scholarly journals Forest Diversity and Modeling Diameter Distribution of the Tropical Dryforest in East Nusa Tenggara, Indonesia

2020 ◽  
Vol 9 (1) ◽  
pp. 21-28
Author(s):  
Aah Ahmad Almulqu ◽  
Keyword(s):  
Forest Management ◽  
Stand Structure ◽  
Likelihood Function ◽  
Dry Forest ◽  
Diameter Distribution ◽  
Structure Model ◽  
Distribution Models ◽  
Forest Diversity ◽  
Product Regulation ◽  
Forest Conditions

The variation of forest conditions shows structural differences, species composition, and potential value as well as stand density. The need and important role of stand structure model in forest management, particularly in forest-based product regulation become the supply demands quantitatively for various forest conditions in Indonesia. The objective of the study was to determine the stand structure model of dry forest. The study was conducted at the dry forest of Binafun, Bonmuti, Letkole and Oelbanu, East Nusa Tenggara Province. Determination of the best stand structure model based on maximum likelihood function of family distribution that tested including the function of exponential, gamma, lognormal and Weibull. A total of 2097 tree individuals, its representing 94 species, 72 genera and 45 families, were found in the research sites. Eucalyptus urophylla were found to be the most dominant species in the research sites and Elattostachys verrucosa have potential to replace Dryobalanops aromatic. Most of family distribution models can describe the stand structure in research sites. The models presented here are the basis for further developments toward the tree diversity for general purpose in tropical dry forest management of East Nusa Tenggara, Indonesia.

scholarly journals Soil Moisture Dynamics in Response to Precipitation and Thinning in a Semi-Dry Forest in Northern Mexico

Water ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 105
Author(s):  
Argelia E. Rascón-Ramos ◽  
Martín Martínez-Salvador ◽  
Gabriel Sosa-Pérez ◽  
Federico Villarreal-Guerrero ◽  
Alfredo Pinedo-Alvarez ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Forest Management ◽  
Water Availability ◽  
Dry Forest ◽  
Rainfall Events ◽  
Rainfall Characteristics ◽  
Northern Mexico ◽  
The Difference ◽  
The Impact ◽  
Moisture Dynamics

Understanding soil moisture behavior in semi-dry forests is essential for evaluating the impact of forest management on water availability. The objective of the study was to analyze soil moisture based in storm observations in three micro-catchments (0.19, 0.20, and 0.27 ha) with similar tree densities, and subject to different thinning intensities in a semi-dry forest in Chihuahua, Mexico. Vegetation, soil characteristics, precipitation, and volumetric water content were measured before thinning (2018), and after 0%, 40%, and 80% thinning for each micro-catchment (2019). Soil moisture was low and relatively similar among the three micro-catchments in 2018 (mean = 8.5%), and only large rainfall events (>30 mm) increased soil moisture significantly (29–52%). After thinning, soil moisture was higher and significantly different among the micro-catchments only during small rainfall events (<10 mm), while a difference was not noted during large events. The difference before–after during small rainfall events was not significant for the control (0% thinning); whereas 40% and 80% thinning increased soil moisture significantly by 40% and 53%, respectively. Knowledge of the response of soil moisture as a result of thinning and rainfall characteristics has important implications, especially for evaluating the impact of forest management on water availability.

A Blind Spot in the Use of the Weibull Function for Modeling Diameter Distributions

2020 ◽  
Author(s):  
Adrian Norman Goodwin
Keyword(s):  
Lower Bound ◽  
Blind Spot ◽  
Forest Growth ◽  
Growth And Yield ◽  
Diameter Distribution ◽  
Absolute Difference ◽  
Weibull Function ◽  
Distribution Models ◽  
Difference Statistic ◽  
Diameter Distributions

Abstract Diameter distribution models based on probability density functions are integral to many forest growth and yield systems, where they are used to estimate product volumes within diameter classes. The three-parameter Weibull function with a constrained nonnegative lower bound is commonly used because of its flexibility and ease of fitting. This study compared Weibull and reverse Weibull functions with and without a lower bound constraint and left-hand truncation, across three large unthinned plantation cohorts in which 81% of plots had negatively skewed diameter distributions. Near-optimal lower bounds for the unconstrained Weibull function were negative for negatively skewed data, and the left-truncated Weibull using these bounds was 14.2% more accurate than the constrained Weibull, based on the Kolmogorov-Smirnov statistic. The truncated reverse Weibull fit dominant tree distributions 23.7% more accurately than the constrained Weibull, based on a mean absolute difference statistic. This work indicates that a blind spot may have developed in plantation growth modeling systems deploying constrained Weibull functions, and that left-truncation of unconstrained functions could substantially improve model accuracy for negatively skewed distributions.

