Trees Ha-1 Research Articles

Climatic Variations Influenced Distribution and Productivity of Different Agroforestry Systems in Rajasthan, India

Farmers of Rajasthan conserve and promote scattered trees and shrubs growing on farmlands to dealwith climatic adversities. These woody perennials sustain livelihoods by providing economic, social, and environmental benefits. Tree-based farming systems were surveyed in all 10 agroclimatic zones (ACZs) of Rajasthan for screening best models and suggests for further improvement. Trees were assessed for density, and growth parameters in 0.5 ha plots, whereas agricultural crops yields were estimated in1 m2 plots laid at 1 m from tree trunk, canopy edge and 5 m away from trees canopy (control). There were 107 tree-crop combinations involving 14 trees and 21 crop species. P. cineraria-based systems were dominant in the arid western, whereas A. nilotica dominated in semi-arid to dry sub-humidregions. Average tree density was 11.7 trees ha-1 ranging from 3.3 tree ha-1 in ACZ-IIIb to 23.6 tree ha-1 in ACZ-IIa. Senegalia senegal showed highest (27.6 tree ha−1) density. Height and canopy diameter were 11.73 m and 10.35 m respectively, in irrigated ACZ- IIIb and decreased to 6.53 m and 5.02 m in ACZ-IIb, respectively. Both height and density decreased with the decrease in rainfall from south-east to north-west. D. sissoo and T. grandis were taller, S. oleoides was thicker and Z. mauritiana was shorter and thinner than other species. Grain yields varied from 0.66 in ACZ-Ia to 1.85 Mg ha-1 in ACZ-IIIa, but exhibited low yield as compared to control. Crop yield reduced by 22.9-47.3% between ACZs, 20.3-56.5% between agroforestry systems, and 15.9-79.8% between intercrops highlighting the interactive effects of these components. S. senegal, T. undulata, P. cineraria, Z. mauritiana, S. oleoides, V. tortilis and P. juliflora based systems showed 29.1-54.9% low, whereas V. nilotica, D. sissoo, A. indica, T. grandis and V. leucophloea based systems showed 4.5-51.7% high yield over the state average. The yield of groundnut (IIIa), cotton (IVa), barley (IIIa), jowar (IVa), maize (IVa), paddy (V), pearl millet (IIIa) and wheat (V) with A. nilotica was above state average

Agroforestry status, services, and its role in climate change mitigation through carbon sequestration under semi-arid conditions

Agroforestry systems play a dynamic role in sequestering atmospheric carbon to keep the environment safe and provide various benefits such as food, fodder, fuel wood, increased farm income, biodiversity maintenance, and soil conservation. The present study assessed agroforestry's status, services, and role in climate change mitigation through carbon sequestration in three districts of Punjab, Pakistan: Chiniot, Faisalabad, and Sargodha. In the current study, the administrative geographical division, which is the village, union council, Tehsil, and district, was considered for sampling. Field visits were carried out in 175 rural union councils of 14 Tehsils of selected districts to collect socio-economic data through validated questionnaires and tree inventory data to estimate carbon stocks. Research results revealed that most of the respondents in the study area were middle-aged, had about 8–10 years of education, and had less than 5 hectares of landholding. Nearly 34 % to 36 % of farmers earned 359.59 to 1438.37 USD annually, with farming as a major income source. Linear planting was the dominant form of agroforestry, with P. deltoides, D. sissoo, and E. camaldulensis being major tree species. The current number of trees ha-1 was 19–25, while the potential trees ha-1 could be 57–72 in the study area. Across 14 tehsils of selected districts, the maximum total tree carbon stock (8.97 Mg ha-1) and total tree CO2 sequestration (32.21 Mg ha-1) was estimated in Tehsil Lalian of district Chiniot while the lowest total tree carbon stock (1.82 Mg ha-1) and total tree CO2 sequestration (7.34 Mg ha-1) were estimated in Tehsil Faisalabad of district Faisalabad. The results of this study highlight that the eco-friendly advantages of agroforestry can be used to improve approvals and strategies on the selection and management of tree species, along with land use systems for designing effective carbon sequestration projects in Pakistan.

