Eucalyptus Monoculture Research Articles

Assessment of Impacts of the Forest Incentive Program based on Eucalyptus Monoculture with the 'INOVA-Tec System'

The paper and cellulose industry uses as a source of raw material wood only from harvested forests, either in one’s own lands or in other people’s cultivated land, through land lease agreement or forest development programs. The present work suggests the use of a method created to evaluate the impacts of technological innovations, the Inova-tec System with modifications, to evaluate the impacts of the ‘Forest Incentive Program (Programa de Fomento Florestal) based on a Eucalyptus monoculture’. The method ‘INOVA-Tec System’ is a system that allows the analysis of: i) the scenario to develop the program, and ii) the performance evaluation of the program, through the analysis of indicators performance. With the data on hands, it is easier for the evaluator to elaborate his/her recommendation list to guarantee a proper culture management and the best impact management, in order to mitigate the potentially problematic characteristics for the environment and for the society.

Impacto do manejo de resíduos orgânicos durante a reforma de plantios de eucalipto sobre indicadores de qualidade do solo

O uso agrícola do solo causa alterações em suas características físicas, químicas e microbiológicas. A conseqüência dessas alterações pode ser a perda da qualidade do solo, o que compromete a sustentabilidade do uso desse recurso. A análise de indicadores bioquímicos e microbiológicos de qualidade do solo é relevante para monitorar mudanças na qualidade do solo e no desempenho de suas funções-chave, como a capacidade de ciclar e armazenar nutrientes. Neste estudo, avaliaram-se indicadores químicos, físicos e microbiológicos do solo em plantios de eucalipto 5,5 anos após terem sido submetidos a diferentes métodos de manejo durante a fase de reforma do povoamento. A avaliação baseou-se na determinação de 18 atributos físicos e químicos, além de 12 outros de caráter bioquímico ou microbiológico, os quais foram adotados como indicadores da qualidade do solo. Os indicadores bioquímicos e microbiológicos mostraram-se mais sensíveis para avaliar mudanças qualitativas no solo devidas ao manejo, quando comparados com os químicos ou físicos. O maior distúrbio causado pelos tratamentos em que houve remoção ou queima do material orgânico da superfície do solo foi evidenciado pelos maiores valores de qCO2 e menores valores de qMIC na camada superior do solo (0 a 5 cm). A análise de componentes principais permitiu visualizar as semelhanças entre as áreas com base em todas as variáveis analisadas. A área de vegetação natural de mata secundária, usada como referência de qualidade do solo, foi a que apresentou a maior distância gráfica das demais áreas, demonstrando que a introdução da monocultura do eucalipto modifica a qualidade do solo estudado. A qualidade do solo da área de eucalipto onde não se efetuou o corte das árvores no primeiro ciclo (povoamento com 11 anos de idade) obteve a maior aproximação da área de vegetação natural, seguindo-se os solos sob eucalipto submetido a manejos que priorizaram a conservação dos resíduos orgânicos por ocasião da reforma do povoamento. Contrariamente, as áreas onde ocorreu a remoção ou a queima do material orgânico da superfície do solo foram as que mais se distanciaram da área de referência. Esses resultados demonstram que o sistema de manejo adotado na reforma dos povoamentos de eucalipto analisados influencia, em médio prazo, o potencial dos solos de estocar e ciclar nutrientes por meio da biomassa microbiana e das atividades bioquímicas ligadas a ela. A maior aproximação entre a área com vegetação nativa e a de eucalipto com 11 anos leva a supor que ciclos mais longos nas florestas de eucalipto, contrastando com o padrão atualmente em uso no Brasil (cerca de sete anos), pode ser relevante para se manter a sustentabilidade da atividade florestal em longo prazo, a despeito de uma menor produtividade média anual. Nesse caso, a opção pela produtividade de curto ou médio prazo, ou pela sustentabilidade do uso do solo, com a conseqüente manutenção da sua qualidade para as gerações futuras, poderá ser repensada a partir dos dados aqui apresentados.

Two new species of ant-mimicking spiders of the genus Ianduba Bonaldo (Araneae, Corinnidae) from Southern Bahia, Brazil

Two new species of the ant mimicking spider genus Ianduba Bonaldo (Araneae, Corinnidae), I. mugunza sp. nov. and I. abara sp. nov., are described based on males and females from Porto Seguro, in the state of Bahia, Brazil. All specimens were collected in pitfall traps, installed in two forested areas: Estação Ecológica de Vera Cruz, a well preserved Atlantic forest fragment, and a contiguous field of Eucalyptus monoculture.

