John N. Williams

The tropical rainforest canopy : a method of providing total access

An aerial rope network was constructed, using three emergent trees as supports, which provides access to a large volume of tropical rain forest from ground level to above the canopys upper surface. The virtually unexplored canopy community thus becomes accessible for a broad range of scientific research. THE CANOPY OF THE TROPICAL FOREST possesses one of the most complex and diverse communities on the earth, yet there have been few effective methods for studying this aerial zone, and none of these provides comprehensive access to a large volume of forest. To observe the canopy, which varies in height from about 15 meters to above 60 meters, early investigators built towers and platforms in tall trees (Hingston 1932, Bates 1944, McClure 1966). Immobile structures such as these proved to be biased observation posts due to the high spatial heterogeneity in plant species and associated animal activities of tropical forests (Elton 1973). The usefulness of treetop platforms was expanded by Muul and Liat (1970), who built transects of catwalks extending hundreds of meters at various heights in the canopy. This method faciliated observations, but access to surrounding vegetation was severely limited. Further, catwalks were not ecologically benign since they offered new routes for canopy animals that in turn could influence colonization patterns on nearby limbs by epiphytes (Perry 1978b). Using advances made by Denison et al. (1972), Perry (1978a) developed highly mobile tree-climbing methods that made the peripheral regions of every strong tree and the volume of forest under its crown accessible to investigation. Nevertheless, important regions of the forest remained inaccessible: i.e., the upper surface of the canopy with its high activity of insect and bird species, and a large fraction of the forest which is composed of weak trees unsafe for climbing, whose heights commonly reach 30 meters. To gain complete access to the latter regions for studies of pollination biology, we developed an aerial network of ropes, which provided access to about an acre of forest from ground level to above the historically inaccessible upper surface. The study site was Finca La Selva, a field station owned by the Organization for Tropical Studies, located near Puerto Viejo, Heredia Province, Costa Rica. The work required only two people and was begun on 8 March, and ended on 1 April 1979. Following the lead of Muul and Liat (1970), who used trees as structural supports for their catwalks in a Malaysian forest, our minimum canopy research facility was constructed using three emergent trees in undisturbed lowland rain forest of the southeast corner of the University of Washington Research Plot I. The trees formed a triangle of approximately 100 meters on a side. Each was taller than the surrounding canopy by about 15 meters, a height that was essential to the function of the web. A small platform was constructed in one tree at a height of 32 meters which serves for sleeping, equipment storage, and access to the web. From the platform we shot 20 lb. test monofilament lines, using a crossbow and arrows, to and between the two opposite trees, making a continuous loop (fig. 1). The position of these initial lines was adjusted to avoid abrasion against limbs, which would weaken the ropes when the web was in operation. The lines were replaced by 200 lb. test braided Nylon cords that were strong enough for use in pulling the 8600 lb. test, 1/2 inch in diameter, perimeter rope into place. The rope brand is Continental Dacron over Dacron, and is available through Continental Western Corporation, 2931 South Avil Avenue, Commerce, California 90040. Dacron was selected because it is nearly stretch-free and resistant to sunlight, though this rope does abrade easily. Because of this hazard, all ropes, especially where they extend into a tree crown, should be clearly visible so they can be inspected regularly. Rodents should not be overlooked as a source for abrasion since they may BIOTROPICA 13(4): 283-285 1981 283 This content downloaded from 157.55.39.72 on Wed, 14 Sep 2016 06:13:03 UTC All use subject to http://about.jstor.org/terms

Assessment of carbon in woody plants and soil across a vineyard-woodland landscape

