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Summary There is a lack of consensus in theoretical and empirical literature on whether height–diameter (H:D) relationships of canopy trees are asymptotic. To investigate H:D allometry, particularly in the transition to the canopy, we focused on shade-tolerant Abies balsamea, across steep physical gradients associated with elevation, and correlated biotically generated gradients of stem density, canopy height and canopy species composition. We addressed these questions: A. What is the relation between H:D allometric form and emergence into the canopy? B. Is H:D allometry asymptotic? C. What aspects of the H:D relationship are most sensitive to environmental conditions? Using maximum likelihood, we compared the performance of alternative H:D forms (linear, power function, non-sigmoid asymptotic and sigmoid asymptotic), incorporating elevation and local canopy height as covariates. Abies balsamea H:D allometric form was clearly sigmoid asymptotic, by a wide AIC margin, across all gradients, to an asymptote slightly above canopy height. The commonly used power function had essentially no empirical support (ΔAIC >> 10). Canopy height decreased with elevation, but with much variation, so elevation was a poor predictor of the asymptote. Across environmental gradients, H:D allometries overlapped for trees far below the canopy, but diverged strongly for trees approaching different canopy heights. Changes in resource allocation and modification of growth form that could generate asymptotic H:D allometries are consistent with known physical forces and diverse research findings in tree developmental biology and physiology. Synthesis. The H:D asymptote and its tight relation to canopy height, unapparent in aggregated H:D data, became clear only when canopy height and elevation were included explicitly in allometric models. Asymptotic H:D allometries may be the norm, though often undetected, in unmanaged forests without recent catastrophic disturbance. Appropriate asymptotic H:D models may reduce error in forest carbon and biomass estimation and promote theoretical and empirical integration in the ecology and evolution of tree allometry.

To determine if manipulation of milkweed's natural phenology would increase monarch reproduction, strips were mowed in fields in upstate New York in early Jul., late Jul., and mid Aug., 2006, for comparison to an unmowed control. Common milkweed (Asclepias syriaca) was then monitored from Jul. 29 through Sep. 24 for plant height, vegetative stage, level of herbivory, condition, monarch eggs and larvae, and the position of eggs on leaves and stems. We found mowing on Jul. 1 and 24 spurred the regrowth of milkweed and sustained a more continuously suitable habitat for monarch oviposition and larval development than the control. Mowing on Aug. 17 proved too late for recovery of the milkweeds. Significantly more eggs were laid on the fresh resprouted milkweeds than on the older and taller control plants. In the strips mowed on Jul. 1, peak egg densities occurred in late Jul.; in the strips mowed in late Jul., peak egg densities occurred in early to mid Aug. Depending on the timing of mowing, the milkweed plant height, developmental stage, and condition differed. As predicted, the mowing of fields with Asclepias syriaca extended the monarchs' breeding season and increased overall monarch reproduction. However, timing of mowing was critical and must be determined empirically for different milkweed species and in different locations. This mitigation procedure could be fostered along roadsides, along edges of fields and pastures, in USDA conservation reserve program lands, and along power lines and other rights of way.

Much of the structural, floristic and dynamic variation in the hyperdiverse dipterocarp forest on the 52 ha long term ecological research plot at Lambir, Sarawak, is associated with soil differences, as indicated by topography, labile topsoil nutrients, and humus. This review expands the edaphic characterisation of the plot by collation of published and unpublished data on soil morphology, physical properties and non-labile nutrients. Topographically the plot consists of two dipslopes at different elevations with a steep and unstable intervening scarp. Sandstone underlies the main upper dipslope and shale the lower, and the scarp has mixed clastic sedimentary lithology. Most of the dipslope soils are moderately developed Red Yellow Podzolics (Acrisols/Udults). They are of medium depth, with thin topsoils and reddish yellow blocky subsoils that become redder, finer textured, firmer and blockier with depth. Textures vary with lithology, and range from loamy sand over sandy loam on sandstone to silty clay over clay on shale. The scarp has shallower, stonier and less horizonated Skeletal soils (Cambisols/Inceptisols). All of the soils are very acid, and have low contents of all labile nutrients. Contents of non-labile forms of P are low and those of Ca extremely low, but K and Mg are moderate. All nutrients are significantly lower in sandstone soils than on shale. The differences are more pronounced for non-labile than labile forms and in subsoils than topsoils. Ratios of mineral nutrient are stoichiometrically typical for Red Yellow Podzolics on clastic sediments, and differ from morphologically similar soils on other parent materials. The ecologically significant reserves of K and Mg are attributed to small but sustained replenishments by mica weathering.

