Add corresponding MODIS LAI band to Sentinel-1 log(VH/VV) data in Google Earth Engine

I am trying to determine the correlation between Sentinel-1 log(VH/VV) data and the corresponding MODIS 4 day LAI product. For the first step, I am trying to add the corresponding LAI data as a band to the Sentinel-1 log(VH/VV) collection. My code so far is provided. I am getting the errors shown below.

var point = ee.Geometry.Point(-96.47664, 41.16506);
var proj = ee.Projection('EPSG:32614');

var reproject = function(image) {
  var reprojected = image.reproject(proj, null, 1000);
  return reprojected};

var LogRatio = function(img) {
  var logVV = img.select('VV');
  var logVH = img.select('VH');
  var logratio = logVH.subtract(logVV).rename('logVH/VV');
  var logratio_float = logratio.toFloat();
  return img.addBands(logratio_float)};

var S1 = ee.ImageCollection('COPERNICUS/S1_GRD');
var S1_TempFilt = S1.filterDate('2017-01-01', '2020-02-20');
var S1_TempFilt_Resamp = S1_TempFilt.map(reproject);
var S1_TempSpatFilt_Resamp = S1_TempFilt_Resamp.filterBounds(point);
var S1_TempSpaceFiltResamp_W_LogCR = S1_TempSpatFilt_Resamp.map(LogRatio);
var S1_Log_VH_VV = S1_TempSpaceFiltResamp_W_LogCR.select('logVH/VV');
print('S1_Log_VH_VV',S1_Log_VH_VV);

var MODIS = ee.ImageCollection('MODIS/006/MCD15A3H');
var MODIS_TempFilt = MODIS.filterDate('2017-01-01', '2020-02-20');
var MODIS_TempFilt_Resamp =  MODIS_TempFilt.map(reproject);
var MODIS_TempSpatFilt_Resamp = MODIS_TempFilt_Resamp.filterBounds(point);
var M_LAI = MODIS_TempSpatFilt_Resamp.select('Lai');
print(M_LAI);

var Find_MODIS_LAI = function(image2) {
  var S1date = ee.Date(image2.get('system:time_start'));
  var LAI_start_date_min = S1date.advance(-1,"day");
  var LAI_start_date_max = S1date.advance(2,"day");
  var MODIS_LAI = M_LAI.filterDate(LAI_start_date_min, LAI_start_date_max);
  return MODIS_LAI};

var MODIS_LAI = S1_Log_VH_VV.map(Find_MODIS_LAI);
print('MODIS_LAI', MODIS_LAI);

var LAI_Band = MODIS_LAI.select('Lai');
print('LAI_Band',LAI_Band);
var LogCR_LAI = S1_Log_VH_VV.addBands(LAI_Band);

Error:

ImageCollection (Error)
Error in map(ID=S1A_IW_GRDH_1SDV_20170108T002112_20170108T002137_014733_017FB8_9BC3):
Image.select, argument 'input': Invalid type. Expected: Image<unknown bands>. Actual: ImageCollection.

S1_Log_VH_VV.addBands is not a function