Remnant Tree Research Articles

Effects of tree diversity and stand structure on above-ground carbon storage in evergreen broad-leaved and deciduous forests in Southeast Vietnam

Understanding the relationship between tree species diversity and above-ground carbon (AGC) storage in tropical forests is essential for a sustainable flow of ecosystem goods and services. Although tropical forests of Vietnam are of particular interest due to their high biodiversity and carbon density, few studies have evaluated the relative importance of species composition, tree species diversity and forest structure on AGC storage by forest vegetation type. In this study, we tested for the influence of taxonomic diversity, forest structure and species composition on AGC storage in evergreen broad-leaved and deciduous forests of Southeast Vietnam. Data was collected within 137 rectangular plots (25 m × 20 m), randomly selected across a deciduous forest (DF) and four evergreen broad-leaved forest (EB) categories, with different stand­ing volumes levels: very poor (EBG), poor (EBP), medium (EBM) and rich (EBR). In total, we identified 3687 individuals from 110 tree species belonging to 46 families in 6.85 hectares of sampled area. AGC stor­age significantly differed among forest categories, ranging from 14.81 Mg ha−1 in EBG to 146.74 Mg ha−1 in EBR. There was higher AGC in the medium diameter class (20-40 cm), except for EBR where there was higher AGC within individuals of 40-60 cm in diameter. Taxonomic diversity was weakly correlated with AGC while stand structure (stem density and maximum diameter) were strongly correlated. Our results suggest that maintaining the abundance distributions of remnant tree species, particularly that of large trees, is one important method to enhance AGC storage in the tropical ecosytems of southern Vietnam.

Logging effects on seedling regeneration and diversity in a tropical moist semi-deciduous forest in Ghana

ABSTRACT The effect of time lag after logging on seedling dynamics was assessed in logged and unlogged forest plots located in the Pra-Anum Forest Reserve. Remnant tree attributes were sampled in six plots with sizes of 25 × 25 m in each forest type. Within each forest type, ten subplots with sizes 1 × 1 m were established for sampling seedling regeneration dynamics. Enumerated seedlings were grouped as pioneer, non-pioneer light demander, and shade-tolerant species. Regenerating seedlings were more diverse in the recently logged forest area characterised by Broussonetia papyrifera and Musanga cecropioides, and least in the unlogged forest driven predominantly by Celtis mildbraedii and Baphia nitida. Pioneer species were primarily dominant in the recently logged forest, while shade-tolerant and non-pioneer light-demanding species characterised the logged-over forest. Species richness and canopy openness of remnant stands explained 32 percent of the variations in regeneration richness between the logged and unlogged areas. Twenty-seven percent of the variations in seedling abundance was also explained by remnant trees richness, their size diameter and the degree to which their canopy has been opened. Logging-induced disturbance favours the sporadic emergence of pioneer species in recently disturbed areas which are later replaced by non-pioneer light-demanding or shade-tolerant species as light becomes limiting in the understory.

Remnant trees increase bat activity and facilitate the use of vineyards by edge-space bats

Conversion of natural habitats to vineyard monoculture is rapidly increasing both globally and on the California central coast. Although agricultural expansion typically decreases species diversity and abundance, landscape heterogeneity can maintain biodiversity, ecosystem function, and provide pest control services within agricultural systems. Large remnant oak trees are sometimes retained within vineyards, yet little is known about their value to biodiversity or the beneficial services to grape growers. While insectivorous bats (order: Chiroptera) are natural predators of agricultural pests and commonly utilize trees for foraging and roosting, no study has quantified the influence of remnant trees within vineyards on bat abundance and diversity. During 2014 and 2015, we recorded bat activity and species richness as well as insect abundance at isolated remnant trees and paired open areas within 14 vineyards in coastal central California. We used generalized linear mixed models to assess the influence of remnant trees on total and species-specific bat activity and insect abundance, and how these effects were influenced by individual tree and landscape-scale characteristics. We recorded 11,465 bat passes representing 11 bat species. Overall, bat activity rates were 1.5 times greater at trees compared to open areas. Activity levels of low-frequency echolocators adapted to open habitats did not differ between trees and open areas; however, activity levels of high frequency echolocators adapted to edge habitats were 2.4 times higher at trees than open areas. Bat activity at trees increased with larger tree size, closer neighboring remnant trees, and lower remnant tree density in the surrounding landscape. Our study indicates that remnant trees within vineyards provide important habitat value for bats at the landscape-scale by allowing edge-space adapted bat species access to vineyards. Retention of individual large trees can help to maintain biodiversity and ecological function in vineyard landscapes, a benefit for both conservation and agricultural production.

