Lecture 07

追加: 2026-05-06

[00:00:19]My dear students and friends, I'm professor Uru Silas working in department of wildlife sciences, Aligar Muslim University. And today we'll be discussing about the sampling theory and biodiversity assessment. So under the sampling theory, uh under the sampling strategies, there are two kind of strategies. We have already discussed why sample is required. Why sample is needed? Sample is needed because we want to count the number. We want to know how much is the population. So to assess the population of the species, uh we do the sampling and that population assessment is important to see the trend over a time. See the trend of the population of that species over a time. So today we'll be discussing about the pound point count method. uh uh a plot method. There are two kind of method. One is the plot method, another is the plot, another is the plot list method. In plot method, the area is already decided. Okay. So, uh let's start with this. So, uh biodiversity assessment is scientific process to evaluate the presence, richness and abundance of organism in an area. Okay. So uh it helps uh scientists and conservationists understand which species are thriving or declining and how ecosystem are functioning. These assessment support uh decision about protected areas, habitat restoration and species recovery. Assessment vary in scale from microhabitat inter inventories to landscape level biodiversity assessment.

[00:01:57]Okay. So uh basically scientific evaluation of a species, presence, abundance and distribution uh quantitative and qualitative study of a species, ecosystem and genes and help identify richness, abundance and uh distribution of organism. So applied in ecological monitoring, conservation planning and environmental impact studies enables long-term biodiversity tracking and threat evaluation. So key objective of biosity assessment the primary goal of biology assessment are to identify species present in given area and estimate how many individual exist. So over time these assessments allow scientists to detect population trend and biodiversity losses. They are they are also crucial for evaluating the impact of conservation action habitat uh disturbances and climate changes. So like in India we do the human census population census. So how we know what is the population of India? It's at present there are 140 kores. So we are literally counting. Okay. So we are counting the uh we are counting the uh head human head and that's how we are saying these are the population. Same we we do for the animals whether it's a birds plants or birds mammals herpona or whatever. So what we do we do the counting we identify the species and we try to find out how many species are there existing and this will give you over the time this data will uh give us the understanding whether the population is increasing or not increasing.

[00:03:44]Population increasing or declining. If it is declining how much and do we have to really take care of the species so that population increases. So that is why we do the assessment of the population.

[00:03:59]So create detailed species inventories across landscape. Determine population size, density and structure and monitoring. Monitor changes due to climate change or human activities.

[00:04:11]Evaluate effectiveness of conservation measure and policies. support environmental education and decision making.

[00:04:19]So plot sampling overview plot sampling involve uh I have just I have mentioned in the start of the um uh talk that there are two kind of sampling. One is the plot sampling and another is the plotless sampling. So plot sampling is uh concern uh cornerstone of biodiversity fieldwork and researchers decline a plot either uh a square, circular or along a line and identify and count the species inside. The data is extrapolated to estimate biodiversity across larger landscape. For example, in degraded forest near Kazinag National Park, circle plot can help access tree regeneration. uh success success following conservation intervention. So uh plot sampling involves serving uh define area of estimated biodiversity use for plants sedentry uh sedentary animals and uh some birds mammals studies data includes species richness abundance and habitat structure. So plots can be fixed or transit based any size of any shape of the plant we can do but within the plots the data should be manageable. If we are doing for the birds plot should not be so big that we cannot identify the bird species. Okay. If you are doing the herbs and grasses counting the herbs and grasses the quadrant is small or the circle plot is small. So that easily can so plot is should be manageable. we can easily count the species within the given area. So it plot size varies according to the species according to the habitar and the support statistical analysis and long-term monitoring.

[00:06:11]Let's start with the point count uh methods. Point counts are ideal for surveying birds especially in varied habitat like wetland or forestages. An example is uh Hawker wetland in Kashmir where morning point count are used to monitor migratory uh water births like uh northern pinttail and common teal. Each count provide data on species presence and abundance over time contributing to trend analysis and conservation planning.

[00:06:42]So the pointcon method is widely used techniques for uh sampling and monitoring bird population. Observer stand at a fixed point and records all species seen her mostly used for birds and vocal amphibians and radius usually 25 to 50 m duration 5 to 10 m. This is the the picture itself is self-explanatory. I'm standing in the center of the plot and I have taken 25 m radius circular plot and within that plot what we are doing we are counting all the births for 5 to 10 minutes.

