Tree communities of different aged logged areas in an Afrotropical rainforest

Predicting the recovery processes in tree communities after logging is critical when developing conservation strategies. We assessed the patterns in tree communities in logged and primary forests in Kibale National Park, Uganda, representing 9‐ to 19‐year‐old clear‐cuts of former conifer plantations, 42‐ to 43‐year‐old logged forests and primary forests. Species density and diversity were lower and dominance higher in the 9‐ to 19‐year‐old forests compared to the 42‐ to 43‐year‐old forests or primary forests. The tree species density, diversity and dominance of 42‐ to 43‐year‐old forests did not differ significantly from primary forests. However, they had a lower stem density, and higher cover of Acanthus pubescens, a shrub known to arrest the succession in Kibale. The tree community compositions of 9‐ to 19‐year‐old, 42‐ to 43‐year‐old and primary forests differed from each other. A large group of tree species (21) were primary forest indicators, that is, they were either missing or relatively rare in logged forests. The results of this study show that even after four decades of natural recovery, logged Afrotropical forests can still be distinguished from primary forests in their tree community compositions, emphasizing the slow community recovery and the important role of primary forests when preserving the tree communities in tropical rainforests.     

Forest succession in Kibale National Park, Uganda: implications for forest restoration and management

Forest succession was studied in four plots in former grasslands at the Ngogo study area in Kibale National Park, Uganda. The plots were located in areas that had been protected from fire for 0.58, 25, 9 and ≈30 years for plots 1, 2, 3 and 4, respectively. Species richness reflected the length of time that the plot had been protected from fire; it was highest in plot 4 and lowest in plot 1. Species density, stem density and basal area were all highest in plot 4 and lowest in plot 1. The species densities of plots 2 and 3 were not different. Similarly, plots 2 and 4 did not differ with regard to stem density or basal area. Animal seed dispersers played a vital role in the colonization of grasslands by forest tree species.     

Forest Succession and Distance from Forest Edge in an Afro‐Tropical Grassland1

Forest succession on degraded tropical lands often is slowed by impoverished seed banks and low rates of seed dispersal. Within degraded landscapes, remnant forests are potential seed sources that could enhance nearby forest succession. The spatial extent that forest can influence succession, however, remains largely unstudied. In abandoned agricultural lands in Kibale National Park, Uganda, recurrent fires have helped perpetuate the dominance of tall (2–3 m) grasses. We examined the effects of distance from forest and grassland vegetation structure on succession in a grassland having several years of fire exclusion. At 10 and 25 m from forest edge, we quantified vegetation patterns, seed predation, and survival of planted tree seedlings. Natural vegetation was similar at both distances, as was seed (eight species) and seedling (six species) survival; however, distance may be important at spatial or temporal scales not examined in this study. Our results offer insight into forest succession on degraded tropical grasslands following fire exclusion. Naturally recruited trees and tree seedlings were scarce, and seed survival was low (20% after 7 mo). While seedling survival was high (95% after 6 to 8 mo), seedling shoot growth was very slow (x?= 0.5 cm/100 d), suggesting that survivorship eventually may decline. Recurrent fires often impede forest succession in degraded tropical grasslands; however, even with fire exclusion, our study suggests that forest succession can be very slow, even in close proximity to forest.     

Beyond hectares: four principles to guide reforestation in the context of tropical forest and landscape restoration

New climate change agreements emerging from the 21st Conference of the Parties and ambitious international commitments to implement forest and landscape restoration (FLR) are generating unprecedented political awareness and financial mobilization to restore forests at large scales on deforested or degraded land. Restoration interventions aim to increase functionality and resilience of landscapes, conserve biodiversity, store carbon, and mitigate effects of global climate change. We propose four principles to guide tree planting schemes focused on carbon storage and commercial forestry in the tropics in the context of FLR. These principles support activities and land uses that increase tree cover in human‐modified landscapes, while also achieving positive socioecological outcomes at local scales, in an appropriate contextualization: (1) restoration interventions should enhance and diversify local livelihoods; (2) afforestation should not replace native tropical grasslands or savanna ecosystems; (3) reforestation approaches should promote landscape heterogeneity and biological diversity; and (4) residual carbon stocks should be quantitatively and qualitatively distinguished from newly established carbon stocks. The emerging global restoration movement and its growing international support provide strong momentum for increasing tree and forest cover in mosaic landscapes. The proposed principles help to establish a platform for FLR implementation and monitoring based on a broad set of socioenvironmental benefits including, but not solely restricted, to carbon mitigation and wood production.     