Regional landscape-scale comparison of species composition and recruitment in remnant tree patches 3 years after the 2011 Great East Japan Earthquake and tsunami

Understanding species composition and other characteristics of remnant trees that survive large-scale low-frequency disturbances such as tsunamis is an important step in monitoring and managing the process of recovery. This research was implemented in a study area along the shores of Sendai Bay, a region that was heavily damaged by the tsunami following the Great East Japan Earthquake of 2011. Field surveys of all the remnant patches of trees in the study area were conducted in 2014, three years after the disturbance. A total of 202 remnant patches were identified, and all the tree species, including both canopy trees and newly established seedlings, were recorded for each patch. The identified trees totaled 88 species, which were classified into three indicator-species types by a hierarchical cluster analysis. Comparisons based on species composition and similarity showed that species composition and other characteristics of the remnant patches were influenced by vegetation histories and other factors that only become visible at the regional landscape scale. The number of tree and seedling species per unit area was highest in patches that originated from pine plantations. Seven of the 25 seedling species identified were not present in any of the canopy layers in the study area, indicating that they dispersed from outside this area. These results show that, despite the immense scale of the tsunami, many diverse patches of trees managed to survive the disturbance. These patches function as hubs for species dispersion and accelerate recovery of species diversity in the disturbed area.

Landscape change alters reproductive phenology and sex expression in Attalea palms (Arecaceae) of southwestern Amazonia

As deforestation and land-use/land-cover change advance in tropical forest regions, an understanding of how plants adjust phenology and reproductive dynamics to altered landscapes can provide insights into plasticity, productivity, and population persistence. We compared the reproductive phenology, sex expression, and flower and fruit production of two monoecious Amazonian palms, Attalea phalerata and Attalea speciosa, in old-growth forest and as remnant trees growing in actively grazed pastures. Using 2 years of phenology data collected from natural populations near Vila Extrema, Rondonia, and eastern Acre, Brazil, we compared flowering and fruiting in the two habitats and tested for effects of palm height, crown size, and light availability on inflorescence and sex expression. Forest conversion to pasture stimulated greater overall flowering and fruiting in individual Attalea palms. As a population, remnant pasture palms continuously bore flowers and fruits year-round, while forest palms flowered seasonally in isolated peaks with consecutive months of inactivity. Crown size and greater light exposure affected flowering and fruiting dynamics in A. phalerata and A. speciosa, respectively, and increased light availability shifted A. speciosa sex expression towards greater female investment, primarily through regulation of sex determination and bud abortion. Removal of tropical forest does not always lead to the downfall of remnant tree populations, and under favorable conditions, such as abandonment of cropland and pasture, higher levels of reproduction can facilitate recovery of future generations. Tree species with flexible sex expression may be particularly resilient in the face of land-use and land-cover change.

Tree species diversity and utilities in a contracting lowland hillside rainforest fragment in Central Vietnam