Mixed-species plantations of Eucalyptus with nitrogen-fixing trees: A review

Mixed-species plantations of Eucalyptus with a nitrogen (N 2) fixing species have the potential to increase productivity while maintaining soil fertility, compared to Eucalyptus monocultures. However, it is difficult to predict combinations of species and sites that will lead to these benefits. We review the processes and interactions occurring in mixed plantations, and the influence of species or site attributes, to aid the selection of successful combinations of species and sites. Successful mixtures, where productivity is increased over that of monocultures, have often developed stratified canopies, such that the less shade-tolerant species overtops the more shade-tolerant species. Successful mixtures also have significantly higher rates of N and P cycling than Eucalyptus monocultures. It is therefore important to select N 2-fixing species with readily decomposable litter and high rates of nutrient cycling, as well as high rates of N 2-fixation. While the dynamics of N 2-fixation in tree stands are not well understood, it appears as though eucalypts can benefit from fixed N as early as the first or second year following plantation establishment. A meta-analysis of 18 published studies revealed several trials in which mixtures were significantly ( P < 0.001) more productive than monocultures, and no instances in which mixtures were less productive than monocultures. Regression analyses of such data were more informative than indices of relative yield, and were more informative in trials that contrasted four or more different species compositions. Thus replacement series examining compositions of 100:0, 67:33, 33:67, and 0:100 were more informative than minimalist 100:0, 50:50 and 0:100 series.

Twenty years of stand development in pure and mixed stands of Eucalyptus saligna and nitrogen-fixing Facaltaria moluccana

Abstract The vast majority of tropical tree plantations are monocultures, and only a few case studies have examined growth of mixed-species plantations. Mixtures that contain nitrogen (N)-fixing species may have the potential to increase overall plantation yields, but too few case studies are available to provide general insights. We extended previous measurements of 10 years of stand development in a mixed-species experiment in Hawaii through age 20 years. The plots had a constant total number of stems initially (2500 ha−1), but varying ratios of Eucalyptus saligna (Sm.) to nitrogen-fixing Facaltaria moluccana (Miquel) Barneby & Grimes (=Albizia Facaltaria (L.) Fosberg, and Paraserianthes Facaltaria (L.) I. Nielsen). Eucalyptus stem growth declined strongly in monocultures after age of 7 years, but showed no decline in mixtures. After 10 years of stand development, Eucalyptus stem mass was greatest in the monoculture, averaging about 155 Mg/ha (versus 140 Mg/ha in the 0.5 Facaltaria treatment); total (combined) stem mass for both species was almost twice as great in mixtures as in monocultures. By the age of 20 years, Eucalyptus stem mass was within a 20% range across treatments (260 Mg/ha), and total stem mass ranged up to 430 Mg/ha in the 0.75 Facaltaria treatment. Losses of stem mass from mortality were moderate for Eucalyptus between 18 and 20 years, averaging 20–25% of gross stem growth in mixed-species treatments, but 60% in the Eucalyptus monoculture. Mortality losses of stem mass were extremely high for Facaltaria in all plots, matching or exceeding gross stem growth from age 18 to 20 years. The size of individual Eucalyptus trees was much greater in the mixed plots than in the monoculture plots, so any short-term economic gain from the mixed-species plots may derive from larger tree sizes rather than from more wood mass per hectare. The longer term benefits of mixed plots may include the effects of Facaltaria on soil fertility and community diversity. Overall, these very large changes in ecosystem production in mixtures underscores the need for a large number of additional studies to examine other species combinations, sites, and silvicultural systems.

Productivity, nutrient cycling, and succession in single- and mixed-species plantations of Casuarina equisetifolia, Eucalyptus robusta, and Leucaena leucocephala in Puerto Rico

Tree growth, biomass productivity, litterfall mass and nutrient content, changes in soil chemical properties and understory forest succession were evaluated over a 8.5-year period in single- and mixed-species (50 : 50) plantations of two N 2-fixing species, Casuarina equisetifolia and Leucaena leucocephala, and a non-fixing species, Eucalyptus robusta. At the optimal harvest age for maximum biomass production (4 years), total aboveground biomass ranged from 63 Mg ha −1 in the Eucalyptus monoculture to 124 Mg ha −1 in the Casuarina/ Leucaena mixture, and was generally greater in the mixed-species than in single-species treatments due to increased productivity of the N-fixing species in the mixed stands. Total litterfall varied from 5.3 to 10.0 Mg ha −1 year −1 among treatments, or between 5.9% and 13.2% of net primary production. Litterfall production and rates of nutrient return for N, P, K, Ca and Mg were generally highest for Leucaena, intermediate for Casuarina and lowest for Eucalyptus. These rates were usually higher in the mixed-species than in monospecific stands due to differences in biomass productivity, but varied considerably depending on their species composition. Total system carbon and nutrient pools (in biomass plus soils to 40-cm depth) for N, P, K, Ca, Mg, Mn at four years were consistently greater in the plantation treatments than in the unplanted control plots. Relative to the single-species plantations, these system pools were generally larger in the mixed-species plantations for C (−10% to +10%), N (+17% to +50%), P (−1% to +63%), K (−19% to +46%), Ca (−10% to +48%), Mg (+5% to +57%) and Mn (+19% to +86%). Whole-tree harvests at four years would result in substantial system carbon and nutrient losses, although these estimated losses would not exceed the estimated gains realized during the four-year period of tree growth at this site. At 7.5 years, soil organic matter and effective cation exchange capacity were reduced in all plantation treatments relative to the control. Changes in soil nutrient content from 0 to 7.5 years were highly variable and not significantly different among treatments, although stands containing Leucaena generally showed higher rates of nitrogen and phosphorus accretion in soils than those with Eucalyptus and/or Casuarina. Natural regeneration of secondary forest tree and shrub species increased over time in all plantation treatments. A total of 24 native or naturalized forest species were recorded in the plantations at 8.5 years. Woody species abundance at this age was significantly greater beneath Casuarina than either Eucalyptus or the Eucalyptus/ Leucaena mixed stands. Species richness and diversity, however, were greatest beneath stands containing Eucalyptus and/or Leucaena than in stands with Casuarina.

