Uromi Manage Goodale

Ecological Significance of Crown Functional Traits Across Size Classes and Disturbance Environments in Eight Pioneer Species in a Sri Lankan Rain Forest

Information on tree crown characteristics has been used in forestry to assess tree and ecosystem health and productivity. Although there are well known differences in crown functional traits between light-demanding pioneer species and later successional species, data is limited usually to regeneration phases. Further, information on variation between species within the pioneer guild is needed in order to select pioneer species for facilitation of reforestation, more shade demanding species, and for monitoring and evaluation of such efforts. In this study we assessed three crown functional characteristics—crown surface area, crown volume, and live crown ratio—in eight pioneer species commonly found in the tropical rain forests of Sri Lanka: Alstonia macrophylla Wallich ex G. Don, Dillenia triquetra (Rottb.) Gilg, Macaranga indica Wight, Macaranga peltata (Roxb.) Muell, Melastoma malabathricum L., Schumacheria castaneifolia Vahl, Trema orientalis (L.) Blume, and Wendlandia bicuspidata Wight & Arn. We modeled the influence of species, tree size, and environmental factors on these crown functional traits in seedling, sapling, and larger tree size classes using generalized linear models. We found that the disturbance environment was only influential at the larger tree size class. For smaller size classes, the majority of the variation in crown characteristics was explained by tree size characteristics. In larger trees, among the three functional traits, live crown ratio showed the strongest relationship with the disturbance environment and crown surface area and crown volume had higher correlation with tree height and diameter. While crown characteristics were influenced by species irrespective of size class, in the larger trees species varied in their relationship between tree crown functional traits and the disturbance environment. In larger trees, four species—M. indica, D. triquetra, S. castaneifolia, and W. bicuspidata, which are more commonly found in small gaps—had stronger relationships between crown surface area, live crown ratio and canopy openness than T. orientalis and M. peltata, which are more commonly found in large canopy openings, and A. macrophylla and M. malabathricum, two generalist species. The small gap specialists may develop deeper crowns to overcome the short duration of direct light in small gaps and more efficiently utilize lateral light which is a larger fraction of total light in these environments compared to large canopy openings. The differences among species must be considered in selecting pioneers for reforestation efforts and designing silvicultural treatments. We recommend a step wise introduction of species starting with the more high light restricted and generalist pioneers followed by the small gap restricted species and finally the late successional species.

Effect of topography and litterfall input on fine-scale patch consistency of soil chemical properties in a tropical rainforest

AimsSpatial aggregation of soil chemical properties, or nutrient patches, may be generated by topography and plants and can seasonally fluctuate because of climate. Whether nutrient patches maintain consistency (no change in ranking through sequential sampling), through temporal scales, and whether topography and litterfall contribute to the persistence of such ranking is rarely tested.MethodsIn a 1-ha tropical rainforest plot in Southwest China, we measured soil pH, total N, NH4–N, NO3–N, and available P and K for four times and assessed the patch structure (patterns of patch distribution) and their temporal consistency. We then tested how structure and consistency of chemical soil properties were affected by topography and chemical inputs from litterfall.ResultsAll soil chemical properties showed significant seasonal fluctuations, but patch consistency was higher for soil pH, total N, and available P and K compared to NH4–N or NO3–N. Topography influenced pH patch consistency while annual litterfall input was important for maintaining patch consistency in total N and available P and K.ConclusionsFine-scale consistency of patches in soil pH, total N, and available P and K suggest they may exert stable selection pressures on species for niche differentiation, while consistency of soil NH4–N and NO3–N require further study.

Conservation and the agricultural frontier: collapsing conceptual boundaries.

Agriculture and forest conservation are frequently placed in opposition to each other at the levels of both science and policy. However, in this article, we outline the ways in which these two fields of practice overlap and argue that—particularly in the context of the global economic crisis and predictions of climate change—it is urgent for conservationists and agricultural specialists to strengthen their collaborative work. We subsequently summarize the articles in this compilation, which demonstrate that human activities at the forest-agriculture interface are complex and multifaceted, and that sustainability is mediated by many factors—including land management practices, economic conditions, and the policy environment. Finally, we summarize a few take-home messages, suggesting new directions and principles for future research at the forest-agriculture interface.