Dasometric variables that determine fuel load in oak forests in Guerrero, Mexico

Climate change and the lack of fuel management in oak forests promote favorable conditions for the occurrence of forest fires. The objective of the present research was to know the relationship of dasometric variables, terrain slope (Pe), depth of leaf litter (Ph) and depth of mulch (Pm) on the fuel load in oak forests in the Mountain region of Guerrero. The dasometric variables mean diameter (Dm), mean height (Am), number of trees ha-1 (Na) and basal área ha-1 (Ab) were evaluated according to the sampling design of the 2015 National Forest and Soil Inventory; At each sampling site, three planar intersection lines were established for sampling woody material (Ml), leaf litter (Ho) and mulch (Ma) were collected in 0.09 m2. The total fuel load ranged from 23.2 to 46.5 t ha-1 (p < 0.05), the Ma presented the highest load with 43%, followed by woody material (Ml) and leaf litter (Ho) with 31 and 26%. The total charge (Ct) showed a relationship with Ma, Ho and Ml (r = 0.81 to 0.41), Ho with Ph and Pe (r = 0.71 and -0.72). The c1h showed a relationship with Na, Ma, Pe and Dm (r = 0.72 to -0.41), the c10h showed a correlation with Ab, Pe and Na (r = 0.51 to 0.42). The dasometric variables only explain the fuel load with a diameter less than or equal to 2.5 cm.

Fenotipos sobresalientes de Pinus chiapensis y Pinus douglasiana en rodales bajo manejo forestal en Oaxaca

In some areas of Oaxaca, Mexico, it is necessary to implement plantations that use seeds of genetic quality, to increase productivity and phenotypic quality. The objective was to select outstanding phenotypes of Pinus chiapensis (Martínez) Andresen and P. douglasiana Martínez, evaluating quantitative and qualitative characteristics. In 2021, 15 superior phenotypes per species were selected to evaluate inventory variables (height, diameter), density (trees ha-1), age and chip increments, recording climate and site data. Crown area (m2), basal area (m2) and total volume with bark (VTcc, m3) were determined for each tree; site index (SI) was determined based on anamorphic curves, density guides and average VTcc. Data were analyzed with Student's t tests, Pearson's correlation (a = 0.05), cluster analysis, and principal component analysis. The species showed significant differences (p ≤ 0.01) in dasometric characteristics. Using the average volume as a selection criterion, six P. chiapensis trees presented volumes above average (≥ 9.76 m3) and seven P. douglasiana trees presented volume above average (> 4.14 m3) and clear stem height (18.7 m), in places with high precipitation; while comparing morphological, of site and climatic characteristics, 10 individuals of P. chiapensis and six of P. douglasiana with excellent quality IS were selected. The selected trees have outstanding characteristics of wood quality and volume, so it is convenient to use them to collect seeds in the study area.

Risk analysis and cacao pod survivorship curves to improve yield forecasting methods