scholarly journals Evaluation of the efficacy of neonicotinoid and pyrethroid insecticides in Diaphorina citri Kuwayama (Hemiptera: Liviidae) populations in Colombia

2018 ◽  
Vol 12 (2) ◽  
pp. 358-368
Author(s):  
Augusto Ramírez-Godoy ◽  
Gina Puentes-Pérez ◽  
Hermann Restrepo-Díaz
Keyword(s):  
Tropical Dry Forest ◽  
Dry Forest ◽  
Asian Citrus Psyllid ◽  
Insect Vector ◽  
Diaphorina Citri ◽  
Pyrethroid Insecticides ◽  
Lambda Cyhalothrin ◽  
The Mean ◽  
Number Of Individuals ◽  
Forest Conditions

The Asian citrus psyllid Diaphorina citri is the insect vector of the disease known as huanglongbing (HLB), which is the most devastating disease of citrus crops in the world. The Asian citrus psyllid was officially reported in Colombia in 2007, and a national phytosanitary emergency was declared because of the presence of HLB in 2015. Two different experiments were carried out in two locations (Apulo and Jerusalén, Department of Cundinamarca) in Colombia to evaluate the effectiveness of neonicotinoid (clothianidin, imidacloprid and thiamethoxan) and pyrethroid applications (bifenthrin, deltamethrin and lambda cyhalothrin) on the control of D. citri populations (adults, nymphs and eggs) in ‘Tahiti’ lime trees established under tropical dry forest conditions. In the first experiment, trees were foliarly treated as follows: (1) untreated trees; (2) trees treated with 100 g ha-1 of imidacloprid; (3) trees treated with 60 g ha-1 of bifenthrin; (4) trees treated with 12.5 g ha-1 of deltamethrin and (5) trees treated with a co-formulation of 70 g ha-1 of a neonicotinoid (thiametoxan) and 53 g ha-1 of a pyrethroid (lambda cyhalothrin). In the second experiment, trees were treated with 100 g ha-1 of clothianidin. Foliar insecticide applications were carried out at 0 and 4 weeks after the initiation of treatments (WAT). In the first trial, the control presented a mean number of individuals per flush of ≈1.14, whereas the trees treated with neoinicotinoids and pyrethroids showed 50% fewer individuals (0.53-0.61). For the population of immatures, the number of nymphs was 2.25 nymphs per flush in the control, as compared to 0.82-1.22 individuals observed in the treatments with insecticides. The mean number of eggs was also between 80-100% higher in the control trees (2.37 individuals), as compared to the treated trees (1.14-1.78). In the second trial, the use of clothianidin showed a higher control of eggs. The results suggest that the rotation of neonicotinoids with pyrethroids can be a tool to reduce populations and delay resistance processes in D. citri in citrus trees established under tropical dry forest conditions in Colombia.

scholarly journals Thinning Response and Potential Basal Area in a Mixed Sub-humid Low-elevation Oak-Hornbeam Forest

2021 ◽  
Author(s):  
Mathias Neumann ◽  
Hubert Hasenauer
Keyword(s):  
Stand Structure ◽  
Basal Area ◽  
Climatic Conditions ◽  
Diameter Distribution ◽  
Stem Density ◽  
Growing Stock ◽  
A Site ◽  
Water Nutrients ◽  
Related Mortality

Abstract Competition for resources (light, water, nutrients, etc.) limits the size and abundance of alive trees a site can support. This carrying capacity determines the potential carbon sequestration in alive trees as well as the maximum growing stock. Lower stocking through thinning can change growth and mortality. We were interested in the relations between stand structure, increment and mortality using a long-unmanaged oak-hornbeam forest near Vienna, Austria, as case study. We expected lower increment for heavy thinned compared to unmanaged stands. We tested the thinning response using three permanent growth plots, whereas two were thinned (50% and 70% basal area removed) and one remained unmanaged. We calculated stand structure (basal area, stem density, diameter distribution) and increment and mortality of single trees. The heavy thinned stand had over ten years similar increment as the moderate thinned and unthinned stands. Basal area of the unthinned stand remained constant and stem density decreased due to competition-related mortality. The studied oak-hornbeam stands responded well even to late and heavy thinning suggesting a broad “plateau” of stocking and increment for these forest types. Lower stem density for thinned stands lead to much larger tree increment of single trees, compared to the unthinned reference. The findings of this study need verification for other soil and climatic conditions.

scholarly journals Stand structure links up canopy processes and forest management

