Compensatory Recruitment, Growth, and Mortality as Factors Maintaining Rain Forest Tree Diversity

Connell, Joseph H.; Tracey, J. G.; Webb, L. J.

doi:10.2307/1942659

Cited by 350 publications

(229 citation statements)

References 53 publications

Supporting

Mentioning

198

Contrasting

Unclassified

Order By: Relevance

“…Quadrat-based analyses are likely to be more productive if long-term demographic data are available, and Connell et al (32) have found some frequency-dependent effects in two Queensland (Australia) rainforests.…”

Section: Discussionmentioning

confidence: 99%

Strong density- and diversity-related effects help to maintain tree species diversity in a neotropical forest

Wills

Condit²,

Foster³

et al. 1997

Proc. Natl. Acad. Sci. U.S.A.

275

294

View full text Add to dashboard Cite

Intraspecific density-dependent effects in the Barro Colorado Island (Panama) study area are far stronger, and involve far more species, than previously had been suspected. Significant effects on recruitment, many extremely strong, are seen for 67 out of the 84 most common species in the plot, including the 10 most common. Significant effects on the intrinsic rate of increase are seen in 54 of the 84 species. These effects are far more common than interspecific effects, and are predominantly of the type that should maintain tree diversity. As a result, the more diverse an area in the forest is, the higher is the overall rate of increase of the trees in that area, although sheer crowding has by itself a negative effect. These findings are consistent with, but do not prove, an important role for host-pathogen interactions (defined broadly) in the maintenance of diversity. Ways are suggested by which to test host-pathogen models and competing models.Tropical rainforests vary greatly in tree species richness, but in most of the humid tropics mature communities with diversities of up to 300 species of tree per hectare are common (1, 2). Equilibrium models (3) have been proposed to explain such high species richness and the maintenance of many different species over long periods. These require unique resource-heterogeneity and resource-utilization niches for each species (4, 5). If there is spatial partitioning (reviewed in ref. 6), or temporal partitioning of light gaps created by treefalls, this would increase the number of niches (7-11). Such habitat partitioning predicts positive density-and frequency-dependence within species. The effect of light gaps on niche partitioning has, however, recently been called into question (12).Another class of models is based on negative density-or frequency-dependence. We define density-dependence as correlations of life history parameters with total biomass at the outset of the census, and frequency-dependence as correlations of life history parameters with the numbers of trees present at the outset of the census. These measures are often, but not always, correlated.We can divide these models into two categories. The first, which we will call abiotic models, have only rarely been investigated (13). They are based on density-dependent abiotic factors in the immediate environment. Density-dependence might be the result of the removal of nutrients from the soil or of a buildup of toxic waste products. When the density is reduced through mortality, nutrients are replenished and toxins are degraded, allowing the cycle to begin anew. The second category is made up of biotic models, and deals with interactions of tree species with their enemies (pest pressure). As Gillett (14) was the first to point out, pests increase the diversity of the local environment, effectively increasing the number and diversity of ecological niches for host species in the forest. The best-known of these models is that of Janzen (15) and Connell (16), which predicts that species-specific pests will te...

show abstract

Section: Discussionmentioning

confidence: 99%

Strong density- and diversity-related effects help to maintain tree species diversity in a neotropical forest

Wills

Condit²,

Foster³

et al. 1997

Proc. Natl. Acad. Sci. U.S.A.

275

294

View full text Add to dashboard Cite

show abstract

“…Most important, when trying to explain diversity in tropical forests, is the fact that the effect becomes stronger as species diversity increases. The assumptions of the hypothesis appear to be true in many systems, resulting in characteristic dispersion patterns (66,(81)(82)(83)(84), but it remains to be seen whether it can explain diversity or species composition. A limitation of the current paradigm-both theory and observation-is that it invokes no intrinsic species differences.…”

