A Comparative Test of Mechanized and Manual Transplanting of Eelgrass, Zostera marina, in Chesapeake Bay

Abstract The laborious process of manual seagrass transplanting has often limited the size of seagrass restoration efforts. This study tested the efficiency of a mechanized planting boat, previously used for transplanting Halodule wrightii, relative to manual transplanting methods for establishing Zostera marina in Chesapeake Bay. Eelgrass planting was conducted at two sites, one each in the Rappahannock and James rivers, in October 2001. The methods were evaluated by three criteria: (1) initial planting success = proportion of attempted planting units (PUs) initially established (number confirmed in sediment by divers/number attempted); (2) survival = proportion of the initially established PUs persisting over 1, 4, and 24 weeks; and (3) efficiency = labor (in person·seconds) invested in each surviving PU. Initial planting success was significantly lower for the planting boat (24 and 56% at the Rappahannock and James sites, respectively) than for manual transplanting (100% at both sites). At the Rappahannock site, survival of initially established PUs declined over time for both methods, but while mean survival was always higher for manually planted rows, differences in survival between methods were not statistically significant. At the James site, survival to 1 and 4 weeks was significantly lower for the machine than for the manual method, but survival to 24 weeks was not significantly different. While the machine was able to attempt PUs faster than the manual method (2.2 s/PU vs. 5.8 s/PU, respectively), this speed was offset by poorer planting success rates, resulting in a much greater total labor investment for each machine‐planted PU that persisted to 24 weeks than for each similarly persisting manually planted PU (40.6 person·seconds/PU and 22.4 person·seconds/PU, respectively, averaged across sites). In summary, those PUs successfully planted by the machine survived similarly to PUs planted by hand, but as a result of poorer initial planting success, the machine required a greater investment of labor and plant donor stock for each PU surviving to 24 weeks. Therefore, in its tested configuration this planting boat is not a significant improvement over the manual method for transplanting eelgrass.     

Factors affecting the establishment of <Emphasis Type="Italic">Schoenoplectus</Emphasis><Emphasis Type="Italic">tabernaemontani</Emphasis> (C.C. Gmel.) Palla in urban lakeshore restorations

Despite their central role in lakeshore restoration, most littoral wetland plantings fail. The reasons for these failures are poorly understood, in part due to limited information on the effects of planting time, water depth, and propagation on the survival of emergent macrophyte plantings. We planted pots and prevegetated mats of softstem bulrush (Schoenoplectus tabernaemontani (C.C. Gmel.) Palla) at two different water depths (0–30 and 31–60 cm) in five lakes each month between May and September 2006 to evaluate the effects of planting month, water depth, and transplant type on the survival of planted S. tabernaemontani. Overall survival decreased from 73% at 30 days after planting to 40% pre-winter to 15% post-winter. The timing of planting was the most important factor influencing bulrush survival. Survival of bulrush planted later in the growing season is poor, regardless of the transplant type used, and should be avoided. During the optimal planting season of early-to-mid summer, transplants from pots are more likely to outperform mats, despite lower pre-planting biomass. Water depth is only important immediately after planting, after which time, its influence on successful establishment diminishes. Overall, our research indicated that key choices made by the practitioner can improve the likelihood that transplants establish in littoral wetland restorations.     

Diving and foraging behaviour of Adélie penguins in areas with and without fast sea-ice

