Evaluation of native tree species for the rehabilitation of deforested areas in a Mexican cloud forest

Four native tree species (Liquidambar styraciflua, Juglans pyriformis, Podocarpus matudae, and Carpinus caroliniana) were evaluated for their suitability in rehabilitating degraded areas of Mexican cloud forest. Plant survival and growth in height and diameter were determined in three mixed-experimental plantations with different land use histories; their performance was compared with two on-farm plantations started by landowners for forest restoration. Nearby forest fragments were controls for soil compaction. An experimental plantation with remnant trees had the highest plant survival (82%), height, basal diameter and relative growth rate. The plantation with the steepest slope had high plant survival (63%) and growth. The plantation characterized by dominance of grasses and compacted soils had the lowest survival (22%) and growth. On-farm plantations had good establishment of planted trees (5–10 species planted), and facilitated the recruitment of 9–11 woody species. Carpinus and Liquidambar appear to be suitable species for reforestation in all these areas. Podocarpus grew relatively slowly, although it performed well in two experimental sites. Juglans had high survival (76%) under the stressful conditions of the most adverse site, and therefore may be useful for rehabilitation of degraded sites. Differences among species and sites strongly suggest that species success depends on plantation site quality.     

Conservation of forest biodiversity and ecosystem properties in a pastoral landscape of the Ecuadorian Andes

High Andean cloud forests are home to a diversity of unique wildlife and are important providers of ecosystem services to people in the Andean regions. The extent of these cloud forests has been widely reduced through conversion to pasture for livestock, which threatens the forests’ ability to support biodiversity and provide ecosystem services. This paper explores whether impacts on woody plant biodiversity and four ecosystem properties (woody plant species richness, juvenile timber tree abundance, soil organic matter content and soil moisture) from converting forest to pasture can be mitigated if some woody forest vegetation is maintained within pastures. Woody vegetation in pastures was found to conserve those woody plant species that are more tolerant to exposure and grazing, but conservation of the high montane cloud forest community required areas of forest from which livestock were restricted. The sampled sites clustered according to woody plant species cover; these clusters represented a gradient from pasture with patches of shrubs to mature forest. Clusters differed in both woody plant species richness and number of juvenile timber trees whereas soil organic matter and soil moisture were observed to be similar among all clusters. This suggests that the different habitats may have some equivalent ecosystem properties. We conclude that the presence of woody vegetation in pastures may reduce some of the impacts of converting forest to pasture, but should not be considered a substitute for protecting large areas of forest, which are essential for maintaining woody plant species diversity in high Andean cloud forest.     

Plant species cover,frequency, and biomass: Early responses to clearcutting,burning, windrowing,discing, and bedding in Pinus elliottii flatwoods

Pinelands in a 49 ha naturally-regenerated, mature flatwoods forest in north Florida were clearcut harvested in the fall of 1978, site prepared by burning, shearing and piling, discing, and bedding, and planted to slash pine (Pinus elliottii) in 1979. Three vegetation surveys were conducted: one prior to harvest in the summers of 1977 and 1978, and two subsequent to planting in the summers of 1980 and 1981.Cover and frequency of all plant species encountered were assessed on permanent transects. Foliage biomass by species was assessed by destructive sampling of distinct subplots within permanent plots. The aim was to assess plant species cover, frequency, and biomass responses to the forest operations imposed.Pine was eliminated as a dominant genus by harvesting. Planted pines were a fast increasing, but not dominant, component of the vegetation at 2 years of age. Previously dominant shrubs were severely reduced — often by approximately two orders of magnitude. Indeed, woody species were severely reduced: woody cover from 151 to 12% of surface area at plantation age 2 years; woody biomass from 6223 to 521 kg/ha.Conversely, herbaceous species were substantially increased: herbaceous cover from 38 to 51% of surface area at 2 years; herbaceous biomass from 382 to 1439 kg/ha. Thus, a predominantly woody ecosystem was converted to a predominantly herbaceous one for 2 years following planting.There was little change in plant species richness as a result of forest operations. Plant diversity changes were mixed the 1st year but diversity substantially increased the 2nd year. Comparisons with a companion study (Conde et al., 1983) suggest that, while increases in diversity following maximum site preparation may lag increases following minimum site preparation, cover, frequency, and biomass diversity all converge to common values after 2 years despite disparity in treatments.     

