Land Condition in the Tropical Tallgrass Pasture Lands. 1. Effects on Herbage Production.

1995 ◽  
Vol 17 (1) ◽  
pp. 69 ◽  
Author(s):  
John G. Mcivor ◽  
Andrew J. Ash ◽  
Garry D. Cook
Keyword(s):  
Basal Area ◽  
Nutrient Status ◽  
Condition Index ◽  
Perennial Grasses ◽  
Individual Species ◽  
Growing Seasons ◽  
North East ◽  
Linear Relationships ◽  
Run Off ◽  
Land Condition

A quantitative condition index based on vegetation (botanical composition and basal area of perennial grasses) and soil characteristics (erodibility, nutrient status and availability, partitioning of rainfall into infiltration and run-off) was developed for tropical tallgrass pastures near Charters Towers (north-east Queensland) and Katherine (Northern Territory). Herbage growth and the responses of individual species at 10 sites over two growing seasons were related to the index. At all sites there were significant linear relationships between herbage growth and condition index although the values differed between sites. Annual grasses increased and most perennial grasses decreased as condition declined but Bothriochloa pertusa and Bothriochloa ewartiana were most abundant at intermediate condition levels. The response of Chrysopogon fallax varied widely between sites. The lower herbage production on poor condition sites will result in lower carrying capacity.

Pasture management in semi-arid tropical woodlands: dynamics of perennial grasses

2007 ◽  
Vol 29 (1) ◽  
pp. 87 ◽  
Author(s):  
John G. McIvor
Keyword(s):  
Perennial Grasses ◽  
Individual Species ◽  
Stocking Rate ◽  
Pasture Management ◽  
Management Options ◽  
Exotic Grasses ◽  
Heteropogon Contortus ◽  
Basal Cover ◽  
Growing Seasons ◽  
North East

The effects of a range of pasture management options (introduced legumes and grasses, superphosphate, timber treatment, cultivation before sowing and stocking rate) on the basal cover of perennial grasses were measured from 1982 to 1991 at two sites, ‘Hillgrove’ and ‘Cardigan’, near Charters Towers, in north-east Queensland. Colonisation and survival of eight native and exotic grasses were followed in permanent quadrats in a subset of treatments. Overall, there were significant changes in total basal cover of plots between years and with tree killing, but no significant differences in sown pastures, fertiliser or stocking rate. Basal cover increased when defoliation levels were less than 40% but increases were smaller at higher levels of defoliation and basal cover often declined when defoliation was greater than 60%. Basal cover declined when growing seasons were <10 weeks, remained static with 10–15 weeks growth, and increased when growing seasons were 16 weeks or longer. There was some colonisation in all years but large differences between years. The differences in colonisation between systems were generally small but there was a general trend for higher colonisation at higher stocking rates. Bothriochloa ewartiana (Domin) C.E.Hubb. and Chrysopogon fallax S.T.Blake had low, Heteropogon contortus (L.) P.Beauv. ex Roem.&Schult., Cenchrus ciliaris L. and Aristida spp. had intermediate, and Bothriochloa pertusa (L.) A.Camus and Urochloa mosambicensis (Hack.) Dandy had high colonising ability. Survival of individual species was generally similar at both sites except for Urochloa mosambicensis. Heteropogon contortus and U. mosambicensis at ‘Hillgrove’ were short-lived (<10% survival after 4 years), B. ewartiana, Themeda triandra Forssk. and Aristida spp. had intermediate survival (10–50%), and C. ciliaris, C. fallax, B. pertusa and U. mosambicensis at ‘Cardigan’ were long-lived (>50% survival). Annual survival rates increased with plant age, were higher in good growing seasons than in poor seasons, were higher for large plants than small plants, and were lower at high defoliation levels than where defoliation was less severe. The differences between species in ability to colonise and survive, and the small influence of management compared to seasonal effects on survival, are discussed to explain species performance in pastures.