The diving and foraging behaviours of Adélie penguins, Pygoscelis adeliae, rearing chiks at Hukuro Cove, Lützow-Holm Bay, where the fast sea-ice remained throughout summer, were compared to those of penguins at Magnetic Island, Prydz Bay, where the fast sea-ice disappeared in early January. Parent penguins at Hukuro Cove made shallower (7.1–11.3 m) but longer (90–111 s) dives than those at Magnetic Island (22.9 m and 62 s). Dive duration correlated with dive depth at both colonies (r ² = 0.001 ∼ 0.90), but the penguins atg Hukuro Cove made longer dives for a given depth. Parents at Hukuro Cove made shorter foraging trips (8.1–14.4 h) with proportionally longer walking/swimming (diving < 1 m) travel time (27–40% of trip duration) and returned with smaller meals (253–293 g) than those at Magnetic Island, which foraged on average for 57.2 h, spent 2% of time walking/swimming ( < 1 m) travel, and with meals averaging 525 g. Trip duration at both colonies correlated to the total time spent diving. Trip duration at Hukuro Cove, but not at Magnetic Island, increased as walking/swimming ( < 1 m) travel time increased. These differences in foraging behaviour between colonies probably reflected differences in sea-ice cover and the availability of foraging sites. Received: 3 November 1995/Accepted: 29 May 1996     

Evaluation of Seagrass Planting and Monitoring Techniques: Implications for Assessing Restoration Success and Habitat Equivalency

Restoration has become an integral part of coastal management as a result of seagrass habitat loss. We studied restoration of the seagrass (Halodule wrightii) near Tampa Bay, Florida. Experimental plots were established in June 2002 using four planting methods: three manually planted and one mechanically transplanted by boat. Seagrass cover was recorded at high resolution (meter scale) annually through July 2005. Natural seagrass beds were concurrently examined as reference sites. We also evaluated the suitability of a commonly used protocol (Braun‐Blanquet scores, BB) for comparing the development of seagrass cover using the planting methods and quantifying spatial patterns of cover over time. Results show that BB scores mirrored conventional measures of seagrass characteristics (i.e., shoot counts and above‐ and belowground biomass) well when BB scores were either low or very high. However, more caution may be required at intermediate cover scores as judged by comparison of BB scores with direct measurement of seagrass abundance. Significant differences in seagrass cover were detected among planting methods and over time (2002–2005), with manual planting of rubber band units resulting in the highest cover. In contrast, the peat pot and mechanical planting methods developed very low cover. Recovery rates calculated from development of seagrass spatial cover were less than those reported for natural expansion. Importantly, time to baseline recovery may be substantially greater than 3 years and beyond standard monitoring timelines. Prolonged recovery suggests that the rate of service returns, critical for estimating compensatory restoration goals under habitat equivalency analysis, may be severely underestimated.     

Evaluating a Large‐Scale Eelgrass Restoration Project in the Chesapeake Bay

Approximately 90,000 shoots of eelgrass (Zostera marina) were planted over 3 years (2003–2005) at Piney Point (PP) in the lower Potomac River estuary in the Chesapeake Bay (mid‐Atlantic coast of North America) following 3 years of habitat evaluation using a Preliminary Transplant Suitability Index (PTSI) and test plantings. Initial survival was high for the 2003 and 2004 plantings; however, most of the eelgrass died during the summer following the fall planting. Habitat quality and restoration success were monitored for the 2005 plantings and compared to a nearby restoration site (St. George Island [SGI]). Eelgrass planted at PP in the fall of 2005 declined through the summer of 2006 with some recovery in the spring of 2007, but was gone by the end of the summer of 2007. The summer decline from late July to mid‐August of 2006 coincided with water temperatures greater than 30°C, hypoxic oxygen (0–3 mg/L) concentrations, and low percent light at leaf level (PLL < 15%). Epiphyte loads were much heavier at PP than at SGI, despite similar water quality. We suggest that this was the result of higher wave exposure at PP. All of these factors are likely to have contributed to the mortality of the 2005 plantings. Submerged aquatic vegetation habitat quality based on the PTSI, median PLL during the growing season, and test plantings did not explain the decline of the plantings. Restoration site selection criteria should be expanded to include the effects of wave exposure on self‐shading and epiphyte loads, and the potential for both short‐term exposures to stressful conditions and long‐term changes in habitat quality.     

