Browsing by Autor "Joseph W. Veldman"

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Clarifying the confusion: old-growth savannahs and tropical ecosystem degradation
(Royal Society, 2016) Joseph W. Veldman
Ancient tropical grassy biomes are often misrecognized as severely degraded forests. I trace this confusion to several factors, with roots in the nineteenth century, including misinterpretations of the nature of fire in savannahs, attempts to reconcile savannah ecology with Clementsian succession, use of physiognomic (structural) definitions of savannah and development of tropical degradation frameworks focused solely on forests. Towards clarity, I present two models that conceptualize the drivers of ecosystem degradation as operating in both savannahs and forests. These models highlight how human-induced environmental changes create ecosystems with superficially similar physiognomies but radically different conservation values. Given the limitation of physiognomy to differentiate savannahs from severely degraded forests, I present an alternative approach based on floristic composition. Data from eastern lowland Bolivia show that old-growth savannahs can be reliably distinguished by eight grass species and that species identity influences ecosystem flammability. I recommend that scientists incorporate savannahs in tropical degradation frameworks alongside forests, and that savannah be qualified as old-growth savannah in reference to ancient grassy biomes or derived savannah in reference to deforestation. These conceptual advances will require attention not only to tree cover, but also to savannah herbaceous plant species and their ecologies.This article is part of the themed issue 'Tropical grassy biomes: linking ecology, human use and conservation'.
Comment on “The global tree restoration potential”
(American Association for the Advancement of Science, 2019) Joseph W. Veldman; Julie C. Aleman; Swanni T. Alvarado; T. Michael Anderson; Sally Archibald; William J. Bond; Thomas W. Boutton; Nina Buchmann; Élise Buisson; Josep G. Canadell
Bastin et al (Reports, 5 July 2019, p. 76) claim that 205 gigatonnes of carbon can be globally sequestered by restoring 0.9 billion hectares of forest and woodland canopy cover. Reinterpreting the data from Bastin et al, we show that the global land area actually required to sequester human-emitted CO2 is at least a factor of 3 higher, representing an unrealistically large area.
Grass-dominated vegetation, not species-diverse natural savanna, replaces degraded tropical forests on the southern edge of the Amazon Basin
(Elsevier BV, 2011) Joseph W. Veldman; Francis E. Putz
Grassy biomes: An inconvenient reality for large‐scale forest restoration? A comment on the essay by Chazdon and Laestadius
(Wiley, 2017) Joseph W. Veldman; Fernando A. O. Silveira; Forrest Fleischman; Nataly Ascarrunz; Giselda Durigan
In their essay, Forest and landscape restoration: Toward a shared vision and vocabulary, Chazdon and Laestadius (2016) made an impassioned case for the restoration of deforested land at the global scale. Unfortunately, they did not address the risks posed to the world's ancient grassy biomes (i.e., grasslands, savannas, and open-canopy woodlands) by forest-biased conservation agendas that promote tree planting and fire exclusion, and indirectly incentivize agricultural conversion of ecosystems with naturally low tree cover (Parr et al., 2014; Overbeck et al., 2015; Searchinger et al., 2015; Veldman et al., 2015a, b). The risk of misapplying forest restoration, resulting in the establishment of forests where they did not historically occur (i.e., afforestation and forest expansion; Fig. 1), is particularly high in the tropics where, for at least a century, European and North American ecologists have confused old-growth savannas (shaped over millions of years by fire and megafaunal herbivores; Veldman et al., 2015a; Bond, 2016) with deforested land, recently cleared by humans (Fairhead and Leach, 1996; Veldman, 2016). We agree with Chazdon and Laestadius that forest restoration can provide benefits when implemented on deforested and degraded forest land, but misapplication of tree-promoting land management strategies in historically grassy biomes has many clear, long-lasting, negative consequences for people and nature. Such negative consequences include the loss of pastoral livelihoods, perpetuation of poverty, reduced groundwater recharge, and declines in plant and animal diversity (Cao et al., 2011; Fleischman, 2014; Parr et al., 2014; Overbeck et al., 2015). Ancient grassy biomes (left, an old-growth savanna in Bolivia) are important to human livelihoods (e.g., livestock production) and support a tremendous diversity of long-lived herbaceous plants and endemic animals (Parr et al., 2014; Veldman et al., 2015a). Misapplication of forest restoration to grassy biomes results in afforestation (center, a Eucalyptus plantation in Brazil), forest expansion (right, due to fire exclusion in Brazil), and declines in biodiversity and ecosystem services (Veldman et al., 2015b). It is not our intent to fully reiterate these previously published concerns, but rather to address their relevance with respect to two assertions advanced by Chazdon and Laestadius (2016). These assertions were (1) to achieve the level of political support necessary for the success of large-scale forest restoration, scientists need to be more pragmatic in their selection of evidence and attention to detail; and (2) such pragmatism is essential to the development of a “shared vision and vocabulary”, understandable to both scientists and policymakers. While we fully agree with Chazdon and Laestadius about the need to bridge science and policymaking in a process