Discrete humus layers are common on podzols under temperate coniferous and tropical heath forests, and patchy layers also occur under some temperate broadleaved forests on non-podzolic soils. We used multiple data sets to test the reported association of humus with oligotrophic but non-podzolic soils under non-heath dipterocarp forest at Lambir, Sarawak. We examined the distribution, morphology and nutrient dynamics of necromass on soils derived from sandstone and shale. Concentrations of the main mineral nutrients were lower in fresh litter on the very oligotrophic sandstone soils than on shale. The rates of litterfall were similar, so that annual litterfall fluxes of all nutrients were lower on sandstone. The lower nutrient concentrations and fluxes in the litter on sandstone resulted in slower decomposition, longer residence times and larger standing crops of forest-floor necromass, with lower concentrations of nutrients. The necromass on sandstone sequestered significantly more N, K and Mg but less Ca and Mn than on shale, with no significant difference for P. The variations in necromass nutrient dynamics were associated with morphological differences. There were mats of densely rooted humus under the litter on sandstone, whereas litter lay directly over the mineral topsoil on shale. Spatial associations with soil nutrients were weak for necromass thickness, but clear for humus. The proportions of nutrients in the litterfall and necromass reflected the stoichiometric profiles of the soils. We attribute the differences in necromass nutrient dynamics and their association with soil reserve nutrients to lower rates of nutrient replenishment from the weathering of sandstone than from shale. Necromass characteristics are robust field indicators of multivariate edaphic differences in these and other tropical forests on Acrisols/Ultisols derived from Tertiary clastic sediments.

Summary 1 We conducted a field experiment to test whether aggregated spatial distributions were related to soil variation in locally sympatric tree species in the rain forests of Sarawak, Malaysia. Dryobalanops aromatica , Shorea laxa , and Swintonia schwenkii are naturally aggregated on low-fertility humult ultisols, Dryobalanops lanceolata and Hopea dryobalanoides on moderate-fertility udult ultisols and Shorea balanocarpoides is found on both soil types. 2 Seedlings of all six species were grown in a nested-factorial experiment for 20 months in humult and udult soils in gaps and in the understorey to test for soil-specific differences in performance. Phosphorus addition was used to test for effects due to P-limitation. 3 Four species showed significantly higher growth on their natural soils, but one humultsoil species ( D. aromatica ) and the broadly distributed species were not significantly affected by soil type. 4 One udult-soil species, D. lanceolata , had both lower relative growth rate and lower mycorrhizal colonization on humult soil. However, humult soils also had lower levels of Ca, Mg, K, N and probably water availability. 5 The overall ranking of growth rates among species was similar on the two soils. Growth rates were strongly positively correlated with leaf area ratio and specific leaf area among species in both soils. With the exception of D. aromatica , species of the higher-nutrient soils had higher growth rates on both soils. 6 Although P addition led to elevated soil-P concentrations, elevated root- and leaf-tissue P concentrations on both soils, there was no significant growth enhancement and therefore no evidence that P availability limits the growth or constrains the distribution of any of the six species in the field. Differences in soil water availability between soils may be more important. 7 Our results suggest that habitat-mediated differences in seedling performance strongly influence the spatial distributions of tropical trees and are therefore likely to play a key role in structuring tropical rain forest communities.