BackgroundWithin the highly bio-diverse ‘Northern Vietnam Lowland Rain Forests Ecoregion’ only small, and mostly highly modified forestlands persist within vast exotic-species plantations. The aim of this study was to elucidate vegetation patterns of a secondary hillside rainforest remnant (elevation 120–330 m, 76 ha) as an outcome of natural processes, and anthropogenic processes linked to changing forest values.MethodsIn the rainforest remnant tree species and various bio-physical parameters (relating to soils and terrain) were surveyed on forty 20 m × 20 m sized plots. The forest's vegetation patterns and tree diversity were analysed using dendrograms, canonical correspondence analysis, and other statistical tools.ResultsForest tree species richness was high (172 in the survey, 94 per hectare), including many endemic species (>16%; some recently described). Vegetation patterns and diversity were largely explained by topography, with colline/sub-montane species present mainly along hillside ridges, and lowland/humid-tropical species predominant on lower slopes. Scarcity of high-value timber species reflected past logging, whereas abundance of light-demanding species, and species valued for fruits, provided evidence of human-aided forest restoration and ‘enrichment’ in terms of useful trees. Exhaustion of sought-after forest products, and decreasing appreciation of non-wood products concurred with further encroachment of exotic plantations in between 2010 and 2015. Regeneration of rare tree species was reduced probably due to forest isolation.ConclusionsDespite long-term anthropogenic influences, remnant forests in the lowlands of Vietnam can harbor high plant biodiversity, including many endangered species. Various successive future changes (vanishing species, generalist dominance, and associated forest structural-qualitative changes) are, however, expected to occur in small forest fragments. Lowland forest biodiversity can only be maintained if forest fragments maintain a certain size and/or are connected via corridors to larger forest networks. Preservation of the forests may be fostered using new economic incentive schemes.

Estudio de hongos micorrizógenos arbusculares bajo árboles remanentes en un pastizal tropical

The remnant trees in casttle have a significant ecological importance because they alter the microhabitat and also affect biological interactions. Ali these factors improve mycorrhizal fungi establishment and forest vegetation species proliferation. The objective of this study was to determine space-temporal variation of the morphospecies of arbuscular mycorrhiza and their spores number under remnant trees. This study was carried out in a casttle, in the northern edge of the Biology Station of "Los Tuxtlas", Veracruz, Mexico. Four isolated trees (Ampelocera hottlei, Poulsenia armata and Ficus sp.) were chosen. Soil samples were collected under each tree cover during dry, rainy and "nortes" seasons. Thirteen arbuscular mycorrh izal species of the Glomaceae, Acaulosporaceae and Gigasporaceae families were observed. The number of spores among climatic seasons was significant different, the highest value was presented in "nortes" season and the lowest occurred in the dry season. There were no significant differences among isolated tree species, this could imply that the remnant tree function as a unit. Differential water availability, a long the year, may explain spores production variation.

The role of remnant trees in carbon sequestration, vegetation structure and tree diversity of early succession regrowing fallows in eastern Sierra Leone

AbstractRemnant tree presence affects forest recovery after slash‐and‐burn agriculture. However, little is known about its effect on above‐ground carbon stocks, especially in Africa. We focused our study on Sierra Leone, part of the Upper Guinean forests, an important centre of endemism threatened by encroachment and forest degradation. We studied 99 (20‐m‐radius) plots aged 2–10 years with and without remnant trees and compared their above‐ground carbon stocks, vegetation structure (stem density, basal area) and tree diversity. Above‐ground carbon stocks, stem density, basal area, species richness and tree diversity increased significantly with fallow age. Remnant tree presence affected significantly tree diversity, species dominance and above‐ground carbon stocks, but not vegetation structure (stem density, basal area). Number of remnant trees and number of species of remnant trees were also important explanatory variables. Although other factors should be considered in future studies, such as the size and dispersal modes of remnant trees, our results highlight that more strategic inclusion of remnant trees is likely to favour carbon stock and forest recovery in old fallows. To our knowledge, this is the first study on early succession regrowing fallows in West Africa.

The Importance of Ficus (Moraceae) Trees for Tropical Forest Restoration

AbstractForest restoration is an increasingly important tool to offset and indeed reverse global deforestation rates. One low cost strategy to accelerate forest recovery is conserving scattered native trees that persist across disturbed landscapes and which may act as seedling recruitment foci. Ficus trees, which are considered to be critically important components of tropical ecosystems, may be particularly attractive to seed dispersers in that they produce large and nutritionally rewarding fruit crops. Here, we evaluate the effectiveness of remnant Ficus trees in inducing forest recovery compared to other common trees. We studied the sapling communities growing under 207 scattered trees, and collected data on seed rain for 55 trees in a modified landscape in Assam, India. We found that Ficus trees have more sapling species around them (species richness = 140.1 ± 9.9) than non‐Ficus trees (79.5 ± 12.9), and significantly more saplings of shrub and large tree species. Sapling densities were twice as high under Ficus trees (median = 0.06/m2) compared to non‐Ficus (0.03/m2), and seed rain densities of non‐parent trees were significantly higher under Ficus trees (mean = 12.73 ± 3/m2/wk) than other fruit or non‐zoochorous trees (2.19 ± 0.97/m2/wk). However, our regression model found that canopy area, used as a proxy for tree size, was the primary predictor of sapling density, followed by remnant tree type. These results suggest that large trees, and in particular large Ficus trees, may be more effective forest restoration agents than other remnant trees in disturbed landscapes, and therefore the conservation of these trees should be prioritized.