that “integrates the best available technical, traditional, and practical knowledge” (p. 1870), these two assertions warrant critical evaluation by scientists. With regard to pragmatism and evidence, we are concerned that Chazdon and Laestadius, along with their colleagues at the World Resources Institute (WRI) and the International Union for Conservation of Nature (IUCN; i.e., Laestadius et al., 2015; DeWitt et al., 2016), continue to overestimate the amount of deforested and degraded forest land that is suitable for reforestation. Chazdon and Laestadius (2016, p. 1869) write “Over 2 billion hectares (7,722,043 square miles) of dysfunctional land (former forest and mixed woodland) provide opportunities for forest landscape restoration (Laestadius et al., 2011).” This estimate—based on remote sensing of tree cover and the overly simplistic assumption that low tree cover is evidence of deforestation (Laestadius et al., 2011)—mistakenly includes nearly 1 billion hectares of the world's grassy biomes (i.e., 40% of the total “opportunities for forest landscape restoration”; Veldman et al., 2015b). Much of these classification errors occurred in tropical regions where tree cover is an unsuitable metric to diagnose ecosystem degradation (Veldman, 2016), let alone prioritize landscapes for restoration efforts (Bond, 2016). This same flawed analysis (i.e., Laestadius et al., 2011) is the basis for the interactive online Atlas of Forest Restoration Opportunities (WRI, 2014). Promoted by WRI (2014) as an information management tool for stakeholders and decision makers, the Atlas allows users to peruse the globe and zoom in on identified “deforested” and “degraded” land, categories that erroneously include many old-growth savannas and grasslands (Veldman et al., 2015b). Given the ecological and human risks posed by misapplied reforestation efforts, a politically pragmatic approach requires that scientists provide policymakers with the best possible information (Pielke, 2007). In this case, the best information should be used to substantially narrow the area deemed suitable for restoration and thereby help governments and funding organizations allocate limited resources to truly degraded land. The reliance of Chazdon and Laestadius (2016) on analyses that overestimate forest degradation and misrepresent grassy biomes as deforested (Veldman et al., 2015b) is also worrisome given their goal to establish a “shared vision and vocabulary” for forest restoration globally. We are particularly concerned about language that seems to equate “grazing land” with “cleared land” (p. 1869), given that herbivores (native and domestic) are important to the maintenance of old-growth grassland biodiversity and are critical to human livelihoods (e.g., Trauernicht et al., 2013). Similarly, we are concerned by calls to “return forest cover to barren lands” while broadly referring to low tree cover ecosystems as “dysfunctional” (p. 1869). We urge scientists and politicians to take great care to avoid vocabulary that is reminiscent of the degradation discourse of western European colonialism, which portrayed indigenous land management practices—such as savanna burning and livestock grazing—as causes of degradation and served as a pretext for the subjugation of native peoples and the appropriation of natural resources (Fairhead and Leach, 1996). Moving forward, thoughtful vocabulary will be important to avoid the pitfalls of other well-intentioned conservation initiatives that inadvertently play a negative role in processes of dispossession and environmental degradation in many parts of the world (Larson and Ribot, 2007; Kashwan, 2017). Indeed, there is a long history of oversights in the communication of ecological knowledge that translated into long-lasting policy prescriptions with negative environmental and social consequences (Fleischman, 2014). Although the best defense against such mistranslations is to clearly communicate both knowledge and uncertainty at the outset, Chazdon and Laestadius omit reference to cautionary literature on the implementation of Forest and Landscape Restoration (FLR) in grassy biomes. Such omission may reflect a general viewpoint among FLR proponents that concerns over threats to grassy biomes are unwarranted (but see Mansourian et al., 2017). For example, in response to Veldman et al. (2015b) and Bond (2016), Laestadius et al. (2015, p. 1210) and DeWitt et al. (2016, p. 1036) wrote: “FLR does not call for increasing tree cover beyond what would be ecologically appropriate for a particular location, and should not cause any loss or conversion of natural forests, grasslands, or other ecosystems.” Unfortunately, such assurances provide no safeguard against the entrenched interests of forestry bureaucrats and timber companies who plant trees, often under the guise of restoration, without regard to ecological histories or cultural values (Fleischman, 2014; Andersson et al., 2016). We thus urge Chazdon and Laestadius to seriously consider the risks of misapplied forest restoration efforts (e.g., water shortages; Cao et al., 2011) and ask that their WRI and IUCN colleagues (Laestadius et al., 2015; DeWitt et al., 2016) either revise, or take off-line, their flawed map of forest restoration opportunities (WRI, 2014). More generally, we encourage scientists and environmental policymakers to better acknowledge the conservation values of tropical savannas (e.g., Searchinger et al., 2015) and to work with us to incorporate grasslands and fire, alongside forests, in conservation and restoration efforts (Overbeck et al., 2015; Veldman, 2016). The authors thank W. J. Bond, R. F. Noss, and two anonymous reviewers for helpful comments on previous versions of this manuscript.