Experimental Restoration of Disturbed Cliff-Edge Forests in Bruce Peninsula National Park, Ontario, Canada

Abstract Restoration of degraded natural vegetation in parks is often complicated by the need to maintain public access. We tested whether the natural canopy species, Thuja occidentalis, can be restored to degraded cliff edges in Bruce Peninsula National Park, Ontario, Canada without reductions in visitor numbers. Eighty 10‐year‐old and 80 4‐year‐old container‐grown saplings and 1,400 seeds were planted and monitored for 4 years. Eight treatments were applied that tested for effects of planting site (distance from cliff edge and pathways) and supportive measures (soil, water, cages, or signs) on survival, growth, and damage. No trees became successfully established from seed. Younger trees showed faster initial establishment and growth, but 4‐year survival was the same for both age groups (39%). Supplemental soil improved the health of planted trees, and both soil and water slightly improved their survival. Cages did not affect survival and growth but decreased damage to 4‐year‐old trees and increased it for 10‐year‐olds. Signs had no effect on any measured variable. Trees planted away from the cliff edge and from pathways had the greatest establishment success, 4‐year survival, and general health. Relative visitor density, as estimated from spot counts of visitors, had the largest effect on restoration success; the results suggest a threshold of visitor density above which restoration may be impossible. Planting location, especially with respect to shade, was also important. The planting of 4‐year‐old trees without supportive measures is suggested as the most cost‐effective restoration technique at this site. The results indicate that restoration of open woodland habitats is possible without total visitor exclusion but that some restrictions on visitor numbers or activities are necessary.     

Restoring for the present or restoring for the future: enhanced performance of two sympatric oaks (Quercus ilex and Quercus pyrenaica) above the current forest limit

Reforestation is common to restore degraded ecosystems, but tree‐species choice often neglects ongoing environmental changes. We evaluated the performance of planted seedlings of two oak species at two sites in a Mediterranean mountain (Sierra Nevada, SE Spain): one located within the current altitudinal forest range (1,600–1,760 m), and one above the upper forest limit (1,970–2,120 m). The forest service planted 1,350 seedlings of the deciduous Pyrenean oak and the evergreen Holm oak in a postfire successional shrubland. After 2 years, seedlings were monitored for survival, and a subset of 110 Pyrenean oaks and 185 Holm oaks were harvested for analyses of biomass and foliar nutrient status, δ¹³C, and δ¹⁸O. Both species showed the highest survival and leaf N status above the upper forest limit, and survival increased with altitude within each plot. The deciduous oak benefited most from planting at higher altitude, and it also had greater biomass at the higher site. Correlations between foliar N, δ¹⁸O, and δ¹³C across elevations indicate tighter stomatal control of water loss and greater water‐use efficiency with increasing plant N status at higher altitude, which may represent a so‐far overlooked positive feedback mechanism that could foster uphill range shifts in water‐limited mountain regions. Given ongoing trends and future projections of increasing temperature and aridity throughout the Mediterranean region, tree‐species selection for forest restoration should target forecasted climatic conditions rather than those prevailing in the past. This study highlights that ecosystem restoration provides an opportunity to assist species range shifts under rapidly changing climate.     

Factors Affecting Revegetation of Carex lacustris and Carex stricta from Rhizomes

The revegetation of sedge meadows has been problematic because natural recolonization does not occur under many circumstances and because planted propagules often fail to reestablish successfully. In this study, detached rhizomes of Carex lacustris Willd. and Carex stricta Lam. were transplanted in both fall (September) and spring (May) into three experimental wetlands to determine the effects of both planting season and hydrology on survival and establishment. Each experimental wetland had the same mean water depth across 5% slopes, but one had a constant water depth (0.5 m) throughout the growing season, another fell from a mean depth of 0.75 m to 0.25 m, and a third rose from a mean depth of 0.25 m to 0.75 m. Initial rhizome survival, shoot growth, and soil characteristics were recorded over 2 years. Neither planting proved successful (6.9% versus 0.5%) for C. stricta, a tussock-forming sedge. For C. lacustris, a sedge with spreading rhizomes, spring planting had greater rhizome survival (53.2% survival) than fall planting (0.7%). Since both species initiate new shoots in the fall, they are susceptible to transplant failure during this season. The highest survival rates (71–100%) and plant production (736.0 and 494.5 g/m²) for C. lacustris occurred near the water’s edge in both the constant and falling basins. In the rising basin, establishment and growth of this species was high at all water depths (71–96%; 399 g/m²). C. lacustris grew optimally at the same elevations where rhizome survival was greatest, suggesting that shoots are more sensitive to early-season than late-season water levels.     