Co‐benefits of biodiversity and carbon sequestration from regenerating secondary forests in the Philippine uplands: implications for forest landscape restoration

Shifting cultivation is a widespread practice in tropical forested areas that policy makers often regard as the major cause of forest degradation. Secondary fallow forests regrowing after shifting cultivation are generally not viewed as suitable for biodiversity conservation and carbon retention. Drawing upon our research in the Philippines and other relevant case studies, we compared the biodiversity and carbon sequestration in recovering secondary forests after shifting cultivation to other land uses that commonly follow shifting cultivation. Regenerating secondary forests had higher biodiversity than fast growing timber plantations and other restoration options available in the area. Some old plantations, however, provided carbon benefits comparable the old growth forest, although their biodiversity was less than that of the regenerating forests. Our study demonstrates that secondary forests regrowing after shifting cultivation have a high potential for biodiversity and carbon sequestration co‐benefits, representing an effective strategy for forest management and restoration in countries where they are common and where the forest is an integral part of rural people's livelihoods. We discuss the issues and potential mechanisms through which such dynamic land use can be incorporated into development projects that are currently financing the sustainable management, conservation, and restoration of tropical forests.     

Establishment of tree seedlings in the understory of restoration plantations: natural regeneration and enrichment plantings

Little is known about the potential of restoration plantations to provide appropriate understory conditions to support the establishment of seeds arriving from neighboring native forests. In this article, we investigated how seedling establishment is affected in the understory of restoration sites of different ages and assessed some of the potential environmental factors controlling this ecological process. We first compared the density and richness of native tree seedlings among 10‐, 22‐, and 55‐year‐old restoration plantations within the Atlantic Forest region of southeastern Brazil. Then, we undertook a seed addition experiment in each study site, during the wet season, and compared seedling emergence, survival, and biomass on local versus old‐growth forest soil (transferred from a reference ecosystem), in order to test whether local substrate could hamper seedling establishment. As expected, the oldest restoration site had higher density and richness of spontaneously regenerating seedlings. However, seedling establishment was less successful both in the oldest restoration planting and using substrate transferred from a reference ecosystem, where emergence and survival were lower, but surviving seedlings grew better. We attribute these results to lower light availability for seedlings in the understory of the oldest site and speculate that higher incidence of pathogens on old‐growth forest soil may have increased seedling mortality. We conclude that the understory of young restoration plantations provides suitable microsite conditions at the early establishment phases for the spontaneous regeneration or enrichment planting of native trees.     

A pre‐adaptive approach for tropical forest restoration during climate change using naturally occurring genetic variation in response to water limitation

Effective reforestation of degraded tropical forests depends on selecting planting material suited to the stressful environments typical at restoration sites that can be exacerbated by increased duration and intensity of dry spells expected with climate change. While reforestation efforts in nontropical systems are incorporating drought‐adapted genotypes into restoration programs to cope with drier conditions, such approaches have not been tested or implemented in tropical forests. As the first effort to examine genetic variation in plant response to drought in a tropical wet forest, we established a watering experiment using five replicated maternal lines (i.e. seedlings from different maternal trees) of five dipterocarp species native to Borneo. Apart from the expected species level variation in growth and herbivory (3‐fold variation in both cases), we also found intraspecific variation so that growth in some cases varied 2‐fold, and herbivory 3‐fold, among genetically different maternal lines. In two species we found that among‐maternal line variation in growth rate was negatively correlated with tolerance to water limitation, that is, the maternal lines that performed the best in the high water treatment lost proportionally more of their growth during water limitation. We argue that selection for tolerance to future drier conditions is not only likely to impact population genetics of entire forests, but likely extends from forest trees to the communities of canopy arthropods associated with these trees. In tropical reforestation efforts where increased drought is predicted from climate change, including plant material resilient to drier conditions may improve restoration effectiveness.     