English

Agricultural production in northern Benin is characterized by smallholder traditional agroforestry systems, with on-farm remnant tree species. Among its numerous advantages, agroforestry is known for its valuable contribution to biodiversity conservation. This study quantifies the importance of Vitellaria paradoxa C.F. Gaertn agroforests in terms of woody species conservation in Atacora district in Benin. Forest inventories were performed within 50×50 m plots constructed on a net grid map of Atacora district. Diversity indices were computed for both adult and juvenile species in two land management regimes: fields and fallows. Overall 41 woody species were recorded; 28 in fields and 36 in fallows. Taking into account matured and juvenile individuals, the diversity of woody species increased: 86 species in total; 69 species in fields and 78 in fallows. The biodiversity of V. paradoxa’s agroforestry parklands increases from fields to fallows, and decreases from bulk species (considering mature and juvenile species) to adult ones. Leguminosae and Combretaceae were the most abundant families registered. From the Cover Value Index, V. paradoxa, Parkia biglobosa, Lannea microcarpa, Lannea acida and Diospiros mespiliformis were the most abundant species. Support for maintaining this kind of agricultural system is needed, as this exemplifies the synergy for providing, provisioning and supporting services and biodiversity conservation. Key words: Agroforestry, conservation, ecosystem services, farmland, shea tree.

Spatial genetic structure of Cavanillesia arborea K. Schum. (Malvaceae) in seasonally dry Tropical forest: Implications for conservation

Worldwide, Seasonally Dry Tropical Forests (SDTF) are among the least known and most degraded vegetation types. Cavanillesia arborea (Malvaceae) is an endemic dry forest tree that is bat-pollinated and the seeds are wind-dispersed. The present study sought to characterize the spatial genetic structure (SGS) in natural populations of C. arborea growing in SDTF fragments in Minas Gerais State, Brazil, using ISSR molecular markers. Seven ISSR primers generated 81 polymorphic loci in 175 individuals. In three populations (FU, MO and PC), we found random distributions of genotypes, while two populations (JAN and MV) showed SGS in their first distances classes (171 m and 17 m, respectively), with significant kinship (Sp) values (0.0189 and 0.0005 respectively; P < 0.05). Sp values for these populations indicate that the effects of kinship can be minimized by collecting seeds from distance classes beyond the species' first distance class. The continuous anthropogenic impacts on remnant tree populations, low species densities, and the observed genetic structure, all indicate the need to preserve large areas of dry forest vegetation for conservation purposes.

Effect of variable retention cutting on the relationship between growth of coarse roots and stem of Picea mariana

Silviculture heading for structural heterogeneity creates many single trees standing at stand margins, inner edges or in remnant tree groups. As they played just a minor role in the age class forest, the growth behaviour of strongly released trees is rather unexplored. Here we show how retention cutting, presently spreading in the boreal of Québec province, affects stem and coarse root growth of remained single black spruce [Picea mariana (Mill.) Britton]. Increment cores from roots and stems of 125 trees show that retention cutting triggers coarse root growth of the remaining trees. Compared with reference trees retention trees accelerate root in relation to stem growth. Mean and variability of the root–stem allometry significantly rise after retention cutting. The found acceleration of root in relation to stem growth means mechanical stabilisation of the retention trees and corroborates the retention cutting method. Evaluation of silvicultural treatments can be incomplete and misleading as long as they are just based on aboveground reactions and neglect root growth.

Remnant tree decline in agricultural regions of South Australia.