We investigated the spatial distribution of fruiting in Dryobalanops aromatica (Dipterocarpaceae), a mast-seeding emergent tree that is found in the tropical rain forests of Borneo. Of 393 adults (diameter at breast height (dbh) > 30 cm) in a 52-ha area, 143 (36.4%) individuals fruited. A second-order spatial analysis, based on Ripley's K-function, revealed that fruiting trees were significantly (P < 0.05) aggregated with respect to the total population over distances of 15-115 m. Thus, the spatial distribution of fruiting trees was more aggregated than expected from the adult tree distribution, which itself was aggregated within the study plot. Logistic regression analysis showed that fruiting trees had a significantly greater dbh and were surrounded by more conspecific adults per ha than non-fruiting individuals. Moreover, fruiting trees were found at higher elevations, on steeper slopes, and on sandy rather than clayey soils. In contrast, annual diameter growth, adult density over areas < 1 ha, and slope convexity did not significantly affect fruiting probability. The ratio of seedling (20 cm ≤ h < 60 cm) and sapling (60 cm ≤ h < 300 cm) density to adult density was higher in sites at higher elevations, on steeper slopes, and on sandy soils than that for lower elevations, flat slopes and clayey soils. This suggests that the aggregation of fruiting trees occurred not only at the time of the study, but that it had occurred repeatedly in the past, at the high-elevation, steep-sloped, sandy sites. Thus, site conditions probably affect the dynamics and spatial structure of local populations through differences in fruiting frequency among trees experiencing different site conditions.

Relationships between spatial distributions and site conditions, namely topography and soil texture, were analyzed for two congeneric emergent trees, Dryobalanops aromatica and Dryobalanops lanceolata (Dipterocarpaceae), in a tropical rainforest in Sarawak, East Malaysia. A 52-ha permanent plot was divided into 1300 quadrats measuring 20 m × 20 m; for each Dryobalanops species, the number and total basal area of trees ≥1 cm in d.b.h. were compared among groups of quadrats with different site conditions. Because spatial distributions of both Dryobalanops and site-condition variables were aggregated, Monte-Carlo permutation tests were applied to analyze the relationships. Both single and multifactor statistical tests showed that the density and basal area distributions of the two species were significantly non-random in relation to soil texture and topographic variables. D. aromatica was significantly more abundant at higher elevations, in sandy soils, and on convex and steep slopes. In contrast, D. lanceolata preferred lower elevations and less sandy soils. In the study plot, there were very few sites (3 of 1150 quadrats tested) where the models of Hayashi’s method predicted the co-occurrence of the two species. These results suggest that between-species differences in habitat preferences are so large that they alone explain the spatially segregated distributions of these two species within the 52-ha study plot.

The diversity and niche specificity of hemi-epiphytic figs in a lowland dipterocarp forest in Sarawak were investigated in 1998. Twenty-seven fig species (264 individuals, c. 120 ha) colonized a diversity of host taxa (35 families), but densities were very low and only 1.77% of trees> 30 cm d.b.h. were occupied. There were no significant associations with host taxa or host-bark roughness but among 11 common species (≥9 individuals) the distributions of all other parameters (host-d.b.h., height and position of colonization, crown illumination, soil-texture and slope-angle) were significantly different, and we identified five fig guilds. The guilds corresponded to canopy strata, and appeared to reflect the establishment microsite requirements of different species. A fundamental trade-off within the hemi-epiphytic habit was revealed: Species colonizing larger hosts were rarer, because of lower host densities and more specific microsite requirements, but had better light environments and attained a larger maximum size. The single strangler species appeared to escape many of these constraints, and an important source of mortality caused by host-toppling, indicating the advantages of this strategy. Thus, the hemi-epiphytic figs in this community have come to fill a remarkable diversity of niches, despite low levels of competition, through the exigencies of a complex environment. © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 78, 439–455

