Lucas A. Cernusak, The Australian National Uni- versity, Canberra, Australia. Hylton Adie, Univer- sity of KwaZulu?Natal, Scottsville, South Africa. Peter J. Bellingham and Ian A. Dickie, Landcare Research, Lincoln, New Zealand. Edward Biffin, The University of Adelaide, Adelaide, South Aus- tralia, Australia. Timothy J. Brodribb, University of Tasmania, Hobart, Tasmania, Australia. David A. Coomes, University of Cambridge, Cambridge, UK. James W. Dalling, University of Illinois at Urbana- Champaign, Urbana, Illinois, USA. Neal J. Enright and Philip G. Ladd, Murdoch Uni- versity, Murdoch, Western Australia, Australia. Kanehiro Kitayama, Kyoto University, Kyoto, Japan. Hans Lambers, The University of Western Australia, Crawley, Western Australia, Austra- lia. Michael J. Lawes, School for Environmental Research, Charles Darwin University, Darwin, Northern Territory, Australia. Christopher H. Lusk, Macquarie University, Sydney, New South Wales, Australia. Robert J. Morley, Palynova Lim- ited, Littleport, UK, and University of London, Egham, UK. Benjamin L. Turner, Smithsonian Tropical Research Institute, Balboa, Anc?n, Re- public of Panama. Correspondence: L. Cernusak, Lucas.Cernusak@anu.edu.au. Expanded author information precedes the Refer- ences section. Manuscript received 13 April 2010; accepted 9 July 2010. 12 Podocarpaceae in Tropical Forests: A Synthesis Lucas A. Cernusak, Hylton Adie, Peter J. Bellingham, Edward Biffin, Timothy J. Brodribb, David A. Coomes, James W. Dalling, Ian A. Dickie, Neal J. Enright, Kanehiro Kitayama, Philip G. Ladd, Hans Lambers, Michael J. Lawes, Christopher H. Lusk, Robert J. Morley, and Benjamin L. Turner The Podocarpaceae comprises 18 genera and about 173 species of ever- green, coniferous trees and shrubs. It is the most successful gymnosperm family in angiosperm- dominated tropical forests (Brodribb, this volume). Podocarps are distributed mainly in the Southern Hemisphere, with populations also ex- tending as far north as China and Japan and to Mexico and the Caribbean in the neotropics (Dalling et al., this volume; Enright and Jaffr?, this volume; Adie and Lawes, this volume). Molecular and fossil evidence suggests that the Podocarpaceae originated during the Triassic? Jurassic in Gondwana (Biffin et al., this volume; Morley, this volume). Currently, the greatest generic diversity of the Podocarpaceae is in Malesia (Enright and Jaffr?, this volume). Podocarps did not migrate into tropi- cal latitudes until later in their evolutionary history, appearing for the first time in Southeast Asia during the late Eocene, probably dispersing via the Indian Plate (Morley, this volume). Thus, the present latitudinal distributions have emerged in Asia and Africa over the last 40 million years. Although extinction rates in general appear to have been high within the family, a major shift in di- versification rate is estimated to have taken place in the mid- to Late Cretaceous and Paleocene, with most extant genera becoming established in Gondwana 1 9 0 ? S M I T H S O N I A N C O N T R I B U T I O N S T O B O TA N Y during this period. This shift could reflect reduced extinc- tion and/or increased speciation in response to the expan- sion of angiosperm- dominated tropical forests (Biffin et al., this volume). An alternative explanation for the Late Cretaceous and Paleocene diversification could be the on- set of wetter and warmer climatic conditions associated with the opening of the Southern Ocean (Morley, this volume). Some podocarp taxa show widespread and/or disjunct distributions. In the absence of molecular data, it is dif- ficult to infer migration patterns or the potential for gene flow among these disjunct populations. Patterns of relat- edness among populations in tropical forests could help reveal whether current populations are relicts of cooler tropical climates associated with the Last Glacial Maxi- mum or the consequence of postglacial occupancy of suit- able habitat. Tropical