Nutrient pulsing as a regulator of phytoplankton abundance and community composition in Galveston Bay, Texas

Galveston Bay, Texas, is a large shallow estuary with a watershed that includes 60% of the major industrial facilities of Texas. However, the system exhibits low to moderate (2-20 μg l⁻¹) microalgal biomass with sporadic phytoplankton blooms. Both nitrogen (N) and phosphate (P) limitation of phytoplankton growth have been proposed for the estuary. However, shifts between N and P limitation of algae growth may occur due to annual fluctuations in nutrient concentrations. The primary goal of this work was to determine the primary limiting nutrient for phytoplankton in Galveston Bay. Nutrient addition bioassays were used to assess short-term (1-2 days) phytoplankton responses (both biomass and community composition) to potentially limiting nutrients. The experimental bioassays were conducted over an annual cycle using natural water collected from the center to lower part of the estuary. Total phytoplankton biomass increased in the nitrate (10 μM) additions in 11 of the 13 bioassays, but no significant increases were detected in the phosphate (3 μM)-only additions. Bioassay results suggest that the phytoplankton community was usually not phosphate limited. All major groups increased in biomass following nitrate additions but diatoms increased in biomass at a faster rate than other groups, shifting the community composition toward higher relative abundance of diatoms. The results of this study suggest that pulsed N input events preferentially favor increases in diatom biomass in this estuary. The broader implications of this study are that N pulsing events, primarily due to river discharge, play an important role in structuring the phytoplankton community in the Galveston Bay estuary.     

Study on ecological restoration in near-shore zone of a eutrophic lake, Wuli Bay, Taihu Lake

A two-year restoration period, large-scale ecological restoration demonstration engineering project was carried out in the near-shore zones of Wuli Bay, Taihu Lake. Various methods to restore the aquatic biodiversity and prevent ecological degradation were employed and their effects on water quality and aquatic plants were investigated. The results showed that water quality had been significantly improved in the demonstration zones. The concentrations of TN and TP were about half of those of the reference site in Wuli Bay. The water transparency was 30 cm higher than that in the reference site. The species, cover and biomass of aquatic plants were also significantly increased in the demonstration zones.     

水分和种植密度对干热河谷车桑子生长性状及种内相互关系的影响

水分是干热河谷植物生长过程中最主要的限制因子,种植密度增加也会引起植物生长的资源限制,两者交互作用下植物生长性状及种内关系的变化特征还不清楚。以干热河谷优势植物——车桑子为研究对象,根据元谋干热河谷年均生长季降雨量设置3种水分梯度:高水分、中水分和低水分,同时在各水分梯度下设置4个种植密度:1、2、4、9株/盆,探究水分、种植密度及其交互作用对车桑子生长性状、生物量分配及种内相互作用的影响。结果表明:(1)低水分条件下,车桑子生长和水分生理受到抑制,但车桑子在较低的叶水势下依然能够保持较高的相对含水量;(2)干旱胁迫显著降低了车桑子总生物量和单株生物量,显著增加了枯叶生物量比例,低水分和中水分条件下,增加种植密度对总生物无显著影响;而高水分条件下,增加种植密度显著提高了车桑子总生物量;(3)低水分显著增加了茎、叶生物量的异速生长指数,将更多生物量分配到叶,而种植密度增加显著降低了茎、叶生物量的异速生长指数,增加了茎的生物量分配;(4)通过相对邻体效应的计算,各处理条件下,车桑子种内关系均表现为竞争作用,并且,这种竞争作用的强度随水分的减少和密度的增加而增加。在高密度条件下(9棵/盆),...     