Cocoa attainable yields are affected by a complex of pests and diseases in a particular agro-environment. Estimation of yield loss is critical for agronomic and economic decision-making at the farm level. For over 15 months, we monitored 1100 pods from six cocoa clones (PMCT-58, CC-137, CATIE-R1 CATIE-R4, ICS-95, and CCN-51) to assess the incidence of pests and diseases and to elucidate their survival behavior. Cocoa clones grow in a 12-year timber-based cocoa agroforestry plot (1330 cocoa plants ha-1, 100 shade trees ha-1, and 65% shade cover), in La Montaña, Turrialba, Costa Rica. Between 6-12 trees and 120-140 pods per clone of four size classes (very small – 2.5-7 cm, small – 7.1-14 cm, medium – 14.1-21 cm, and large – ≥21 cm) were tagged and measured fortnightly. Pods were selected at two vertical strata along the tree trunk (below and above 1.5 m) and grouped into three generations (rainy, transition, and dry). Competitive risk and survival analysis were performed per clone, generation, pod size class, and pod position along the tree trunk. Overall, pods reached maturity at the age of 155-165 days and were exposed to several hazards that disrupted their development. The Cox model that better described the cumulative risk during pod development included two covariables with substantial explicative power, generation, and clones. Regardless of clone and pod generation, a combination of diseases/pests accounted for about 45% to 65% of yield losses. The Kaplan-Meier survival analysis showed that pod survival was similar between generations but differed among clones within generations. Pods from CATIE-R1, CATIE-R4 and CC-137 clones showed greater survival rates than those of ICS-95, CCN-51 and PMCT-58 clones. The position of the pod along the tree trunk did not influence pod survival rates. We combined pod counting and pod survival rates calculated in this study and contrasted our yield estimations against a widely used prediction method proposed by a certification body. Overall, yield estimated using the UTZ method applied to 90-day-old pods of CATIE-R1 clone consistently overestimated yield predictions in the range of 27-45%. We proposed the combination of pod counting and pod index with a set of clone-specific discount factors; the survival rates, to reliably forecast on-farm cacao yields over time.

Differential effects on soil water repellency of Eucalyptus and Pinus plantations replacing natural pastures

ABSTRACT Land-use changes from native pastures to forest plantations in humid temperate areas have raised concerns about their potential impact on the environment. This study aimed to assess the effects of such changes on soil water properties, focusing on the impact of the forest species planted and their relationship with changes in soil C content. Specifically, we aimed to identify the development of surficial soil hydrophobicity and changes in soil water holding capacity. A long-term forest experiment with variable planting densities (816, 1111, and 2066 trees ha -1 ) of Eucalyptus grandis Hill ex Maiden and Pinus taeda L. was established in 2004 on native pasture vegetation. Undisturbed soil samples (0.00-0.03 m soil layer) were extracted from the experiment and surrounding pastures and soil water repellency was determined by the water drop penetration time (WDPT) method at three soil matric potential levels (SMP). Bootstrapping was used to test if the sample size was sufficient to obtain robust results. Replacing native pastures with forest plantations significantly increased surficial soil hydrophobicity, which was more pronounced under Eucalyptus grandis than under Pinus taeda. Soil water repellency increased with decreasing SMP, particularly in land-uses that generated higher initial hydrophobicity. Additionally, the soils under forest cover had less water retention capacity than those under pastures at each SMP, with larger differences when the soil was dried to more negative SMP. More research is necessary to determine if soil alterations from converting native pastures to forest plantations in temperate climates will lead to a significant decrease in soil water holding capacity and an increase in hydrophobicity at deeper depths.

Thinning increases forest ecosystem carbon stocks

Thinning, a major measure of forest management, is known to alter carbon sequestration by affecting the forest microclimate and soil environmental conditions. However, how thinning effect on forest ecosystem carbon stocks have presented inconsistent results. Therefore, we conducted 1776 pairs of thinning experiment observations worldwide to explore how thinning affects forest vegetation and soil carbon stocks. The results showed that overall thinning significantly increased total tree aboveground biomass carbon stocks (AGCtotal, +23.9%, +1.3 Mg ha-1 yr-1), understory vegetation carbon stocks (UVC, +68.3%, 0.12 Mg ha-1 yr-1), and soil organic carbon stocks (SOCstocks, +4.8%, 1.0 Mg ha-1 yr-1) at the global, but exhibited significantly decreased carbon stocks of litterfall (LBC, –9.6%, –0.03 Mg ha-1 yr-1). Belowground biomass carbon stocks remained unchanged under thinning. The sensitivity of carbon sequestration to thinning gradually disappeared after 6 years, except for AGCtotal, as they were jointly subject to stand density and thinning intensity and not just recovery ages. The response to UVC was more positive in medium-density (1500 – 3000 trees ha-1) and moderately thinned (30 – 50%) stands, and the thinning effects on UVC and SOCstocks were more noticeable in the subtropical and temperate zones. In summary, thinning enhanced forest ecosystem carbon sinks (+2.4 Mg ha-1 yr-1) but reduced carbon stocks in low-density stands (≤ 1500 trees ha-1). Soil moisture content (SMC, +6.6%) and bulk density (BD, –1.5%) dynamics after thinning were important factors regulating vegetation growth and soil carbon cycling processes.