The Goals and Challenges of the March 30-31, 2001 Yale ISTF Conference Entitled

SUMMARY On March 30 and 31 of 2001, the Yale chapter of the International Society of Tropical Foresters (Yale ISTF) convened scientists, managers, policy-makers, and community leaders for an interdisciplinary exploration of issues and challenges associated with the management of transboundary protected areas. Thirteen papers and four posters were presented at the conference held at the Yale School of Forestry and Environmental Studies in New Haven, CT entitled Transboundary Protected Areas: The Viability of Regional Conservation Strategies. This brief introductory paper provides background concerning the goals and challenges put forth by the conference organizers. Conference participants were challenged to reconcile the seemingly “top-down” eco-regional and transboundary approaches to conservation with currently popular “bottom-up” approaches, to determine if lessons from community-based conservation and other local approaches could be applied to transboundary efforts. The papers contained within this volume reveal that cooperation and leadership among diverse stakeholders at multiple levels and scales will be necessary for successful and sustainable conservation across international boundaries, calling for the simultaneous employment of both top-down and bottom-up conservation strategies.

The effect of land-use on the diversity and mass-abundance relationships of understory avian insectivores in Sri Lanka and southern India

Understory avian insectivores are especially sensitive to deforestation, although regional differences in how these species respond to human disturbance may be linked to varying land-use histories. South Asia experienced widespread conversion of forest to agriculture in the nineteenth century, providing a comparison to tropical areas deforested more recently. In Sri Lanka and the Western Ghats of India, we compared understory insectivores to other guilds, and to insectivores with different vertical strata preferences, both inside mixed-species flocks and for the whole bird community. Overall species richness did not change across the land-use gradient, although there was substantial turnover in species composition between land-use types. We found that the proportion of species represented by insectivores was ~1.14 times higher in forest compared to agriculture, and the proportion of insectivores represented by understory species was ~1.32 times higher in forests. Mass-abundance relationships were very different when analyzed on mixed-species flocks compared to the total community, perhaps indicating reduced competition in these mutualisms. We show that South Asia fits the worldwide pattern of understory insectivores declining with increased land-use intensity, and conclude that these species can be used globally as indicator and/or umbrella species for conservation across different disturbance time scales.

The role of toxic pitohuis in mixed-species flocks of lowland forest in Papua New Guinea

Abstract In many animal taxa, non-toxic species demonstrate Batesian mimicry—appearing or behaving similarly to harmful species—thereby reducing their attractiveness to predators. A potential example of Batesian mimicry occurs in Papua New Guinea (PNG), where birds of the genus Pitohui have been found to contain toxic compounds; pitohuis are frequent members of mixed-species flocks and several observers have hypothesised that species in flocks are imitating each other in their plumage and vocalisations. If non-toxic species participate in flocks to associate with pitohuis, we predicted that pitohuis should play an important role in flocks, such that flock composition should be strongly influenced by their presence, and that other species should be attracted towards their vocalisations. We found, however, that in the lowland rainforests of Madang Province, flock composition was less influenced by the presence of pitohuis than by the presence of Rufous Babblers (Pomatostomus isidori), a non-toxic leading species. In playback experiments, Rufous Babblers were as attractive to heterospecifics as pitohuis. Our study provides the first empirical test of the connection between toxicity and flock organisation in PNG and our primarily negative results suggests that toxicity does not drive the organisation of flocks in our study area.

A Synthesis of the March 2001 Conference on the Viability of Transboundary Protected Areas at the Yale School of Forestry and Environmental Studies

SUMMARY Efforts to protect land on an ecosystem scale have led to the creation of numerous transboundary protected areas, often called international peace parks. In some cases, the appropriate leadership, infrastructure, community support, and political and legal frameworks exist to achieve the objectives of a transboundary protected area, and to realize the benefits of transboundary management across national borders despite the inherent costs and risks involved. There is a danger, however, that regional conservation initiatives may be pursued in inappropriate situations or with strategies that do not respect the rights of local populations. The challenge is to determine under what conditions transboundary approaches might be appropriate and what factors can help us make these approaches more effective at achieving their site-specific goals. This paper synthesizes the experiences and perspectives of a diverse group of managers, social and natural scientists, consultants, local leaders and policy makers who met at the Yale University School of Forestry and Environmental Studies on March 30 and 31, 2001 to discuss if, when, where and how transboundary protected areas should be pursued. The sharing of these individual experiences enabled us to explore when and where transboundary approaches may be appropriate and how they might be more effective. We found that transboundary approaches may be more effective when: (1) a careful analysis of costs and benefits in light of the local context is conducted, (2) people living on both sides of the border share elements of a common vision that is in both of their best interests, (3) the majority of the actors involved are committed to a long-term strategy, (4) strong leadership for transboundary initiatives exists within border communities, and (5) managers of transboundary protected areas are particularly aware of tensions between multiple scales, which helps them ensure that the rights of local populations are not usurped.