Effects of continuous grazing and seasonal closures on the performance and persistence of some sown temperate perennial grasses, North-West Slopes New South Wales

2002 ◽  
Vol 42 (4) ◽  
pp. 431 ◽  
Author(s):  
G. M. Lodge
Keyword(s):  
Festuca Arundinacea ◽  
Perennial Grass ◽  
Basal Area ◽  
Trifolium Subterraneum ◽  
Perennial Grasses ◽  
Individual Species ◽  
North West ◽  
Basal Cover ◽  
Crown Density ◽  
Plant Frequency

A split-plot experiment was sown at Tamworth in 1992 to examine the effects of continuous sheep grazing and seasonal closures (autumn, spring, spring + autumn, and summer + winter) on the herbage mass, plant frequency and basal cover of 5 perennial grasses, when sown as monocultures or with a perennial (Trifolium repens cv. Haifa) or annual legume (Trifolium subterraneum var. subterraneum cv. Seaton Park). Plant basal area and crown density data were also collected. The perennial grasses were Phalaris aquatica cv. Sirosa, Festuca arundinacea, cv.� Demeter, Lolium perenne cv. Kangaroo Valley, Austrodanthonia richardsonii (syn. Danthonia richardsonii) cv.�Taranna, and A. bipartita (syn. D. linkii) cv. Bunderra. There was no significant effect of legume presence on the herbage mass or persistence of the perennial grasses. The only treatment that had a significant effect (P< 0.05) on either herbage mass, plant frequency or basal cover data was the grazing treatment × perennial grass interaction in each of the years 1993-98, except for herbage mass in December 1993 and basal cover in October 1998. In all of the grazing treatments examined, Kangaroo Valley ryegrass failed to persist after spring 1994; Demeter fescue had failed by spring 1997 and Sirosa phalaris by spring 1998. Six years after sowing the only temperate grass cultivars that were persisting in all grazing treatments were the native perennials, Taranna and Bunderra. Hence, the data represent the entire stand life from sowing to eventual failure for the 3 introduced cultivars. While grazing treatment effects within years for individual species were significant, overall grazing had little effect on the rate of decline in herbage mass and persistence of Kangaroo Valley, Demeter and Sirosa. By 1998, grazing treatment had no significant effect on the herbage mass and basal cover of Taranna and Bunderra, but their plant frequencies were lowest in the spring rest and summer + winter rest treatments.

Techniques for estimating plant basal area and assessing the herbage mass of some native perennial grasses.

1981 ◽  
Vol 3 (1) ◽  
pp. 83 ◽  
Author(s):  
GM Lodge ◽  
JA Taylor ◽  
RDB Whalley
Keyword(s):  
Plant Density ◽  
Unit Area ◽  
Basal Area ◽  
Ground Level ◽  
Field Studies ◽  
Fertilizer Application ◽  
Perennial Grasses ◽  
Individual Species ◽  
Laboratory Studies ◽  
Plant Parts

Techniques for using grid and unmarked transparent perspex overlays to estimate the area of tufted native perennial grasses were investigated in field and laboratory studies. Basal area was overestimated by using an unmarked overlay to trace the periphery of actual or atificial plant bases at ground level; this was caused by the amount of airspace included in the estimate. The compression of hand-held tufts reduced the airspace and improved the estimate of plant basal area. In the laboratory studies, the estimation by eye of filled cells in a transparent grid overlay was accurate over a range of areas from 0.02 to 10.39 cm2, although it required considerable operator training. Changes in herbage mass occur as a result of change in the number of plants per unit area (plant density), the basal area of individual plants or the plant mass per unit of basal area of individual plants. Field studies were undertaken at two sites to collect data on each of these components of herbage mass and to investigate whether or not such information could be used to estimate the herbage mass of individual species in a pasture. The relationship between the mass per unit basal area of certain plant parts would appear to have some potential for use in studies of the seasonal changes in various plant components, such as green leaf and stem. This relationship could be used to examine the response of some species to fertilizer application, grazing and defoliation and hence the process of change in species composition with management. Estimates of the herbage mass per unit area of individual native perennial grasses calculated from plant density, plant basal area and mass per unit of basal area data compared favourably with estimates of total herbage mass of individual species obtained from clipped quadrats. Suggested techniques for collecting data in the field and the time involved in sampling are discussed.

