Mature Secondary Forest Research Articles

Forest land-use history affects the species composition and soil properties of old-aged hillock forests in Estonia

Decisions regarding forest typology, management and protection are often based on the structures of present-day forests, ignoring their successional history. Forests growing on kames, eskers and various moraine hillocks common in regions with Holocene glaciation are good examples of this approach. In Estonia, these forests locally persist as fragments of continuous primary forest, but usually they are situated on former slash-and-burn areas (bushlands) or reforested agricultural land. Our aim was to elucidate the strength of the effect of long-term land-use history on the present-day vegetation compositions of mature hillock forests and their soil chemistry. It appeared that even the mature secondary hillock forests are still distinct from historically continuous stands in terms of species composition. We discovered connections between stand history and species content in hillock forests as well as transformed soil properties. The carbon and nitrogen contents in the humus horizons of secondary forests are lower while their carbon–nitrogen ratios are higher than in continuous forests. The relationship between vegetation and stand history is demonstrated by the higher proportions of anthropophytic and apophytic species in the herb layer of the secondary forests. The presence of species that are tolerant of anthropogenic impact on the secondary hillock forests floor can also be partly explained by the effect of different species in the tree and shrub layers, gaps in the tree canopy, and the boundary effect caused by the small areas of forest patches, neighboring grasslands or fields. The extinction debt in secondary communities should also be considered.

Recognizing Contemporary Roles of Swidden Agriculture in Transforming Landscapes of Southeast Asia

Swidden agriculture is still the most rational land use for farmers in forests in some instances, from both economic and environmental perspectives (Fox et al. 2009; Padoch & Pinedo-Vasquez 2010). Although conservation policies and market forces will likely continue pushing swidden farmers toward commercial agriculture, we think swiddening should be encouraged in areas where it contributes to the preservation of ecosystem services and cultural identity. Relevant to the current global change debate, we believe REDD+ policies should not preclude maintaining or rehabilitating traditional swidden systems with fallow periods that are sufficiently long to allow regeneration of mature secondary forests.

A New Species of Stream Frog (Sanguirana) from the Mountains of Luzon Island, Philippines

We describe a distinctively patterned new species of cascade stream frog from the mountains of Nueva Vizcaya and Aurora provinces, Luzon Island. The new species belongs to the genus Sanguirana, the definition of which we expand to include all Philippine species previously referred to the Rana (Hylarana) everetti complex. The new species is distinguished from other members of the genus by its possession of a bright yellow-green dorsum with conspicuous orange flower-shaped spots in females, bright white, postaxial dermal flanges on the limbs, green-to-purple flank transition, and a highly tuberculate, white venter, in addition to the absence of a dark canthal stripe. The new species is known only from high-gradient, cascading mountain streams between elevations of 750 and 1450 m in mature secondary forest and minimally disturbed primary forests. The discovery of such a distinctive new species emphasizes the relatively high degree to which endemic anuran diversity in the Philippines is still underestimated and underappreciated.

Comparison of Agroforests and Protected Forests in the East Usambara Mountains, Tanzania

Comparative studies on plant species richness, endemism, floristic composition, and structure between protected and unprotected forests are few in the Eastern Arc Mountains, one of the most biodiverse ecosystems in Africa. This study from one mountain range, the East Usambaras, examines floristic and structural tree data from 41–0.5 ha plots in four types of Eastern Arc forest: active agroforests, recently abandoned agroforests, mature secondary forest, and natural forest. Active agroforests had significantly lower tree species richness, endemic species richness, and stand density compared to natural and mature secondary forest. Recently abandoned agroforests contained a higher tree species richness, density, and tree height than active agroforests. Active and abandoned agroforests were dominated by an invasive tree, Maesopsis eminii. This tree species makes up a large percentage of the stems in active agroforests (26%), recently abandoned agroforests (32%), and in the canopy of mature secondary forests ∼ 30 years post logging (30%). Through time the increasing dominance of this non-native tree in active agroforests is a concern when considering the role of agroforests in a landscape scale conservation strategy.