[00:07:19]Suppose we have fixed the uh time 10 minutes. So within 10 minutes whatever birds we see within this plot we will be recording and uh that's how we'll be calculating the density. Suppose we recorded in 10 minutes four bird species. So 4 divided by area. Area we already know the area of a circle is p<unk> r² p<unk> is 22x 7 and r is 25 m.

[00:07:48]We have already decided 25 m. 25 into 25. So this is the uh area of the plot.

[00:07:57]So 4 divided by area will give you the density. So that's how we calculate the density of the of of bird and the this type of small small plots we can lay throughout the area like if we lay the 100 plots it's easy to count the bus within uh 25 m radius plot.

[00:08:18]So repeat at multiple location for landscape level uh inference.

[00:08:25]Best practices in point count um sampling standardization is point count method is key to reliable data. If you are doing a point count in Dachamong National Park, early morning is ideal for detecting species like the Kashmir flying flying catcher. Using a rangefinder help estimate distance bands and repeated visits at different times of year help capture migrant and breeding species.

[00:08:54]Okay. So morning usually uh birds and mammals are active. For plants throughout the day you are you can do the sampling but for uh for uh birds for animals either my morning or the evening hours are best because these are the two time when they are actually very active.

[00:09:12]So when they are active you can take the data otherwise they are taking they have taken they take the shelter inside or in some hidden place where it's difficult to count the species. So best practices in point count sampling is choose early morning hours for best vocal activities.

[00:09:32]Maintain silence and record distance from observer. Avoid counting individual.

[00:09:38]Avoid double counting individuals. Use the same observer or calibrate among observers. Note whether habitat types and time during each each count. So we have to keep the record apart from the number of births. The what if it is good if the one person is doing all the plots or there should be some synchronization uh they are calibrate they should the the people should be calibrated so that one kind of data they can take otherwise if you are uh and same methodology should be used throughout the area along with this data we should collect weather condition whether it's a cloudy sunny or because suppose it's if it is drizzling. So visibility of the bird is less or it is is it is fog. So visibility is very so that is very low.

[00:10:32]So that is why what we do we take the data uh in the sunlight and we always record the weather condition. What is the weather? What kind of habitat is there? If it is a grassland definitely visibility we can see the birds from long distance but it is a woodland thick forest then it's very difficult to see the birds uh which are uh sitting at the far places. So habitat types and time during each count time is also important because morning and evening hours are more active visibility is more and accurate data we can collect but if we are doing the daytime or the night time it's difficult to do.

[00:11:16]So come to the uh second method that is the line transacts are uh line transact overview. Line transits are commonly used in larger mammals monitoring.

[00:11:27]Uh uh for example in Gur Valley walking transit through alpine pasture can detect signs or sightings of Himalayan Ibex or red fox. Researcher know the distance and angle of each observation to later estimate population densities using uh using uh tool like distance software. A line transit is an ecological survey method to observe species for estimation. Systematically recorded along a straight line lead across a study area. Observer walk a straight line recording species on both side. Here there are two kind of line transits. One is the open width another is the close width. Here if we are doing the bird mounting and we are walking on a straight line for 500 m. So 20 m this side and 20 m this side. We will fix the area on this within this 20 m distance we will be taking the we'll be recording the birds or mammals so that we know the area. So 500 m into 20 in 20 + 20 40 m.

[00:12:33]So this is the area of the um uh transact uh line transact application and changes uh detectability varies with the species habitat and observer skill.

[00:12:45]Thick vegetation can reduce visibility.

[00:12:47]GPS making improve accuracy of transexs.

[00:12:51]Repeated survey help identify trends over time ideal for combining the camera traps and uh sign survey. While effective line transacts are sensitive to observe error and habitat condition in dense Himalayas forest, spotting marur or mustier can be difficult. Using binocular uh laser rainfinder and GPS mapping improve data reliability. Camera trap place along transexs uh uh can supplement data on elusive uh species.

[00:13:25]Circle plot sampling. We have already discussed about the circle plot sampling. It is widely used in forest studies. For example, in Kazinang National Park, 10 m radius circle plot are used to assess oak tree density and associated undergrowth.