Alterations in the phytoplanktonic community in two tropical lakes induced by monoculture of Eucalyptus spp., Minas Gerais, Brazil

(1998). Alterations in the phytoplanktonic community in two tropical lakes induced by monoculture of Eucalyptus spp., Minas Gerais, Brazil. SIL Proceedings, 1922-2010: Vol. 26, No. 4, pp. 1767-1771.

Decomposition of Eucalyptus globulus leaves and three native leaf species (Alnus glutinosa, Castanea sativa and Quercus faginea) in a Portuguese low order stream

Leaf decomposition of the exotic evergreen Eucalyptus globulus (eucalyptus), and three native deciduous tree species, Alnus glutinosa (alder), Castanea sativa (chestnut) and Quercus faginea (oak), was compared in a second order stream in Central Portugal. Changes in dry weight, nitrogen and polyphenolic compounds and microbial colonization were periodically assessed for three months. Negative exponential curves fit the leaf weight loss with time for all leaf species. Mass loss rate was in the order alder (K = 0.0161) > chestnut (K = 0.0079) > eucalyptus (K = 0.0068) > oak (K = 0.0037). Microbial colonization followed the same pattern as breakdown rates. Evidence of fungal colonization was observed in alder after 3 days in the stream, whereas it took 21 days in oak leaves to have fungal colonization. Fungal diversity was leaf species-dependent and increased with time. In all cases, percent nitrogen per unit leaf weight increased, at least, at the initial stages of decay while soluble polyphenolics (expressed as percentage per unit leaf weight) decreased rapidly in the first month of leaves immersion. Intrinsic factors such as nitrogen and polyphenolic content may explain differences in leaf decomposition. The possible incorporation of eucalyptus litter into secondary production in a reasonable time span is suggested, although community balance and structure might be affected by differences in allochthonous patterns determined by eucalyptus monocultures.

An Investigation into the effect of monocultural plantation of eucalyptus camaldulensis on soil fertility status

The effect of Eucalyptus camaldulensis monoculture on soil fertility statusin the dry zone was studied comparatively with another monoculture of Tectonagrandis and a naturalforest located in the same area over a period of 5 months. Total litter production of Eucalyptus was 370.68 kglha as compared with1349.07 kglha in Tectona grandis (study period overlapped the leaf senescence)and 217.75 kglha in the natural forest. Litter decomposition was 40.22% inEucalyptus while it was 40.27% and 44.95% in naturalforest, and Tectona respectively.Nutrient release to litter at the time of fall did not differ between thevegetation types. However, it differed between the tree components and nutrients,the orders being leaves>twigs>bark and N>P>K>Ca. Significant differences (p;;;::0.05)were seen in moisture content, pH, organicmatter content, total nitrogen percentage, available potassium and calcium betweenthe soils in the vegetation types.

Growth and biomass production by young Eucalyptus tereticornis under agroforestry at Morogoro, Tanzania

A trial involving Eucalyptus tereticornis was planted in a Latin square design with five treatment plots: (1) Eucalyptus monoculture kept free from weeds (clean-weeded); (2) Eucalyptus monoculture not given any weeding after planting (unweeded); (3) Eucalyptus clean-weeded and intercropped annually with beans; (4) Eucalyptus clean-weeded and intercropped annually with maize; and (5) Eucalyptus clean-weeded and intercropped annually with sorghum. After 3 years, trees representing all size classes were harvested from the trial and used to determine above-ground biomass production and nutrient content; other trees were excavated for root biomass determination. The whole experiment was later felled to determine height, basal area and volume production in each plot. Plot mean values were in the ranges 53–94% survival, 6.4–9.2 m height, 7.6–37.8 m 3 ha −1 volume, and 8.2–45.2 tha −1 total biomass. Unweeded plots showed unsatisfactory growth and survival throughout. Other treatments grew fast and at a rate comparable to young tree plantations reported for tropical and subtropical climates. Clean-weeded monocultures and Eucalyptus intercropped with beans gave the best growth in height, volume and biomass, showing statistical significance over Eucalyptus yields under intercropping with maize and sorghum. The production data satisfy the initial objective of providing high fuelwood and pole yields under short rotations. The trees showed compatibility with the food crops studied, although a wide spacing had been recommended earlier for sustained intercropping. Nutrient concentrations were considered adequate. The accumulation of N, Mg and Ca in the biomass was small compared to soil reserves. However, P and K contents in the biomass formed up to 123 and 34% of the respective soil ‘available’ reserves.