podocarps are most abundant in mid- to high- elevation forests, suggesting that the habitat re- quirements of temperate ancestors have been retained as podocarps radiated into the tropics. Podocarps also oc- cur occasionally in lowland tropical rainforest, but this is the exception, rather than the rule (Dalling et al., this volume; Enright and Jaffr?, this volume; Adie and Lawes, this volume; Coomes and Bellingham, this volume). One such exception is their prominence in lowland heath forests (kerangas) on Borneo (Enright and Jaffr?, this volume). Thus, in Asia, podocarp taxa have apparently dispersed through both lowland and montane habitats. For example, the dispersal pathway for Dacrydium ap- pears to have been via India through kerangas, i.e., heath forests growing on acidic, sandy soils that are low in nu- trients, during the Paleogene. On the other hand, Dacry- carpus and Phyllocladus appear to have jumped between islands of montane/alpine habitat via New Guinea at the time of Plio?Pleistocene global cooling (Morley, this vol- ume; Enright and Jaffr?, this volume). A similar pattern of distributions can also be found in the neotropics, where podocarps are mainly montane, but with notable lowland exceptions (Dalling et al., this volume). There, podocarps are absent from most of the Amazon lowlands, except for the white sands around Iquitos, Peru, and nutrient- poor soils of the Guyana Shield. However, podocarps do occur at sea level on islands off both the Pacific and Atlantic coasts of Central America. It should also be noted that podocarp pollen was relatively common in lake sediments from the Amazon lowlands during the Last Glacial Maxi- mum approximately 18,000 years ago but decreased to trace amounts during the Holocene, presumably as a re- sult of climate warming (Colinvaux et al., 1996). Given that podocarps in lowland tropical forests ap- pear to achieve their highest abundance on low- fertility soils (Dalling et al., this volume; Enright and Jaffr?, this volume; Coomes and Bellingham, this volume), do they have high nutrient use efficiency and/or unique mecha- nisms for acquiring nutrients? Nutrient use efficiency can be defined as the product of nutrient productivity and mean nutrient residence time (Berendse and Aerts, 1987; Aerts and Chapin, 2000). Nutrient productivity is a rate variable, expressed as carbon uptake per unit of nutrient per unit time. Mean nutrient residence time is the aver- age amount of time that a unit of nutrient spends in the plant between acquisition from the environment and loss through above- and below- ground litter production. Leaf- level measurements suggest that podocarps do not have nutrient productivities that can match those of tropical angiosperms. In a comparison of conifer and angiosperm seedlings grown in Panama, Podocarpus guatemalensis had photosynthetic nitrogen productivity of 38 ?mol CO 2 mol-1 N s-1, whereas mean values were 64 and 162 ?mol CO 2 mol-1 N s-1 for three other conifer species and 11 angiosperm species, respectively (Cernusak et al., 2008). Mean values for photosynthetic phosphorus productiv- ity were 0.5, 0.7, and 2.5 mmol CO 2 mol-1 P s-1 for P. guatemalensis, three other conifer species, and 11 angio- sperm species, respectively. In general, podocarps have low photosynthetic rates per unit leaf mass compared to angiosperms, in common with other conifer taxa (Lusk, this volume). Low mass- based photosynthetic rates con- tribute to low leaf- level nutrient productivities (Aerts and Chapin, 2000). It seems likely, therefore, that any advantage that tropical podocarps have in terms of nutrient use efficiency should derive from mean nutrient residence time, rather than from nutrient productivity. Mean nutrient residence time can vary as a function of leaf and root life spans, tis- sue nutrient concentrations, and the efficiency of nutrient resorption from senescing tissues. In common with other conifers, podocarps do tend to have long leaf life