in different size. The probability of fecundity both <em>Pometia</em> and stands were significantly different among size. The population of <em>Pometia</em> has been increasing for about a decade as the population of all stands was growing as well. Moreover, the regular documentation of species composition and structure before and after logging is necessary as a control of biodiversity. Therefore, a proper protocol to monitor the biodiversity should be designed by government and disseminated it to logging companies. </p><p><strong>How to Cite</strong></p><p>Murdjoko, A., Marsono, D., Sadono, R. &amp; Hadisusanto, S. (2016). Population Dynamics of Pometia for The Period of Post-Selective Logging in Tropical Rainforest, Southern Papua, Indonesia. <em>Biosaintifika: Journal of Biology &amp; Biology Education</em>, 8(3), 321-330. </p>