Density, diversity and community composition of trees in tropical thorn forest, peninsular India

Tropical thorn forests (TTFs) are characterized by the presence of small and thorny trees which usually shed their leaves in dry season. A quantitative phytosociological study was conducted in Uthumalai Reserve Forest of Peninsular India to record density, species richness, diversity and population structure of trees. Diameter of all free standing trees ≥1 cm diameter at breast height (DBH, cm) was measured at 1.37 m above the ground. A sum of 4135 trees ≥1cm DBH recorded from one hectare study plot. With 2272 (54.94%) individuals Dalbergia spinosa dominated the study plot followed by Commiphora berryi (484, 11.70%), Grewia flavescens (259, 6.26%), Dichrostachys cinerea (206, 4.98%) and Anogeissus pendula (171, 4.14%). In total, 26 species belonged to 19 genera and 15 families found in one ha study plot. The family Mimosaceae had a large number of species followed by Apocynaceae, Capparidaceae, Tiliaceae, Rhamnaceae. Rubiaceae (each 2 species). Stand basal area of tree community recorded as 15.238 m2 ha-1. Commiphora berryi constituted 50.80% (7.74 m2 ha-1) of stand basal area followed by Dalbergia spinosa (19.43%, 2.96 m2 ha-1). The forest showed a reverse J shaped population structure. Shannon diversity (H), equitability (H’) and Simpson’s dominance (D) indices of study area recorded as 1.76, 0.54 and 0.335, respectively. Dalbergia spinosa, Commiphora berryi, Grewia flavescens, Dichrostachys cinerea and Anogeissus pendula topped the species important value index with 87.80, 73.53, 20, 19.79, 17.43 scores, respectively. In family important value index, Papilionaceae topped the list followed by Burseraceae and Mimosaceae with scores 129.32, 74.23 and 34.43, respectively. The study area endowed with a moderate species richness and diversity, and acts as one of the homes for an IUCN’s vulnerable tree species.

Forest Degradation and Inter-annual Tree Level Brazil Nut Production in the Peruvian Amazon

Brazil nuts are an economically important non-timber forest product throughout the Amazon Basin, but the forests in which they grow are under threat of severe degradation by logging, road building, agricultural expansion, and forest fires. As a result, many Brazil nut trees grow within a mosaic of young secondary forest, primary forest remnants and agricultural fields. Little is known about the reproductive ecology and fruit production of Brazil nut in such degraded landscapes. Previous studies on Brazil nut productivity did not explicitly address forest degradation as a factor. In this study, we analyzed the extent to which Brazil nut fruit production is affected by the level of forest degradation. We collected 3 years of fruit production data of 126 Brazil nut trees occurring in degraded forest (the above-mentioned mosaics) and closed canopy (i.e., undegraded) forest in and around the Tambopata National Reserve in Madre de Dios, Peru. We analyzed the effect of forest degradation at two different levels: at the site type (i.e., degraded vs. undegraded forest) and the individual tree level (quantified as stand basal area and stem density around the individual Brazil nut trees). Stand basal area around the individual Brazil nut trees significantly positively influenced tree fruit production in all 3 years and stem density in year 2 and 3, with strongest effects in the 3rd year, and weakest effect in the 1st year, coinciding with an El Niño year. Trees in undegraded forest produced more fruits in the 2nd and 3rd year than trees in degraded forest (29.4% and 35.8% more, respectively), but not in the 1st year in which trees in undegraded forest produced 31.7% less fruits than trees in degraded forest. These within year effects were not significant, although the effects significantly differed between years. Our results show that forest degradation can affect Brazil nut fruit production, and suggest that the strength (and possibly the sign) of this effect might be different in (extreme) El Niño years. This illustrates the potential importance of restoring degraded forest to enhance resilience and protect the livelihoods of people depending on the Brazil nut trade.

Effect of Thinning on Pericopsis elata (Harms) Meeuwen (Fabaceae) Found in Forest Plantations in the East and South Regions of Cameroon

This paper assesses the response of Pericopsis elata trees to silvicultural operations conducted in abandoned plantations settled between 1972 and 1975 in the East and South regions of Cameroon. Trees quality and DBH were evaluated before and 6 years after 2009 thinning. The silvicultural treatment of thinning improved the quality (physiognomy), the annual diameter increment and the stand basal area of trees. The average percentage of winding trees dropped from 82.8% in 2009 before thinning to 44.1%, six years later after thinning (2015). The most important average diameters were observed in thinned plots (27.3 ±10.4 cm - 30.5 ±10.0 cm) compared to non-thinned plots (22.9±13.2 cm-23.3±10.8 cm). Thinned plots gained at least 6 cm in diameter in 6 years, which is trice compared to the 2 cm observed in the non-thinned plots. The average annual diameter increment was 0.45 cm/year in thinned plots against 0.34 cm/year in non-thinned plots in the same period. Thinned plots have gain at least 6 m²/ha in the stand basal area against 1 m²/ha for non-thinned plots.