Agricultural landscapes in southern Australia were once dominated by temperate eucalypt woodlands of which only fragmented patches and scattered trees in paddocks remain. This study focuses on the decline of scattered trees in the Mount Lofty Ranges and South East agricultural regions of South Australia. A combination of digitized aerial photography and satellite imagery was used to extend a previous assessment of decline undertaken in the early 1980s and increase the period over which decline was assessed to 58–72 years. A total of 17 049 scattered trees were counted from the earliest time period assessed over 11 sites of which 6 185 trees were lost by 2008 — a 36 % decline. Recruitment of 2 179 trees during this period was evident. Imagery indicates that clearing for agricultural intensification is the primary cause of the decline. A range of management options and policy settings are required to reverse the decline notwithstanding the challenges of implementation at a landscape scale across privately owned land.

Spatial analysis of remnant tree effects in a secondary Abies-Betula forest on the eastern edge of the Qinghai–Tibetan Plateau, China

Remnant trees, remaining after large-scale disturbance of forests, have been shown to exhibit noticeable ecological effects on the recovery of ecosystem functions. Although it is well known that remnant trees may serve as dispersal foci, their effects on the spatial pattern of later stages of dominant tree species in natural secondary forest have not been fully appreciated. To explore the spatial influences of remnant trees on later stages of dominant tree species of a secondary Abies-Betula forest on the eastern edge of the Qinghai–Tibetan Plateau, we mapped all the trees in a 200m×200m plot. We used spatial point pattern analysis including O-ring statistics to analyze the spatial associations between old-growth remnant trees and two dominant tree species of later stages. Abies faxoniana and Betula albo-sinensis, comparing different size-classes at different spatial scales. Our results showed that saplings, small trees, and medium trees of the shade-tolerant species, A. faxoniana, showed significantly positive associations to the old-growth remnant trees of both dominant species, suggesting that remnant trees provided favourable sites for the regeneration of shade-tolerant species. In contrast, small, and medium trees of the shade-intolerant species, B. albo-sinensis, showed significantly negative associations to old-growth remnant trees of both dominant species, suggesting that the remnant trees hinder their regeneration. For old-growth remnant trees, the O12(r) function value (density) of their seedlings, saplings, small trees, and medium trees was calculated at increasingly greater concentric scales (with radius from 0 to 100m from the remnant trees). Tree density first increased rapidly from 0 to 10m or 20m radius (distance from remnant tree) and then decreased continually away from remnant trees, consistent in part with the population recruitment curve proposed by the Janzen–Connell model. We found that saplings, small trees, and medium trees of A. faxoniana tended to distribute within a particular range of annuli around the remnant trees of A. faxoniana, with the densities of the three largest size-classes reaching a maximum within 3–6m of the remnant tree. The densities beyond the parent remnant trees continued to show an increasingly expanding zone of attraction around the remnant tree. In effect, the small and medium A. faxoniana trees coalesced around remnant trees to create increasingly enlarged canopy cover areas, which served simultaneously as protected zones for A. faxoniana regeneration and extended exclusion zones for B. albo-sinensis and similar shade intolerant species.

Implications of shifts in coffee production on tree species richness, composition and structure on small farms around Mount Kenya

Small coffee farms around Mount Kenya in Kenya contain many planted and remnant tree species but little is known in the region about the relationship between trees on farms and the methods and dynamics of coffee production. Shifts in production may alter tree diversity and potentially impact on future biodiversity conservation efforts by affecting niches available for indigenous trees on farms. Here, knowledge was gathered on how changes in coffee production on 180 small farms around Mount Kenya may affect tree diversity, categorizing farms according to coffee yield levels over a period of five years as increasing, decreasing or stable production. Tree species richness, abundance and composition were analyzed using species accumulation curves, Renyi diversity profiles, rank abundance and ecological distance ordinations, and the effects of coffee production examined using quasi-Poisson generalized linear regressions. Species richness were positively correlated with tree basal area but negatively related to coffee, banana and maize yields value. A difference in average tree species richness, abundance and basal area on increasing farms was observed compared to the decreasing and stable farms, even though formal tests on richness and densities differences were inconclusive. These dynamics do not significantly influence vegetation structure but seem to have a bearing on species composition on farms of different coffee production. The overall low abundance (23 % of trees) but high richness (78 % of species) of indigenous trees on coffee farms could change markedly if the dynamics observed in the current study persist, indicating the need for the development of intensified multi-species cropping systems.