spans compared to angiosperms (Lusk, this volume). Podocarps can also have lower leaf nutrient concentrations than an- giosperms: P. guatemalensis had leaf nitrogen and phos- phorus concentrations of 1.5% and 2.5?, respectively, compared with values of 1.2% and 2.9? for three other conifer species and 1.7% and 3.1? for 11 angiosperm spe- cies grown under similar soil conditions in Panama (Cer- nusak et al., 2008). Similarly, Podocarpus urbanii also had lower leaf nitrogen and phosphorus concentrations than co- occurring angiosperms in Jamaica (Dalling et al., this volume), but on Mount Kinabalu in Borneo nitrogen and n u m b e r 9 5 ? 1 9 1 phosphorus concentrations in the phyllodes of Phyllocla- dus hypophyllus were not different from those in leaves of co- occurring angiosperms (Kitayama et al., 2004). More data are therefore needed to determine whether leaf nutri- ent concentrations in tropical podocarps tend, in general, to be lower than in co- occurring angiosperm trees. There are no data that we are aware of for nutrient resorption efficiency from senescent leaves of tropical podocarps. Nor are we aware of data for root life spans, root nutri- ent concentrations, or resorption efficiency from senescing roots. Thus, although it is likely that tropical podocarps will have longer mean nutrient residence times than tropi- cal angiosperms, the evidence currently available is insuf- ficient to demonstrate this conclusively. In response to the second part of the question posed above, podocarps do not appear to possess any unique mechanism for acquiring nutrients. They do have conspic- uous nodules on their roots that grow in the absence of fungi or bacteria; their function remains unclear, although they appear to play no significant role in atmospheric ni- trogen fixation. Podocarp roots show very high rates of infection by arbuscular mycorrhizal fungi in both long and short nodular roots (Dickie and Holdaway, this vol- ume). Thus, the nodules may simply serve to increase root volume for interaction with symbiotic mycorrhizal fungi. Dickie and Holdaway (this volume) argue that the nod- ules could minimize root construction and turnover costs while maximizing the root volume available to support mycorrhizal associations. On the basis of measurements on Mount Kinabalu, Borneo, Kitayama et al. (this volume) further suggest that podocarps may form loose symbiotic associations with soil microbial communities. In summary, there does not appear to be a single, out- standing feature that can explain why podocarps are rela- tively most successful on infertile soils in lowland tropical forests. The explanation may rather lie in a suite of traits that combine to enable podocarps to compete successfully when the productivity advantage of angiosperms is di- minished by nutrient poverty (Brodribb and Feild, 2010). Some possible examples of such traits are long mean nu- trient residence times associated with long leaf and root life spans and low tissue nutrient concentrations, efficient manipulation of mycorrhizal symbioses, and some degree of control over the composition of soil microbial commu- nities by root exudates and the quality and quantity of leaf litter (Kitayama et al., this volume). Despite the frequent association of tropical podocarps with low- nutrient soils, it would be incorrect to assume that they are strictly confined to those soils. Broad- leaved podocarps, in particular, can also occur on more productive sites. This may be because broad leaves are im- portant for light interception efficiency and competitive- ness with co- occurring angiosperms at nutrient- rich sites, where dense canopies cast a pronounced shadow over re- generating seedlings (Adie and Lawes, this volume). Broad- leaved podocarps tend to be faster growing and shorter lived and have shorter leaf longevity and higher leaf litter quality than imbricate- leaved genera (Enright and Jaffr?, this volume). These traits in broad- leaved podocarps may