A comparative assessment on regeneration status of indigenous woody plants in Eucalyptus grandis plantation and adjacent natural forest

Diversity, density and species composition of naturally regenerated woody plants under Eucalyptus grandis plantation and the adjacent natural forest were investigated and compared. Twenty plots, with an area of 20 m × 20 m for each, were established in both of E. grandis plantation and adjacent natural forest, independently. In each plot, species name, abundance, diameter and height were recorded. Numbers of seedling were collected in five sub-plots (4 m²) within each major plot. A total of 46 species in the plantation, and 52 species in the natural forest, which belongs to 36 families were recorded. The diversity of species (H′) is 2.19 in the plantation and 2.74 in the natural forest. The density of understory woody plant was 3842 stems/ha in the plantation and 4122 stems/ha in the natural forest. The densities of seedlings in the natural forest and the plantation were 8101 stems/ha and 4151 stems/ha, respectively. High similarity of woody species composition was found between the natural forest and the plantation. The E. grandis plantation was found favoring the regeneration and growth of Millitia ferruginia and Coffea arabica in a much better way than other underneath woody species.     

Native woody species regeneration in exotic tree plantations at Munessa-Shashemene Forest,southern Ethiopia

Regeneration of native woody species was studied in the plantations and the adjacent natural forest at Munessa-Shashemene Forest Project Area, Ethiopia. The aim of the study was to test the hypothesis that tree plantations foster regeneration of native woody species. A total of 60 plots, having 10 × 10 m area each, were studied in monoculture plantations of 4 exotic species (Cupressus lusitanica, Eucalyptus globulus, E. saligna, Pinus patula) and an adjacent natural forest. Ages of the plantations ranged between 9 and 28 years. Soil seed bank analysis was also undertaken from soil samples collected in each of the 60 plots to examine the similarity between the soil seed flora and aboveground vegetation. A total of 56 naturally regenerated woody species were recorded beneath all plantation stands with densities ranging between 2300 and 18650 individuals / ha in different stands. There was a significant difference among plantation stands with regard to understorey density (standard deviation: 4836 ± 1341). Vegetation diversity was assessed through analyses of floristic composition, species richness and abundance. Generally, seedling populations were the most abundant components of the regeneration in most of the plantation stands, forming 68 % of the total regeneration count in all stands. A total of 77 plant species represented by 44 herbs, 13 woody species, 8 grasses and 12 unidentified species were recorded in the soil seed bank from all stands. Similarity between the soil seed bank and aboveground flora was very low implying that the role of soil seed banks is negligible rather dispersal plays an important role in the process of regeneration. These results support the concept that forest plantations can foster the regeneration of native woody species, thereby increasing biological diversity, provided that there are seed sources in the vicinity of the plantations.     

Effects of preparation of clear‐cut forest sites on the soil mycobiota with consequences for Scots pine growth and health

Fungal abundance and diversity were assessed in two differently managed forest soils. In soil 1, chipped woody debris had been spread on the top soil and mixed with the soil by standard deep ploughing to 50 cm. In soil 2, woody debris was removed and there was no ground preparation. Ten years later, the different methods of management resulted in unexpectedly distinctive habitat heterogeneity with a high variation in structure of the mycobiota communities. Incorporation of woody debris into soil resulted in lower abundance of fungi but greater fungal diversity (which may enhance ecosystem stability) and was beneficial for the growth of Scots pines. Removal of post‐harvest woody debris from the surface of the clear‐cut site with no subsequent ground preparation, compared with incorporating chipped debris and deep ploughing, resulted in the soil of the subsequent 10‐year‐old Scots pine plantation having: (a) 159‐fold greater abundance of fungi, (b) lower fungal diversity, (c) different fungal community composition, (d) higher proportion of mycorrhizal fungi, (e) no root rot pathogens, (f) less tree biomass. The study showed that removal of post‐harvest woody debris and no ground preparation is potentially beneficial for the health of young coniferous trees.     