Birds in remnant woodland vegetation in the central wheatbelt of New South Wales during the drought declared years 2005 to 2009

The woodlands of southern Australia have been extensively cleared for agriculture. The loss and fragmentation of the native vegetation has been followed by dramatic declines in woodland-dependant species. Here we present data from the Central Western Plains of New South Wales on the occurrence of birds in woodlands that have been highly fragmented and structurally altered over the last 150 years. The species composition of the region is still very similar to that recorded 3 decades earlier but many small insectivorous and nectivorous woodland birds are rare and restricted, while the woodland patches and remnant tree groves in the landscape are now dominated by the Galah, Noisy Miner, Australian Magpie, Crested Pigeon, Apostlebird, Magpie-lark, Grey-crowned Babbler, Australian Raven, Eastern Rosella and Pied Butcherbird.

Mating system and early viability resistance to habitat fragmentation in a bird-pollinated eucalypt.

Habitat fragmentation has been shown to disrupt ecosystem processes such as plant-pollinator mutualisms. Consequently, mating patterns in remnant tree populations are expected to shift towards increased inbreeding and reduced pollen diversity, with fitness consequences for future generations. However, mating patterns and phenotypic assessments of open-pollinated progeny have rarely been combined in a single study. Here, we collected seeds from 37 Eucalyptus incrassata trees from contrasting stand densities following recent clearance in a single South Australian population (intact woodland=12.6 trees ha(-1); isolated pasture=1.7 trees ha(-1); population area=10 km(2)). 649 progeny from these trees were genotyped at eight microsatellite loci. We estimated genetic diversity, spatial genetic structure, indirect contemporary pollen flow and mating patterns for adults older than the clearance events and open-pollinated progeny sired post-clearance. A proxy of early stage progeny viability was assessed in a common garden experiment. Density had no impact on mating patterns, adult and progeny genetic diversity or progeny growth, but was associated with increased mean pollen dispersal. Weak spatial genetic structure among adults suggests high historical gene flow. We observed preliminary evidence for inbreeding depression related to stress caused by fungal infection, but which was not associated with density. Higher observed heterozygosities in adults compared with progeny may relate to weak selection on progeny and lifetime-accumulated mortality of inbred adults. E. incrassata appears to be resistant to the negative mating pattern and fitness changes expected within fragmented landscapes. This pattern is likely explained by strong outcrossing and regular long-distance pollen flow.

Composição florística e estrutura de um trecho de floresta ombrófila densa atlântica com uso pretérito de produção de banana, no parque estadual da Pedra Branca, Rio de Janeiro, RJ

Este estudo teve como objetivos caracterizar florística e estruturalmente um trecho de Floresta Ombrófila Densa Submontana urbana e avaliar os fatores que contribuíram para a regeneração, a partir do último uso do solo para produção de banana, há 50 anos. Para a amostragem da área foram implantadas 25 parcelas de 100 m², totalizando 0,25 ha. O critério de inclusão adotado foi diâmetro à altura do peito (DAP) &gt; 5 cm. Foram amostrados 311 indivíduos de 92 espécies, 67 gêneros e 31 famílias. A área basal total foi de 34,18 m²/ha, enquanto a densidade, de 1.244 ind./ha. As espécies mais importantes na comunidade, representando 42% do valor de importância (VI) da área, foram: Aiouea saligna Meisn., Tachigali paratyensis (Vell.) H.C. Lima, Ficus insipida Willd., Bathysa gymonocarpa K. Schum, Chrysophyllum flexuosum Mart., Piptadenia gonoacantha (Mart.) J.F. Macbr., Piper rivinoides Kunth., Hyeronima alchorneoides Allemão, Miconia cinnamomifolia (DC.) Naudin e Guarea guidonia (L.) Sleumer. O elevado valor do Índice de diversidade de Shannon (H'= 4,13 nats/ind.), bem como o de equabilidade (J = 0,91), compara-se aos valores referenciados para florestas conservadas e inventariadas no Sudeste brasileiro. A floresta amostrada encontra-se em processo de regeneração e representa um estágio intermediário de sucessão. O cultivo da banana, após seu abandono, permitiu a entrada de espécies com estratégias de estabelecimento e propagação em condições de pouca luminosidade. A presença de uma árvore remanescente, do gênero Ficus, está relacionada a uma crença popular que acabou influenciando a estrutura da vegetação. Dessa forma, as espécies amostradas neste estudo refletiram o uso do solo passado e a cultura local.