Riparian land use and the relationship between the benthos and litter decomposition in tropical montane streams

Summary1. Although stream–catchment interactions have been analysed in some detail in temperate environments, little is known about the effects of land‐use changes in the tropics. Here, we analyse differences in benthic communities (macroinvertebrates and fungi) under two contrasting land uses (mature secondary forest and pasture) in montane streams in north‐western Ecuador and their influence on the rates of litter processing.2. Between 2005 and 2006, we used a combination of coarse and fine mesh bags to study the relative contribution of macroinvertebrates and fungi to processing of two types of litter, Alnus acuminata and Inga spectabilis, in three‐first‐order streams running through mature secondary montane forests and adjacent downstream reaches running through pastures. At the same time, we characterised the assemblages of shreddering macroinvertebrates and fungi communities and the litter processing rates in stream reaches under both vegetation types.3. Litter processing rates attributable to invertebrate feeding (coarse mesh bags) were significantly slower in streams running through pastures. Nevertheless, shredder diversity and richness were similar between pasture and forest sections, while shredder abundance was significantly higher in forest streams (mainly Phylloicus sp. :Trichoptera). Fungal reproductive activity and litter processing rates were low (fine mesh bags) and did not differ significantly between pasture and forest stream reaches.4. Phylloicus sp. abundance was the best predictor of the percentage of litter remaining in coarse mesh bags across pasture and forest sites. Neither shredder diversity nor their species richness was a significant predictor of mass loss, as most of the decomposition was performed by a single keystone species. Although litter decomposition by microbial decomposers was low, fungal biomass (but not diversity) was the best variable explaining the percentage of litter remaining in fine mesh bags.5. Our data suggest that, in these Neotropical montane streams, land use can have a significant impact on the rates of critical ecosystem processes, such as litter decomposition. In this study, this effect was not mediated by a major shift in the structure of the benthos, but by a decrease in the abundance and relative representation of a single species whose life history makes it critical to litter processing.6. This study highlights the significant role that macroinvertebrate fauna can have in the processing of litter in Neotropical streams and the predominant role that single species can have in terms of controlling stream ecosystem‐level processes. Understanding the extent to which these patterns affect the long‐term and large‐scale functioning of stream ecosystems still needs further research and will become increasingly important in terms of managing lotic ecosystems in the context of rapid land‐use change.

Radial Growth Responses of Three Co-Occurring Species to Small Canopy Disturbances in a Secondary Hardwood Forest on the Cumberland Plateau, Tennessee

We analyzed the radial growth patterns of Liriodendron tulipifera, Acer rubrum, and Acer saccharum growing in 39 canopy gaps in a mature secondary hardwood forest on the Cumberland Plateau in Tennessee to compare species-specific growth responses to small canopy disturbances. We tested for differences between mean radial growth increases during the year of release initiation (i.e., first year of discernible growth increase) over the year prior, mean percent growth increases during the year of release initiation over the year prior, mean release durations, and mean lag times between canopy gap formation and radial growth response. At each level of analysis (i.e., by species, canopy position, and gap position) only the radial growth increase during the year of release initiation over the year prior revealed significant differences. In each case where a systematic difference was noted, the growth increase of L. tulipifera was greater than one or both of the Acer species. However, field observation indicated accelerated growth of L. tulipifera was largely negated in the relatively small and short-lived gaps. Our findings provide information on the successional pathway of the forest, the physiological responses of these species to small canopy openings, and the applicability of these species to reconstruct canopy gap formation in secondary stands from tree-ring records.

Recovery of litter inhabiting beetle assemblages during forest regeneration in the Atlantic forest of Southern Brazil

Abstract. 1. As mature tropical forests disappear, secondary forests with their potential to conserve mature tropical forest species are increasingly of interest in a conservation context.2. We investigated the recovery of litter inhabiting beetle diversity and composition during natural forest regeneration in the coastal submontane forest of Southern Brazil, using chronosequences on two different soil types: cambisol and gleysol. Secondary forests, ranging in ages from 5 to 50 years, as well as old‐growth forests were studied. Beetles were sifted from leaf litter and extracted using the Winkler technique.3. Young secondary forests had a very low species density and a significantly different and heterogeneous species composition compared to old‐growth forests. During forest regeneration, species density greatly increased and the species composition of older secondary forests was similar to that of old‐growth forests. The recovery pattern of species density and composition differed between soil types; nonetheless, they showed the same tendencies generally. Thus, mature secondary forests of about 35–50 years can be assumed to contribute substantially to the maintenance of forest beetle species.4. Litter quantity was not only significantly correlated with species density; but, even reflected the density pattern of both soil types. Thus, litter quantity is an important factor for maintaining or recovering high beetle densities. The composition of beetle assemblages was strongly affected by soil type. Thus, soil type should be considered in regional biodiversity monitoring and conservation actions.

