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1.
Temporal change in forest fragmentation at multiple scales 总被引：1，自引：0，他引：1
Previous studies of temporal changes in fragmentation have focused almost exclusively on patch and edge statistics, which
might not detect changes in the spatial scale at which forest occurs in or dominates the landscape. We used temporal land-cover
data for the Chesapeake Bay region and the state of New Jersey to compare patch-based and area–density scaling measures of
fragmentation for detecting changes in the spatial scale of forest that may result from forest loss. For the patch-based analysis,
we examined changes in the cumulative distribution of patch sizes. For area–density scaling, we used moving windows to examine
changes in dominant forest. We defined dominant forest as a forest parcel (pixel) surrounded by a neighborhood in which forest
occupied the majority of pixels. We used >50% and ≥60% as thresholds to define majority. Moving window sizes ranged from 2.25
to 5,314.41 hectares (ha). Patch size cumulative distributions changed very little over time, providing no indication that
forest loss was changing the spatial scale of forest. Area–density scaling showed that dominant forest was sensitive to forest
loss, and the sensitivity increased nonlinearly as the spatial scale increased. The ratio of dominant forest loss to forest
loss increased nonlinearly from 1.4 to 1.8 at the smallest spatial scale to 8.3 to 11.5 at the largest spatial scale. The
nonlinear relationship between dominant forest loss and forest loss in these regions suggests that continued forest loss will
cause abrupt transitions in the scale at which forest dominates the landscape. In comparison to the Chesapeake Bay region,
dominant forest loss in New Jersey was less sensitive to forest loss, which may be attributable the protected status of the
New Jersey Pine Barrens. 相似文献
2.
Temporal change in fragmentation of continental US forests 总被引：1，自引：0，他引：1
James D. Wickham Kurt H. Riitters Timothy G. Wade Collin Homer 《Landscape Ecology》2008,23(8):891-898
Changes in forest ecosystem function and condition arise from changes in forest fragmentation. Previous studies estimated
forest fragmentation for the continental United States (US). In this study, new temporal land-cover data from the National
Land Cover Database (NLCD) were used to estimate changes in forest fragmentation at multiple scales for the continental US.
Early and late dates for the land-cover change data were ca. 1992 and ca. 2001. Forest density was used as a multi-scale index
of fragmentation by measuring the proportion of forest in neighborhoods ranging in size from 2.25 to 5314.41 ha. The multi-scale
forest density maps were classified using thresholds of 40% (patch), 60% (dominant), and 90% (interior) to analyze temporal
change of fragmentation. The loss of dominant and interior forest showed distinct scale effects, whereas loss of patch forest
was much less scale-dependent. Dominant forest loss doubled from the smallest to the largest spatial scale, while interior
forest loss increased by approximately 80% from the smallest to the second largest spatial scale, then decreased somewhat.
At the largest spatial scale, losses of dominant and interior forest were 5 and 10%, respectively, of their ca. 1992 amounts.
In contrast, patch forest loss increased by only 25% from the smallest to largest spatial scale. These results indicate that
continental US forests were sensitive to forest loss because of their already fragmented state. Forest loss would have had
to occur in an unlikely spatial pattern in order to avoid the proportionately greater impact on dominant and interior forest
at larger spatial scales. 相似文献
3.
Calcareous grasslands are among the most species-rich ecosystems in temperate countries. However, these ecosystems have suffered
from fragmentation and destruction during the last century. We studied the response of calcareous grassland plant diversity
to landscape changes in Belgium. Results indicated that high area loss (since 1965) old habitat patches exhibited an extinction
debt inverse to low area loss old habitat patches, little depending on the area loss threshold (60%, 70%, 80% or 90%) considered
for the distinction between the high and low area loss patches. However, human activities also created new habitat patches
in the landscape and therefore provided opportunities for calcareous grassland plant species to colonize new habitats. This
also provided opportunities to study species colonization abilities in the context of habitat restoration. We analyzed species
richness in new patches compared to old patches in order to detect colonization credit. We detected the presence of a colonization
credit in new patches when using high loss old patches (area loss >80%, exhibiting an extinction debt) or all old patches
as a reference. However, when the reference was low loss old patches alone (area loss <80%, less likely to exhibit an extinction
debt), no colonization credit was detected. In addition, species composition was similar between new patches and old patches.
These results are encouraging for restoration programs. However, the results indicated that the presence of an extinction
debt in reference habitats could lead to inaccurate conclusions in restoration monitoring. Therefore, extinction debt should
be considered when choosing reference habitats to evaluate restoration success. 相似文献
4.