[00:13:43]Okay. What we have done in a forest, we have laid 10 m radius circle plot to and we will be counting the species and their individual like curicus species is there. So how many individual of curus are found within 10 m radius circle plot at that particular pl point. So that's how we do the counting of the uh trees.

[00:14:06]So the area is easy to calculate using the formula p<unk> r². This matters is less errorrone or slope or uneven ground than rectangular plots. Okay. So uh used to assess tree density, canopy cover and vegetation structure. Easy to lay out with a measuring rope or pre uh marked cords. Reduce corner area by seen in square plots. Common in forest in inven inventories and wildlife uh habitat studies. Circular plot data collected and analysis. U uh uh record uh in a typical circle plot uh in a uh diode diodar forest you might record 15 trees of different species. Each trees uh uh diameter at breast height height and height are measured to calculate biomass and carbon storage. And um additionally noting undergrowth composition helps uh assess habitat suitability for wildlife uh like the Himalayan monal or mier.

[00:15:12]Uh so measure tree height, canopy layers and species identity. Calculate basal area and tree density per hectare. Also notes sign of grazing, logging or fire.

[00:15:23]These are the disturbance sign within the habitat. you have to record useful in carbon stock and uh regeneration studies.

[00:15:31]Quadrate sampling again this is just the change of the um shape of the plot.

[00:15:38]Again it is a plot sampling. Quadrant is square or rectangular plot 1 m²ared to 100 m square used for herbs shrubs and ground insect. The species are counted, measured, and sometime clipped. Allow estimates of cover, frequency, and relative abundance, often repeated across habitat habitat types for uh for uh comparison. Quartrate sampling is essential for studies on ground level vegetation. In alpine meadows of uh Tajas area 1 m into 1 m quadrates are used to record medicinal herbs like seria costa 10 quadrate across the midos can provide average species richness ground cover and help detect early sign of overg grazing. So uh quadrate uh parameters for example for instance in a disturbed grassland near agriculture field quadrates might show dominance of uh parthnium uh hysteria forest and invasive species. We know parthnium is invasive species. Uh so data from these quadrates can guide management strategies like selective weeds fencing or native species uh uh plantation integration with soil and microclimate data at ecological context. So we can do uh this kind of uh this techniques we can use for different purposes.

[00:17:09]So a quadrate method uh is species richness and abundance per unit area frequency how often a species appear across quadrates. Related density and coverage we can calculate and disturbance indicator like trampling uh litter soil pH temperature and moisture often recorded within that plot.

[00:17:29]Quadrates parameter and example. Species richness and abundance per unit area.

[00:17:34]Frequency how often a species appear across quadrate. Relative density and coverage and disturbance indicator like trampling uh trampling uh litter. Soil pH, temperature and mush often recorded.

[00:17:48]For instance, in a disturbed glass near agriculture field quadrant might show dominance of a particular invasive species that we can record. selecting the right technique. Now it is up to you if you are talking about the uh line transits. So line transs are not very successful in Himalayan region because if you're doing the monitoring by the time line transit is a straight line passing through different habitat. So conclusion and conservation relevance plot sampling is fundamental for ecological research. supports conservation planning, habitat mapping and species monitoring. Data can inform uh forest policy impact assessment and reing efforts. Integrates well with uh techniques like GIS and camera trap vital forest research and uh citizen science initiative.

[00:18:43]So basically plot sampling provides baseline data crucial for biodiversity conservation whether assessing species richness in hungul habitat uh h or monitoring uh restoration in x mining areas. These techniques are invaluable.

[00:19:01]They are aligned well with modern tool like drones and GIS. Creating powerful database data sets engaging local communities and students in such survey build conservation capacity and awareness.

[00:19:17]So uh this is the uh plot sampling is good for the area where uh intensive study you have to do because you have to stratified the area accordingly and or habitat wise or beatwise management unit wise you have to stratify and then you have to lay the plots. These plots can be temporary for longtime monitoring.

[00:19:44]These plots can be permanent. You have to mark the plot. So uh plot samplings takes time because you have to lay the plots uh for intensive studies and after this we'll be studying the plot listing techniques. So this is all about the uh plot techniques and these are the references uh like BB CJ burgers hill uh this book is actually very important to study the bird uh census techniques but there are other southerntherland is the best best uh um m best book to to to to study the sampling techniques. So thank you very much we'll be meeting in our next class.

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