Edge Effect on Acorn Removal and Oak Seedling Survival in Mexican Lower Montane Forest Fragments

Vegetation structure of forest edges and type of adjacent field can affect seed and seedling survival patterns of tree species. We investigated acorn removal and seedling survival of Quercus germana and Q. xalapensis in relation to woody plant density across old field-forest gradients with soft and abrupt edges. Experiments were established along four parallel bands located at 40–50 m in the forest, forest and field edges (0–10 m to each side of the border), and 20–30 m in the old field. Within each band, woody plant and acorn density was measured, and four points for acorn and seedling removal experiments were randomly positioned. In each position, 20 acorns or four seedlings were placed. Survival was monitored during one month. In abrupt edges, acorn density was higher along edges than in forest interior. Also, higher acorn removal and seedling mortality were observed in the adjacent old-field whereas acorn and seedling survival was the highest at the edges. Acorn and seedling survival was positively correlated to woody vegetation density. As the vegetation density of field and forest edges grows, abrupt edges develop into soft edges, and they become more hospitable to oak recruitment and then to forest cover expansion.     

Plant community responses to a gradient of site preparation intensities in pine plantations in the Coastal Plain of North Carolina

Intensively managed loblolly pine (Pinus taeda) forests are common in the southeastern United States and offer opportunities for conservation of biologic diversity. Within intensively managed landscapes, stand establishment relies on combinations of mechanical and chemical site preparation and herbaceous weed control (HWC) to manage competing vegetation and increase pine production. However, few long-term studies have described relationships between intensity of stand establishment and effects on plant communities. Therefore, we examined effects of 6 treatments that varied in intensity via combinations of mechanical (wide spacing and strip shear or narrow spacing and roller chop) and chemical (application or no application) site preparation treatments with HWC (broadcast or banded) from 1 to 8 years after site preparation on plant communities in loblolly pine plantations (n = 6) in the Coastal Plain of North Carolina, USA. All treatments resulted in abundant and diverse plant communities. Chemical site preparation had short lived (?4 year) effects on the herbaceous community but long-term effects on woody plants and pine cover. Increasing management intensity by including broadcast HWC or roller chop/narrow spacing did not additively reduce woody vegetation cover or species richness. However, broadcast HWC reduced grass, vine, and forb cover in the first year post-treatment. Average Morista community similarity values ranged from 0.69 to 0.89 among treatments and plots receiving the same chemical site preparation contained the most similar plant communities. Banded HWC can be paired with wide spacing to maximize herbaceous plant growth important for many wildlife species, particularly in the first few years after site preparation. Site preparation techniques should be tailored to local site conditions, plant communities, and management objectives.     

整地干扰对人工林植物多样性的影响

本文通过对不同造林方式培育的人工森林群落的样方调查和多样性分析,探讨不同整地干扰强度对森林群落不同层次植物多样性的影响。结果表明：（1）造林整地方式对群落植物多样性有显著的影响,其中穴状造林整地培育的森林群落具有最高的植物多样性;（2）整地方式对群落不同层次植物多样性影响不同,其中对草本层的影响最大;（3）草本层对整个群落的植物多样性贡献率最大。建议在中亚热带阔叶林区植被恢复与重建过程中,适宜采用穴状整地或封山育林方式以保育生物多样性。     

Experimental test of the impacts of feral hogs on forest dynamics and processes in the southeastern US