scholarly journals Deer Browse Response to Pine-Hardwood Thinning Regimes in Southeastern Arkansas

1999 ◽  
Vol 23 (1) ◽  
pp. 16-20 ◽  
Author(s):  
David G. Peitz ◽  
Philip A. Tappe ◽  
Michael G. Shelton ◽  
Michael G. Sams
Keyword(s):  
Loblolly Pine ◽  
Basal Area ◽  
Individual Species ◽  
Growing Seasons ◽  
Deer Browse ◽  
Japanese Honeysuckle ◽  
Stand Thinning ◽  
Browse Species ◽  
Understory Biomass ◽  
Biomass Availability

Abstract Understanding relationships between stand thinning and browse production allows land managers to encourage both white-tailed deer (Odocoileus virginianus) browse production and timber production. In our study, browse biomass was determined before thinning and two and four growing seasons after thinning a 35 yr old natural loblolly pine-hardwood stand (initially 27 m2/ha of pine and 8 m2/ha of hardwood basal area). Combinations of 3 loblolly pine (15, 18, and 21 m2/ha) and 3 hardwood (0, 3.5, and 7 m2/ha) basal areas were replicated 3 times, resulting in a total of 27 0.08 ha plots. Understory biomass was determined for 14 browse species on 25 understory plots systematically located within each plot. Browse production following thinning was dominated by grape (Vitis spp.), blackberry (Rubus spp.), Japanese honeysuckle (Lonicera japonica), and greenbrier (Smilax spp.). Most deer browse species responded negatively to retained pine and/or hardwood basal areas, with hardwoods having the greater impact. Thinning improved overall browse biomass availability for deer, but responses varied by individual species. South. J. Appl. For. 23(1):16-20.

scholarly journals The Difficulty of Predicting Eastern Spruce Dwarf Mistletoe in Lowland Black Spruce: Model Benchmarking in Northern Minnesota, USA

Forests ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 843
Author(s):  
Ella R. Gray ◽  
Matthew B. Russell ◽  
Marcella A. Windmuller-Campione
Keyword(s):  
Stand Structure ◽  
Black Spruce ◽  
Forest Health ◽  
Basal Area ◽  
Predictive Performance ◽  
Stand Age ◽  
Management Decisions ◽  
Dwarf Mistletoe ◽  
Growing Seasons ◽  
Model Interpretation

Insects, fungi, and diseases play an important role in forest stand development and subsequently, forest management decisions and treatments. As these disturbance agents commonly occur within and across landscapes, modeling has often been used to inform forest planning and management decisions. However, models are rarely benchmarked, leaving questions about their utility. Here, we assessed the predictive performance of a Bayesian hierarchical model through on–the-ground sampling to explore what features of stand structure or composition may be important factors related to eastern spruce dwarf mistletoe (Arceuthobium pusillum Peck) presence in lowland black spruce (Picea mariana (Mill.) B. S. P.). Twenty-five state-owned stands included in the predictive model were sampled during the 2019 and 2020 growing seasons. Within each stand, data related to the presence of eastern spruce dwarf mistletoe, stand structure, and species composition were collected. The model accurately predicted eastern spruce dwarf mistletoe occurrence for 13 of the 25 stands. The amount of living and dead black spruce basal area differed significantly based on model prediction and observed infestation, but trees per hectare, total living basal area, diameter at breast height, stand age, and species richness were not significantly different. Our results highlight the benefits of model benchmarking to improve model interpretation as well as to inform our understanding of forest health problems across diverse stand conditions.