2009 ◽  
Vol 51 (1) ◽  
pp. 40-48
Author(s):  
Toomas Frey
Keyword(s):  
Forest Management ◽  
Stand Structure ◽  
Net Primary Production ◽  
Stand Density ◽  
Tree Height ◽  
Belowground Biomass ◽  
Unit Mass ◽  
Total Biomass ◽  
Individual Tree ◽  
Mean Values

Stand structure links up canopy processes and forest management Above- and belowground biomass and net primary production (Pn) of a maturing Norway spruce (Picea abies (L.) Karst.) forest (80 years old) established on brown soil in central Estonia were 227, 50 and 19.3 Mg ha correspondingly. Stand structure is determined mostly by mean height and stand density, used widely in forestry, but both are difficult to measure with high precision in respect of canopy processes in individual trees. However, trunk form quotient (q2) and proportion of living crown in relation to tree height are useful parameters allowing describe stand structure tree by tree. Based on 7 model trees, leaf unit mass assimilation activity and total biomass respiration per unit mass were determined graphically as mean values for the whole tree growth during 80 years of age. There are still several possible approaches not used carefully enough to integrate experimental work at instrumented towers with actual forestry measurement. Dependence of physiological characteristics on individual tree parameters is the missing link between canopy processes and forest management.

scholarly journals Tropical mountain cradles of dry forest diversity

2005 ◽  
Vol 102 (31) ◽  
pp. 10757-10758 ◽  
Author(s):  
C. W. Dick ◽  
S. J. Wright
Keyword(s):  
Dry Forest ◽  
Forest Diversity ◽  
Tropical Mountain

scholarly journals A New Diameter Distribution Model for Unmanaged Loblolly Pine Plantations in East Texas

2006 ◽  
Vol 30 (1) ◽  
pp. 13-20 ◽  
Author(s):  
Young-Jin Lee ◽  
Dean W. Coble
Keyword(s):  
Loblolly Pine ◽  
Pine Plantations ◽  
Growth And Yield ◽  
Distribution Model ◽  
Diameter Distribution ◽  
Yield Prediction ◽  
East Texas ◽  
Distribution Models ◽  
Parameter Recovery ◽  
Diameter Classes

Abstract A parameter recovery procedure for the Weibull distribution function based on four percentile equations was used to develop a diameter distribution yield prediction model for unmanaged loblolly pine (Pinus taeda L.) plantations in East Texas. This model was compared with the diameter distribution models of Lenhart and Knowe, which have been used in East Texas. All three models were evaluated with independent observed data. The model developed in this study performed better than the other two models in prediction of trees per acre and cubic-foot volume per acre (wood and bark, excluding stump) across diameter classes. Lenhart’s model consistently underestimated the larger-diameter classes because it was developed originally with data mostly collected in young plantations. Knowe’s model overestimated volume in sawtimber-sized trees, which could lead to overestimations of volume in older loblolly pine plantations found in East Texas. An example also is provided to show users how to use this new yield prediction system. These results support the recommendation that forest managers should use growth and yield models designed and/or calibrated for the region in which they are implemented.South. J. Appl.For. 30(1):13–20.

scholarly journals Stand structure indices as tools to support forest management: an application in Trentino forests (Italy)

2013 ◽  
Vol 59 (No. 4) ◽  
pp. 159-168 ◽  
Author(s):  
F. Pastorella ◽  
A. Paletto
Keyword(s):  
Spatial Distribution ◽  
Forest Management ◽  
Species Diversity ◽  
Species Composition ◽  
Tree Species ◽  
Stand Structure ◽  
Composite Index ◽  
Mutual Position ◽  
Tree Species Composition ◽  
North East

Stand structure and species diversity are two useful parameters to provide a synthetic measure of forest biodiversity. The stand structure is spatial distribution, mutual position, diameter and height differentiation of trees in a forest ecosystem and it highly influences habitat and species diversity. The forest stand and species diversity can be measured through indices that provide important information to better address silvicultural practices and forest management strategies in the short and long-term period. These indices can be combined in a composite index in order to evaluate the complex diversity at the stand level. The aim of the paper is to identify and to test a complex index (S-index) allowing to take into account both the tree species composition and the stand structure. S-index was applied in a case study in the north-east of Italy (Trentino province). The results show that the Norway spruce forests in Trentino province are characterized by a medium-low level of complexity (S-index is in a range between 0.14 and 0.46) due to a low tree species composition rather than to the stand structure (diametric differentiation and spatial distribution of trees). &nbsp;

Sign in / Sign up

Export Citation Format

Share Document