Relações entre o espaçamento arbóreo e características do campo nativo em sistemas silvipastoris no bioma Pampa

ABSTRACT: The current study assessed the association of eucalyptus-tree spacing with forest growth and yield, as well as with the floristic composition, diversity and yield of natural grassland grown in silvopastoral systems in Pampa biome. Data were collected in six family cattle-ranching area in Bagé County (RS). The effect of two different genetic materials (seminal-origin Eucalyptus dunnii plant and one Eucalyptus grandis clone) on shading features of plants grown in 3 planting-spacing dimensions(625, 312 and 208 trees ha-1) was assessed, as well as their association with herbaceous extract (bare soil; green cover; forage dry matter; floristic composition; species richness; and grass, legumes and winter - and summer-growth species rates) and forestry (litter accumulation, diameter at breast height, total height and volume per hectare) variables. Planting carried out at the highest tree density (625 trees ha-1) has increased forest yield. However, it reduced green cover, herbaceous extract dry-matter yield and species richness, mainly in grasses and legumeswith greater forage potential. Conversely, it is possible combining forestry and animal yield to the preservation of native forage species at low tree densities (204 to 312 trees ha-1).

Vegetation composition, tree diversity, Biomass and carbon stock of Kanger Valley National Park

This study focuses on vegetation composition, tree diversity, biomass and carbon stock within Kanger Valley National Park of Bastar district (C.G), a biodiverse hot spot located in central India. The research comprised of systematic field surveys to identify and document tree species present in various zones of the park. A combination of quantitative measures such as Phytosociological analysis, diversity indices, biomass and carbon stock were estimated. Density and basal cover of tree layer across the three study sites were 220 to 520 trees ha-1 and 18.56 to 26 m2 ha-1, respectively. Sapling layer density and basal cover across the three study sites were 110-260 trees ha-1 and 0.34-0.74 m2 ha-1, respectively. Shannon-Wiener diversity index respectively ranges from 2.88 to 3.39 for tree layer and 2.29 to 3.96 for saplings layer. Equitability were from 1.10-1.25 and 1.29 -1.59, respectively for tree and sapling layer, whereas, species richness was from 3.08- 5.53 for tree layer and 3.64 to 13.58 for sapling layer. Total biomass across the study sites was between 286.43 and 3144.44 t ha-1, and was maximum on site-1 and minimum on site III. Litter layer also followed the similar trend being maximum (3.85 t ha-1) on site I and minimum on site III (2.62 t ha-1). The total carbon stock ranged between 110.52t ha-1 and 133.87 t ha-1, being maximum on site I, and minimum on site III. The dominated tree species on site I was Anogesisssus latifoia and Caseria graveolens, site II was dominated by Shorea robusta and Pterocarpus marusupium ans site III was dominated by Schleichera oleosa and Semecarpus anacardium. Study revealed that the structure, diversity, biomass and carbon stock in present sudy site are the result of protection and conservation.

Goupia glabra não recupera seu estoque de madeira após um ciclo de corte de 35 anos na Amazônia brasileira: evidências de monitoramento de longo prazo em múltiplas áreas