The foraging activities of nonindigenous feral hogs (Sus scrofa) create widespread, conspicuous soil disturbances. Hogs may impact forest regeneration dynamics through both direct effects, such as consumption of seeds, or indirectly via changes in disturbance frequency or intensity. Because they incorporate litter and live plant material into the soil, hogs may also influence ground cover and soil nutrient concentrations. We investigated the impacts of exotic feral hogs in a mixed pine-hardwood forest in the Big Thicket National Preserve (Texas, USA) where they are abundant. We established sixteen 10 m × 10 m plots and fenced eight of them to exclude feral hogs for 7 years. Excluding hogs increased the diversity of woody plants in the understory. Large seeded (>250 mg) species known to be preferred forage of feral hogs all responded positively to hog exclusion, thus consumption of Carya (hickory nuts), Quercus (acorns), and Nyssa seeds (tupelo) by hogs may be causing this pattern. The only exotic woody species, Sapium sebiferum (Chinese tallow tree), was more than twice as abundant with hogs present, perhaps as a response to increased disturbance. Hogs increased the amount of bare soil by decreasing the amounts of plant cover and surface litter. Plots with hogs present had lower soil C:N, possibly due to accelerated rates of nitrogen mineralization. These results demonstrate that hogs may influence future overstory composition and reduce tree diversity in this forest. Management of hogs may be desirable in this and other forests where large-seeded species are an important component of the ecosystem. Further, by accelerating litter breakdown and elevating nitrogen in the soil, hogs have the potential to impact local vegetation composition via nitrogen inputs as well.     

Nestedness and modularity in fragmented Shasha Forest Reserve,southwestern Nigeria

Species co-occurrence and nestedness pattern in Shasha forest reserve were investigated with a view to determining the effect of interactions to species contribution. Three distinct sites (Gmelina arborea plantation, undisturbed forest, and Pinus carribaea (plantation) were selected in the forest reserve. Four 25 m × 25 m plots were established in each of the site within the forest reserve. Species enumeration, identification,, and distribution into families of the standing vegetation were carried out. Woody species represented the most diverse life form. Plant species diversity was highest in UF and lowest in Gmelina plantation. Differences in woody species composition among the three forest types were determined by non-metric multidimensional scaling (NMDS) analysis, analysis of similarity (ANOSIM), and similarity of percentages. Using z-score and NODF (a nestedness metric based on overlap and decreasing fill). Three modules were detected and modularity score Q = 0.2. The composition analyses (NMDS and ANOSIM) revealed a significant difference in the woody species composition among the forest types. Our research may contribute to understand species assemblage in one of the diverse forests of Africa. Current work highlighted species occurrence in Shasha forest and highlighted the importance of non-random pattern which could serve as framework for conservation perspective.     

Species Composition,Distribution, and Diversity of Woody Species in a Tropical Dry Forest of India

We investigated the composition of tropical dry forest woody species at adult, sapling, and seedling stages, in terms of plant diversity, distribution, and importance value index (IVI), and identified the dominant and ubiquitous species in the five study sites having variable edaphic properties. Species varied markedly in the composition and IVI at different sites. The semi-evergreen species, Shorea robusta, was dominant at the wettest site at all the three growth stages; at the driest site, highly deciduous species Lannea coromandelica was the dominant adult species and Nyctanthis arbortristis the dominant sapling and seedling species. Soil moisture content (SMC) altered the distribution of about 8% of the adult species. ANOVA indicated significant site-wise differences in the Shannon-Wiener index, Whittaker’s evenness, Margalef’s species richness, and β-diversity for the woody species at all the three stages. The Shannon-Wiener index, Whittaker’s evenness, Margalef’s species richness, and β-diversity were greater in seedlings as compared to adult and saplings of tree species. These variations in species composition and distribution are evidently on account of different levels of SMC as well as habitat heterogeneity as indicated by β-diversity which was independent of SMC.     

Tree shelters and weed control: Effects on protection,survival and growth of cherrybark oak seedlings planted on a cutover site

In the southern USA oaks (Quercusspp.) are often favored by forest owners havingmultiple objectives for forest ownership as oaksprovide mast for wildlife, are consideredaesthetically pleasing, and are valuable for timberproducts. Regeneration and early seedling growth isa concern to those forest owners interested insustaining oaks as a component of their forests. Theeffects of tree shelters and herbaceous weed controlon second-year seedling survival, browse by deer andrabbits, and seedling growth of hand-plantedcherrybark oak (Quercus pagoda Raf.) wereexamined. The study was established on a cutovermixed pine-hardwood forest in Alabama. Fourtreatments were: weed control only, tree shelter only,tree shelter with weed control, and a controlconsisting of a seedling without a tree shelter orweed control. No significant difference in seedlingsurvival was found among the treatments after twoyears. Tree shelters were effective in preventingbrowsing. No seedlings in the tree-shelter-onlytreatment were browsed. There was no significant,difference, however, in the percentage of seedlingsbrowsed between the control treatment and the weedcontrol treatment. The use of tree shelters with weedcontrol was the most effective treatment for promoting2-year ground-line diameter, height, and stem volumegrowth.     

