Robert E. Slye

LONG-TERM SURVIVORSHIP AND CROWN AREA DYNAMICS OF TROPICAL RAIN FOREST CANOPY TREES

Lateral shading of direct-beam irradiation among neighboring canopy tree crowns in a nonequatorial tropical rain forest canopy was modeled as a function of solar position using a photogrammetric database derived from large-scale color aerial stereopairs (1:1500–1:3000 scale) acquired in 1976. The interception of direct-beam irradiation by the orthogonally projected crown area of each tree was computed at hourly intervals over a full calendar year using a Parameterization model of cloud-attenuated direct-beam availability. The annual totals of intercepted direct-beam irradiation (Ib) ranged from 1.81 to 4.13 GJ·m−2·yr−1. Expressed as a percentage of the available incident direct-beam irradiation, these values ranged from 44% to 100%. Approximately 20% of the sample population intercepted <70% of the available annual direct-beam irradiation. The long-term effects of lateral shading and the intertree differences in Ib were assessed using repeat aerial stereophotography of the same section of forest 18 yr later in 1994 for the determination of the mortality, survivorship, and crown growth of the canopy trees delimited in the 1976 stereopairs. Mortality over the 18-yr period amounted to 27.2%. Based on the lateral shading simulations, the mean annual Ib totals of the survivors and those that died were significantly different (P < 0.001). Approximately 40% of the survivors experienced crown area reductions. Although there was no significant difference in the Ib of survivors with crown growth and those with crown reductions, a relationship was established between Ib and the extent of crown area change. Canopy trees that intercept the most direct-beam irradiation and experience the least lateral shading have higher probabilities of survivorship and significant crown area changes that may be in the form of crown growth or crown reduction. Their laterally shaded neighbors have a lower survivorship probability, and those that survive persist in an inhibited state with limited crown area change. We conclude that the effects of lateral shading are not limited to the margins of treefall gaps and that lateral shading determined by crown position in the uneven upper canopies of nonequatorial tropical rain forests has a detectable effect on the long-term fates of neighboring canopy trees.

Redefining the ecological niche of a tropical rain forest canopy tree species using airborne imagery: long-term crown dynamics of Toona ciliata

Past controlled growth experiments indicate that the seedling and sapling responses of the tropical rainforest canopy tree species Toona ciliata are most consistent with a light-demanding, early successional pioneer. This ecological niche assignment was tested in the mature stage of its life cycle after it achieves a position in the upper canopy. Mortality, survivorship and crown growth rates over the 18-y period 1976-1994 were measured using co-registered repeat airborne stereophotographic coverage of a representative forest stand in northeast Queensland, Australia, where T. ciliata had the fourth highest relative importance in a population of 46 co-occurring canopy tree species. The airborne re-inventory was conducted in a 3.6-ha sample area and limited to only canopy trees. The results were compared with a ground-based inventory of both canopy and subcan- opy trees l10 cm dbh in a 0.5-ha permanent plot. Over the period 1976-1994, there was no mortality and no evidence of decline among T. ciliata conspecifics having crown areas >60 m2 and trunk diameters >30 cm. In the 3.6-ha airborne sample area, more than 85% of T. ciliata survivors experienced positive crown growth, in contrast to only 57% of the other co-occurring canopy trees. Toona ciliatas crown growth rates were highest in the 60-80-m2 crown size class. Upon reaching an upper canopy position, T. ciliata not only persisted as a dominant canopy tree species, but it also achieved some of the largest crown areas (> 100 m2). Toona ciliata mortality in the ground-based plot involved mainly subcanopy trees of 10-30 cm dbh that had not yet assumed a canopy position and were not detectable in the aerial stereopairs. Both the crown and dbh growth rates of T. ciliata indicate enhanced vigour in the later stage of its life cycle. Its long-term survivorship and growth patterns are indicative of a persistent canopy tree species