ABSTRACT Single-rule management is often adopted for various tropical forest timber species due to limited knowledge on species-specific growth and the relationship between logging intensity and recovery time. This study provides information to support sustainable management of Goupia glabra by simulating its wood stock recovery over a 35-year period following logging using data from six areas in the Brazilian Amazon. Monitoring periods after the first harvest cycle varyed from 16 to 29 years, and logging intensity from 0.000 to 0.696 m² ha-1. Tree density of G. glabra varied from 0 to 22 trees ha-1 and dominance from 0.00 to 7.39 m² ha-¹. Frequency of tree diameters was almost evenly distributed across diameter classes, slightly higher in the first (20-30 cm) class. These parameters generated estimations of recovery rate from 12 to 85%, showing that 35 years is insufficient for trees with DBH ≥ 20 cm in all study areas to grow and replace the stock of trees with DBH ≥ 50 cm harvested during the first cycle. Minimum recovery periods from 48 to 83 years were estimated to guarantee the recovery of the wood stock in the study areas. These findings reinforce the need to adapt management rules according to the population dynamics of each timber species and each logging area, and suggest the need for changes in the current legal requirements that define forest management in the Amazon.

Sistema de silvipastoril com alta densidade de árvores acelera a degradação de capim tropical

ABSTRACT Tree density is an important aspect in silvopastoral system (SPS) planning, since low luminosity can limit forage perenniality, especially for tropical forages of C4 metabolism. The objective with this study was to verify if an SPS with high tree density accelerates the pasture degradation process and changes the forage chemical composition. The experiment was carried out by comparison of marandu palisade grass [Urochloa brizantha (Hochst. ex A. Rich.) R. D. Webster] pasture in two systems: silvopastoral and open pasture. In the SPS, teak (Tectona grandis) was planted with a density of 750 trees ha-1. Evaluations were carried out over three years (2015, 2016 and 2017). SPS shading reduced herbage mass, tiller density and soil cover over the years. In the marandu palisade grass in the SPS there was a greater stem proportion, which favoured lesser potential digestible dry matter in the first year. Even with a higher amount of stem, higher crude protein concentration and minerals were observed in the SPS. Due to the high density of trees, excessive shading accelerated the process of degradation of the pasture, which demonstrates that planning of the spatial arrangement of tree species is crucial.

Tree species composition, growing stock and biomass carbon dynamics of the major timber species in Hindu Kush regions of Pakistan.

Using inventory data, this study evaluates the species composition, growing stock volume (GSV), and biomass carbon (BMC) of the five major timber species in the sub-tropical, and temperate/sub-alpine regions of Pakistan. It was found that the stem density varies between 50 and 221 trees ha -1, with a mean of 142 trees ha-1 (13.68 million trees for entire forest area). Among the species, Pinus wallichiana showed a high species composition (27.80%) followed by Picea smithiana (24.64%). The GSV was found in the range of 67.81 to 425.94 m3 ha-1, with a total GSV value of 20.68 million m3 for the entire region. Similarly, The BMC ranged from 27.04 to 169.86 Mg ha-1, with a mean BMC value of 86.80 Mg ha-1. The total amount of stored carbon was found at 8.69 million tons for a total of 95842 ha of commercially managed forest. Furthermore, the correlation analysis between the basal area (BA) and GSV and BMC showed that BA is the best predictor of GSV and BMC. The findings provide insights to the policy makers and forest managers regarding the sustainable commercial forest management as well as forest carbon management in the recent global carbon management for climate change mitigation.

Cocoa agroforestry systems and yield dynamics within the Offinso Municipality of Ghana.

Cocoa production remains an important player in Ghana’s economy. Over the years, there has been a shift from the traditional cocoa agroforestry system to full-sun cocoa production. Due to extreme exposure to high temperatures, sunlight and drought, the photosynthetic mechanism of cocoa is altered, reducing yield.Cocoa agroforestry provides economic, social, and ecological benefits and plays subsistence functions such food and fuelwood. The study was carried out to assess cocoa agroforestry systems based on shade and its effect on yield in the Offinso Municipality of Ghana. The study aimed to identify the types of cocoa agroforestry systems based on shade, determine the factors affecting cocoa agroforestry systems and assess the impact of shade regime on cocoa yield in the municipality. Purposively cocoa farmers were randomly and were adminis-tered with questionnaires. The study revealed that farmers in the Offinso Municipality practice all types of cocoa agroforestry systems (full sun, low shade, medium shade, and heavy shade). The cultivation of cocoa under medium shade (15–18 trees ha-1) proved to be beneficial and essential for the long-term production ofcocoa. The medium-shade cocoa recorded a higher average yield of 1576 kg ha-1. Six common shade trees identified include Terminalia superba (ofram), Ricinodendron heudelotii (wawa) and Chlorophora excelsa (odum). Some challenges faced as a result of practicing the cocoa agroforestry system were pest infestationand diseases such as that of the black pod. Cocoa agroforestry still holds the key to sustainable future outputs in cocoa production as it drives the realization of SDG goal 13 (climate action). There is therefore the need to educate farmers on managing their farms with trees for optimum ecological and economic benefits.