Do tropical forest leaves suffer more insect herbivory? A comparison of tropical versus temperate herbivory, estimated from leaf litter

AbstractIt is generally believed that tropical forests suffer more herbivory, as a proportion of leaf area, than do temperate forests. Reviews so far have compared studies performed by different authors using very different methodologies. Here we carried out studies on 125 samples at 86 localities in eastern North America and on 75 samples taken at five localities in Malaysia and Singapore, including both mature secondary and primary forest. Samples in North America were spread over 3 years. In tropical Asia, the samples were taken at four time slices at least 8 months apart, scattered over a 4‐year period. Total herbivore damage during the lifetime of tree leaves was estimated from the percentage area damaged in recently fallen, undecayed leaves from the forest floor, using scanner‐linked software. In terms of percentage damage per leaf, the results suggest that lowland tropical forest has significantly higher leaf herbivory (5.82%) than temperate forest (5.48%). This is in accord with the general expectation that aseasonal tropical forests should have more herbivory damage. However, when percentage damage ‘per unit time of growing season’ is calculated based on an estimate of leaf lifetime in the tropics, tropical lowland herbivory damage turns out to be a fraction (about one half) of that in the temperate zone. Thus, these results tend to put in question the widely held view that herbivore damage is markedly more intense in the tropics. Over total leaf lifetime, the intensity of damage in the tropical area is only slightly higher than temperate regions. In terms of intensity of herbivory on leaves per unit of time, the opposite seems to be the case. It is uncertain which index should be taken as more significant in interpreting the selection pressure for anti‐herbivore defenses in the tropics.

Basal area growth and mortality of Betula maximowicziana affected by crown dieback in a secondary forest in Hokkaido, northern Japan

Since the late 1990s, decline of B. maximowicziana Regel has been observed in mature secondary forests in various parts of Hokkaido, northern Japan. To develop a method of thinning for large-timber production of B. maximowicziana, we measured basal area growth and the mortality of 217 trees during a four-year period (1999–2003) in a 90-year-old secondary forest with serious tree damage. We analyzed growth and mortality in relation to the degree of crown dieback (DC), symmetric and asymmetric competition from neighbors, and initial tree size. Individual basal area growth decreased with increasing DC, with increasing symmetric (two-sided) competition, and with decreasing initial tree size. During the four-year period, 4.1% of the observed trees died. Logistic regression analysis revealed that mortality rate increased with increasing DC and with increasing symmetric competition. These results suggest that both growth and mortality rates were affected by the same factors (i.e., DC and symmetric competition). We concluded that the resource for which individuals were competing at the study site was underground, most likely water. Modeled growth and mortality rates can be used to improve the management of damaged forests. A management plan for the damaged study site is proposed.

How resilient are Andean montane forest bird communities to habitat degradation?

The threatened forest habitats of the tropical Andes are reportedly being modified and destroyed 30% faster than their lowland tropical counterparts, but impacts on the hyper-diverse resident avifauna have received little systematic study. We present a baseline analysis of the effects of habitat modification on birds in a lower montane forest landscape in Ecuador, comparing avian community composition in landscape elements subjected to different levels of human modification: primary forest, secondary forest, edge habitat and agricultural land. We use data from a point count survey of 300 counts at 150 sites to test whether community composition and density of birds with different reported habitat preferences and foraging strategies change among landscape elements. Species richness and diversity were lowest in agricultural land, but on some measures, equally low in primary forest. Richness and diversity peaked in secondary forest and edge habitat, but ordination and density analysis revealed clear differences in their species composition. While secondary forest contained mostly forest-preferring species, edge habitat harboured a mix of forest and open-land birds. There was a clearly structured gradient in species composition across landscape elements, with densities of habitat specialists, foraging guilds and families varying considerably from primary forest to agricultural land. Agricultural land was characterised by an assemblage of widespread, abundant species very different from that in core forest habitats. As such, while the majority of montane forest birds appear resilient to a certain level of habitat modification, they cannot persist, and are displaced, where forest has been cleared outright. We argue that, for Andean montane forests, preservation of mature secondary forest offers flexibility in supplementing preserved primary forest areas to provide sufficient habitat for the persistence of this incredibly diverse but severely threatened bird community.