Section: Ch Ysophyllum Cainito Tachigali Versicolormentioning

confidence: 99%

Long-Term Studies of Vegetation Dynamics

Rees¹,

Condit

Crawley³

et al. 2001

Science

499

458

View full text Add to dashboard Cite

By integrating a wide range of experimental, comparative, and theoretical approaches, ecologists are starting to gain a detailed understanding of the long-term dynamics of vegetation. We explore how patterns of variation in demographic traits among species have provided insight into the processes that structure plant communities. We find a common set of mechanisms, derived from ecological and evolutionary principles, that underlie the main forces shaping systems as diverse as annual plant communities and tropical forests. Trait variation between species maintains diversity and has important implications for ecosystem processes. Hence, greater understanding of how Earth's vegetation functions will likely require integration of ecosystem science with ideas from plant evolutionary, population, and community ecology.The past decade has seen the emergence of a new synthesis in plant ecology that draws together a variety of once disparate approaches in studies of vegetation dynamics. Questions about the determinants of plant life histories, species composition, diversity, productivity, and stability-previously considered separate areas of inquiry-have become increasingly closely integrated. Findings from long-term experimental and observational studies, combined with comparative and theoretical work, have helped synthesize the questions and approaches of evolutionary ecology, population ecology, and ecosystem ecology. The link has come from the realization that many of the same environmental constraints and organismal tradeoffs that shape the evolution of plant morphologies, life histories, and physiologies also influence the dynamics of interspecific interactions and the mechanisms of coexistence that control community and ecosystem functioning (1-3). We provide a brief tour of the developments in vegetation science, highlighting areas where known patterns of variation in demographic rates between species have provided insights into the structure, dynamics, and functioning of plant communities.

show abstract

“…Indeed, the existing empirical evidence for a CCTeffect appears weak (Connell et al 1984;Welden et al 1991;Webb & Peart 1999). Figure 3 illustrates why this may be the case in communities in which species share generalist pathogens.…”

Section: Introductionmentioning

confidence: 96%

“…Connell et al 1984). This relationship has been termed the community-level compensation trend (CCT; Webb & Peart 1999).…”

Section: Introductionmentioning

confidence: 99%

Pathogens, density dependence and the coexistence of tropical trees

2006

View full text Add to dashboard Cite

There is increasing interest in the role played by density-dependent mortality from natural enemies, particularly plant pathogens, in promoting the coexistence and diversity of tropical trees. Here, we review four issues in the analysis of pathogen-induced density dependence that have been overlooked or inadequately addressed. First, the methodology for detecting density dependence must be robust to potential biases. Observational studies, in particular, require a careful analysis to avoid biases generated by measurement error, and existing studies could be criticized on these grounds. Experimental studies manipulating plant density and pathogen incidence will often be preferable, or should be run in parallel. Second, the form of density dependence is not well understood and, in particular, there are no data indicating whether pathogens cause compensating or overcompensating density responses. Owing to this, we argue that the potential for pathogen-induced density dependence to generate diversity-enhancing outcomes, such as the Janzen-Connell effect, remains uncertain, as coexistence is far more probable if density dependence is overcompensating. Third, there have been few studies examining the relative importance of intra-or interspecific density dependence resulting from pathogens (or, more widely, natural enemies). This is essentially equivalent to asking to what extent pathogens are host-specific. If pathogens are generalists, then mortality rates will respond to overall plant density, irrespective of plant species identity. This will weaken the intraspecific density dependence and reduce the diversity-promoting effects of pathogens. Finally, we highlight the need for studies that integrate observations and experiments on pathogens and density dependence into the whole life cycle of trees, because as yet it is not possible to be certain of the degree to which pathogens contribute to observed dynamics.

show abstract

Compensatory Recruitment, Growth, and Mortality as Factors Maintaining Rain Forest Tree Diversity

Cited by 350 publications

References 53 publications

Strong density- and diversity-related effects help to maintain tree species diversity in a neotropical forest

Strong density- and diversity-related effects help to maintain tree species diversity in a neotropical forest

Long-Term Studies of Vegetation Dynamics

Pathogens, density dependence and the coexistence of tropical trees

Contact Info

Product

Resources

About