Forest Structure and Tree Species Diversity of the Abasumba Globally Significant Biodiversity Area, Ghana

We studied the forest structure and tree species diversity with diameter-at-breast-height (dbh) ≥ 10 cm in the Abasumba Globally Significant Biodiversity Area Ghana. Sixteen 25 m * 25 m plots were demarcated and trees with dbh ≥ 10 cm were inventoried following International Plant Nomenclature Index. The characteristic three–storey structure of tropical forests was shown, 68.7% of trees were in the lower 4.5–18 m and middle 18–30 m storeys. A majority 91.4% of 342 trees was in the dbh of 10–30 cm and a least 8.6% of 32 trees in 31–60 cm had dbh ˃ 60 cm. Total of 46 species, 38 genera and 17 families, with mean Alpha, Shannon and Simpson’s Diversity indices of 13.9, 1.44 and 0.07 and importance value index of 300.0 for 374 trees ha-1 was recorded. Plant families Sterculiaceae, Meliaceae, Leguminosae, Ulmaceae and Bombacaceae was the majority encountered while Triplochiton scleroxylon, Cola millenii, Trichilia monadelpha, Hymenostegia afzelii, Celtis mildbraedii, Ceiba pentandra and Ficus sur was the most occurring species in 54.0% of the plots accounting for 52.0% of the IVI for all trees. Blighia sapida, Bridelia grandis, Dialium guineense, Draceana arborea, Ficus sur, Holarrhena floribunda, Holoptelea grandis, Margaritaria discoidea, Rauvolfia vomitoria, Trilepisium madagascariense, Vitex ferruginea, Ximenia americana and Xylia evansii had one individual in the 10,000 m2 area indicated that they are rare and should be given conservation priority in the forest reserve.

Biodiversity and biomass relationships in a cerrado stricto sensu in Southeastern Brazil.

Deforestation accounts for the majority of greenhouse gas emissions in developing countries. In Brazil, deforestation represents ~ 70% of the nation's greenhouse gas emissions. Among the main deforested vegetation, Cerrado (Brazilian savanna) occupies a prominent position as it is the second biggest biome in Brazil. Despite its importance, there are still few estimates of above and belowground biomass of Cerrado vegetation encompassing its structural and spatial complexity. Also, Cerrado holds a specific biodiversity that is normally undervalued and which is being lost in the fires of agricultural fronts. In this context, this study aimed to verify the relationship of the existing flora biodiversity in a cerrado stricto sensu with its aboveground biomass and carbon stocks. The possibility of a relationship between fine root mass and soil organic carbon content was also verified. The study area presented a total of 67 species and 798 trees (average: 1596 trees ha-1). The mean total aboveground biomass and carbon stocks were 77.08Mgha-1 and 38.54Mgha-1 respectively. Soil organic carbon stock (0-30cm) was 8.51Mgha-1 whereas fine roots were 1.637Mgha-1. Total aboveground biomass presented a highly significant asymptotic relationship with biodiversity demonstrating its importance in reaching high biomass accumulation. A significant relationship between soil organic carbon content and fine root biomass was found making easier belowground biomass estimates.