scholarly journals Ecosystem physio-phenology revealed using circular statistics

2019 ◽  
Author(s):  
Daniel E. Pabon-Moreno ◽  
Talie Musavi ◽  
Mirco Migliavacca ◽  
Markus Reichstein ◽  
Christine Römermann ◽  
...  
Keyword(s):  
Climate Variability ◽  
Gross Primary Production ◽  
Ecosystem Dynamics ◽  
Circular Statistics ◽  
Individual Species ◽  
Vegetation Types ◽  
Linear Predictor ◽  
Growing Seasons ◽  
Circular Model ◽  
Circular Regression

Abstract. Quantifying responses of vegetation phenology to climate variability is a key prerequisite to predict shifts in how ecosystem dynamics due to climate change. So far, many studies have focused on responses of classical phenological events (e.g. budburst or flowering) to climatic variability for individual species. Comparatively little is known on physio-phenological events such as the timing of the maximum gross primary production (DOYGPPmax). However, understanding this type of physio-phenological phenomena is an essential element in predicting the response of the terrestrial carbon cycle to climate variability. In this study, we aim to understand how DOYGPPmax depends on climate drivers across 52 eddy-covariance (EC) sites in the FLUXNET network for different regions of the world. Most phenological studies rely on linear methods that cannot be generalized across both hemispheres and therefore do not allow for deriving general rules that can be applied for future predictions. Here we explore a new class of circular-linear (here called circular) regression approach that may show a path ahead. Circular regression allows relating circular variables (in our case phenological events) to linear predictor variables (e.g. climate conditions). As a proof of concept, we compare the performance of linear and circular regression to recover original coefficients of a predefined circular model on artificial and EC data. We then quantify the sensitivity of DOYGPPmax to air temperature, short-wave incoming radiation, precipitation and vapor pressure deficit using circular regressions. Finally, we evaluate the predictive power of the regression models for different vegetation types. Our results show that the DOYGPPmax of each FLUXNET site has a unique signature of climatic sensitivities. Overall radiation and temperature are the most relevant controlling factors of DOYGPPmax across sites. The circular approach gives us new insights at the site level. In a Mediterranean shrub-land, for instance, we find that the two growing seasons are controlled by different climatic factors. Although the sensitivity of the DOYGPPmax to the climate drivers is very site specific, it is possible to extrapolate the circular regression model across vegetation types. From a methodological point of view, our results reveal that circular regression is a robust alternative to conventional phenological analytic frameworks. In particular global analyses can benefit, where phase shifts play a role or double peaked growing seasons may occur.

scholarly journals Loblolly Pine Outperforms Slash Pine in Southeastern Georgia and Northern Florida

2000 ◽  
Vol 24 (1) ◽  
pp. 31-36 ◽  
Author(s):  
Barry D. Shiver ◽  
John W. Rheney ◽  
Kenneth L. Hitch
Keyword(s):  
Loblolly Pine ◽  
Species Interactions ◽  
Basal Area ◽  
Pinus Elliottii ◽  
Slash Pine ◽  
Stand Volume ◽  
Growing Seasons ◽  
The Difference ◽  
Stand Basal Area ◽  
Better Than

Abstract A total of 141 paired plot installations remain of the 160 that were planted with slash (Pinus elliottii Engelm.) and loblolly (P. taedaL.) pine across southeastern Georgia and northern Florida, after 14 growing seasons. Installations were evenly distributed across eight soil types. Analyses indicate that loblolly performed equal to or better than slash pine. There were no soil X species interactions. After 14 yr, loblolly pine had significantly higher survival (71% vs. 66%), stand basal area (98 vs. 81 ft2/ac), total stand volume (1857 vs. 1721 ft3/ac), merchantable stand volume (1497 vs. 1310 ft3/ac), total green weight (53 tons vs. 47 tons), and merchantable green weight (45 vs. 35 tons/ac) than slash pine. Growth over the period from age 11 to age 14 was also higher for loblolly than for slash indicating that the difference in the two species is diverging over time. South. J. Appl. For. 24(1): 31-36.