Seed and seedling responses to inoculation with mycorrhizal fungi and root nodule bacteria: implications for restoration of degraded Mediterranean‐type Tuart woodlands

Inoculation with beneficial soil microorganisms has the potential to enhance success of restoration, particularly in harsh Mediterranean‐type ecosystems (MTEs). We investigated the effects of microorganisms (mycorrhizal fungi and root nodule bacteria) and planting material (seed and nursery‐raised seedlings) on early establishment and growth of two key postdisturbance colonizing species with different life histories, life forms and functional types (Eucalyptus gomphocephala and Acacia saligna) under field conditions. Establishment and growth were monitored at 13 months, following the first MTE drought period. For E. gomphocephala, establishment was higher for seedlings (81%) than for seeding (7.5%). Inoculation with ectomycorrhizal fungal spores was not beneficial. For A. saligna, establishment was also higher for seedlings (84%) than for seeding (42.5%). Mycorrhizal fungal inoculum had no effect on establishment or growth. This study has shown that in harsh MTE conditions, the use of seedlings is more effective than seeding in degraded woodlands even when attempting to reintroduce key colonizing species. The microorganism treatments tested did not result in significant improvement in establishment or growth.     

Hardness of cercopithecine foods: implications for the critical function of enamel thickness in exploiting fallback foods

We evaluate the hardness of foods consumed by sympatric Cercopithecus ascanius (redtail guenons) and Lophocebus albigena (grey-cheeked mangabeys), and consider how selection might operate to influence foraging adaptations. Since L. albigena has among the thickest dental enamel in extant primates and is commonly referred to as a hard-object consumer, we predicted that their diet would be harder than that of the guenon. Data on diet and food hardness (as measured by resistance to puncture and crushing) were collected between June-October of 1997 at Kibale National Park, Uganda, and were compared to similar data collected in Kibale between 1991-1994. Contrary to what we predicted, there was no difference in dietary hardness when the puncture resistance of all fruit consumed by the two species was compared (31 tree species in both study periods). However, in June-October 1997, L. albigena exploited a diet more resistant to puncture and crushing than C. ascanius. This difference is largely explained by the higher percentage of bark and seeds consumed by the L. albigena during this period. We suggest that it is the difference in the mechanical properties of fallback foods during critical periods that may have served as the selective pressure for thick enamel in L. albigena.     

Chronosequence predictions are robust in a Neotropical secondary forest,but plots miss the mark

Tropical secondary forests (TSF) are a global carbon sink of 1.6 Pg C/year. However, TSF carbon uptake is estimated using chronosequence studies that assume differently aged forests can be used to predict change in aboveground biomass density (AGBD) over time. We tested this assumption using two airborne lidar datasets separated by 11.5 years over a Neotropical landscape. Using data from 1998, we predicted canopy height and AGBD within 1.1 and 10.3% of observations in 2009, with higher accuracy for forest height than AGBD and for older TSFs in comparison to younger ones. This result indicates that the space‐for‐time assumption is robust at the landscape‐scale. However, since lidar measurements of secondary tropical forest are rare, we used the 1998 lidar dataset to test how well plot‐based studies quantify the mean TSF height and biomass in a landscape. We found that the sample area required to produce estimates of height or AGBD close to the landscape mean is larger than the typical area sampled in secondary forest chronosequence studies. For example, estimating AGBD within 10% of the landscape mean requires more than thirty 0.1 ha plots per age class, and more total area for larger plots. We conclude that under‐sampling in ground‐based studies may introduce error into estimations of the TSF carbon sink, and that this error can be reduced by more extensive use of lidar measurements.     

Habitat use by endemic and introduced rodents along a gradient of forest disturbance in Madagascar

We used logistic and Poisson regression models to determine factors of forest and landscape structure that influence the presence and abundance of rodent species in the rain forest of Ranomafana National Park in southeastern Madagascar. Rodents were collected using live-traps along a gradient of human disturbance. All five endemic rodent species (Nesomys rufus, N. audeberti, Eliurus tanala, E. minor and E. webbi) and the introduced rat Rattus rattus were captured in both secondary and primary forests, but the introduced Mus musculus was only trapped in secondary forest. The abundance of R. rattus increased with the level of habitat disturbance, and it was most common in the heavily logged secondary forest. Furthermore, the probability of the presence of R. rattus increased with decreasing distance from forest edge and decreasing canopy cover, while the probability of presence increased with increasing herbaceous cover, altitude and overstory tree height. The species was never observed farther than 500 m away from human habitation or camp-site. N. rufus prefered selectively-logged forest at altitudes above 900 m a.s.l. Its probability of presence increased with increasing canopy cover, herbaceous cover and distance from forest edge, and with decreasing density of fallen logs, overstory tree height and distance from human habitation. N. audeberti prefered heavily-logged areas, while E. tanala was the only species occurring along the entire range of forest disturbance. We suggest that in the Ranomafana National Park the spread of R. rattus is associated with deforestation.     