approach those of co- occurring angiosperms. Under Afri- can forest conditions, superior shade tolerance by broad- leaved podocarps allows them to dominate competing angiosperms over a range of soil nutrient conditions (Adie and Lawes, 2009). Phylogenetic analyses suggest that the broad- leaved podocarps may have a higher diversification rate than genera with imbricate leaves (Biffin et al., this volume), possibly linked to differences between the two groups in metabolic rates. The ability to produce flattened, plagiotrophic leaves and shoots is fundamental to the success of podocarps in competition for light with angiosperms. Leaf flattening is a prominent feature within the Podocarpaceae and distin- guishes the broad- leaved podocarps from most other co- nifer taxa. Flattened leaves are likely to be a key factor enabling shade tolerance of podocarps (Brodribb, this vol- ume). The flattened leaves contain sclereids, which increase water transport from the leaf midvein to the sites of evapo- ration in the leaf lamina. Freed from the temperate- zone constraint of freezing, tropical broad- leaved podocarps can increase leaf size and thus have converged upon a strat- egy of leaf architecture that resembles that of co- occurring angiosperms. Whereas temperate podocarps tend to have lower leaf area ratios than co- occurring angiosperms, trop- ical podocarps may be more able to emulate shade- tolerant tropical angiosperms and intercept sunlight with a similar efficiency. In general, podocarps do not tolerate drought. This may be because they possess wood that is vulnerable to embolism by water stress and are unable to refill embo- lized tracheids (Brodribb, this volume). Additionally, the vascular system associated with homoxylous conifer wood may be insufficient to supply water to the relatively large leaf area carried by broad- leaved podocarps under condi- tions of high evaporative demand and/or low soil water potential. This may lead to excessively low leaf water potentials and sharply curtailed photosynthetic rates un- der such conditions. An extreme exception to the general intolerance to drought among podocarps occurs in the Mediterranean- type climate of southwest Australia. There, Podocarpus drouynianus forms a lignotuber that allows it 1 9 2 ? S M I T H S O N I A N C O N T R I B U T I O N S T O B O TA N Y to resprout following shoot dieback caused by fire and/or drought (Ladd and Enright, this volume). Kerangas forests are also subject to occasional drought, and species grow- ing in them, including podocarps, show an array of leaf traits, in combination with reduced plant size, that reduce water loss (Enright and Jaffr?, this volume). Podocarps are long- lived in the temperate zone, and there is evidence that they also have a longevity advantage over competing angiosperms in the tropics (Kitayama et al., this volume). They are often subcanopy components and not emergent in tropical forests, unlike many New Zea- land podocarps (Coomes and Bellingham, this volume). Landscape- scale disturbance is probably not necessary for regeneration of tropical podocarps, even though many spe- cies occur in areas where disturbances such as cyclones and landslides are common. Tropical podocarps are fire intoler- ant. In general, podocarp seedlings show low abundance. Thus, in many cases, slow growth and high persistence likely facilitate their ultimate recruitment to the canopy. Little is known about herbivory in tropical podocarps or their defenses against herbivores. Similarly, pollination and seed dispersal in tropical podocarps have been little studied. CONSER V ATION, MANAGEMENT, AND GLOBAL CHANGE In common with most tropical trees, the immediate threat to tropical podocarps is deforestation associated with timber extraction, mining, and other modern anthro- pogenic activities, including drainage of peat swamps and expansion of agricultural activities onto poor soils. Several podocarps are local montane endemics, and these may