Effects of an invasive tree on community structure and diversity in a tropical forest in Puerto Rico

We report the effects of an invasive tree ( Syzygium jambos, Myrtaceace) on species composition, plant diversity patterns, and forest regeneration in primary and secondary forest in the Luquillo Mountains of northeastern Puerto Rico, including the area in and around the Caribbean National Forest (CNF) and the Luquillo Long Term Ecological Research site (Luquillo LTER). Land use history was reconstructed using aerial photographs from 1936 to 1989 and study sites were categorized into four groups that corresponded to their status in 1936: unforested, young secondary, mature secondary, and primary forests. In randomly selected forest stands in each forest type, we measured the abundance of invasive and native tree species, seedling recruitment for S. jambos as well as soil nutrient pools and tested for the effects of land use history on S. jambos density and diversity. A partial Mantel test was used to control for historical and elevational differences across study sites. The results indicate that S. jambos density was highest in habitats classified in 1936 as unforested, young, or mature secondary forests. Compared to all other forest classes, species diversity was significantly higher in primary forests. However, there was no statistically significant difference between observed and estimated species richness across the four forest types. S. jambos density and species diversity were strongly negatively correlated, even after controlling for land use history and elevation. There was significantly higher S. jambos seedling recruitment in areas that were either unforested or had young secondary forests in 1936. The results also indicate that S. jambos is able to establish viable populations in habitats with different soil nutrient status. S. jambos has also altered vegetation composition and diversity patterns in habitats where it is the dominant tree species. After nearly 185 years since its introduction to the island, S. jambos is not only well established within 30 m of stream channels, its presence does not appear to be limited by topographic, soil nutrient, or elevational conditions. This study suggests that land use change and subsequent plant invasions have produced a new vegetation assemblage that has led to potentially long-term changes in community structure, species composition, and successional trajectory in regenerating secondary forests in the Luquillo Mountains.

Comparison of breeding bird and vegetation communities in primary and secondary forests of Great Smoky Mountains National Park

We compared breeding bird communities and vegetation characteristics at paired point locations in primary (undisturbed) and mature secondary forest (70–100 years old) sites in Great Smoky Mountains National Park, USA to understand how sites logged prior to creation of the park compare to undisturbed sites following 70 years of protection from human disturbance. We found that bird and vegetation communities are currently similar, but retain some differences in species composition. Rank abundance curves for primary and secondary forest bird communities showed very similar patterns of species dominance. Species composition was also similar on the two sites which shared 24 of the 25 most frequently recorded species. Nonetheless, comparisons of density estimates derived from distance sampling showed three bird species were more abundant on primary forest sites and that one bird species was significantly more abundant on secondary forest sites. Notably, comparisons based on raw counts (unadjusted for potential differences in detectability) produced somewhat different results. Analyses of vegetation samples for the paired sites also showed relative similarity, but with some differences between primary and secondary forests. Primary forest sites had more large trees (trees greater than 50 cm diameter at breast height) and late successional species. Primary forest sites had a denser tall shrub layer while secondary forest sites had a denser canopy layer. Nonetheless, tree species richness, basal area of live trees and number of standing snags did not differ between primary and secondary forest sites. Results indicate that breeding bird communities on sites within the park that were logged commercially 70 years ago are currently quite similar to bird communities on sites with no history of human disturbance. Similarities between the bird communities on previously disturbed and undisturbed sites in Great Smoky Mountains National Park may exceed those on more fragmented landscapes because large patches of primary forest, adjacent to commercially logged sites, remained in the park when it was established in 1935. These patches of primary forest may have served as source areas for commercially logged sites.