Avocado (Persea americana Mill.) production in Huatusco, Veracruz, Mexico

Objective: To characterize the avocado production system in Huatusco, Veracruz. Design/Methodology/Approach: Interviews based on the snowball method were applied to avocado producers in Huatusco, Veracruz. Meanwhile, fruit and water samples were used to perform a multiresidue analysis of pesticides. Results: The monoculture plantations are rainfed. They have a density of 100-150 trees ha-1. The Hass variety predominates in Andosols, with 5-100% slopes. Most of the producers (92%) carry out conventional management, applying pesticides and chemical fertilizers. Herbicides and brushcutters are used to control weeds. No pesticides were detected in the water samples, while Imidacloprid, Thiabendazole, and alpha-Cypermethrin were identified in a fruit sample, with 0.0038 ± 0.0014 mg/kg, 0.0022 ± 0.0009 mg/kg and 0.0703 ± 0.000 mg /kg concentrations, respectively. These concentrations fall within the limits allowed in Mexico. Study Limitations/Implications: A detailed and frequent sampling of avocado fruits should be carried out to determine pesticide residues. It is also necessary to analyze samples of running water near the orchards to prevent pollution. Findings/Conclusions: The empirical knowledge of the producers about the type of soil is more precise than the scientific classification: they identify five classes of soils beyond Andosols. Additionally, there is a marked inequality in land tenure, since large-scale producers (25% of all producers) own 86% of the established area. Although, in a preliminary sampling, pesticide concentrations did not exceed the limits of residues allowed in the avocado pulp, the number of pesticide applications should be reduced.

Natural regeneration and species diversification after seed-tree method cutting in a maritime pine reforestation

Forest adaptation to global change has become one of the main objectives of forest management in recent years. Species and structural diversification by thinning is a well-known adaptation measure, often applied by managers in monospecific even-aged stands. However, regeneration fellings may be more efficient for enhancing naturalization and resilience of monospecific reforested pine stands, widely distributed throughout the Mediterranean basin. This work focuses on the evaluation of natural regeneration after seed-tree method cuttings, adopted as a diversification strategy in a 60-year old P. pinaster reforestation with varying presence of broad-leaved species (mainly Quercus spp.) in mountains of Southern Spain. A trial consisting of 78 circular plots (1 m radius) was installed to monitor annual tree-species regeneration over seven years, classified into seedlings (0-10 cm height) and saplings (10-130 cm). Scrub coverage and other ecological variables were also measured. Sampling was carried out in three stand types (Pure, Mixed 1 and Mixed 2, in order of increasing presence of broad-leaved species), according to forest species composition before the felling. Maritime pine regeneration was successfully achieved by the end of the study period (over 2000 trees ha-1 widely distributed throughout the stand), whereas Quercus spp. seedlings even colonised plots in which there were no seed trees. Pine seedling density was positively affected by summer precipitation and the presence of conspecific adult pines, and negatively influenced by scrub coverage. High temperatures during the mid-summer months (especially August) negatively affected the seedling to sapling change ratio as well as sapling survival during the study period. Our results point to regeneration fellings with retention of pine and broadleaf species as a suitable method for diversifying species composition in Pinus pinaster reforestations in the Mediterranean region.

Historical record of the problem of the natural repopulation of the linaloe Bursera linanoe (La Llave) Rzedowski, Calderón & Medina

The linaloe it is a tree that produces a fine resin. Produces essential chemical, aromatic, cosmetic, pharmaceutical, and industrialcompounds of high commercial value, only grows in Mexico, in the middle portions of the Papaloapan and Balsas River basins.The excessive use of its wood and its fruit to obtain essential oil, the destruction of the low forest where it lives, disorderly grazingand some environmental and biological constraints have generated an excessively low, discontinuous and sparse naturalrepopulation. The study of the causes of this threatening scenario is scarce and discouraging, insufficient to propose appropriatesolutions. This motivated the present analysis of silvicultural conditions, present regeneration and basic aspects of reproductivebiology in three natural populations from Oaxaca, Puebla and Guerrero. Very few trees ha-1 (36 to 45) were found, with fewfemales (35%). Diameters ranged from 5 to 35 cm, with maximum heights from 10 to 14 m. The regeneration in Chiautla was 21individuals ha⁻¹, while in Los Cués and Xalitla no regeneration was found. When reviewing the reproductive biological factors ofthe species, it was observed that the stages of flowering, fruiting and seed dispersal are seriously limited by low rainfall and theoccurrence of these in short, rare and irregular pulses. The flowering potential is high and increases with the diameter of the femaletrees, but the conversion of flowers to full and viable fruits produced is limited by the rainfall regime. Germination is notablydecimated by the frugivorous activity of birds and mammals. The new plants are trampled and browsed by livestock and wildmammals. The simultaneous occurrence of some or all of the limitations dangerously endangers populations. Assisted propagationis suggested to guarantee the permanence of the species.