BackgroundQuantification of ecosystem services, such as carbon (C) storage, can demonstrate the benefits of managing for both production and habitat conservation in agricultural landscapes. In this study, we evaluated C stocks and woody plant diversity across vineyard blocks and adjoining woodland ecosystems (wildlands) for an organic vineyard in northern California. Carbon was measured in soil from 44 one m deep pits, and in aboveground woody biomass from 93 vegetation plots. These data were combined with physical landscape variables to model C stocks using a geographic information system and multivariate linear regression.ResultsField data showed wildlands to be heterogeneous in both C stocks and woody tree diversity, reflecting the mosaic of several different vegetation types, and storing on average 36.8 Mg C/ha in aboveground woody biomass and 89.3 Mg C/ha in soil. Not surprisingly, vineyard blocks showed less variation in above- and belowground C, with an average of 3.0 and 84.1 Mg C/ha, respectively.ConclusionsThis research demonstrates that vineyards managed with practices that conserve some fraction of adjoining wildlands yield benefits for increasing overall C stocks and species and habitat diversity in integrated agricultural landscapes. For such complex landscapes, high resolution spatial modeling is challenging and requires accurate characterization of the landscape by vegetation type, physical structure, sufficient sampling, and allometric equations that relate tree species to each landscape. Geographic information systems and remote sensing techniques are useful for integrating the above variables into an analysis platform to estimate C stocks in these working landscapes, thereby helping land managers qualify for greenhouse gas mitigation credits. Carbon policy in California, however, shows a lack of focus on C stocks compared to emissions, and on agriculture compared to other sectors. Correcting these policy shortcomings could create incentives for ecosystem service provision, including C storage, as well as encourage better farm stewardship and habitat conservation.

Forest structure, stand composition, and climate-growth response in montane forests of Jiuzhaigou National Nature Reserve, China.

Montane forests of western China provide an opportunity to establish baseline studies for climate change. The region is being impacted by climate change, air pollution, and significant human impacts from tourism. We analyzed forest stand structure and climate-growth relationships from Jiuzhaigou National Nature Reserve in northwestern Sichuan province, along the eastern edge of the Tibetan plateau. We conducted a survey to characterize forest stand diversity and structure in plots occurring between 2050 and 3350 m in elevation. We also evaluated seedling and sapling recruitment and tree-ring data from four conifer species to assess: 1) whether the forest appears in transition toward increased hardwood composition; 2) if conifers appear stressed by recent climate change relative to hardwoods; and 3) how growth of four dominant species responds to recent climate. Our study is complicated by clear evidence of 20th century timber extraction. Focusing on regions lacking evidence of logging, we found a diverse suite of conifers (Pinus, Abies, Juniperus, Picea, and Larix) strongly dominate the forest overstory. We found population size structures for most conifer tree species to be consistent with self-replacement and not providing evidence of shifting composition toward hardwoods. Climate-growth analyses indicate increased growth with cool temperatures in summer and fall. Warmer temperatures during the growing season could negatively impact conifer growth, indicating possible seasonal climate water deficit as a constraint on growth. In contrast, however, we found little relationship to seasonal precipitation. Projected warming does not yet have a discernible signal on trends in tree growth rates, but slower growth with warmer growing season climates suggests reduced potential future forest growth.

From berries to blocks: carbon stock quantification of a California vineyard

Background Quantifying terrestrial carbon (C) stocks in vineyards represents an important opportunity for estimating C sequestration in perennial cropping systems. Considering 7.2 M ha are dedicated to winegrape production globally, the potential for annual C capture and storage in this crop is of interest to mitigate greenhouse gas emissions. In this study, we used destructive sampling to measure C stocks in the woody biomass of 15-year-old Cabernet Sauvignon vines from a vineyard in California’s northern San Joaquin Valley. We characterize C stocks in terms of allometric variation between biomass fractions of roots, aboveground wood, canes, leaves and fruits, and then test correlations between easy-to-measure variables such as trunk diameter, pruning weights and harvest weight to vine biomass fractions. Carbon stocks at the vineyard block scale were validated from biomass mounds generated during vineyard removal. Results Total vine C was estimated at 12.3 Mg C ha−1, of which 8.9 Mg C ha−1 came from perennial vine biomass. Annual biomass was estimated at 1.7 Mg C ha−1 from leaves and canes and 1.7 Mg C ha−1 from fruit. Strong, positive correlations were found between the diameter of the trunk and overall woody C stocks (R2 = 0.85), pruning weights and leaf and fruit C stocks (R2 = 0.93), and between fruit weight and annual C stocks (R2 = 0.96). Conclusions Vineyard C partitioning obtained in this study provides detailed C storage estimations in order to understand the spatial and temporal distribution of winegrape C. Allometric equations based on simple and practical biomass and biometric measurements could enable winegrape growers to more easily estimate existing and future C stocks by scaling up from berries and vines to vineyard blocks.