be further threatened by shifting climatic zones associated with global climate change and deforestation (Walther, 2004; Jump et al., 2009). These species could become in- creasingly rare within narrowing altitudinal bands, par- ticularly on islands and mountains. Tropical podocarps are fire and drought intolerant, so they will be particularly adversely affected wherever climate change leads to hotter, drier conditions with more frequent fires. Although podocarp timber has many uses for human activities, their slow growth rates make their exploitation ecologically unsustainable. Therefore, continued harvest- ing of existing individuals from natural stands threatens populations (Lawes et al., 2007). Habitat specialization restricts the potential area of suitable sites for podocarps, which requires broad- scale habitat conservation to capture potential conservation sites. The association with unusually infertile soils is also significant with regard to podocarp conservation. Inter- national Union for Conservation of Nature (IUCN) as- sessments of species conservation status are effectively determined by range sizes, in the absence of data on pop- ulation number or population change. Many podocarps have large ranges (i.e., thousands of square kilometers) but probably only occupy a fraction of that area. Thus, if podocarps really are restricted to unusual habitats, then they may be more endangered than current assessments suggest. Additionally, if conservation priorities are defined by phylogenetic diversity, podocarps have a high conser- vation value because their nearest living sister taxa are separated by about 250 million years (Biffin et al., this volume). A summary of tropical podocarp species that are threatened based on assessments in the 2009 IUCN Red List of Threatened Species (IUCN, 2009) is provided in Table 12.1. In addition to these species, a number of taxa are also considered ?near threatened? or ?data deficient.? Thus, Table 12.1 likely represents a conservative estimate of the true number of tropical podocarp species currently under threat of extinction. Taking this conservative esti- mate, roughly one- fourth of tropical podocarp species are threatened, with five species considered critically endan- gered, 18 species endangered, and 16 species vulnerable (Table 12.1). Many of the species in Table 12.1 are island endemics, including four species from Madagascar, six species from New Caledonia, and seven species from Bor- neo. In addition, there are a number of species endemic to islands in the Western Pacific and the Caribbean. Because podocarp- dominated forests are often associ- ated with ecosystems that have poor drainage and large accumulations of organic material on the forest floor, they play an important role in carbon storage. Leaf and litter characteristics of podocarps generally result in slow de- composition rates, leading to an accumulation of carbon in the litter layer and in the soil. This carbon can be rap- idly lost when podocarp- dominated forests are cleared for other land uses (Freier et al., 2010). Thus, the UN global initiative to reduce emissions from tropical deforestation and degradation should place a high value on podocarp- dominated forests. RECOMMENDATIONS FOR FUTURE RESEARCH Podocarps are potentially good indicators of environ- mental change over their 250 million year history. Impor- tant aspects of the phylogeny of Podocarpaceae remain to n u m b e r 9 5 ? 