Non-destructive biomass estimation for protected tree species is necessary to understand their population dynamics and the ecological factors affecting species scarcity. We present a method for estimating aboveground biomass of bole, branches and foliage, using data obtained by climbing live trees to collect limited samples and measurements. This method was . applied to 26 individuals of Fitzroya cupressoides Mol. Johnston, a protected Chilean conifer, and to 12 individuals of a . second, morphologically similar, but unprotected species, Pilgerodendron u˝iferum D. Don. Florin. Trees were climbed, ´ basal diameter of all branches ) 1 cm were recorded and four branches per tree were removed for further measurement. The sampled branches were used to develop allometric equations predicting branch, twig and foliar biomass from branch basal diameter. These equations were used to generate whole tree canopy biomass estimates based on climber's measurements of branch basal diameter. Bole biomass was estimated from serial measurements of height, diameter and wood density. Whole tree canopy and bole biomass estimates were then used to develop allometric equations predicting wood and foliar biomass from diameter at breast height. Five of the P. u˝iferum trees were felled and weighed by conventional methods, and the data used to evaluate error in the non-destructive technique. Although the technique was labor intensive, it was found to yield mean estimates for canopy components that are expected to be within 10% of the true mean for large populations of trees .watershed level studies . Accurate estimation of individual trees may be less reliable, as the amount of dispersion about . some of the regressions was quite high ) 20% . q 1998 Elsevier Science B.V.

Patterns of both above- and belowground biomass and production were evaluated using published information from 200 individual data-sets. Data sets were comprised of the following types of information: organic matter storage in living and dead biomass (e.g. surface organic horizons and soil organic matter accumulations), above- and belowground net primary production (NPP) and biomass, litter transfers, climatic data (i.e. precipitation and temperature), and nutrient storage (N, P, Ca, K) in above- and belowground biomass, soil organic matter and litter transfers. Forests were grouped by climate, foliage life-span, species and soil order. Several climatic and nutrient variables were regressed against fine root biomass or net primary production to determine what variables were most useful in predicting their dynamics. There were no significant or consistent patterns for above- and belowground biomass accumulation or NPP change across the different climatic forest types and by soil order. Similarly, there were no consistent patterns of soil organic matter (SOM) accumulation by climatic forest type but SOM varied significantly by soil order—the chemistry of the soil was more important in determining the amount of organic matter accumulation than climate. Soil orders which were high in aluminum, iron, and clay (e.g. Ultisols, Oxisols) had high total living and dead organic matter accumulations-especially in the cold temperate zone and in the tropics. Climatic variables and nutrient storage pools (i.e. in the forest floor) successfully predicted fine root NPP but not fine root biomass which was better predicted by nutrients in litterfall. The importance of grouping information by species based on their adaptive strategies for water and nutrient-use is suggested by the data. Some species groups did not appear to be sensitive to large changes in either climatic or nutrient variables while for others these variables explained a large proportion of the variation in fine root biomass and/or NPP.

The approximately 300 (298, 95% CI: 152-581) elephants in the Lower Kinabatangan Managed Elephant Range in Sabah, Malaysian Borneo are a priority sub-population for Borneo's total elephant population (2,040, 95% CI: 1,184-3,652). Habitat loss and human-elephant conflict are recognized as the major threats to Bornean elephant survival. In the Kinabatangan region, human settlements and agricultural development for oil palm drive an intense fragmentation process. Electric fences guard against elephant crop raiding but also remove access to suitable habitat patches. We conducted expert opinion-based least-cost analyses, to model the quantity and configuration of available suitable elephant habitat in the Lower Kinabatangan, and called this the Elephant Habitat Linkage. At 184 km(2), our estimate of available habitat is 54% smaller than the estimate used in the State's Elephant Action Plan for the Lower Kinabatangan Managed Elephant Range (400 km(2)). During high flood levels, available habitat is reduced to only 61 km(2). As a consequence, short-term elephant densities are likely to surge during floods to 4.83 km(-2) (95% CI: 2.46-9.41), among the highest estimated for forest-dwelling elephants in Asia or Africa. During severe floods, the configuration of remaining elephant habitat and the surge in elephant density may put two villages at elevated risk of human-elephant conflict. Lower Kinabatangan elephants are vulnerable to the natural disturbance regime of the river due to their limited dispersal options. Twenty bottlenecks less than one km wide throughout the Elephant Habitat Linkage, have the potential to further reduce access to suitable habitat. Rebuilding landscape connectivity to isolated habitat patches and to the North Kinabatangan Managed Elephant Range (less than 35 km inland) are conservation priorities that would increase the quantity of available habitat, and may work as a mechanism to allow population release, lower elephant density, reduce human-elephant conflict, and enable genetic mixing.