Gestich Carla C. Arroyo-Rodr&#;guez V&#;ctor Saranholi Bruno H. da Cunha Rog&#;rio G. T. Setz Eleonore Z. F. Ribeiro Milton C. 《Landscape Ecology》2022,37(1):147-157
Landscape Ecology - Forest loss and fragmentation are rapidly expanding across the tropics. Although forest loss is a major driver of the current biodiversity crisis, the effect of fragmentation... 相似文献
5.
The reliability of ants as bioindicators of ecosystem condition is dependent on the consistency of their response to localised
habitat characteristics, which may be modified by larger-scale effects of habitat fragmentation and loss. We assessed the
relative contribution of habitat fragmentation, habitat loss and within-patch habitat characteristics in determining ant assemblages
in semi-arid woodland in Queensland, Australia. Species and functional group abundance were recorded using pitfall traps across
20 woodland patches in landscapes that exhibited a range of fragmentation states. Of fragmentation measures, changes in patch
area and patch edge contrast exerted the greatest influence on species assemblages, after accounting for differences in habitat
loss. However, 35% of fragmentation effects on species were confounded by the effects of habitat characteristics and habitat
loss. Within-patch habitat characteristics explained more than twice the amount of species variation attributable to fragmentation
and four times the variation explained by habitat loss. The study indicates that within-patch habitat characteristics are
the predominant drivers of ant composition. We suggest that caution should be exercised in interpreting the independent effects
of habitat fragmentation and loss on ant assemblages without jointly considering localised habitat attributes and associated
joint effects.
The State of Queensland's right to retain a non-exclusive, royalty free license in and to any copyright is acknowledged. 相似文献
6.
Cook Rachel N. Ramirez-Parada Tadeo Browne Luke Ellis Mike Karubian Jordan 《Landscape Ecology》2020,35(12):2825-2841
Landscape Ecology - Tropical forest loss and fragmentation and the associated loss in species diversity are increasing in both magnitude and scope. Much attention has been paid to how attributes of... 相似文献
7.
对广东省揭阳市蔬菜品种资源情况进行了概述,并对其蔬菜品种资源丧失的原因进行了分析,指出经济体制改革,良种繁育途径变化,品种使用周期缩短,品种资源保存不力等是导致蔬菜品种资源丧失的重要原因,最后提出今后关于蔬菜品种资源保护及开发的建议. 相似文献
8.
采后操作对荔枝果实品质、失水与呼吸的影响 总被引：2，自引：0，他引：2
探讨了98℃热水处理、熏硫及结合酸浸等技术、包装方式与贮藏条件对‘黑叶’荔枝果实品质、失重与呼吸作用的影响。结果表明：热浸、熏硫结合酸浸处理可提高果皮酸度,对果肉可溶性固形物含量与酸度无影响;无包装自然放置与有孔或无孔塑料盒包装相比,无孔塑料盒包装的果实失重显著减缓;贮藏于4℃的热处理果实与对照果实有相似的失重曲线;无论包装方式与贮藏环境的温湿度如何,果实均不存在呼吸高峰;呼吸速率在贮藏初期随着果实失重的增加而下降,后期变化趋于平稳。 相似文献
9.
烹调方式及冷藏时间对葱蒜类蔬菜中VB1、VB2和VC含量的影响 总被引：1，自引：0，他引：1
选取4种葱蒜类蔬菜,按常规烹调方式及烹调后两个冷藏时间段进行处理,采用国标法分别测
定新鲜样品、烹调后以及冷藏保存后VB1、VB2和VC含量,探讨不同烹调方式及冷藏时间对常见葱蒜类蔬菜中维生素（VB1、VB2和VC）含量的影响。结果表明：不同烹调方式对食物中3种维生素含量有不同程度的影响,其中炒影响最低,蒸影响最大;3种维生素在食物冷藏过程中均有不同程度的损失,且损失量随时间的延长而逐渐增大。 相似文献
10.
在季节外休闲期间,以休闲为对照,采用"天紫22号"糯玉米作为填闲作物种植,通过同位素标记技术以及渗漏计技术,比较不同处理下的氮素去向和夏季填闲作物的提氮作用。结果表明:夏季填闲期间所有处理各土层土壤Nmin均有所降低,以表层0～30cm下降最快,减少量最大。种植糯玉米与休闲处理氮素损失量分别为172.44、224.23kg/hm2,种植填闲作物可有效减少氮素的损失。另外,15 N标记试验表明,在种植填闲作物的条件下,可以有效的减少氮素的淋洗损失,比对照处理要减少11%。试验证实了种植填闲作物糯玉米具有有效利用菜田土壤残留氮与阻控氮淋洗风险的作用,为北方日光温室典型种植模式氮素优化管理提供了科学参考。 相似文献
11.