Abundance and habitat associations of parrots at a hillforest site in Papua New Guinea

Despite New Guinea's importance for parrot species, there is an almost total lack of quantitative data on abundances or habitat associations of parrots on the island. We present such data for 15 parrot species within the species-rich (21 species) Crater Mountain Wildlife Management Area, Papua New Guinea. The four most abundant parrot species made up 70% of all parrots recorded in primary forest and 76% in old gardens. Several species had estimated densities of 10?60 birds per km2 and we suggest that the most abundant species on New Guinea are at least as common as those on the surrounding islands. Two species of particular conservation importance, Palm Cockatoo Probosciger aterrimus and Pesquefs Parrot Psittrichas fulgidus had estimated densities of just one bird per km2, while several other notably rare species included Dusky Lory Pseudeos fuscata and the fig-parrots Cyclopsitta diopthalma and Psittaculirostris desmarestii. Most parrot species were strongly associated with the lower and flatter areas of the site, where mature secondary forest dominated. Again, this is a pattern shared with parrots on nearby islands, and the finding emphasizes the importance of protecting lower-altitude mature forests within the region.

Edge effects on vegetation and soils in a Virginia old-field

We investigated the effect of proximity to forest edge on plant community structure and ecosystem properties during succession, using field measurements of leaf area index (LAI), species composition, and soil carbon. Data were collected along four transects within a 14-year-old temperate successional field in north-central Virginia over the 2000 growing season. Additionally, the normalized difference vegetation index (NDVI) was calculated from LANDSAT 7 satellite data at a resolution of 30 m for the entire field. Results showed that relative frequencies of trees increased with proximity to forest edge suggesting a more advanced stage of succession in areas close to the adjacent secondary forest. Significant negative relationships were observed between distance from forest edge and both peak season LAI and NDVI. LAI and NDVI values within 60 m of the forest edge, however, were not significantly different from those values in the adjacent mature secondary forest, suggesting that some community level properties may take relatively short periods of time to reach undisturbed states. The presence of several key plant species, particularly Celastrus scandens (climbing bittersweet), exhibited a strong control on the spatial variability of LAI and potentially the aboveground net primary production. Soil carbon levels did not show a significant increase at sites close to the adjacent secondary forest (relative to an adjacent crop field), as seen with LAI and NDVI, suggesting no recovery of soil carbon in these systems after 14 years. This study points to the complexity of factors that influence spatial patterns of succession in old-fields and suggests that invasive species may play an important role in successional pathways and carbon cycling.

Plant influences on native and exotic earthworms during secondary succession in old tropical pastures

Land-use changes can drastically alter earthworm communities. Native species are often lost and few exotic species, such as Pontoscolex corethrurus, rapidly prevail when tropical forests are converted to pastures. However, this process can be reversed when forests recover from abandoned pastures through secondary succession. We hypothesized (1) that the formation of forest floor mass during secondary succession in pastures promotes the recovery of native, anecic earthworms and (2) that the shift from grass vegetation in pastures to woody plants in secondary forests decreases the abundance and biomass of the exotic, endogeic P. corethrurus. To test the first hypothesis, we developed a litter manipulation experiment by removing and adding plant litter in plots of mature secondary forests in the Cayey Mountains, Puerto Rico. To test the second hypothesis we performed a greenhouse experiment to examine the influence of a pasture grass species Axonopus compressus and a dominating woody species Miconia prasina of the secondary forests on the number and biomass of the earthworm P. corethrurus. We found in the litter manipulation experiment that earthworm diversity, density and fresh weight were not affected by litter input. However, in the greenhouse experiment, A. compressus increased the number and biomass of P. corethrurus, whereas M. prasina decreased the exotic, endogeic earthworm. Our results suggest that the quantity of litter does not promote rapid changes (<1 year) in native, anecic earthworm diversity, and that the exotic, endogeic P. corethrurus is favored by grass A. compressus compared to the woody plant M. prasina. The shift in vegetation from grass to woody plants promotes the decrease in the density and biomass of the exotic, endogeic P. corethrurus during secondary succession in old tropical pastures.