Restoration Ecology of an Endangered Plant Species: Establishment of New Populations of Cirsium pitcheri

We determined the effects of shade, burial by sand, simulated herbivory, and fertilizers on the survival and growth of artificially planted population of Cirsium pitcheri—an endangered plant species of the sand dunes along Lake Huron. Sand burial experiments showed that greenhouse grown plants should optimally be transplanted into areas receiving 5 cm of sand deposition: burial at this depth maximized emergence, survivorship, and below‐ground biomass. Under field conditions, simulated herbivory of up to 50% of the plant height produced a slight increase in biomass after one year of growth. Field observations showed that when white‐tailed deer removed more than 50% of the transplant's leaf tissue, the plant died. The application of a 20:20:20 (N:P:K) water‐soluble fertilizer produced a significant increase in the dry leaf biomass, total leaf area, and total dry biomass relative to control plants. We also tested for the presence or absence of a persistent seed bank. Few seeds were recovered from soil samples collected from Pinery Provincial Park and Providence Bay. However, C. pitcheri has the ability to form a persistent seed bank under field conditions but only at soil depths of 15 cm. Cirsium pitcheri seeds are able to germinate and seedlings can emerge from a burial depth of up to 6 cm. Thus, seeds planted in open, sunny areas will probably maximize emergence, growth, and survivorship of seedlings. Populations of C. pitcheri can be restored by planting seeds at shallow depths, transplanting greenhouse‐grown plants, applying water soluble fertilizers, and protecting plants from herbivores.     

Effects of water depth on clonal characteristics and biomass allocation of Halophila ovalis (Hydrocharitaceae)

Aims Halophila ovalis is a dioecious seagrass with a wide geographical and water depth range. The objective of this study was to understand its plasticity in clonal characteristics and biomass and also its allocation between above- and belowground in seagrass beds at different water depths.Methods Four monospecific H. ovalis beds, Shabei, Xialongwei, Beimu and Yingluo, which have different water depths at maximum tide level (MTL) but otherwise similar environmental conditions, were studied. We measured main clonal characteristics, i.e. horizontal internodal length, branching angle, shoot height, leaf length and width, and rhizome diameter. Above- and belowground biomasses of H. ovalis were also estimated using a harvest method.Important findings We found no significant differences in coverage, leaf pair density or number of stem nodes per square meter between the four study sites. However, horizontal internodal length, leaf length, width, rhizome diameter and shoot height all increased significantly with the increases in water depth from 2- to 9-m MTL and decreased when the water depths were greater than 9-m MTL. No significant difference in above- or belowground biomass between the seagrass beds was found. However, the ratio of above- to belowground biomass was significantly higher in the shallowest site compared to the other three seagrass beds, indicating that more biomass was stored belowground in deeper water. The results demonstrated plastic responses in clonal characteristics and biomass allocation in H. ovalis across the water depth gradient.     

Fauna of Natural Seagrass and Transplanted Halodule wrightii (Shoalgrass) Beds in Galveston Bay, Texas

Abstract We compared nekton and benthos densities and community compositions in a natural mixed seagrass bed dominated by Halodule wrightii (shoalgrass) with those found in three shoalgrass transplant sites and adjoining sand habitats in western Galveston Bay, Texas, U.S.A. Quantitative drop traps and cores were used to compare communities up to seven times over 36 months post‐transplant where transplant beds survived. Total densities of fishes, decapods, annelids, benthic crustaceans, and most dominant species were significantly higher in natural seagrass than in transplanted shoalgrass or sand habitats during most sampling periods. On occasion, fish and decapod densities were significantly higher in transplanted shoalgrass than in adjoining sand habitats. No consistent faunal differences were found among transplant sites before two of three sites failed. Taxonomic comparison of community compositions indicated that nekton and benthos communities in natural seagrass beds were usually distinct from those in transplanted beds or sand habitats, which were similar. We conclude that reestablishing a shoalgrass bed that resembles a natural seagrass bed and its faunal communities in the Galveston Bay system will take longer than 3 years, provided that transplants persist.     