埃塞俄比亚东南部Dello Menna森林植被的植物区系和结构分析(英文)

描述了埃塞俄比亚东南部Dello Menna森林植被的植物区系组成和植被结构。鉴定和描述了50个20m×20m的样方的植物群落类型、物种多样性、丰富度和均匀性,分析了已鉴定植物群落类型与环境因子的相关性,还描述了木本植物种群结构。每个样方内,均记录木本植物的物种、丰富度、高度和胸径以及海拔、坡度。利用PC-ORD软件对植被进行分类。用Sorensen相似性系数探测群落之间的差异性。计算Shannon-Wiener多样性指数、物种丰富度、Shannon均匀性来描述各种植物群落的物种多样性。共记录了53个科的171个维管植物种。豆科植物是主要的优势植物科系,包括13个属26种(1 5%),其次依次是菊科、唇形科和槭树科,各包括8个物种(4.6%)。根据植物分类结果,识别并描述了3个植物群落(Dalbergia microphylla群落、Grewia bicolar-Acaciabrevispica群落、Combretum molle-Combretum collinum群落)。植物区系之间的物种丰富度、多样性和均匀性存在差异。物种丰富度和多样性随海拔变化呈现出贝尔型分布。群落间植物随海拔梯度有一定的变化,表明海拔是决定植物群落分布的重要因素之一。Dalbergia microphylla群落物种丰富度和多样性均最高。优势种群落结构呈现出各种模型。植被可持续利用是今后的研究方向。     

Diversity of naturally-regenerated native woody species in forest plantations in the Ethiopian highlands

Woody species diversity and ground layervegetation cover were studied in plantations ofPinus patula, Cupressus lusitanica,Grevillea robusta, and Juniperusprocera, and in surrounding natural forests inWondo Genet, Ethiopia. In the understory of theplantations, a total of 53 naturallyregenerated tree and shrub species belonging to31 families were recorded. Important indigenoustimber species were also represented. Treesaccounted for 72% of all naturally-regeneratedwoody plant species. On the average, 78% ofthe woody species found in plantations werealso found in the natural forest. There was nosignificant variation in understory woodyspecies richness among plantations. C.lusitanica plantations had a significantlyhigher abundance of woody species than those ofP. patula, but the difference wasnot significant in relation to J. procera,G. robusta and the adjacent natural forest.The herbaceous ground cover percentage in G. robusta and P. patula stands wasconsiderably higher than in C. lusitanicaand J. procera stands. Relative toplantations of other species, plantations ofthe native tree species J. procera hadhigher understory species richness, mediumwoody species abundance and low ground cover.Although there was a marked variation inoverstory plantation density, its effect onunderstory species richness and abundance wasnot significant. The density ofnaturally-regenerated woody species inplantations was over three times the usualplanting density in Ethiopia, indicating a highpotential of forest plantations for restoringthe natural forest ecosystems on degraded landsat a comparatively low cost.     

Woody plant species diversity and composition in and around Debre Libanos church forests of North Shoa Zone of Oromiya,Ethiopia