Author(s): Bjorklund, Brian M.; Thomas, Howard H.; Palmiotto, Peter A.; Algeo, Timothy P.; Slate, Dennis; Chipman, Richard B.; Chandler, Monte D.; Wilda, Donald J. | Abstract: USDA APHIS Wildlife Services has been a primary cooperator in the Cape Cod Oral Rabies Vaccination Program (CCORVP) in southeastern Massachusetts since 2001. The CCORVP (1994 - present) was originally designed to reduce the incidence of terrestrial rabies adjacent to the Cape Cod Canal in order to prevent its spread on to peninsular Cape Cod. However, since the barrier breach in 2004, CCORVP is now focused on rabies control in this coastal resort area southeast of Boston, MA. An integral component of wildlife rabies management is oral vaccination with vaccine-laden baits. Consequently, maximizing bait uptake rates is critical to achieving sufficient population immunity to reduce rabies prevalence and achieve control. To that end, knowledge of raccoon food habits, especially at ORV bait delivery times (spring and fall on Cape Cod) is crucial. We undertook a study of raccoon food selection in southeastern Massachusetts to assess the presence of and interest in competing food resources. We collected intact stomachs from raccoons found dead or euthanized for rabies testing within the CCORVP zone during 2006 (n = 33) and 2007 (n = 109) for analysis. Stomach contents were dominated by vegetation (80%), followed by invertebrates (43%), non-food items (41%), vertebrates (35%), and hair (primarily raccoon based on appearance) (15%). Food item occurrence appears to be related to age. We present findings, potential management implications, and suggestions for assessing food use related to rabies control in other locations.

Managers and researchers are currently defining and setting objectives for ecosystem management; however, it is not clear what ecological information is needed as a basis for setting specific management goals and priorities, or to implement ecosystem-based management in the field. The focus of this chapter is to describe how and what type of data have been collected in the past to assess ecosystems. The objective of this section is to identify what tools and bodies of knowledge are currently available to guide the planning and implementation of ecosystem-based management.

Many useful tools exist that can be utilized at appropriate spatial scales to study ecosystems as described in Chapter 3. These methods, as presently utilized, have been very useful for increasing our understanding of the functions, structures, and feedbacks controlling processes at the individual plant to the ecosystem level. However, they have not been particularly effective for early detection of changes in ecosystems due to either chronic pollution or to small changes in abiotic environmental parameters (such as air temperatures). Most of our tools are very effective at detecting sudden, major changes (i.e., pulse perturbations) in the ecosystem in which a part has been dramatically manipulated by either its elimination (e.g., tree removal and herbicide applications to limit plant regrowth; Bormann and Likens 1979) or due to natural disturbances (e.g., hurricanes or landslides; Lugo and Scatena 1995). Difficulties associated with these questions and tools used to answer them include the following: 1. It is difficult to identify the present state of an ecosystem with respect to other ecosystems whose land-use and natural disturbance histories have differed. This difficulty stems from uncertainty as to what type of difference should be expected between impacted and non-impacted sites, and a set of measures that will allow discernment of differences between these ecosystems. Historical land uses can leave a legacy on the site that may or may not be difficult to detect (Hamburg and Sanford 1986, Garcia-Montiel and Scatena 1994). None of the criteria currently available allow us to determine where the site exists along a gradient of potential states and whether two sites with presently very different total productivities should exist in similar states or conditions. For example, one ecosystem may exist at a different state because it was influenced by human disturbances (e.g., pollution or previous land use) that overrides normal abiotic controls on plant growth (see further discussion of this in Section 4.2.1). 2. It is difficult to detect how far the current state of system is from the non—human-impacted condition. 3. It is difficult to identify how past land-use activities and other ecosystem legacies may be modifying how the current ecosystem is responding to disturbances or other manipulations. 4. It is difficult to identify the probability of adverse ecological changes, that is, current tools do not provide estimates of the risks associated with a management activity and/or natural disturbance(s) (i.e., make accurate predictions about future ecosystem state). 5. It is difficult to characterize the resilience and/or resistance of ecosystems to various disturbances. 6. It is difficult to determine if sustainable ecosystem management is being achieved in the short or long term.