1 9 3 be resolved, and more and better information would aid their use as environmental indicators. A phylogeographic perspective could help in understanding population con- nectivity under changing climate in the Holocene. Dispersal and recruitment dynamics of infrequent lowland tropical podocarps are largely unknown. As podocarps are mostly dispersed by large- bodied animals, local extinction of dispersers may particularly impact upon podocarp regeneration and recruitment and genetic diversity, especially on islands. Population genetic data could effectively address issues of pollen and seed disper- sal, genetic diversity, and relatedness. TABLE 12.1. Conservation status of threatened tropical species of the Podocarpaceae (IUCN, 2009). Abbreviations: CR, critically endangered; EN, endangered; VU, vulnerable. Species Status Location Habitat Acmopyle sahniana CR Fiji Montane forest Afrocarpus mannii VU S?o Tom?, Gulf of Guinea Montane forest A. usambarensis VU East African highlands Montane forest Dacrydium comosum EN Malay Peninsula Montane Forest D. ericoides VU Sarawak, Borneo Hill forest, ultrabasic D. gracile VU Sabah, Borneo Montane forest D. guillauminii CR New Caledonia Riparian D. leptophyllum VU Irian Jaya Montane heath forest D. nausoriense EN Fiji Montane rainforest Falcatifolium angustum VU Sarawak, Borneo Lowland rainforest Nageia maxima VU Sarawak, Borneo Peat swamp forest Parasitaxus usta VU New Caledonia Montane rainforest understory Podocarpus affinis VU Fiji Montane rainforest P. angustifolius EN Cuba Montane rainforest P. aristulatus VU Cuba, Hispaniola Montane forest P. beecherae EN New Caledonia Wet maquis P. brevifolius VU Sabah, Mount Kinabalu Montane forest P. capuronii EN Madagascar Montane forest P. costalis EN Philippines, Taiwan Montane forest P. costaricensis VU Costa Rica Lowland to montane forest P. decumbens CR New Caledonia Montane stunted forest P. deflexus EN Malay Peninsula, Sumatra Montane forest P. gibbsii VU Sabah, Mount Kinabalu Montane forest P. globulus EN Sabah, Borneo Lowland to montane forest P. hispaniolensis EN Dominican Republic Montane forest P. humbertii EN Madagascar Montane forest, heath P. laubenfelsii EN Sarawak, Borneo Kerangas, montane heath P. longifoliolatus EN New Caledonia Montane rainforest understory P. lophatus VU Philippines Montane forest P. nakaii EN Taiwan Subtropical forest P. palawanensis CR Philippines Lowland rainforest P. pallidus VU Tonga Montane forest P. pendulifolius EN Venezuela Montane rainforest P. perrieri CR Madagascar Montane forest P. polyspermus EN New Caledonia Montane forest P. purdieanus EN Jamaica Montane forest P. rostratus EN Madagascar Montane forest Retrophyllum minus EN New Caledonia Riparian R. rospigliosi VU Venezuela, Colombia, Peru Montane forest 1 9 4 ? S M I T H S O N I A N C O N T R I B U T I O N S T O B O TA N Y Podocarps colonize second- growth forests in some temperate regions. The potential for podocarps to colo- nize second- growth tropical forests, which are increasing in area in some tropical regions, is unknown. Physiologi- cal and growth responses of podocarps to variation in atmospheric CO 2 concentration are unknown but could have important implications for their use as indicators of environmental change. Understanding why tropical podocarps are mostly re- stricted to wet, infertile environments requires informa- tion about their ecophysiology. For example, seedling leaf area ratios of temperate podocarps are generally low rela- tive to co- occurring angiosperms, but virtually nothing is known of leaf area ratios of large- leaved lowland tropical podocarps. More information about physiological mecha- nisms of drought sensitivity, including stomatal function and susceptibility to cavitation, is key to understanding current podocarp distributions. The physiological adap- tations allowing podocarp success on infertile soils, po- tentially including conspicuous root nodules, mycorrhizal symbioses, and nutrient retention strategies, are key areas for further research. A better understanding of podocarp ecophysiology is likely to be achieved through integrated, whole- plant studies, rather than by addressing nutrient, carbon, and water relations independently of each other. Finally, podocarps are poorly represented in perma- nent census plots in tropical forests, which limits knowl- edge of demography and habitat associations. Important demographic factors and environmental drivers are likely to be longevity, relative shade