Initiating Autogenic Restoration on Shallow Semiarid Sites

Our objectives were to evaluate the use of microcatchments in the establishment of Leucaena retusa (little-leaf leadtree) and Atriplex canescens (four-wing saltbush) and their role in the initiation of autogenic landscape restoration processes on a shallow semiarid site. Three six-month-old seedlings of either Leucaena retusa or Atriplex canescens were planted in 1.5-m² microcatchments. An equal number of seedlings was planted in control plots (unmodified soil surface). The water collection effects on shrub survival, standing biomass, and the natural immigration of herbaceous vegetation were determined over 42 months. Planting in microcatchment basins doubled Leucaena seedling survival and resulted in a five-fold increase in standing biomass, compared to the control, during the first growing season. There was a significant increase in soil organic matter in the microcatchment basins within 32 months. At the same time, microcatchments planted with Atriplex canescens seedlings had a ten-fold increase in seedling standing biomass compared to the control. Forty-two months after transplanting, the herbaceous standing crop was significantly greater near Atriplex canescens or in microcatchment basins than in plots with unmodified surface soil. Basins containing Atriplex produced significantly more herbaceous vegetation than basins containing Leucaena, and empty basins produced the least herbaceous vegetation of three basin treatments. These data suggest that landscape-scale procedures that concentrate scarce resources (water, organic matter, nutrients, and propagules), establish keystone species, and ameliorate microenvironmental conditions can initiate autogenic restoration of degraded semiarid ecosystems.     

Foliage production of the mangrove from San Andrés Island,Colombian Caribbean coast

Litter fall from a San Andres Island mangrove (12 degrees 32' N, 81 degrees 41' W, Colombian Caribbean coast), was collected monthly (1994-1995) with mesh baskets, keeping results separate for the three species (Rhizophora mangle, Avicennia germinans and Laguncularia racemosa), and taking a sample and a replica per case. Nine sampling sites were selected in two groups of woodlands: one in the inner side behind a sand-bar and the coast road (Mount Pleasant, Salt Creek, Sound Bay and Smith Channel) and a peripheral site, exposed to the waves (Bahía Hooker-Bahía Honda and El Cove). Productivity was greater for all species in the inner group, and higher in the rainy seasons. Rhizophora mangle was the only species contributing reproductive components throughout the year.     

Environmental investigations of Vibrio parahaemolyticus in oysters after outbreaks in Washington, Texas, and New York (1997 and 1998)

Total Vibrio parahaemolyticus densities and the occurrence of pathogenic strains in shellfish were determined following outbreaks in Washington, Texas, and New York. Recently developed nonradioactive DNA probes were utilized for the first time for direct enumeration of V. parahaemolyticus in environmental shellfish samples. V. parahaemolyticus was prevalent in oysters from Puget Sound, Wash.; Galveston Bay, Tex.; and Long Island Sound, N.Y., in the weeks following shellfish-associated outbreaks linked to these areas. However, only two samples (one each from Washington and Texas) were found to harbor total V. parahaemolyticus densities exceeding the level of concern of 10,000 g(-1). Pathogenic strains, defined as those hybridizing with tdh and/or trh probes, were detected in a few samples, mostly Puget Sound oysters, and at low densities (usually <10 g(-1)). Intensive sampling in Galveston Bay demonstrated relatively constant water temperature (27.8 to 31.7 degrees C) and V. parahaemolyticus levels (100 to 1,000 g(-1)) during the summer. Salinity varied from 14.9 to 29.3 ppt. A slight but significant (P < 0.05) negative correlation (-0.25) was observed between V. parahaemolyticus density and salinity. Based on our data, findings of more than 10,000 g(-1) total V. parahaemolyticus or >10 g(-1) tdh- and/or trh-positive V. parahaemolyticus in environmental oysters should be considered extraordinary.     