Long‐term recovery of the functional community assembly and carbon pools in an African tropical forest succession

On the African continent, the population is expected to expand fourfold in the next century, which will increasingly impact the global carbon cycle and biodiversity conservation. Therefore, it is of vital importance to understand how carbon stocks and community assembly recover after slash‐and‐burn events in tropical second growth forests. We inventoried a chronosequence of 15 1‐ha plots in lowland tropical forest of the central Congo Basin and evaluated changes in aboveground and soil organic carbon stocks and in tree species diversity, functional composition, and community‐weighted functional traits with succession. We aimed to track long‐term recovery trajectories of species and carbon stocks in secondary forests, comparing 5 to 200 + year old secondary forest with reference primary forest. Along the successional gradient, the functional composition followed a trajectory from resource acquisition to resource conservation, except for nitrogen‐related leaf traits. Despite a fast, initial recovery of species diversity and functional composition, there were still important structural and carbon stock differences between old growth secondary and pristine forest, which suggests that a full recovery of secondary forests might take much longer than currently shown. As such, the aboveground carbon stocks of 200 + year old forest were only 57% of those in the pristine reference forest, which suggests a slow recovery of aboveground carbon stocks, although more research is needed to confirm this observation. The results of this study highlight the need for more in‐depth studies on forest recovery in Central Africa, to gain insight into the processes that control biodiversity and carbon stock recovery.     

The role of land-use history in driving successional pathways and its implications for the restoration of tropical forests

Secondary forests are increasingly important components of human-modified landscapes in the tropics. Successional pathways, however, can vary enormously across and within landscapes, with divergent regrowth rates, vegetation structure and species composition. While climatic and edaphic conditions drive variations across regions, land-use history plays a central role in driving alternative successional pathways within human-modified landscapes. How land use affects succession depends on its intensity, spatial extent, frequency, duration and management practices, and is mediated by a complex combination of mechanisms acting on different ecosystem components and at different spatial and temporal scales. We review the literature aiming to provide a comprehensive understanding of the mechanisms underlying the long-lasting effects of land use on tropical forest succession and to discuss its implications for forest restoration. We organize it following a framework based on the hierarchical model of succession and ecological filtering theory. This review shows that our knowledge is mostly derived from studies in Neotropical forests regenerating after abandonment of shifting cultivation or pasture systems. Vegetation is the ecological component assessed most often. Little is known regarding how the recovery of belowground processes and microbiota communities is affected by previous land-use history. In published studies, land-use history has been mostly characterized by type, without discrimination of intensity, extent, duration or frequency. We compile and discuss the metrics used to describe land-use history, aiming to facilitate future studies. The literature shows that (i) species availability to succession is affected by transformations in the landscape that affect dispersal, and by management practices and seed predation, which affect the composition and diversity of propagules on site. Once a species successfully reaches an abandoned field, its establishment and performance are dependent on resistance to management practices, tolerance to (modified) soil conditions, herbivory, competition with weeds and invasive species, and facilitation by remnant trees. (ii) Structural and compositional divergences at early stages of succession remain for decades, suggesting that early communities play an important role in governing further ecosystem functioning and processes during succession. Management interventions at early stages could help enhance recovery rates and manipulate successional pathways. (iii) The combination of local and landscape conditions defines the limitations to succession and therefore the potential for natural regeneration to restore ecosystem properties effectively. The knowledge summarized here could enable the identification of conditions in which natural regeneration could efficiently promote forest restoration, and where specific management practices are required to foster succession. Finally, characterization of the landscape context and previous land-use history is essential to understand the limitations to succession and therefore to define cost-effective restoration strategies. Advancing knowledge on these two aspects is key for finding generalizable relations that will increase the predictability of succession and the efficiency of forest restoration under different landscape contexts.     