Evaluating the current ecological status and proposing rehabilitation interventions for the low flooded riparian reserve forest in Punjab Pakistan

Aim of Study: The complex community of riparian reserve forest has become of great concern for researchers to develop more viable management strategies. The paper aimed to evaluate the current structural diversity of vegetation and its association with the physical environment of low-lying forest for proposing the rehabilitation interventions. Area of Study: We studied two forests, Chung-Mohlanwal and Dhana-Bheni on both riverbanks along river Ravi in the Jhok riparian reserve forest situated in the southwest of Lahore, Pakistan.Material and Methods: A methodological framework was developed based firstly, on direct comparison of diversity (measured by Hill numbers) and structure of existed vegetation layers (trees, shrubs, herbs, and grasses) and environmental factors (canopy structure, anthropogenic activities, microclimate, and soil characteristics) between the two forests and secondly, on environment-vegetation association using Canonical Correspondence Analysis (CCA) ordination method.Results: Dhana forest was more diverse vegetation layers (Shannon Diversity index 1D < 11) and intact due to plantation of uneven-aged tree stands of varied stand basal area and stem density. Microclimate under this forest could not support the dominant understory positively unlike the monoculture forest. On the contrary, Chung-Mohlanwal forest was under the influence of uncontrolled grazing activities, fuelwood extraction, and invasive species. Multivariate analysis CCA elucidated that most variance was shown by soil characteristics (38.5 %) for understory vegetation in both forests.Research Highlights: Overstory stand structure, species composition, distance to nearby communities, and soil characteristics should be considered for developing forest planting and management strategies.Keywords: Vegetation Structure; Hill Numbers; Grazing; Environment; Management.Abbreviation used: CCA (Canonical Correspondence Analysis); 1D (Shannon Diversity); Ca + Mg (Calcium + Magnesium); Na (Sodium); ECe (Electrical Conductivity); DBH (Diameter at Breast Height); IUCN (International Union for Conservation of Nature); SBA (Stand Basal area); BA (Basal Area); 0D (Richness); 2D (Simpson Index); IVI (Importance Value Index); LU (Livestock Unit); GPS (Global Positioning System); OC (Organic Carbon); OM (Organic matter); SAR (Sodium Adsorption Ratio); N (Nitrogen); P (Phosphorous); K (Potassium); DCA (Detrended Correspondence Analysis); S (Shrub); H (Herb); G (Grass).

The Effect of Structural and Environmental Changes on Litter Decomposition of in Pinus Sylvestris Stands

Background: Decomposition of litter has an important role in primary production with its influence on nutrient release for plant uptake and carbon flux in forest ecosystems. Thus, understanding the effects of the intervention on litter decomposition is crucial for sustainable forest management. In this study, the effect of structural change and facing slope on litter decomposition in Scots pine stands (Pinus sylvestris L.) were investigated.Results: The decomposition rate of litter decreased as the stand age increased. Litter decomposed more rapidly on northern slopes than southern slopes. Cutting caused to accelerate the decomposition at a rate of up to 58% depending on its intensity. The k values were found to fluctuate though the time from 0.189 in moderately dense canopied stands to 0.317 in open canopied over-mature stands. Stand basal area, incubation time, and remaining carbon concentration of the litter accounted for 75% of the variation in the decomposition constant. Conclusions: Cutting-induced stand structural changes affected the litter decomposition process in forest ecosystems due to the micro environmental change as well as the change in litterfall composition and chemistry. Heavy treatments can change the litter decomposition process drastically, while moderate thinning may not have a clear effect in the long run. The stand specific k value should be considered to use in forest carbon models for more accurate estimation. Decomposition constant should be calculated by considering stand structure and incubation time of at least 1050 days. Besides, due to the significant effect of canopy closure on decomposition rate, stand specific or recalculated k constants according to stand basal area, incubation time, and remaining carbon concentration of the litter should be recommended to use in forest carbon models for more accurate carbon budget estimation.

Modeling Early Responses of Loblolly Pine Growth to Thinning in the Western Gulf Coastal Plain Region

Growth response to thinning has long been a research topic of interest in forest science. This study presents the first 3–4 years of response of loblolly pine (Pinus taeda L.) growth to thinning at different intensities. Data were collected from the East Texas Pine Research Project’s region-wide loblolly pine thinning study, which covers a wide variety of stand conditions. Four treatments, light, moderate, and heavy thinning, respectively having 370, 555, and 740 residual trees per hectare after thinning, and an unthinned control, were included. Individual tree diameter at breast height (dbh) and total height were recorded annually for the first 3–4 years after thinning. Results indicate significant differences between treatments in dbh growth in each year after thinning, as well as for all years combined. Each thinning treatment had significantly greater dbh growth than the control in the first growing season with this positive response being more evident in the case of the heavier thinning or at the later years post-thinning. Conversely, the thinning effect on tree height growth was initially negligibly negative, then becoming positive after 2–4 years, with the heavier thinning becoming positive sooner. Tree size class, assigned based on prethinning dbh, had a significant effect on both dbh and height growth responses. Compared to the control, small trees had a greater response both in dbh and in height growth than the medium and large trees over the measurement period. At the stand level, the heavier thinning had significantly less stand basal area per hectare, but the difference in stand basal area per hectare between the thinned and the unthinned plots decreased with years post-thinning. Results from this study can improve our understanding in thinning effects and help forest managers make accurate decisions on silvicultural regimes.