LIANG Jie-fang HU Jing-xin YANG Bin-yuan CHEN Sheng-qiang ZHONG Yu LIANG Yu-juan DENG Guang-fei ZHONG Bei-hua HUANG Zhe HUANG Lan-ying GUO Lan-lan 《园艺学报》2006,22(12):2414-2417
AIM:To probe into the anti-epilepsy action of artificial Calculus Bovis, by observing its effect on the behavioral of the experimental epileptic rats, neuron loss in the hippocampus and hilus, and GAD positive cell alteration in the hippocampus. METHODS:SD rats were divided into three groups:group A (artificial Calculus Bovis treatment group);group B (acute epilepsy group) and group C (control group). A model of acute epilepsy rats was established by PTZ. The rat’s behavioral alteration was observed by the Racine’ scale. The neurons in the hippocampus and hilus were calculated by Nissl staining. The GAD positive cells were observed by immunohistochemical staining. RESULTS:The latency of the first seizure in group A was longer than that in group B, while the seizure times in group A was less than that in group B. Besides, in group A, both the neuron loss amount in the hippocampus and hilus and the GAD positive cell loss amount in the hippocampus were less than those in group B. CONCLUSION:The artificial Calculus Bovis prolonged the latency of the first seizure time, decreased the frequency of seizure, and prevented the neuron loss and protected the GAD positive cells. 相似文献
12.
研究了石蜡、蔗糖酯、腐殖酸和CO2抗蒸腾剂对青花菜贮藏期失水的影响。结果表明：稀释50倍的腐殖酸和8% CO2+92% N2对减少青花菜失水有较明显的效果，贮藏期间内压力势降低较小，可以显著延长青花菜贮藏的货架期。 相似文献
13.
Solomon I. Shibairo Peter M. A. Toivonen 《The Journal of Horticultural Science and Biotechnology》2013,88(6):862-866
SummaryThe effect of potassium (K) nutrition on the shelf life of carrots (Daucus carota L., cv. Paramount) was studied using a hydroponic system involving rockwool slabs as an inert support. Carrots were grown for 192 d under greenhouse conditions and with 0, 0.1,1.0,10 and 15 mM K supplied in the nutrient medium. Increase in K concentration in the nutrient medium up to 1 mM decreased postharvest moisture loss. Carrot root weight and tissue K concentration increased, and water potential, osmotic potential and relative solute leakage decreased with increasing K concentration up to 1 mM. Concentrations greater than 1 mM had little or no additional effect on postharvest moisture loss, root water and osmotic potentials and relative solute leakage. Root weight did not increase above 10 mM K. The best subset model obtained by backward stepping and the optimum Mallow’s coefficient showed that carrot root weight and relative solute leakage accounted for most of the variation in moisture loss. Root weight correlated negatively and relative solute leakage positively to moisture loss. 相似文献
14.
Logging significantly reduces the proportion of late-seral stands in managed boreal landscapes. Availability of habitat elements
typical of these stand types, such as standing dead wood, decreases, and dependant species may have their abundance reduced
or become locally extirpated, potentially affecting the ecosystem processes/services in which they take part. We evaluated
the impact of habitat loss on saprophagous wood-boring beetles (Coleoptera: Cerambycidae) in an aspen-dominated landscape
intensively logged for the past 30 years. Sixty natural snags of middle decay class were chosen along a gradient of habitat
loss and disturbance age, cut down and dissected for beetle larvae. We then assessed relationships between species occurrence
and percentage of residual cover and age of disturbance at spatial scales ranging from 40 to 2000 m radii. The most common
species, Anthophylax attenuatus, showed no response, being abundant regardless of the intensity of habitat loss. The second most common species, Bellamira scalaris, showed a negative response, especially in sites which had been fragmented for a longer time. A third species, Trachysida mutabilis, showed an inverse trend, having a higher probability of presence where habitat loss was more severe. Our study shows that
some saprophagous wood-borers do react negatively to habitat loss, but that within a relatively homogenous group the response
can vary significantly between species. Saprophagous wood-borers should be considered potentially sensitive to habitat loss,
and their response to fragmentation remains to be evaluated on a longer time frame. 相似文献
15.
Peter M. Groffman James M. Tiedje Delbert L. Mokma Stephen Simkins 《Landscape Ecology》1992,7(1):45-53
Large scale analyses of biogeochemical processes are necessary for understanding anthropogenic effects on global climate and
environmental quality. Regional scale estimates of denitrification from forest soils in southern lower Michigan USA were produced
by stratifying the region into landscape experimental units using soil texture and natural drainage classes, and extrapolating
data to larger areas using a geographic information system (GIS). Previous landscape-scale research established relationships
between soil texture and drainage and denitrification and quantified annual denitrification N loss in nine soil texture/drainage
groups. All forest soils within the region (64 series) were assigned to one of these nine groups based on their texture and
drainage characteristics and were assigned an annual denitrification N loss value. A regional estimate of denitrification
was produced by multiplying the areal extent of each of the nine soil groups by their annual denitrification N loss value.