tolerance, and edaphic properties. Permanent plot data could provide an oppor- tunity to collate such information. Results could provide a framework to inform decisions about silviculture and forest management of podocarps. exPanded author inforMation Lucas A. Cernusak, Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia; Lucas.Cernusak@anu.edu.au. Hylton Adie, School of Biological and Conservation Sciences, For- est Biodiversity Research Unit, University of KwaZulu? Natal, Private Bag X01, Scottsville 3209, South Africa. Peter J. Bellingham and Ian A. Dickie, Landcare Research, PO Box 40, Lincoln 7640, New Zealand. Edward Bif- fin, Australian Centre for Evolutionary Biology and Bio- diversity, School of Earth and Environmental Science, The University of Adelaide, Adelaide, South Australia 5005, Australia. Timothy J. Brodribb, School of Plant Science, University of Tasmania, Hobart, Tasmania 7001, Australia. David A. Coomes, Forest Conservation and Ecology Group, Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, UK. James W. Dal- ling, Department of Plant Biology, University of Illinois at Urbana- Champaign, 265 Morrill Hall, 505 S. Good- win Avenue, Urbana, Illinois 61081, USA. Neal J. Enright and Philip G. Ladd, School of Environmental Science, Murdoch University, Murdoch, Western Australia 6150, Australia. Kanehiro Kitayama, Graduate School of Agri- culture, Kyoto University, Kyoto 606- 8502, Japan. Hans Lambers, School of Plant Biology, The University of West- ern Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia. Michael J. Lawes, School for Environmental Research, Charles Darwin University, Dar- win, Northern Territory 0909, Australia. Christopher H. Lusk, Department of Biological Sciences, Macquarie Uni- versity, Sydney, New South Wales 2109, Australia. Robert J. Morley, Palynova Limited, 1 Mow Fen Road, Littleport CB6 1PY, UK, and Department of Earth Sciences, Royal Holloway, University of London, Egham TW20 0EX, UK. Benjamin L. Turner, Smithsonian Tropical Research Insti- tute, Apartado 0843- 03092, Balboa, Anc?n, Republic of Panama. REFERENCES Adie, H. and M. J. Lawes. 2009. Explaining Conifer Dominance in Af- rotemperate Forests: Shade Tolerance Favours Podocarpus latifolius over Angiosperm Species. Forest Ecol. Managem. 259: 176?186. Adie, H., and M. J. Lawes. 2011 (this volume). Podocarps in Africa: Temperate Zone Relicts or Rainforest Survivors? In Ecology of the Podocarpaceae in Tropical Forests, B. L. Turner and L. A. Cernu- sak, eds., pp. 79?100. Smithsonian Contributions to Botany, No. 95. Smithsonian Institution Scholarly Press, Washington, D.C. Aerts, R., and F. S. Chapin. 2000. The Mineral Nutrition of Wild Plants Revisited: A Re- evaluation of Processes and Patterns. Advances Ecol. Res. 30: 1?67. Berendse, F., and R. Aerts. 1987. Nitrogen- Use Efficiency: A Biologically Meaningful Definition? Funct. Ecol. 1: 293?296. Biffin, E., J. Conran, and A. Lowe. 2011 (this volume). Podocarp Evo- lution: A Molecular Phylogenetic Perspective. In Ecology of the Podocarpaceae in Tropical Forests, B. L. Turner and L. A. Cernu- sak, eds., pp. 1?20. Smithsonian Contributions to Botany, No. 95. Smithsonian Institution Scholarly Press, Washington, D.C. Brodribb, T. J. 2011 (this volume). A Functional Analysis of Podocarp Ecology. In Ecology of the Podocarpaceae in Tropical Forests, B. L. Turner and L. A. Cernusak, eds., pp. 165?173. Smithsonian Contri- butions to Botany, No. 95. Smithsonian Institution Scholarly Press, Washington, D.C. Brodribb, T. J., and T. S. Field. 2010. Leaf Hydraulic Evolution Led a Surge in Leaf Photosynthetic Capacity during Early Angiosperm Diversification. Ecol. Letters 13: 175?183. Cernusak, L. A., K. Winter, J. Aranda, and B. L. Turner. 2008. Conifers, Angiosperm Trees, and Lianas: Growth, Whole- Plant Water and Nitrogen Use Efficiency, and Stable Isotope Composition (d13C and n u m b e r 9 5 ? 1 9 5 d18O) of Seedlings Grown in a Tropical Environment. Pl. Physiol. 