Impacts of colonial waterbirds on vegetation and potential restoration of island habitats

Colonial waterbirds have impacted forested island ecosystems throughout their breeding range, changing vegetation, and soil characteristics and bird communities. Our objectives were to (1) determine effects of three levels of colonial waterbird exclusion on overall vegetation diversity and growth, and survival of a candidate restoration species (black elderberry; Sambucus nigra canadensis); (2) investigate effects of different planting techniques on survival and growth of black elderberry; and (3) determine effects of waterbird colonization on soil chemistry. In 2012, we investigated effects of three levels of waterbird exclusion (none control plots [CON]; partial, which excluded waterbirds larger than gulls [PEX]; and full which excluded all waterbirds [FEX]) on bird use, existing vegetation growth and diversity, and survival of planted black elderberry on three islands in Door County, WI, Lake Michigan. In 2013, we evaluated survival of black elderberry established with four planting treatments within three waterbird exclusion treatments on two islands in 2013. We also compared soil chemistry characteristics between islands with and without nesting waterbirds for 2 years. Overall plant growth was greater in exclosures, but elderberry survival was similar among treatments. Soil replacement and weed suppression planting treatments did not affect survival, but generally increased overall elderberry biomass. Soil from nesting islands was more acidic and had greater nutrient concentrations than reference islands. Exclusion or removal of colonial nesting waterbirds from islands may improve overall vegetation growth, but successful restoration of woody vegetation may require significant soil manipulation and planting.     

Planting Design Effects on Avian Seed Dispersers in a Tropical Forest Restoration Experiment

Seed dispersal often limits tropical forest regeneration and animals disperse most rainforest tree seeds. This presents two important questions for restoration ecologists: (1) which animals are common seed dispersers? and (2) which restoration techniques attract them? Fourteen restoration sites were planted with four tree species in three designs, (1) controls (no planting, natural regeneration) (2) islands (trees planted in small patches), and (3) plantations (trees planted continuously over a large patch). We sampled birds in November, February, and April 2007–2008 with mist nets, in February and July 2009 with observations, and in July 2008 with both techniques. We documented 30 seed species from fecal samples of captured birds. All identified seed species were early‐successional forms. Four tanager species, three thrushes, two saltators, two flycatchers, and one finch were categorized as common seed dispersers, based on their high likelihood of dispersing seeds. Common dispersers were generalist species with small gape widths (<15 mm). Common dispersers were captured significantly more often in plantations than controls in most seasons and more often in plantations than islands during one season. Common disperser observations were significantly greater in plantations than controls during two periods and in plantations compared with islands in one period. Results indicate that plantation‐style planting is the conservative strategy to maximize attractiveness to common dispersers in tropical restoration sites. Island planting is an alternative when resources are limited although disperser activity may be lower in some seasons than in plantations. Additional research should investigate how to attract large, forest‐associated dispersers.     

3种种植方式下沉水植物恢复效果研究

恢复沉水植物是受污染水体生态修复与重建的有效措施之一,人工快速大面积恢复沉水植物的方法是关键。选取杭州西湖西进区域茅家埠和浴鹄湾近岸水域,分别采用扦插法、沉栽法和播种法对沉水植物菹草、苦草和黑藻进行种植。研究表明：运用沉栽法种植的菹草存活率比用播种法种植的存活率高71.1%;运用扦插法种植的苦草比沉栽法和播种法的存活率分别高84.3%和87.8%;运用扦插法种植的黑藻比用播种法种植的存活率高69%;3种种植方式下最终的单株植物生物量间无显著差异。