Dry afromontane forests are among the most poorly managed and endangered ecosystems.Therefore,we assessed the composition,diversity,and conservation status of woody plant species of the Debre Libanos church forests and surrounding forest lands in Oromiya Regional National State,central Ethiopia in 62 nested circular sample plots spaced 200 m apart along two transect lines.Large circular plots 314 m~2 were used to sample trees with DBH of at least 10 cm,and subplots of 28.26 m~2 were laid in each main plot were used to assess saplings and shrubs;a small subplot of 3.14 m~2 was used to assess seedlings.In total,70 woody plant species belonging to 62 genera and 43 families were recorded.Of these,59,28 and 32 were in the church,government and private forest types,respectively.The most dominant families were Fabaceae and Verbenaceae,each represented by five species.In the forests considered,trees accounted for 61%,and shrubs with diameter at breast height(DBH) of 1-10 cm accounted for ca.33%.Among growth forms of woody species,shrubs and seedlings,followed by trees constituted much of the density of woody species in all the three ownership types of forests.The church forest had the most species(59) and highest Shannon(3.12) and Simpson(0.92) species diversity indices,and the government and private forests had a nearly similar total number of species and Shannon and Simpson species diversity indices.Most of the species with higher importance value indices(IVI) were indigenous in origin within the church forest(Juniperus procera=82),government forest(J.procera=66) and private forest(Acacia abyssinica=84).The composition,diversity,and population structure of woody species in the church forest were significantly higher than in the other forest lands.However,interventions of the government and private sectors to conserve forest systems in the areas,particularly the government-owned forest and specific species such as Olea europaea need active enrichment plantings due to their limited natural regeneration.Without improved management interventions,livelihood income diversification and ecosystem services obtained from the forest will not be sustainable.     

The effect of shelterwood harvesting and site preparation on eastern red-backed salamanders in white pine stands

We studied the effects of the regeneration cut of the shelterwood system and four site preparation options on populations of eastern red-backed salamanders in 90–100-year-old white pine forests in central Ontario, Canada. We established the study in 1994 using a randomized complete block design with three replicates and five treatments: (1) no harvest, no site preparation; (2) harvest, no site preparation; (3) harvest, mechanical site preparation; (4) harvest, chemical site preparation; (5) harvest, mechanical and chemical site preparation. We applied harvest and site preparation treatments from fall 1995 to fall 1997. We collected pre-treatment data in spring and summer of 1995 and post-treatment data from 1998 to 2002. We monitored salamander abundance using a grid of 20 cover boards surveyed 10 times per year within each of the 15 treatment plots. We also quantified changes in overstory and understory cover, supply of downed woody debris, and disturbance to the forest floor. Our data suggest that shelterwood cutting and site preparation can have immediate negative effects on the abundance of red-backed salamander populations in pine forest. However, effects are relatively short lived (<5 years). Changes in abundance appeared to be related to overstory and understory cover, and forest floor disturbance.     

Initial vegetation recovery following a blowdown of a conifer plantation in monsoonal East Asia: Impacts of legacy retention, salvaging, site preparation, and weeding

All or a part of a sequence of forest practices (i.e., salvage logging, site preparation, planting crop trees, and weeding) has been implemented after natural disturbances for the rapid re-establishment of tree cover. Forest policies in Japan have recently changed from monocultural planting of coniferous crop trees to planting native broadleaved trees to restore forests and nurture local biodiversity following large windthrows. However, the effects of this new practice on preserving biodiversity, as well as the effects of legacy retention, have never been verified in Asia. Thus, the objective of our research was to compare the effects of legacy retention with plantation after salvaging on the initial stage of vegetation recovery in a blowdown area, specifically focusing on plant species diversity, the occurrence of alien species, and the composition of plant species. Following the analysis of our results, we finally describe appropriate practices to alter disturbed coniferous plantations to bring the species composition closer to that of the original natural mixed forests.A control (A, legacy retention) and three experimental treatment sites (B, salvage logged, site prepared, and Quercus crispula seedlings planted; C, same as B, but weeded once during the summer; and D, residual rows that emerged after establishing sites for planting) were prepared, and quadrats were set. Eleven indicators of the ground condition and the number of vascular plant species, including ferns, were quantified, and the number and abundance of residual and newly colonized plants of the main woody species were estimated.Our main findings were as follows: (1) in unsalvaged sites and residual rows, the diversity of plant species was poor, but a variety of plant species compositions were observed due to the heterogeneous conditions of the ground and ample residual plants; (2) in the planting site, many species appeared, but little variety of the species composition was observed due to the homogeneous condition of the ground and the destruction of residual plants; (3) a large number of alien species emerged in broad, unvegetated areas; (4) the impact of site preparation overwhelmed the impact of salvage logging on the initial recovery of plant species; and (5) to restore a natural mixed forest, a combination of legacy retention and plantation after salvaging would be the most appropriate.