The status of conservation of urban forests in eastern Amazonia

This study aims to identify the remnant tree flora in six forest fragments in the metropolitan area of Belém and to analyze these fragments in terms of biological conservation, species richness and diversity in the local urban landscape. The fragments and their respective sampling areas were as follows: Amafrutas reserve (15 ha), Trambioca Is. reserve (2 ha), Bosque Rodrigues Alves city park (15 ha), Combu Is. reserve (10 ha), Gunma Park reserve (10 ha) and Mocambo reserve (5 ha). Inventories were built from lineal plots of 250 m² and included trees with DBH equal to or greater than 10 cm at a height of 1.3 m above ground. Sixty-nine families and 759 species, of which eight were officially listed as endangered (Brazilian National Flora: Ministry of Environment, Normative Instruction of September, 2008; Pará State Flora: Decree Nº. 802 of February 2008) were recorded. These endangered species are: Aspidosperma desmanthum Benth. ex Müll. Arg. (Apocynaceae), Cedrela odorata L. (Meliaceae), Eschweilera piresii S.A Mori (Lecythidaceae), Euxylophora paraensis Huber (Rutaceae), Hymenolobium excelsum Ducke (Leguminosae), Manilkara huberi (Ducke) Chevalier (Sapotaceae), Tabebuia impetiginosa (Mart. ex DC.) Standl. (Bignoniaceae), Mezilaurus itauba (Meisn.) Taub. ex Mez (Lauraceae) and Qualea coerulea Aubl. (Vochysiaceae). Emergency actions such as implementing management plans for already existing Conservation Units, the creation of new such units in areas of primary forest fragments (as in the case of the Amafrutas reserve), as well as the intensification of actions of surveillance and monitoring, should be undertaken by Federal, State, and Municipal environmental agencies so as to ensure the conservation of these last primary forest remnants in the metropolitan area of Belém.

Litter Quality of Two Remnant Tree Species Affects Soil Microbial Activity in Tropical Seasonal Pastures in Western Mexico

In degraded soils of tropical seasonal pastures, native remnant tree species that differ in foliar morphology, litter quality, and quantity might be quite useful as an organic input for improving soil fertility. The objective of this study was to analyze litter quality effects on soil microbial activity from two native remnant trees: Caesalpinia eriostachys Benth. (Caesalnaceae) and Cordia elaeagnoides DC (Boraginaceae), located within a tropical seasonal pasture matrix dominated by Panicum maximum Jacq. (Poaceae). The substrate-induced respiration method was used to determine soil microbial activity in a laboratory incubation experiment. A 3 × 3 factorial laboratory experiment for litter type and soil origin was carried out by adding leaf litter to soil in a reciprocal fashion to evaluate the relative effect of litter quality on substrate-induced respiration. Potential C mineralization rate and net microbial C immobilization from soil under C. elaeagnoides and C. eriostachys were higher with endogenous litter (260 ± 24 µg C g−1 d−1 and 242 ± 11 µg C g−1 d−1 for C. elaeagnoides and C. eriostachys, respectively) than with exogenous litter. Potential carbon mineralization and net microbial C immobilization in soil under P. maximum increased with litter from C. eriostachys due to other leaf-litter quality parameters as lignin concentration and lignin:N ratio. Therefore, C. eriostachys litter addition on soil under grass species may help to stabilize soil organic matter, promoting soil microbial biomass and activity. The net immobilization of microbial N under two remnant tree species and grass species was negative, indicating an N mineralization from microbial biomass.