148: 642?659. Colinvaux, P. A., P. E. De Oliveira, J. E. Moreno, M. C. Miller and M. B. Bush. 1996. A Long Pollen Record from Lowland Amazonia: For- est and Cooling in Glacial Times. Science 274: 85?88. Coomes, D. A., and P. J. Bellingham. 2011 (this volume). Temperate and Tropical Podocarps: How Ecologically Alike Are They? In Ecology of the Podocarpaceae in Tropical Forests, B. L. Turner and L. A. Cernusak, eds., pp. 119?140. Smithsonian Contributions to Botany, No. 95. Smithsonian Institution Scholarly Press, Washington, D.C. Dalling, J. W., P. Barkan, P. J. Bellingham, J. R. Healey, E. V. J. Tan- ner, J. T. Murillo. 2011 (this volume). Ecology and Distribution of Neotropical Podocarpaceae. In Ecology of the Podocarpaceae in Tropical Forests, B. L. Turner and L. A. Cernusak, eds., pp. 43?56. Smithsonian Contributions to Botany, No. 95. Smithsonian Institu- tion Scholarly Press, Washington, D.C. Dickie, I. A., and R. J. Holdaway. 2011 (this volume). Podocarp Roots, Mycorrhizas, and Nodules. In Ecology of the Podocarpaceae in Tropical Forests, B. L. Turner and L. A. Cernusak, eds., pp. 175? 187. Smithsonian Contributions to Botany, No. 95. Smithsonian Institution Scholarly Press, Washington, D.C. Enright, N. J., and T. Jaffr?. 2011 (this volume). Ecology and Distribu- tion of the Malesian Podocarps. In Ecology of the Podocarpaceae in Tropical Forests, B. L. Turner and L. A. Cernusak, eds., pp. 57?77. Smithsonian Contributions to Botany, No. 95. Smithsonian Institu- tion Scholarly Press, Washington, D.C. Freier, K. P., B. Glaser, and W. Zech. 2010. Mathematical Modeling of Soil Carbon Turnover in Natural Podocarpus Forest and Eucalyp- tus Plantation in Ethiopia Using Compound Specific d13C Analysis. Global Change Biol. 16: 1487- 1502. International Union for Conservation of Nature (IUCN). 2009. IUCN Red List of Threatened Species. Version 2009.2. http://www.iucnred list.org (accessed 22 December 2009). Jump, A. S., C. M?ty?s, and J. Pe?uelas. 2009. The Altitude- for- Latititude Disparity in the Range Retractions of Woody Species. Trends Ecol. Evol. 24: 694?701. Kitayama, K., S. I. Aiba, M. Takyu, N. Majalap, and R. Wagai. 2004. Soil Phosphorus Fractionation and Phosphorus- Use Efficiency of a Bornean Tropical Montane Rain Forest during Soil Aging with Podozolization. Ecosystems 7: 259?274. Kitayama, K., S. Aiba, M. Ushio, T. Seino, and Y. Fujiki. 2011 (this volume). The Ecology of Podocarps in Tropical Montane Forests of Borneo: Distribution, Population Dynamics, and Soil Nutrient Acquisition. In Ecology of the Podocarpaceae in Tropical Forests, B. L. Turner and L. A. Cernusak, eds., pp. 101?117. Smithsonian Contributions to Botany, No. 95. Smithsonian Institution Scholarly Press, Washington, D.C. Ladd, P. G., and N. J. Enright. 2011 (this volume). Ecology of Fire- Tolerant Podocarps in Temperate Australian Forests. In Ecology of the Podocarpaceae in Tropical Forests, B. L. Turner and L. A. Cer- nusak, eds., pp. 141?155. Smithsonian Contributions to Botany, No. 95. Smithsonian Institution Scholarly Press, Washington, D.C. Lawes, M. J., M. E. Griffiths, and S. Boudreau. 2007. Colonial Logging and Recent Subsistence Harvesting Affect the Composition and Physiognomy of a Podocarp Dominated Afrotemperate Forest. For- est Ecol. Managem. 247: 48?60. Lusk, C. H. 2011 (this volume). Conifer- Angiosperm Interactions: Physi- ological Ecology and Life History. In Ecology of the Podocarpaceae in Tropical Forests, B. L. Turner and L. A. Cernusak, eds., pp. 157? 164. Smithsonian Contributions to Botany, No. 95. Smithsonian Institution Scholarly Press, Washington, D.C. Morley, R. J. 2011 (this volume). Dispersal and Paleoecology of Tropical Podocarps. In Ecology of the Podocarpaceae in Tropical Forests, B. L. Turner and L. A. Cernusak, eds., pp. 21?41. Smithsonian Contributions to Botany, No. 95. Smithsonian Institution Scholarly Press, Washington, D.C. Walther, G. R. 2004. Plants in a Warmer World. Perspect. Pl. Ecol. Evol. Syst. 6: 169?185.