Solar-powered UAV mission for agricultural decision support

In September 2002, NASAs solar-powered Pathfinder-Plus UAV conducted a proof-of-concept mission over the 1500 ha plantation of the Kauai Coffee Company (KCC), Hawaii. While in U.S. National Airspace, the transponder-equipped UAV was supervised by Honolulu air traffic as a conventionally piloted aircraft. Two digital camera systems were housed in exterior-mounted environmental pods, and were controlled from a ground station established at plantation headquarters. During four hours on-station, the UAV exhibited the ability to navigate pre-planned flightlines, as well as perform spontaneous maneuvers to collect imagery in cloud-free areas. A line-of-sight (local area network) telemetry system using unlicensed radio frequency enabled rapid image download at rates exceeding 5 Mbit sec -1 . All images were thus available for viewing, enhancing, and printing within a few minutes of collection. During the latter part of the mission, the payload was operated over an established wide area network by an operator located on the U.S. mainland at a distance of 4000 km. The mission demonstrated the ability of a solar-powered UAV, equipped with downsized imaging systems, to monitor a localized region for an extended time period and deliver high-resolution imagery on demand. I. INTRODUCTION

Nighttime UAV Vineyard Mission: Challenges of See-and-Avoid in the NAS

A Nighttime UAV Vineyard Mission will demonstrate the use of a UAV-based thermal infrared imaging system for improved direction of frost damage mitigation efforts in agricultural crops. The UAV selected for this April 2005 mission is the APV-3. A flight height of 8,000 ft is planned, enabling thermal mapping coverage of the largest vineyard in California on an hourly basis. To accomplish the Nighttime Mission, it is necessary to demonstrate that the ground-based autopilot has the capability to see-and-avoid potentially conflicting aircraft in the National Airspace System (NAS). This paper provides a review of a daytime UAV test flight conducted in-visual range over the vineyard in August 2003 and describes additional tests being conducted to satisfy FAA see-and-avoid requirements for the planned out-of-visual range nighttime mission.

A Multi-Sensor Imaging Payload for Mission-Adaptive Remote Sensing Applications [invited]

†† Future Earth Science remote sensing missions will require aircraft operating as subsystems in support of multi -scale mission systems that integrate data from ground, aircraft, and orbital sensors to provide a comprehensive understanding of global phenomena. Unmanned aerial vehicles (UAVs) will enhance mission range and duration and enable measurements of phenomena considered too risky for manned aircraft. These aircraft also represent a very adaptable element in a sensor web system, having the ability to provide both remotely sensed and in-situ data at a broad range of spatial and temporal scales. The use of on -board autonomous agents to optimize flight profile, sensor, and measurement domain parameters will provide a revolutionary improvement in the utility of remotely sensed data, particularly for the study of temporally localized phenomena, and is extendable to NASA requirements for improved autonomy in space exploration. This paper provides a description of a multi-sensor imaging payload designed around the concept of intelligent mission management using on-board autonomous agents to optimize mission productivity. Imaging sensors include high-resolution color, low-resolution thermal infrared, and push-broom hyper-spectral imagers. Ancillary payload sub-systems provide meta-data for image interpretation and geo-registration, and communications for near-time instrument control and data delivery. The payload has been designed, integrated, and tested on a small (<55 lbs) UAV in a wildfire management mission context.

Compiling And Editing Agricultural Strata Boundaries With Remotely Sensed Imagery And Map Attribute Data Using Graphics Workstations

The USDA presently uses labor-intensive photographic interpretation rocedures to delineate large geographical areas into manageabye size sampling units for the estimation of domestic cro and livestock production. Computer software to automate tfe boundary delineation rocedure, called the computerassisted stratification and sam Eng (CASS) system, was developed by NASA Ames Researclcenter using a HPcolor graphics workstation. The current manual procedure is highly paperoriented. The USDA processes 2 to 3 new states per year, and updates are done from ‘scratch”. The CASS rocedures display TM satellite digital imagery on graphics dispEy workstations as the back-dro for the on-screen delineation of sampling units. USGS’ DL8data for roads and waterways are displayed over the TM imagery to aid in identifying otential sample unit boundaries. Initial analysis conductel with three Missouri counties indicated that CASS was six times faster than the manual techniques in delineating sampling units.