Horizontal and vertical species turnover in tropical birds in habitats with differing land use.

Large tracts of tropical rainforests are being converted into intensive agricultural lands. Such anthropogenic disturbances are known to reduce species turnover across horizontal distances. But it is not known if they can also reduce species turnover across vertical distances (elevation), which have steeper climatic differences. We measured turnover in birds across horizontal and vertical sampling transects in three land-use types of Sri Lanka: protected forest, reserve buffer and intensive-agriculture, from 90 to 2100 m a.s.l. Bird turnover rates across horizontal distances were similar across all habitats, and much less than vertical turnover rates. Vertical turnover rates were not similar across habitats. Forest had higher turnover rates than the other two habitats for all bird species. Buffer and intensive-agriculture had similar turnover rates, even though buffer habitats were situated at the forest edge. Therefore, our results demonstrate the crucial importance of conserving primary forest across the full elevational range available.

Leaf trait variations associated with habitat affinity of tropical karst tree species

Abstract Karst hills, that is, jagged topography created by dissolution of limestone and other soluble rocks, are distributed extensively in tropical forest regions, including southern parts of China. They are characterized by a sharp mosaic of water and nutrient availability, from exposed hilltops with poor soil development to valleys with occasional flooding, to which trees show species‐specific distributions. Here we report the relationship of leaf functional traits to habitat preference of tropical karst trees. We described leaf traits of 19 tropical tree species in a seasonal karst rainforest in Guangxi Province, China, 12 species in situ and 13 ex situ in a non‐karst arboretum, which served as a common garden, with six species sampled in both. We examined how the measured leaf traits differed in relation to species’ habitat affinity and evaluated trait consistency between natural habitats vs. the arboretum. Leaf mass per area (LMA) and optical traits (light absorption and reflectance characteristics between 400 and 1,050 nm) showed significant associations with each other and habitats, with hilltop species showing high values of LMA and low values of photochemical reflectance index (PRI). For the six species sampled in both the karst forest and the arboretum, LMA, leaf dry matter content, stomatal density, and vein length per area showed inconsistent within‐species variations, whereas some traits (stomatal pore index and lamina thickness) were similar between the two sites. In conclusion, trees specialized in exposed karst hilltops with little soils are characterized by thick leaves with high tissue density indicative of conservative resources use, and this trait syndrome could potentially be sensed remotely with PRI.

Co-limitation by nitrogen and water constrains allocation response to drought in deciduous and evergreen shrubs in a semi-arid ecosystem

Semi-arid regions worldwide are expected to experience reduced precipitation with future climate change, in addition to increased intensity of precipitation events, heightening the pulsed nature of water availability in these systems. Shifting biomass allocation is a plastic response of species to altered resource availability, and optimal allocation theory predicts plants should increase allocation to roots when water is limiting to growth. However, optimal allocation could be influenced by other factors, such as plant nutrient status and the seasonality of precipitation. Here, we evaluated the allocation response of eight common shrub species (four deciduous, four evergreen) from the Mediterranean climate region of Southern California to experimental manipulation of nitrogen and water availability, as well as seasonal drought. Evergreen species increased allocation to roots in response to low water availability to a greater degree than deciduous species, and also showed less of a decline in total biomass with water limitation, consistent with the predictions of optimal allocation theory. Deciduous species were more limited by nitrogen than evergreen species, requiring them to maintain high allocation below-ground regardless of water availability. Evergreen species were also able to equalize root allocation in response to early- versus late-season drought, while deciduous species responded non-optimally, reducing allocation to roots when early-season soil moisture was plentiful, resulting in the most strongly reduced growth by late-season drought. These experiments demonstrate how optimal allocation theory can be used to predict species responses to environmental changes in semi-arid systems, but should account for patterns of co-limitation and seasonality of resources.