scholarly journals The significance of organic carbon and nutrient export from peatland-dominated landscapes subject to disturbance, a stoichiometric perspective

2009 ◽  
Vol 6 (3) ◽  
pp. 363-374 ◽  
Author(s):  
S. Waldron ◽  
H. Flowers ◽  
C. Arlaud ◽  
C. Bryant ◽  
S. McFarlane
Keyword(s):  
Organic Carbon ◽  
Soluble Reactive Phosphorus ◽  
Nutrient Status ◽  
Co2 Efflux ◽  
Nutrient Export ◽  
Terrestrial Carbon ◽  
Carbon Export ◽  
Aquatic Respiration ◽  
Linear Relationships ◽  
Reactive Phosphorus

Abstract. The terrestrial-aquatic interface is a crucial environment in which to consider the fate of exported terrestrial carbon in the aquatic system. Here the fate of dissolved organic carbon (DOC) may be controlled by nutrient availability. However, peat-dominated headwater catchments are normally of low nutrient status and thus there is little data on how DOC and nutrient export co-varies. We present nutrient and DOC data for two UK catchments dominated by peat headwaters. One, Whitelee, is undergoing development for Europe's largest windfarm. Glen Dye by comparison is relatively undisturbed. At both sites there are significant linear relationships between DOC and soluble reactive phosphorus and nitrate concentrations in the drainage waters. However, inter-catchment differences exist. Changes in the pattern of nutrient and carbon export at Whitelee reveal that landscape disturbance associated with windfarm development impacts the receiving waters, and that nutrient export does not increase in a stoichiometric manner that will promote increase in microbial biomass but rather supports aquatic respiration. In turn greater CO2 efflux may prevail. Hence disturbance of terrestrial carbon stores may impact the both the aquatic and gaseous carbon cycle. We suggest estimates of aquatic carbon export should inform the decision-making process prior to development in ecosystems and catchments with high terrestrial carbon storage.

scholarly journals Controlling Beech Root and Stump Sprouts Using the Cut-Stump Treatment

2006 ◽  
Vol 23 (3) ◽  
pp. 155-165 ◽  
Author(s):  
Jeffrey D. Kochenderfer ◽  
James N. Kochenderfer ◽  
Gary W. Miller
Keyword(s):  
Radial Distance ◽  
Basal Area ◽  
Fagus Grandifolia ◽  
Complete Control ◽  
Growing Seasons ◽  
Control Root ◽  
Stump Sprouting ◽  
Number Of Stems ◽  
Cut Stump ◽  
Stump Sprouts

Abstract Application costs and efficacy were determined for cut-stump treatments applied to American beech (Fagus grandifolia Ehrh.) to control root and stump sprouts in central West Virginia. Glyphosate as Glypro (53.8%) was applied to the outer 2 in. of beech stumps from trees >6.0-in. dbh within 1 hour after cutting. In addition to treatment plots, individual beech stumps were treated to determine mortality patterns. The treatments were applied in early September 2001 and evaluated 12 months after treatment. A rating system ranging from 1 to 7 (0 to 100% crown affected) based on visual estimates of symptoms was used to evaluate the efficacy of the treatments. Trees with a rating of 5 (75% crown control or greater) were considered controlled. After 12 months, more than 90% of beech root sprouts ≥1-ft tall to 5.9-in. dbh on treated plots were controlled. Complete control of stump sprouting also was achieved. An average of 93 beech stems was controlled around each treated stump. Mortality around treated stumps declined as the radial distance from stumps increased and stump size decreased. Average application cost (chemical and labor) ranged from $39.43 to 62.34 per acre depending on the basal area and number of stems treated. After two growing seasons, the number of beech root sprouts on more than 90% of the treated regeneration plots remained below levels considered as interfering according to guidelines for Allegheny hardwoods. This study demonstrated that herbicide is readily translocated from the surfaces of freshly cut beech stumps via parent root systems to attached live beech stems. The cut-stump method can be applied in areas where beech is the primary species interfering with the establishment and development of desirable regeneration.

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