Not all organizations will want to implement the ecosystem management approach described earlier. However, there exist many different organizations for which the ecosystem management approach holds great utility for managing their resource into the future, including many who presently are not using this approach. Some organizations (i.e., federal agencies) have to implement ecosystem management (see Chapter 2), while others may utilize some aspects of the ecosystem management approach but may not want to adopt the ecosystem management approach in its entirety on their lands (i.e., private timber companies).

The ecosystem management paradigm has been chosen as the approach to be used by federal agencies to manage federal lands. Because of the difficulty that federal agencies and academicians have had in defining what these two words mean and because the perception is that this means more data collection than is currently occurring, ecosystem management has a strong potential to be rejected as the approach to use for managing ecosystems. This would be extremely unfortunate because this approach has elements that are crucial to retain for “good” management of ecosystems. The components of ecosystem management (articulated in earlier chapters) are fundamentally important if ecosystems are to be managed where they function within the range of states natural for that system and at the same time produce the values (i.e., species, timber, nontimber forest products, etc.) humans have identified as desirable. Ecosystem management should be used as a tool that identifies what the trade-offs are in accepting a particular management option. It is an approach that will move the management of our natural ecosystems from being solely based on human “values” to one balanced by scientific information helping to clarify the consequences of the chosen values.

Managers and researchers are currently defining and setting objectives for ecosystem management; however, relatively few workers (NRC 1990) have attempted to determine what ecological information is needed to implement this new management strategy. While many workers agree that consideration of the scale of both natural processes and management practices is critically important under the ecosystem paradigm (Franklin and Forman 1987, Clark et al. 1991, Gordon 1993), and while many others have recently developed and refined theories about scale and natural systems (e.g., Allen and Starr 1982, O’Neill et al. 1986, Allen and Hoekstra 1992, 1994), few have directly applied these theories to guide management.

PEART, D. R., C. V. COGBILL AND P. A. PALMIOTTo (Department of Biological Sciences, Dartmouth College, Hanover, NH 03755). Effects of logging history and hurricane damage on canopy structure in a northern hardwoods forest. Bull. Torrey Bot. Club 119: 29-38. 1992.Canopy structure following the 1938 hurricane and subsequent salvage logging was evaluated from 1942 aerial photographs for six gauged watersheds in the northern hardwoods forest at the Hubbard Brook Experimental Forrest, N.H. Three of the six watersheds that have not been cut since the hurricane were also evaluated from 1978 aerial photographs. A total of 1635 points were sampled on a grid system and categorized as high canopy, low canopy, exposed understory or open, as assessed through a stereoscope. Archival reports on logging and hurricane effects were used to supplement the photographic interpretations. In 1942, percent openness (area whithout canopy cover) ranged from 13% to 38%. From 1942 to 1978, percent openness decreased by a mean of 18%. The reduction in canopy cover due to the hurricane and salvage logging was apparently less than 20% in the gauged watersheds. However, damage was patchy: the most heavily damaged area (72% open) was that which was logged least before the hurricane, and watersheds with most evidence of young second growth prior to the hurricane were apparently the least damaged. Although effects were locally severe, large areas were apparently only lightly damaged in 1938. Recovery of the canopy in the heavily damaged area was rapid: in 1978, only 9% of the area was open, and canopy structure was similar to that in the gauged watersheds. Thus, 40 years of canopy development effectively masked the patchy effects of hurricane damage. Photographic evidence, together with other historical records, provides a better assessment of past disturbance to forest canopies than unquantified eyewitness accounts, and can be evaluated more rapidly and over larger areas than more intensive, field-based investigations.