Temporal variation in the influence of forest succession on caterpillar communities: A long‐term study in a tropical dry forest

Forest succession can influence herbivore communities through changes in host availability, plant quality, microclimate, canopy structure complexity and predator abundance. It is not well known, however, if such influence is constant across years. Caterpillars have been reported to be particularly susceptible to changes in plant community composition across forest succession, as most species are specialists and rely on the presence of their hosts. Nevertheless, in the case of tropical dry forests, plant species have less defined successional boundaries than tropical wet forests, and hence herbivore communities should be able to persist across different successional stages. To test this prediction, caterpillar communities were surveyed during eight consecutive years in a tropical dry forest in four replicated successional stages in Chamela, Jalisco and Mexico. Lepidopteran species richness and diversity were equivalent in mature forests and early successional stages, but a distinctive caterpillar community was found for the recently abandoned pastures. Species composition tended to converge among all four successional stages during the span of eight years. Overall, our results highlight the importance of both primary and secondary forest for the conservation of caterpillar biodiversity at a landscape level. We also highlight the relevance of long‐term studies when assessing the influence of forest succession to account for across year variation in species interactions and climatic factors. Abstract in French is available with online material.     

Limitation of seedling growth by potassium and magnesium supply for two ectomycorrhizal tree species of a Central African rain forest and its implication for their recruitment

In the ectomycorrhizal caesalpiniaceous groves of southern Korup National Park, the dominant tree species, Microberlinia bisulcata, displays very poor in situ recruitment compared with its codominant, Tetraberlinia bifoliolata. The reported ex situ experiment tested whether availabilities of soil potassium and magnesium play a role. Seedlings of the two species received applications of K and Mg fertilizer in potted native soil in a local shade house, and their responses in terms of growth and nutrient concentrations were recorded over 2 years. Amended soil concentrations were also determined. Microberlinia responded strongly and positively in its growth to Mg, but less to K; Tetraberlinia responded weakly to both. Added Mg led to strongly increased Mg concentration for Microberlinia while added K changed that concentration only slightly; Tetraberlinia strongly increased its concentration of K with added K, but only somewhat its Mg concentration with added Mg. Additions of Mg and K had small but important antagonistic effects. Microberlinia is Mg‐demanding and apparently Mg‐limited in Korup soil; Tetraberlinia, whilst K‐demanding, appeared not to be K‐limited (for growth). Added K enhanced plant P concentrations of both species. Extra applied Mg may also be alleviating soil aluminum toxicity, and hence improving growth indirectly and especially to the benefit of Microberlinia. Mg appears to be essential for Microberlinia seedling growth and its low soil availability in grove soils at Korup may be an important contributing factor to its poor recruitment. Microberlinia is highly shade‐intolerant and strongly light‐responding, whilst Tetraberlinia is more shade‐tolerant and moderately light‐responding, which affords an interesting contrast with respect to their differing responses to Mg supply. The study revealed novel aspects of functional traits and likely niche‐partitioning among ectomycorrhizal caesalps in African rain forests. Identifying the direct and interacting indirect effects of essential elements on tropical tree seedling growth presents a considerable challenge due the complex nexus of causes involved.     

鼎湖山三种主要林型水文学过程中总有机碳浓度对比

为了解碳在森林内部以及群落演替过程中的转运动态 ,对鼎湖山 3种主要林型 (马尾松林 ,马尾松针阔混交林和季风常绿阔叶林 )森林水文学过程中总有机碳 (total organic carbon,TOC)浓度进行了一个雨季的观测 ,结果发现 :(1)穿透水中 TOC浓度相对大气降水中 TOC浓度的增量为 :季风常绿阔叶林 >马尾松针阔混交林 1>马尾松针阔混交林 2 >马尾松林 ;(2 )树干茎流平均 TOC浓度为 :马尾松林 >马尾松针阔混交林 2 >马尾松针阔混交林 1>季风常绿阔叶林 ;(3)各林内土壤水 TOC浓度差异不明显 ,但根系层 (2 5～ 30 cm)土壤水 TOC浓度均大于母质层 (5 0～ 80 cm) TOC浓度 ;(4 )马尾松林的溪水具有较高的 TOC浓度和较大的月际波动 ;(5 )总体上 ,整个森林水文学过程中 ,3种林型 TOC浓度变化趋势相似 ,均为 :树干茎流 >穿透水 >根系层土壤水 >母质层土壤水 >溪水 ,但变化幅度不同 :马尾松林的变化幅度最大 ,季风林的最小 ,而两个混交林居中。这表明 ,(1)森林演替过程中 ,林冠层结构、树种构成等的改变可能引起森林水文学过程中 TOC浓度的变化 ;(2 )森林水文学过程转运的碳主要储存在森林内部 ;(3)成熟森林的抗干扰能力高于先锋群落     