Mapping of Mangrove Ecosystem In Segara Anakan Lagoon using Normalized Different Vegetation Index and Dominant Vegetation Index

Mangrove ecosystem in Segara Anakan Lagoon (SAL) Cilacap as a typical and specific semiclosed estuary. SAL is dominated by many species like as Rhizophora spp., Sonneratia spp., Bruguiera spp., Avicennia spp., and other species. The normalized different vegetation index (NDVI) and dominant vegetation index (DVI) are a suitable method to support the mapping analysis of mangrove structure and mangrove density. This research aimed to develop mapping of mangrove species distribution, density and dominated species using NDVI and DVI. The method of this research used NDVI analysis using satellite imagery 2017-2020 and domination vegetation with line and quadrat transect method. The results showed that West Segara Anakan had mangrove dense (25 %), moderate density (25 %), rare density (50%) and East Segara Anakan had mangrove dense (43,86 %), moderate density (47.99 %), rare density (8,24 %). Based on domination species showed that East Segara Anakan was dominated by Rhizophora stylosa (233-1633 trees ha-1), Rhizophora apiculata (100-1067 trees ha-1), Nypa frutican (50-2775 trees ha-1), whereas West Segara Anakan was dominated by Nypa frutican (565-2333 trees ha-1), Avicennia marina (198-933 trees ha-1), Sonneratia caseolaris (132-700 trees ha-1) and Avicennia alba (107-1000 trees ha-1). Keywords : Mangrove density, mapping analysis, Segara Anakan Lagoon, NDVI and NDWI

Forest restoration treatments increased growth and did not change survival of ponderosa pines in severe drought, Arizona.

We report on survival and growth of ponderosa pines (Pinus ponderosa Douglas ex P. Lawson & C. Lawson) 2 decades after forest restoration treatments in the G. A. Pearson Natural Area, northern Arizona. Despite protection from harvest that conserved old trees, a dense forest susceptible to uncharacteristically severe disturbance had developed during more than a century of exclusion of the previous frequent surface-fire regime that ceased upon Euro-American settlement in approximately 1876. Trees were thinned in 1993 to emulate prefire-exclusion forest conditions, accumulated forest floor was removed, and surface fire was re-introduced at 4-years intervals (full restoration). There was also a partial restoration treatment consisting of thinning alone. Compared with untreated controls, mortality of old trees (mean age 243 years, maximum 462 years) differed by <1 tree ha-1 and old-tree survival was statistically indistinguishable between treatments (90.5% control, 92.3% full, 82.6% partial). Post-treatment growth as measured by basal area increment of both old (pre-1876) and young (post-1876) pines was significantly higher in both treatments than counterpart control trees for more than 2 decades following thinning. Drought meeting the definition of megadrought affected the region almost all the time since the onset of the experiment, including 3 years that were severely dry. Growth of all trees declined in the driest 3 years, but old and young treated trees had significantly less decline. Association of tree growth with temperature (negative correlation) and precipitation (positive correlation) was much weaker in treated trees, indicating that they may experience less growth decline from warmer, drier conditions predicted in future decades. Overall, tree responses after the first 2 decades following treatment suggest that forest restoration treatments have led to substantial, sustained improvement in the growth of old and young ponderosa pines without affecting old-tree survival, thereby improving resilience to a warming climate.