Guidelines for including bamboos in tropical ecosystem monitoring
(Wiley, 2020) Belén Fadrique; Joseph W. Veldman; James W. Dalling; Lynn G. Clark; Lía Montti; Eduardo Ruíz-Sánchez; Débora Cristina Rother; Francisca Ely; William Farfán-Ríos; Paul R. Gagnon
Abstract Bamboos are a diverse and ecologically important group of plants that have the potential to modulate the structure, composition, and function of forests. With the aim of increasing the visibility and representation of bamboo in forest surveys, and to standardize techniques across ecosystems, we present a protocol for bamboo monitoring in permanent research plots. A bamboo protocol is necessary because measurements and sampling schemes that are well‐suited to trees are inadequate for monitoring most bamboo species and populations. Our protocol suggests counting all bamboo culms (stems) in the study plot and determining bamboo dimensions based on two different approaches: (a) measuring a random subset of 60 culms and calculating the average dimensions or (b) measuring all culms. With data from 1‐ha plots in the Peruvian Andes, we show that both approaches provide very similar estimates of bamboo basal area. We suggest including all mature culms rooted inside change the to each plot from all woody bamboo species with maximum diameters ≥1 cm. We also present recommendations on how to collect vouchers of bamboo species for identification. Data collected according to our proposed protocols will increase our understanding of regional and global patterns in bamboo diversity and the role of bamboo in forest dynamics. Abstract in Spanish is available with online material.
Long‐distance Dispersal of Invasive Grasses by Logging Vehicles in a Tropical Dry Forest
(Wiley, 2010) Joseph W. Veldman; Francis E. Putz
ABSTRACT Predicting responses of vegetation to environmental factors in human‐altered tropical ecosystems requires an understanding of the controls on plant population expansion across landscapes ( i.e ., long‐distance dispersal) as well as of factors affecting recruitment at local scales ( i.e ., microsite conditions). We studied the roles of light availability, habitat type, soil disturbance, and seed dispersal in a selectively logged forest in lowland Bolivia where the exotic forage grass Urochloa ( Panicum ) maxima is abundant on roads and log landings but does not invade felling gaps or unlogged forest. Shade‐house trials and seed addition experiments with U. maxima revealed that this C 4 grass thrives in high light but also grows in partial shade (10% full sun, but not 1% full sun), and that felling gaps, but not undisturbed forest, are suitable for grass establishment. To determine if seed dispersal by logging vehicles explains the discrepancy between actual and potential grass recruitment sites, we collected grass seeds that fell from trucks onto log landings located long distances (>500 m) from established grass populations. Trucks dispersed an estimated 1800 alien grass seeds per log landing during the early dry season; automobiles also transported seeds of grass (135 seeds/vehicle). The seeds collected (and relative abundances) were the exotics U. (Panicum) maxima (97%) and Urochloa (Brachiaria) brizantha (2%), and the pan‐tropical weeds Sorghum halapense (1%) and Rottboellia cochinchinensis (0.2%). Grasses invade this forest where disturbance coincides with seed dispersal by motor vehicles, while dispersal limitation apparently prevents invasion of many sites otherwise suitable for grass recruitment ( i.e ., felling and natural gaps).
Molecular evidence of cryptic speciation, historical range expansion, and recent intraspecific hybridization in the Neotropical seasonal forest tree Cedrela fissilis (Meliaceae)
(Elsevier BV, 2011) Magali Gonçalves Garcia; Roberta Santos Silva; Maria Antônia Carniello; Joseph W. Veldman; Ana Aparecida Bandini Rossi; Luiz Orlando de Oliveira
Selective logging and fire as drivers of alien grass invasion in a Bolivian tropical dry forest
(Elsevier BV, 2009) Joseph W. Veldman; Bonifacio Mostacedo; Marielos Peña‐Claros; Francis E. Putz