Recovery of Native Earthworms in Abandoned Tropical Pastures

Abstract: Regeneration of secondary forests is recognized as an important means for the recovery of native species biodiversity in human‐disturbed tropical lands. Native earthworms are often replaced with exotic species after deforestation. We studied changes in earthworm diversity and community structure along a chronosequence of abandoned tropical pastures in the Cayey Mountains of Puerto Rico. This chronosequence consisted of active pastures, young secondary forests 25–40 years old, and mature secondary forests&gt;77 years old. Earthworm diversity increased along successional stages. The exotic soil‐feeding earthworm Pontoscolex corethrurus dominated the pastures and young secondary forests. Five native earthworm species ( litter feeders Borgesia sedecimsetae, Estherella sp., Onychochaeta borincana, Neotrigaster rufa, and Trigaster longissimus ) were found in the mature forests, together with P. corethrurus. Earthworm density was highest in the active pastures ( 273 individuals/m2 ), decreased as forest regeneration proceeded, and was lowest in the mature forests ( 88 individuals/m2 ). Our results suggest that regeneration of mature secondary forests, and the consequent increase in litter biomass on the forest floor, can promote the recovery of earthworm diversity and native species of earthworms in old tropical pastures.

Life-history correlates of suboptimal adaptation to rainforest biota by spitting cobras, Naja nigricollis, in southern Nigeria : comparative evidences with sympatric forest cobras, Naja melanoleuca

The region of continuous rainforest in southern Nigeria is inhabited by two species of cobras (Naja melanoleuca and N. nigricollis), and is nowadays subjected to devastating deforestation due to human activity (mainly oil extraction and exploration projects) and overpopulation. Evidence is presented that the forest species (N. melanoleuca) was much more common than the savanna species (N. nigricollis) in the recent past when rates of deforestation were much smaller than today. Nowadays, the savanna species is very common and widespread, not only in suburban and altered habitats, but also in mature secondary forests. Moreover, contrary to the forest species, it is peculiar in that it greatly reduces its feeding rates during the peak of the dry season. These reduced feeding rates were observed in both adults and juveniles, in both males and females, and in three different habitat types (forest, suburbs, and forest-plantation mosaic). No links with reproductive biology can be advocated to explain such a pattern. It is hypothesized that this ecological pattern reflects suboptimal adaptation of the savanna species to rainforest biota, and is a “ghost” of this species’ recent invasion of the rainforest region.

Patterns of Abundance and Human Use of the Vulnerable Understory Palm, Chamaedorea radicalis (Arecaceae), in a Montane Cloud Forest, Tamaulipas, Mexico

Patterns of Abundance and Human Use of the Vulnerable Understory Palm, Chamaedorea radicalis (Arecaceae), in a Montane Cloud Forest, Tamaulipas, Mexico

UNDERSTORY VEGETATION-ENVIRONMENT RELATIONSHIPS IN CLEARCUT AND MATURE SECONDARY FORESTS OF WESTERN MARYLAND

Understory vegetation of 17 clearcuts 1 to 26 years old and three mature secondary forests in Garrett County, Maryland was sampled during the summer to investigate species composition and abundance during forest regen- eration. Canonical correspondence analysis (CCA) was used to determine which measured environmental variables (EVs) were significantly related to species distributions among the sites and to characterize species abundances along these environmental gradients. Stand age and site moisture were the most important EVs related to species distributions. Biplots of EV vectors and species scores indicated early successional and shade-associated species (e.g. Rubus spp. and Arisaema triphyllum, respectively) that were most abundant in recent clearcuts (<10 yr old) and shade-associated species that were most abundant in older clearcuts and mature stands. Early successional species declined or disappeared as regenerating tree canopies started to close. Species distributions were signifi- cantly related to site moisture despite the broad range of light availability associated with differences in stand age and overstory basal area among the study sites.

Understory Vegetation-Environment Relationships in Clearcut and Mature Secondary Forests of Western Maryland

Understory Vegetation-Environment Relationships in Clearcut and Mature Secondary Forests of Western Maryland