Quantitative variability of cyanogenesis in Cathariostachys madagascariensis—the main food plant of bamboo lemurs in Southeastern Madagascar

Giant bamboo (Cathariostachys madagascariensis) is a major food plant for three sympatric species of bamboo‐eating lemurs (Hapalemur aureus, H. griseus, and Prolemur simus) in the rain forests of southeastern Madagascar. This plant species is strongly cyanogenic. However, quantitative data on cyanide concentration in C. madagascariensis are scarce. Previous studies reported 15 mg cyanide per 100 g fresh shoot material (corresponding to approx. 57 µmol cyanide per gram dry weight). However, we found mean concentrations (±SE) ranging from 139.3±19.32 in ground shoots to 217.7±16.80 µmol cyanide per gram dry weight in branch shoots. Thus, cyanogenesis of C. madagascariensis was up to four times higher than reported before. In contrast to the strongly cyanogenic shoots no cyanide could be detected in differently aged leaves of C. madagascariensis confirming earlier studies. Within individual shoots fine‐scaled analysis revealed a characteristic ontogenetic pattern of cyanide accumulation. Highest concentrations were found in youngest parts near the apical meristem, whereas concentrations decreased in older shoot parts. Beyond the general intra‐individual variability of cyanogenic features analyses indicated site‐specific variability of both, the ontogenetic pattern of cyanide concentration as well as the total amount of cyanide accumulated in shoots. Additionally, analyses of soluble proteins—one important nutritive measure affecting food plant quality—demonstrated a converse quantitative relation of protein concentrations in leaves to cyanide concentration in shoots at the site‐specific level. We, thus, suggest integrative analyses on quantitative variation of cyanogenesis together with nutritive plant parameters in future studies. This approach would allow obtaining more detailed insights into spatial variability of giant bamboo's overall browse quality and its impact on lemur herbivores. Am. J. Primatol. 71:305–315, 2009. © 2009 Wiley‐Liss, Inc.     

Environment and landscape rather than planting design are the drivers of success in long‐term restoration of riparian Atlantic forest

Question

Identifying the factors that lead to the success of restoration projects has been a major challenge in ecological restoration. Here we ask which factors, aside from time since restoration began, drive the recovery of tree biomass, density and richness of the understorey in riparian forests undergoing restoration.

Location

Semideciduous Atlantic Forest with tropical climate and deep, fertile soils, southeast Brazil.

Methods

We sampled tree basal area (DBH ≥ 5 cm), density and richness of the understorey (DBH < 5 cm) in 26 riparian forests undergoing restoration (a chronosequence spanning 4–53 years). We assessed the following variables as possible factors, besides time, influencing community attributes: (1) planting design: density and richness of seedlings planted; (2) landscape features: proximity index measuring forest cover within a 1.5‐km radius, distance and size of the nearest forest remnant; and (3) environmental factors: invasive grasses, soil fertility, drought, average annual precipitation and proportion of fine particles in the soil. We performed correlation analyses including predictor and response variables, followed by stepwise backward regression (AIC), multiple and simple linear regressions, to investigate the relationships between those factors and the community attributes.

Results

Tree basal area was primarily influenced by the proportion of small particles in the soil (+) and secondarily by rainfall (?). Understorey richness was influenced by the combination of size (+) and distance (?) of the nearest patch, rainfall (?) and soil fertility (+). Understorey density was primarily influenced by the size of the nearest forest remnant (+) and secondarily by invasive grasses (?). No influence of density or richness of the seedlings planted was observed.

Conclusion

Environmental factors and landscape configuration drive the recovery of tree biomass, density and richness in communities undergoing restoration. The most relevant ecological filters influencing restoration success are availability of soil water and nutrients and the distance and size of the nearest remnant of native vegetation. The expected influence of richness and density of seedlings planted, considered for many years as important drivers of forest restoration success, was not confirmed in this study.     

Lack of Interspecific Plant Competition With a Dominant Grass in the Understory of a Lowland Forest in Colombia

I analyzed a natural experiment of competition involving a dominant herb in Tinigua Park, Colombia. Pharus virescens is a dominant monocarpic grass that synchronously produces seeds once every 5 yr, after which all individuals die. I found no difference in species richness, density, or diversity comparing plots with and without the grass in 381 quadrats (4 m²) and there was no negative relationship between the abundance of the grass and that of other plants.