Loam-textured soils underlie 47% of the regional forest and accounted for 73% of the forest denitrification. Sandy soils were
found under 44% of the regional forest but produced only 5% of the regional denitrification. Clay loam soils underlie 9% of
the regional forest and produced 22% of the denitrification. Annual denitrification N loss for the region was estimated as
1.4×107 kg N/yr. We used denitrification enzyme activity (DEA) as a proxy for annual denitrification N loss to determine if the relationship
between denitrification and soil texture and natural drainage that we observed at the landscape scale held up at the regional
scale. DEA was measured in 22 soils across the region and was strongly related to soil texture and natural drainage (r2=0.61), suggesting that extrapolation of data from the landscape to the regional scale was justified. 相似文献
16.
湖州市地处浙江省北部,太湖南岸,2008年初,自然灾害主要有西北大风、连续低温阴雨、大雪暴雪和低温冻害,给蔬菜生产造成严重的损失,而且设施蔬菜的损失重于露地蔬菜。针对灾情,总结了湖州市设施蔬菜遭遇特大雪灾和连续低温冻害时防灾减灾的生产技术和措施,并对灾后发展棚、室设施提出了自己的观点。 相似文献
17.
Kathryn Brown Andrew J. Hansen Robert E. Keane Lisa J. Graumlich 《Landscape Ecology》2006,21(6):933-951
Loss of aspen (Populus tremuloides) has generated concern for aspen persistence across much of the western United States. However, most studies of aspen change
have been at local scales and our understanding of aspen dynamics at broader scales is limited. At local scales, aspen loss
has been attributed to fire exclusion, ungulate herbivory, and climate change. Understanding the links between biophysical
setting and aspen presence, growth, and dynamics is necessary to develop a large-scale perspective on aspen dynamics. Specific
objectives of this research were to (1) map aspen distribution and abundance across the Greater Yellowstone Ecosystem (GYE),
(2) measure aspen change in the GYE over the past 50 years (3) determine if aspen loss occurs in particular biophysical settings
and (4) investigate the links between biophysical setting and aspen presence, growth, and change in canopy cover. We found
that aspen is rare in the GYE, occupying 1.4% of the region. We found an average of 10% aspen loss overall, much lower than
that suggested by smaller-scale studies. Aspen loss corresponded with biophysical settings with the lowest aspen growth rates,
where aspen was most abundant. The highest aspen growth rates were at the margins of its current distribution, so most aspen
occur in biophysical settings less favorable to their growth. 相似文献
18.
Forest loss has been invoked as a cause for changes in the reproductive success of animal-pollinated woodland plants, associated
with changes in their pollinators. To analyze such effects, it is important to include all of the three key players: landscapes,
pollinators and a plant. We investigated effects of forest loss on an insect-pollinated plant through landscapes in forested
ecosystems to pollinator communities and plant populations. Then we questioned if abundance and species richness in pollinator
communities decrease as forest loss increases, and this in turn leads to a decrease in reproductive output of an insect-pollinated
plant. We made a study with 12 populations of the bee pollinated herb, Erythronium americanum, in a landscape characterized by scattered fragments of deciduous forest within intensively managed agricultural fields.
We also sampled bees as the potential pollinators by pan traps. We quantified the study landscapes using the amount of forest
cover and the length of forest edge within each of the six radii (250, 500, 750, 1,000, 1,250 and 1,500 m). Regression analyses
showed that the abundance and species richness of all collected bees were positively related to only the forest cover at the
radius of 750 m. We also found the positive relationships for the seed set of E. americanum when the forest cover at the same radius and abundance of all collected bees were used as the predictor variables. These
results indicate that forest loss causes negative impacts on potential pollinator communities and seed sets of some woodland
herbs. 相似文献
19.
20.
The effect of conditions of storage on the respiration of apples. VII. The carbon and oxygen balance
When apples of three cultivars were kept in air or in nitrogen at 12 °C, the loss of C02 plus alcohol was equivalent to the loss of carbohydrate plus acid. At lower temperatures, the loss of these substrates exceeded the loss as end products. Sorbitol accumulated in stored apples, in greater amount the lower the temperature. When the carbon of the sorbitol was subtracted from that of the carbohydrate, balance was restored.In air at low temperatures, the observed uptake of oxygen was less than that needed for oxidation of carbohydrate plus acid. When the carbohydrate loss was corrected for sorbitol accumulation, the observed oxygen uptake was equivalent to that required by the net loss of substrates.However, under C.A. conditions, in 5% CO2 plus 3% O2, the observed net loss of substrate exceeded the loss as end products of respiration. 相似文献